diff --git a/src/algorithm.h b/src/algorithm.h
index 2a7f236b..3f2b0575 100644
--- a/src/algorithm.h
+++ b/src/algorithm.h
@@ -418,6 +418,52 @@ namespace etl
     return o_begin;
   }
 
+  //***************************************************************************
+  /// binary_find
+  ///\ingroup algorithm
+  /// Does a binary search and returns an iterator to the value or end if not found.
+  //***************************************************************************
+  template <typename TIterator,
+            typename TValue>
+    TIterator binary_find(TIterator     begin,
+                          TIterator     end,
+                          const TValue& value)
+  {
+    TIterator it = std::lower_bound(begin, end, value);
+
+    if ((it == end) || (*it != value))
+    {
+      it = end;
+    }
+
+    return it;
+  }
+
+  //***************************************************************************
+  /// binary_find
+  ///\ingroup algorithm
+  /// Does a binary search and returns an iterator to the value or end if not found.
+  //***************************************************************************
+  template <typename TIterator,
+            typename TValue,
+            typename TBinaryPredicate,
+            typename TBinaryEquality>
+    TIterator binary_find(TIterator        begin,
+                          TIterator        end,
+                          const TValue&    value,
+                          TBinaryPredicate predicate,
+                          TBinaryEquality  equality)
+  {
+    TIterator it = std::lower_bound(begin, end, value, predicate);
+
+    if ((it == end) || !equality(*it, value))
+    {
+      it = end;
+    }
+
+    return it;
+  }
+
   //***************************************************************************
   /// find_if_not
   ///\ingroup algorithm
diff --git a/src/alignment.h b/src/alignment.h
index 18f20aea..578ae40c 100644
--- a/src/alignment.h
+++ b/src/alignment.h
@@ -113,7 +113,7 @@ namespace etl
       template <typename T>
       operator T& ()
       {
-        STATIC_ASSERT(ALIGNMENT % etl::alignment_of<T>::value == 0, "Incompatible alignment");
+        STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((ALIGNMENT % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
         return reinterpret_cast<T&>(*data);
       }
 
@@ -121,7 +121,7 @@ namespace etl
       template <typename T>
       operator const T& () const
       {
-        STATIC_ASSERT(ALIGNMENT % etl::alignment_of<T>::value == 0, "Incompatible alignment");
+        STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((ALIGNMENT % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
         return reinterpret_cast<const T&>(*data);
       }
 
@@ -129,7 +129,7 @@ namespace etl
       template <typename T>
       operator T* ()
       {
-        STATIC_ASSERT(ALIGNMENT % etl::alignment_of<T>::value == 0, "Incompatible alignment");
+        STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((ALIGNMENT % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
         return reinterpret_cast<T*>(data);
       }
 
@@ -137,7 +137,7 @@ namespace etl
       template <typename T>
       operator const T* () const
       {
-        STATIC_ASSERT(ALIGNMENT % etl::alignment_of<T>::value == 0, "Incompatible alignment");
+        STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((ALIGNMENT % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
         return reinterpret_cast<const T*>(data);
       }
 
@@ -145,7 +145,7 @@ namespace etl
       template <typename T>
       T& get_reference()
       {
-        STATIC_ASSERT(ALIGNMENT % etl::alignment_of<T>::value == 0, "Incompatible alignment");
+        STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((ALIGNMENT % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
         return reinterpret_cast<T&>(*data);
       }
 
@@ -153,7 +153,7 @@ namespace etl
       template <typename T>
       const T& get_reference() const
       {
-        STATIC_ASSERT(ALIGNMENT % etl::alignment_of<T>::value == 0, "Incompatible alignment");
+        STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((ALIGNMENT % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
         return reinterpret_cast<const T&>(*data);
       }
 
@@ -161,7 +161,7 @@ namespace etl
       template <typename T>
       T* get_address()
       {
-        STATIC_ASSERT(ALIGNMENT % etl::alignment_of<T>::value == 0, "Incompatible alignment");
+        STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((ALIGNMENT % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
         return reinterpret_cast<T*>(data);
       }
 
@@ -169,7 +169,7 @@ namespace etl
       template <typename T>
       const T* get_address() const
       {
-        STATIC_ASSERT(ALIGNMENT % etl::alignment_of<T>::value == 0, "Incompatible alignment");
+        STATIC_ASSERT((etl::is_same<T*, void*>:: value || ((ALIGNMENT % etl::alignment_of<T>::value) == 0)), "Incompatible alignment");
         return reinterpret_cast<const T*>(data);
       }
 
diff --git a/src/file_error_numbers.txt b/src/file_error_numbers.txt
index 5cea1e44..24ffa829 100644
--- a/src/file_error_numbers.txt
+++ b/src/file_error_numbers.txt
@@ -34,4 +34,6 @@
 34 fsm
 35 message_router
 36 scheduler
-37 task
\ No newline at end of file
+37 task
+38 message
+39 message_bus
diff --git a/src/fsm.h b/src/fsm.h
new file mode 100644
index 00000000..7c31acfc
--- /dev/null
+++ b/src/fsm.h
@@ -0,0 +1,1204 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#if 0
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+#endif
+
+//***************************************************************************
+// This file has been auto generated. Do not edit this file.
+//***************************************************************************
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -ofsm.h -DHandlers=<n> fsm_generator.h
+// Where <n> is the number of messages to support.
+//
+// e.g.
+// To generate handlers for up to 16 events...
+// python -m cogapp -d -e -ofsm.h -DHandlers=16 fsm_generator.h
+//
+// See generate.bat
+//***************************************************************************
+
+#ifndef __ETL_FSM__
+#define __ETL_FSM__
+
+#include <stdint.h>
+
+#include "array.h"
+#include "nullptr.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "user_type.h"
+#include "message_router.h"
+#include "integral_limits.h"
+#include "largest.h"
+
+#undef ETL_FILE
+#define ETL_FILE "34"
+
+#ifdef ETL_COMPILER_MICROSOFT
+#undef max
+#endif
+
+namespace etl
+{
+  class fsm;
+
+  /// Allow alternative type for state id.
+#if !defined(ETL_FSM_STATE_ID_TYPE)
+    typedef uint_least8_t fsm_state_id_t;
+#else
+    typedef ETL_FSM_STATE_ID_TYPE fsm_state_id_t;
+#endif
+
+  // For internal FSM use.
+  typedef typename etl::larger_type<etl::message_id_t>::type fsm_internal_id_t;
+
+  //***************************************************************************
+  /// Base exception class for FSM.
+  //***************************************************************************
+  class fsm_exception : public etl::exception
+  {
+  public:
+
+    fsm_exception(string_type what, string_type file_name, numeric_type line_number)
+      : etl::exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for null state pointer.
+  //***************************************************************************
+  class fsm_null_state_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_null_state_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:null state", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for invalid state id.
+  //***************************************************************************
+  class fsm_state_id_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_state_id_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:state id", ETL_FILE"B"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for incompatible state list.
+  //***************************************************************************
+  class fsm_state_list_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_state_list_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:state list", ETL_FILE"C"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Interface class for FSM states.
+  //***************************************************************************
+  class ifsm_state
+  {
+  public:
+
+    /// Allows ifsm_state functions to be private.
+    friend class fsm_helper;
+
+    //*******************************************
+    /// Gets the id for this state.
+    //*******************************************
+    etl::fsm_state_id_t get_state_id() const
+    {
+      return state_id;
+    }
+
+  protected:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    ifsm_state(etl::fsm_state_id_t state_id_)
+      : state_id(state_id_),
+        p_context(nullptr)
+    {
+    }
+
+    //*******************************************
+    inline etl::fsm& get_fsm_context() const
+    {
+      return *p_context;
+    }
+
+  private:
+
+    virtual fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message) = 0;
+
+    virtual fsm_state_id_t on_enter_state() { return state_id; } // By default, do nothing.
+    virtual void on_exit_state() {}  // By default, do nothing.
+
+    //*******************************************
+    void set_fsm_context(etl::fsm& context)
+    {
+      p_context = &context;
+    }
+
+    // The state id.
+    const etl::fsm_state_id_t state_id;
+
+    // A pointer to the FSM context.
+    etl::fsm* p_context;
+
+    // Disabled.
+    ifsm_state(const ifsm_state&);
+    ifsm_state& operator =(const ifsm_state&);
+  };
+
+  //***************************************************************************
+  /// Helper class for FSM.
+  /// Allows ifsm_state functions to be private.
+  //***************************************************************************
+  class fsm_helper
+  {
+  public:
+
+    //*******************************************
+    inline void set_fsm_context(etl::ifsm_state& state,
+                                etl::fsm&        context)
+    {
+      state.set_fsm_context(context);
+    }
+
+    //*******************************************
+    inline fsm_state_id_t process_event(etl::ifsm_state&      state,
+                                        etl::imessage_router& source,
+                                        const etl::imessage&  message)
+    {
+      return state.process_event(source, message);
+    }
+
+    //*******************************************
+    inline fsm_state_id_t on_enter_state(etl::ifsm_state& state)
+    {
+      return state.on_enter_state();
+    }
+
+    //*******************************************
+    inline void on_exit_state(etl::ifsm_state& state)
+    {
+      state.on_exit_state();
+    }
+  };
+
+  //***************************************************************************
+  /// The FSM class.
+  //***************************************************************************
+  class fsm : public etl::imessage_router, protected etl::fsm_helper
+  {
+  public:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    fsm(etl::message_router_id_t id)
+      : imessage_router(id),
+        p_state(nullptr)
+    {
+    }
+
+    //*******************************************
+    /// Set the states for the FSM
+    //*******************************************
+    template <typename TSize>
+    void set_states(etl::ifsm_state** p_states, TSize size)
+    {
+      state_list       = p_states;
+      number_of_states = etl::fsm_state_id_t(size);
+
+      ETL_ASSERT((number_of_states > 0), ETL_ERROR(etl::fsm_state_list_exception));
+
+      for (etl::fsm_state_id_t i = 0; i < size; ++i)
+      {
+        ETL_ASSERT((state_list[i] != nullptr), ETL_ERROR(etl::fsm_null_state_exception));
+        fsm_helper::set_fsm_context(*state_list[i], *this);
+      }
+    }
+
+    //*******************************************
+    /// Starts the FSM.
+    /// Can only be called once.
+    /// Subsequent calls will do nothing.
+    //*******************************************
+    void start()
+    {
+      // Can only be started once.
+      if (p_state == nullptr)
+      {
+        p_state = state_list[0];
+        ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+
+        fsm_helper::on_enter_state(*p_state);
+      }
+    }
+
+    //*******************************************
+    /// Top level message handler for the FSM.
+    //*******************************************
+    void receive(const etl::imessage& message)
+    {
+      etl::null_message_router nmr;
+      receive(nmr, message);
+    }
+
+    //*******************************************
+    /// Top level message handler for the FSM.
+    //*******************************************
+    void receive(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t next_state_id = fsm_helper::process_event(*p_state, source, message);
+      ETL_ASSERT(next_state_id < number_of_states, ETL_ERROR(etl::fsm_state_id_exception));
+
+      etl::ifsm_state* p_next_state = state_list[next_state_id];
+
+      // Have we changed state?
+      if (p_next_state != p_state)
+      {
+        do
+        {
+          p_state = p_next_state;
+          fsm_helper::on_exit_state(*p_state);
+
+          next_state_id = fsm_helper::on_enter_state(*p_state);
+          ETL_ASSERT(next_state_id < number_of_states, ETL_ERROR(etl::fsm_state_id_exception));
+
+          p_next_state = state_list[next_state_id];
+
+        } while (p_next_state != p_state); // Have we changed state again?
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //*******************************************
+    /// Does this FSM accept the message id?
+    /// Yes, it accepts everything!
+    //*******************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      return true;
+    }
+
+    //*******************************************
+    /// Gets the current state id.
+    //*******************************************
+    etl::fsm_state_id_t get_state_id() const
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return p_state->get_state_id();
+    }
+
+    //*******************************************
+    /// Gets a reference to the current state interface.
+    //*******************************************
+    ifsm_state& get_state()
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return *p_state;
+    }
+
+    //*******************************************
+    /// Gets a const reference to the current state interface.
+    //*******************************************
+    const ifsm_state& get_state() const
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return *p_state;
+    }
+
+    //*******************************************
+    /// Checks if the FSM has been started.
+    //*******************************************
+    bool is_started() const
+    {
+      return p_state != nullptr;
+    }
+
+    //*******************************************
+    /// Reset the FSM to pre-started state.
+    //*******************************************
+    void reset()
+    {
+      p_state = nullptr;
+    }
+
+  private:
+
+    etl::ifsm_state*    p_state;          ///< A pointer to the current state.
+    etl::ifsm_state**   state_list;       ///< The list of added states.
+    etl::fsm_state_id_t number_of_states; ///< The number of states.
+  };
+
+
+  //***************************************************************************
+  // The definition for all 16 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1 = void, typename T2 = void, typename T3 = void, typename T4 = void, 
+            typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, 
+            typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void, 
+            typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
+  class fsm_state : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        case T13::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T13&>(message)); break;
+        case T14::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T14&>(message)); break;
+        case T15::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T15&>(message)); break;
+        case T16::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T16&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 15 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13, typename T14, typename T15>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        case T13::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T13&>(message)); break;
+        case T14::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T14&>(message)); break;
+        case T15::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T15&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 14 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13, typename T14>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        case T13::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T13&>(message)); break;
+        case T14::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T14&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 13 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        case T13::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T13&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 12 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 11 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 10 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 9 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 8 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 7 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 6 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, T6, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 5 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, T5, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 4 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, T4, void, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 3 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, T3, void, void, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 2 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, T2, void, void, void, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 1 message type.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1>
+  class fsm_state<TContext, TDerived, STATE_ID_, T1, void, void, void, void, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::message_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        default: new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 0 message types.
+  //***************************************************************************
+  template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_>
+  class fsm_state<TContext, TDerived, STATE_ID_, void, void, void, void, void, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    inline TContext& get_fsm_context() const
+    {
+      return static_cast<TContext&>(ifsm_state::get_fsm_context());
+    }
+  private:
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      return static_cast<TDerived*>(this)->on_event_unknown(source, message);
+    }
+  };
+}
+
+#undef ETL_FILE
+
+#ifdef ETL_COMPILER_MICROSOFT
+#define max(a,b) (((a) > (b)) ? (a) : (b))
+#endif
+
+#endif
diff --git a/src/fsm_generator.h b/src/fsm_generator.h
new file mode 100644
index 00000000..0072dbd0
--- /dev/null
+++ b/src/fsm_generator.h
@@ -0,0 +1,569 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+/*[[[cog
+import cog
+cog.outl("#if 0")
+]]]*/
+/*[[[end]]]*/
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+/*[[[cog
+import cog
+cog.outl("#endif")
+]]]*/
+/*[[[end]]]*/
+
+/*[[[cog
+import cog
+cog.outl("//***************************************************************************")
+cog.outl("// This file has been auto generated. Do not edit this file.")
+cog.outl("//***************************************************************************")
+]]]*/
+/*[[[end]]]*/
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -ofsm.h -DHandlers=<n> fsm_generator.h
+// Where <n> is the number of messages to support.
+//
+// e.g.
+// To generate handlers for up to 16 events...
+// python -m cogapp -d -e -ofsm.h -DHandlers=16 fsm_generator.h
+//
+// See generate.bat
+//***************************************************************************
+
+#ifndef __ETL_FSM__
+#define __ETL_FSM__
+
+#include <stdint.h>
+
+#include "array.h"
+#include "nullptr.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "user_type.h"
+#include "message_router.h"
+#include "integral_limits.h"
+#include "largest.h"
+
+#undef ETL_FILE
+#define ETL_FILE "34"
+
+#ifdef ETL_COMPILER_MICROSOFT
+#undef max
+#endif
+
+namespace etl
+{
+  class fsm;
+
+  /// Allow alternative type for state id.
+#if !defined(ETL_FSM_STATE_ID_TYPE)
+    typedef uint_least8_t fsm_state_id_t;
+#else
+    typedef ETL_FSM_STATE_ID_TYPE fsm_state_id_t;
+#endif
+
+  // For internal FSM use.
+  typedef typename etl::larger_type<etl::message_id_t>::type fsm_internal_id_t;
+
+  //***************************************************************************
+  /// Base exception class for FSM.
+  //***************************************************************************
+  class fsm_exception : public etl::exception
+  {
+  public:
+
+    fsm_exception(string_type what, string_type file_name, numeric_type line_number)
+      : etl::exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for null state pointer.
+  //***************************************************************************
+  class fsm_null_state_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_null_state_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:null state", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for invalid state id.
+  //***************************************************************************
+  class fsm_state_id_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_state_id_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:state id", ETL_FILE"B"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for incompatible state list.
+  //***************************************************************************
+  class fsm_state_list_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_state_list_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:state list", ETL_FILE"C"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Interface class for FSM states.
+  //***************************************************************************
+  class ifsm_state
+  {
+  public:
+
+    /// Allows ifsm_state functions to be private.
+    friend class fsm_helper;
+
+    //*******************************************
+    /// Gets the id for this state.
+    //*******************************************
+    etl::fsm_state_id_t get_state_id() const
+    {
+      return state_id;
+    }
+
+  protected:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    ifsm_state(etl::fsm_state_id_t state_id_)
+      : state_id(state_id_),
+        p_context(nullptr)
+    {
+    }
+
+    //*******************************************
+    inline etl::fsm& get_fsm_context() const
+    {
+      return *p_context;
+    }
+
+  private:
+
+    virtual fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message) = 0;
+
+    virtual fsm_state_id_t on_enter_state() { return state_id; } // By default, do nothing.
+    virtual void on_exit_state() {}  // By default, do nothing.
+
+    //*******************************************
+    void set_fsm_context(etl::fsm& context)
+    {
+      p_context = &context;
+    }
+
+    // The state id.
+    const etl::fsm_state_id_t state_id;
+
+    // A pointer to the FSM context.
+    etl::fsm* p_context;
+
+    // Disabled.
+    ifsm_state(const ifsm_state&);
+    ifsm_state& operator =(const ifsm_state&);
+  };
+
+  //***************************************************************************
+  /// Helper class for FSM.
+  /// Allows ifsm_state functions to be private.
+  //***************************************************************************
+  class fsm_helper
+  {
+  public:
+
+    //*******************************************
+    inline void set_fsm_context(etl::ifsm_state& state,
+                                etl::fsm&        context)
+    {
+      state.set_fsm_context(context);
+    }
+
+    //*******************************************
+    inline fsm_state_id_t process_event(etl::ifsm_state&      state,
+                                        etl::imessage_router& source,
+                                        const etl::imessage&  message)
+    {
+      return state.process_event(source, message);
+    }
+
+    //*******************************************
+    inline fsm_state_id_t on_enter_state(etl::ifsm_state& state)
+    {
+      return state.on_enter_state();
+    }
+
+    //*******************************************
+    inline void on_exit_state(etl::ifsm_state& state)
+    {
+      state.on_exit_state();
+    }
+  };
+
+  //***************************************************************************
+  /// The FSM class.
+  //***************************************************************************
+  class fsm : public etl::imessage_router, protected etl::fsm_helper
+  {
+  public:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    fsm(etl::message_router_id_t id)
+      : imessage_router(id),
+        p_state(nullptr)
+    {
+    }
+
+    //*******************************************
+    /// Set the states for the FSM
+    //*******************************************
+    template <typename TSize>
+    void set_states(etl::ifsm_state** p_states, TSize size)
+    {
+      state_list       = p_states;
+      number_of_states = etl::fsm_state_id_t(size);
+
+      ETL_ASSERT((number_of_states > 0), ETL_ERROR(etl::fsm_state_list_exception));
+
+      for (etl::fsm_state_id_t i = 0; i < size; ++i)
+      {
+        ETL_ASSERT((state_list[i] != nullptr), ETL_ERROR(etl::fsm_null_state_exception));
+        fsm_helper::set_fsm_context(*state_list[i], *this);
+      }
+    }
+
+    //*******************************************
+    /// Starts the FSM.
+    /// Can only be called once.
+    /// Subsequent calls will do nothing.
+    //*******************************************
+    void start()
+    {
+      // Can only be started once.
+      if (p_state == nullptr)
+      {
+        p_state = state_list[0];
+        ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+
+        fsm_helper::on_enter_state(*p_state);
+      }
+    }
+
+    //*******************************************
+    /// Top level message handler for the FSM.
+    //*******************************************
+    void receive(const etl::imessage& message)
+    {
+      etl::null_message_router nmr;
+      receive(nmr, message);
+    }
+
+    //*******************************************
+    /// Top level message handler for the FSM.
+    //*******************************************
+    void receive(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t next_state_id = fsm_helper::process_event(*p_state, source, message);
+      ETL_ASSERT(next_state_id < number_of_states, ETL_ERROR(etl::fsm_state_id_exception));
+
+      etl::ifsm_state* p_next_state = state_list[next_state_id];
+
+      // Have we changed state?
+      if (p_next_state != p_state)
+      {
+        do
+        {
+          p_state = p_next_state;
+          fsm_helper::on_exit_state(*p_state);
+
+          next_state_id = fsm_helper::on_enter_state(*p_state);
+          ETL_ASSERT(next_state_id < number_of_states, ETL_ERROR(etl::fsm_state_id_exception));
+
+          p_next_state = state_list[next_state_id];
+
+        } while (p_next_state != p_state); // Have we changed state again?
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //*******************************************
+    /// Does this FSM accept the message id?
+    /// Yes, it accepts everything!
+    //*******************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      return true;
+    }
+
+    //*******************************************
+    /// Gets the current state id.
+    //*******************************************
+    etl::fsm_state_id_t get_state_id() const
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return p_state->get_state_id();
+    }
+
+    //*******************************************
+    /// Gets a reference to the current state interface.
+    //*******************************************
+    ifsm_state& get_state()
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return *p_state;
+    }
+
+    //*******************************************
+    /// Gets a const reference to the current state interface.
+    //*******************************************
+    const ifsm_state& get_state() const
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return *p_state;
+    }
+
+    //*******************************************
+    /// Checks if the FSM has been started.
+    //*******************************************
+    bool is_started() const
+    {
+      return p_state != nullptr;
+    }
+
+    //*******************************************
+    /// Reset the FSM to pre-started state.
+    //*******************************************
+    void reset()
+    {
+      p_state = nullptr;
+    }
+
+  private:
+
+    etl::ifsm_state*    p_state;          ///< A pointer to the current state.
+    etl::ifsm_state**   state_list;       ///< The list of added states.
+    etl::fsm_state_id_t number_of_states; ///< The number of states.
+  };
+
+  /*[[[cog
+  import cog
+  cog.outl("")
+  ################################################
+  # The first definition for all of the events.
+  ################################################
+  cog.outl("//***************************************************************************")
+  cog.outl("// The definition for all %s message types." % Handlers)
+  cog.outl("//***************************************************************************")
+  cog.outl("template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, ")
+  cog.out("          ")
+  for n in range(1, int(Handlers)):
+      cog.out("typename T%s = void, " % n)
+      if n % 4 == 0:
+          cog.outl("")
+          cog.out("          ")
+  cog.outl("typename T%s = void>" % Handlers)
+  cog.outl("class fsm_state : public ifsm_state")
+  cog.outl("{")
+  cog.outl("public:")
+  cog.outl("")
+  cog.outl("  enum")
+  cog.outl("  {")
+  cog.outl("    STATE_ID = STATE_ID_")
+  cog.outl("  };")
+  cog.outl("")
+  cog.outl("  fsm_state()")
+  cog.outl("    : ifsm_state(STATE_ID)")
+  cog.outl("  {")
+  cog.outl("  }")
+  cog.outl("")
+  cog.outl("  inline TContext& get_fsm_context() const")
+  cog.outl("  {")
+  cog.outl("    return static_cast<TContext&>(ifsm_state::get_fsm_context());")
+  cog.outl("  }")
+  cog.outl("")
+  cog.outl("private:")
+  cog.outl("")
+  cog.outl("  etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)")
+  cog.outl("  {")
+  cog.outl("    etl::fsm_state_id_t new_state_id;")
+  cog.outl("    etl::message_id_t event_id = message.get_message_id();")
+  cog.outl("")
+  cog.outl("    switch (event_id)")
+  cog.outl("    {")
+  for n in range(1, int(Handlers) + 1):
+      cog.out("      case T%d::ID:" % n)
+      cog.out(" new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T%d&>(message));" % n)
+      cog.outl(" break;")
+  cog.out("      default:")
+  cog.out(" new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message);")
+  cog.outl(" break;")
+  cog.outl("    }")
+  cog.outl("")
+  cog.outl("    return new_state_id;")
+  cog.outl("  }")
+  cog.outl("};")
+
+  ####################################
+  # All of the other specialisations.
+  ####################################
+  for n in range(int(Handlers) - 1, 0, -1):
+      cog.outl("")
+      cog.outl("//***************************************************************************")
+      if n == 1:
+          cog.outl("// Specialisation for %d message type." % n)
+      else:
+          cog.outl("// Specialisation for %d message types." % n)
+      cog.outl("//***************************************************************************")
+      cog.outl("template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_, ")
+      cog.out("          ")
+      for t in range(1, n):
+          cog.out("typename T%d, " % t)
+          if t % 4 == 0:
+              cog.outl("")
+              cog.out("          ")
+      cog.outl("typename T%d>" % n)
+      cog.out("class fsm_state<TContext, TDerived, STATE_ID_, ")
+      for t in range(1, n + 1):
+          cog.out("T%d, " % t)
+      if t % 16 == 0:
+          cog.outl("")
+          cog.out("               ")
+      for t in range(n + 1, int(Handlers)):
+          cog.out("void, ")
+      if t % 16 == 0:
+          cog.outl("")
+          cog.out("               ")
+      cog.outl("void> : public ifsm_state")
+      cog.outl("{")
+      cog.outl("public:")
+      cog.outl("")
+      cog.outl("  enum")
+      cog.outl("  {")
+      cog.outl("    STATE_ID = STATE_ID_")
+      cog.outl("  };")
+      cog.outl("")
+      cog.outl("  fsm_state()")
+      cog.outl("    : ifsm_state(STATE_ID)")
+      cog.outl("  {")
+      cog.outl("  }")
+      cog.outl("")
+      cog.outl("  inline TContext& get_fsm_context() const")
+      cog.outl("  {")
+      cog.outl("    return static_cast<TContext&>(ifsm_state::get_fsm_context());")
+      cog.outl("  }")
+      cog.outl("private:")
+      cog.outl("")
+      cog.outl("  etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)")
+      cog.outl("  {")
+      cog.outl("    etl::fsm_state_id_t new_state_id;")
+      cog.outl("    etl::message_id_t event_id = message.get_message_id();")
+      cog.outl("")
+      cog.outl("    switch (event_id)")
+      cog.outl("    {")
+      for n in range(1, n + 1):
+          cog.out("      case T%d::ID:" % n)
+          cog.out(" new_state_id = static_cast<TDerived*>(this)->on_event(source, static_cast<const T%d&>(message));" % n)
+          cog.outl(" break;")
+      cog.out("      default:")
+      cog.out(" new_state_id = static_cast<TDerived*>(this)->on_event_unknown(source, message);")
+      cog.outl(" break;")
+      cog.outl("    }")
+      cog.outl("")
+      cog.outl("    return new_state_id;")
+      cog.outl("  }")
+      cog.outl("};")
+  ####################################
+  # Specialisation for zero messages.
+  ####################################
+  cog.outl("")
+  cog.outl("//***************************************************************************")
+  cog.outl("// Specialisation for 0 message types.")
+  cog.outl("//***************************************************************************")
+  cog.outl("template <typename TContext, typename TDerived, const etl::fsm_state_id_t STATE_ID_>")
+  cog.out("class fsm_state<TContext, TDerived, STATE_ID_, ")
+  for t in range(1, int(Handlers)):
+      cog.out("void, ")
+  if t % 16 == 0:
+      cog.outl("")
+      cog.out("               ")
+  cog.outl("void> : public ifsm_state")
+  cog.outl("{")
+  cog.outl("public:")
+  cog.outl("")
+  cog.outl("  enum")
+  cog.outl("  {")
+  cog.outl("    STATE_ID = STATE_ID_")
+  cog.outl("  };")
+  cog.outl("")
+  cog.outl("  fsm_state()")
+  cog.outl("    : ifsm_state(STATE_ID)")
+  cog.outl("  {")
+  cog.outl("  }")
+  cog.outl("")
+  cog.outl("  inline TContext& get_fsm_context() const")
+  cog.outl("  {")
+  cog.outl("    return static_cast<TContext&>(ifsm_state::get_fsm_context());")
+  cog.outl("  }")
+  cog.outl("private:")
+  cog.outl("")
+  cog.outl("  etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)")
+  cog.outl("  {")
+  cog.outl("    return static_cast<TDerived*>(this)->on_event_unknown(source, message);")
+  cog.outl("  }")
+  cog.outl("};")
+  ]]]*/
+  /*[[[end]]]*/
+}
+
+#undef ETL_FILE
+
+#ifdef ETL_COMPILER_MICROSOFT
+#define max(a,b) (((a) > (b)) ? (a) : (b))
+#endif
+
+#endif
diff --git a/src/generate.bat b/src/generate.bat
new file mode 100644
index 00000000..8902cbde
--- /dev/null
+++ b/src/generate.bat
@@ -0,0 +1,5 @@
+python -m cogapp -d -e -ofsm.h -DHandlers=16 fsm_generator.h 
+python -m cogapp -d -e -omessage_router.h -DHandlers=16 message_router_generator.h 
+python -m cogapp -d -e -olargest.h -DNTypes=16 largest_generator.h
+python -m cogapp -d -e -osmallest.h -DNTypes=16 smallest_generator.h
+python -m cogapp -d -e -otype_traits.h -DIsOneOf=16 type_traits_generator.h
\ No newline at end of file
diff --git a/src/generate_fsm.bat b/src/generate_fsm.bat
new file mode 100644
index 00000000..07c25ece
--- /dev/null
+++ b/src/generate_fsm.bat
@@ -0,0 +1 @@
+python -m cogapp -d -e -ofsm.h -DHandlers=16 fsm_generator.h 
diff --git a/src/generate_message_router.bat b/src/generate_message_router.bat
new file mode 100644
index 00000000..b30597fb
--- /dev/null
+++ b/src/generate_message_router.bat
@@ -0,0 +1 @@
+python -m cogapp -d -e -omessage_router.h -DHandlers=16 message_router_generator.h 
diff --git a/src/largest.h b/src/largest.h
index 311adc0b..a3334c99 100644
--- a/src/largest.h
+++ b/src/largest.h
@@ -5,7 +5,7 @@ The MIT License(MIT)
 
 Embedded Template Library.
 https://github.com/ETLCPP/etl
-http://www.etlcpp.com
+https://www.etlcpp.com
 
 Copyright(c) 2014 jwellbelove
 
@@ -28,6 +28,28 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 ******************************************************************************/
 
+#if 0
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+#endif
+
+//***************************************************************************
+// This file has been auto generated. Do not edit this file.
+//***************************************************************************
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -olargest.h -DNTypes=<n> largest_generator.h
+// Where <n> is the number of types to support.
+//
+// e.g.
+// To generate handlers for up to 16 types...
+// python -m cogapp -d -e -olargest.h -DNTypes=16 largest_generator.h
+//
+// See generate.bat
+//***************************************************************************
+
 #ifndef __ETL_LARGEST__
 #define __ETL_LARGEST__
 
@@ -47,9 +69,9 @@ namespace etl
   /// Defines 'size' which is the size of the largest parameter.
   ///\ingroup largest
   //***************************************************************************
-  template <typename T1,         typename T2  = void, typename T3  = void, typename T4  = void,
-            typename T5  = void, typename T6  = void, typename T7  = void, typename T8  = void,
-            typename T9  = void, typename T10 = void, typename T11 = void, typename T12 = void,
+  template <typename T1, typename T2 = void, typename T3 = void, typename T4 = void, 
+            typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, 
+            typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void, 
             typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
   struct largest_type
   {
@@ -78,14 +100,14 @@ namespace etl
   public:
 
     // Define 'largest_other' as 'largest_type' with all but the first parameter. 
-    typedef typename largest_type<T2,  T3,  T4,  T5,  T6,  T7,  T8,  T9,  T10, T11, T12, T13, T14, T15, T16>::type largest_other;
+    typedef typename largest_type<T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16>::type largest_other;
 
     // Set 'type' to be the largest of the first parameter and any of the others.
     // This is recursive.
     typedef typename choose_type<(sizeof(T1) > sizeof(largest_other)), // Boolean
-                                 T1,                                   // TrueType
-                                 largest_other>                        // FalseType
-                                 ::type type;                          // The largest type of the two.
+                                  T1,                                  // TrueType
+                                  largest_other>                       // FalseType
+                                  ::type type;                         // The largest type of the two.
 
     // The size of the largest type.
     enum
@@ -98,10 +120,8 @@ namespace etl
   // Specialisation for one template parameter.
   //***************************************************************************
   template <typename T1>
-  struct largest_type<T1,   void, void, void,
-                      void, void, void, void, 
-                      void, void, void, void, 
-                      void, void, void, void>
+  struct largest_type<T1,   void, void, void, void, void, void, void, 
+                      void, void, void, void, void, void, void, void>
   {
     typedef T1 type;
 
@@ -117,12 +137,14 @@ namespace etl
   /// Defines <b>value</b> which is the largest alignment of all the parameters.
   ///\ingroup largest
   //***************************************************************************
-  template <typename T1,         typename T2  = void, typename T3  = void, typename T4  = void,
-            typename T5  = void, typename T6  = void, typename T7  = void, typename T8  = void,
-            typename T9  = void, typename T10 = void, typename T11 = void, typename T12 = void,
-            typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
+  template <typename T1, typename T2 = void, typename T3 = void, typename T4 = void, 
+              typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, 
+              typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void, 
+              typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
   struct largest_alignment
   {
+  private:
+
     // Determine the largest size.
     template <const size_t size1, const size_t size2>
     struct max_size
@@ -136,22 +158,22 @@ namespace etl
     // All of the alignments.
     enum
     {
-      t1 = alignment_of<T1>::value,
-      t2 = alignment_of<T2>::value,
-      t3 = alignment_of<T3>::value,
-      t4 = alignment_of<T4>::value,
-      t5 = alignment_of<T5>::value,
-      t6 = alignment_of<T6>::value,
-      t7 = alignment_of<T7>::value,
-      t8 = alignment_of<T8>::value,
-      t9 = alignment_of<T9>::value,
-      t10 = alignment_of<T10>::value,
-      t11 = alignment_of<T11>::value,
-      t12 = alignment_of<T12>::value,
-      t13 = alignment_of<T13>::value,
-      t14 = alignment_of<T14>::value,
-      t15 = alignment_of<T15>::value,
-      t16 = alignment_of<T16>::value
+      t1 = etl::alignment_of<T1>::value,
+      t2 = etl::alignment_of<T2>::value,
+      t3 = etl::alignment_of<T3>::value,
+      t4 = etl::alignment_of<T4>::value,
+      t5 = etl::alignment_of<T5>::value,
+      t6 = etl::alignment_of<T6>::value,
+      t7 = etl::alignment_of<T7>::value,
+      t8 = etl::alignment_of<T8>::value,
+      t9 = etl::alignment_of<T9>::value,
+      t10 = etl::alignment_of<T10>::value,
+      t11 = etl::alignment_of<T11>::value,
+      t12 = etl::alignment_of<T12>::value,
+      t13 = etl::alignment_of<T13>::value,
+      t14 = etl::alignment_of<T14>::value,
+      t15 = etl::alignment_of<T15>::value,
+      t16 = etl::alignment_of<T16>::value
     };
 
   public:
@@ -216,6 +238,27 @@ namespace etl
 
     typedef typename etl::smallest_int_for_bits<etl::integral_limits<T>::bits + 1>::type type;
   };
+
+  //***************************************************************************
+  /// Template to determine the largest type, size and alignment.
+  /// Supports up to 16 types.
+  /// Defines <b>value</b> which is the largest type, size and alignment of all the parameters.
+  ///\ingroup largest
+  //***************************************************************************
+  template <typename T1, typename T2 = void, typename T3 = void, typename T4 = void, 
+            typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, 
+            typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void, 
+            typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
+  struct largest
+  {
+    typedef typename etl::largest_type<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16>::type type;
+
+    enum
+    {
+      size      = etl::largest_type<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16>::size,
+      alignment = etl::largest_alignment<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16>::value
+    };
+  };
 }
 
 #endif
diff --git a/src/largest_generator.h b/src/largest_generator.h
new file mode 100644
index 00000000..27464662
--- /dev/null
+++ b/src/largest_generator.h
@@ -0,0 +1,323 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2014 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+/*[[[cog
+import cog
+cog.outl("#if 0")
+]]]*/
+/*[[[end]]]*/
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+/*[[[cog
+import cog
+cog.outl("#endif")
+]]]*/
+/*[[[end]]]*/
+
+/*[[[cog
+import cog
+cog.outl("//***************************************************************************")
+cog.outl("// This file has been auto generated. Do not edit this file.")
+cog.outl("//***************************************************************************")
+]]]*/
+/*[[[end]]]*/
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -olargest.h -DNTypes=<n> largest_generator.h
+// Where <n> is the number of types to support.
+//
+// e.g.
+// To generate handlers for up to 16 types...
+// python -m cogapp -d -e -olargest.h -DNTypes=16 largest_generator.h
+//
+// See generate.bat
+//***************************************************************************
+
+#ifndef __ETL_LARGEST__
+#define __ETL_LARGEST__
+
+///\defgroup largest largest
+///\ingroup utilities
+
+#include "type_traits.h"
+#include "smallest.h"
+#include "static_assert.h"
+
+namespace etl 
+{
+  /*[[[cog
+  import cog
+  cog.outl("//***************************************************************************")
+  cog.outl("/// Template to determine the largest type and size.")
+  cog.outl("/// Supports up to %s types." % NTypes)
+  cog.outl("/// Defines 'value_type' which is the type of the largest parameter.")
+  cog.outl("/// Defines 'size' which is the size of the largest parameter.")
+  cog.outl("///\ingroup largest")
+  cog.outl("//***************************************************************************")
+  cog.out("template <typename T1, ")
+  for n in range(2, int(NTypes)):
+      cog.out("typename T%s = void, " % n)
+      if n % 4 == 0:
+          cog.outl("")
+          cog.out("          ")
+  cog.outl("typename T%s = void>" % int(NTypes))
+  cog.outl("struct largest_type")
+  cog.outl("{")
+  cog.outl("private:")
+  cog.outl("")
+  cog.outl("  // Declaration.")
+  cog.outl("  template <const bool Boolean, typename TrueType, typename FalseType>")
+  cog.outl("  struct choose_type;")
+  cog.outl("")
+  cog.outl("  // Specialisation for 'true'.")
+  cog.outl("  // Defines 'type' as 'TrueType'.")
+  cog.outl("  template <typename TrueType, typename FalseType>")
+  cog.outl("  struct choose_type<true, TrueType, FalseType>")
+  cog.outl("  {")
+  cog.outl("    typedef TrueType type;")
+  cog.outl("  };")
+  cog.outl("")
+  cog.outl("  // Specialisation for 'false'. ")
+  cog.outl("  // Defines 'type' as 'FalseType'.")
+  cog.outl("  template <typename TrueType, typename FalseType>")
+  cog.outl("  struct choose_type<false, TrueType, FalseType>")
+  cog.outl("  {")
+  cog.outl("    typedef FalseType type;")
+  cog.outl("  };")
+  cog.outl("")
+  cog.outl("public:")
+  cog.outl("")
+  cog.outl("  // Define 'largest_other' as 'largest_type' with all but the first parameter. ")
+  cog.out("  typedef typename largest_type<")
+  for n in range(2, int(NTypes)):
+      cog.out("T%s, " % n)
+      if n % 16 == 0:
+          cog.outl("")
+          cog.out("                                ")
+  cog.outl("T%s>::type largest_other;" % int(NTypes))
+  cog.outl("")
+  cog.outl("  // Set 'type' to be the largest of the first parameter and any of the others.")
+  cog.outl("  // This is recursive.")
+  cog.outl("  typedef typename choose_type<(sizeof(T1) > sizeof(largest_other)), // Boolean")
+  cog.outl("                                T1,                                  // TrueType")
+  cog.outl("                                largest_other>                       // FalseType")
+  cog.outl("                                ::type type;                         // The largest type of the two.")
+  cog.outl("")
+  cog.outl("  // The size of the largest type.")
+  cog.outl("  enum")
+  cog.outl("  {")
+  cog.outl("    size = sizeof(type)")
+  cog.outl("  };")
+  cog.outl("};")
+  cog.outl("")
+  cog.outl("//***************************************************************************")
+  cog.outl("// Specialisation for one template parameter.")
+  cog.outl("//***************************************************************************")
+  cog.outl("template <typename T1>")
+  cog.out("struct largest_type<T1,   ")
+  for n in range(2, int(NTypes)):
+      cog.out("void, ")
+      if n % 8 == 0:
+          cog.outl("")
+          cog.out("                    ")
+  cog.outl("void>")
+  cog.outl("{")
+  cog.outl("  typedef T1 type;")
+  cog.outl("")
+  cog.outl("  enum")
+  cog.outl("  {")
+  cog.outl("    size = sizeof(type)")
+  cog.outl("  };")
+  cog.outl("};")
+  ]]]*/
+  /*[[[end]]]*/
+
+  /*[[[cog
+  import cog
+  cog.outl("//***************************************************************************")
+  cog.outl("/// Template to determine the largest alignment.")
+  cog.outl("/// Supports up to %s types." % int(NTypes))
+  cog.outl("/// Defines <b>value</b> which is the largest alignment of all the parameters.")
+  cog.outl("///\ingroup largest")
+  cog.outl("//***************************************************************************")
+  cog.out("template <typename T1, ")
+  for n in range(2, int(NTypes)):
+      cog.out("typename T%s = void, " % n)
+      if n % 4 == 0:
+          cog.outl("")
+          cog.out("            ")
+  cog.outl("typename T%s = void>" % NTypes)
+  cog.outl("struct largest_alignment")
+  cog.outl("{")
+  cog.outl("private:")
+  cog.outl("")
+  cog.outl("  // Determine the largest size.")
+  cog.outl("  template <const size_t size1, const size_t size2>")
+  cog.outl("  struct max_size")
+  cog.outl("  {")
+  cog.outl("    enum")
+  cog.outl("    {")
+  cog.outl("      value = (size1 > size2) ? size1 : size2")
+  cog.outl("    };")
+  cog.outl("  };")
+  cog.outl("")
+  cog.outl("  // All of the alignments.")
+  cog.outl("  enum")
+  cog.outl("  {")
+  for n in range(1, int(NTypes)):
+      cog.outl("    t%s = etl::alignment_of<T%s>::value," %(n, n))
+  cog.outl("    t%s = etl::alignment_of<T%s>::value" % (NTypes, NTypes))
+  cog.outl("  };")
+  cog.outl("")
+  cog.outl("public:")
+  cog.outl("")
+  cog.outl("  // The largest of all of them.")
+  cog.outl("  enum")
+  cog.outl("  {")
+  cog.out("    value = ")
+  for n in range(1, int(NTypes)):
+      cog.out("max_size<t%s, " %n)
+      if n % 8 == 0:
+          cog.outl("")
+          cog.out("            ")
+  cog.outl("t%s>" % int(NTypes))
+  cog.out("            ")
+  for n in range(1, int(NTypes) - 1):
+      cog.out("::value>")
+      if n % 8 == 0:
+          cog.outl("")
+          cog.out("            ")
+  cog.outl("::value")
+  cog.outl("  };")
+  cog.outl("};")
+  ]]]*/
+  /*[[[end]]]*/
+
+  //***************************************************************************
+  /// Defines a type that is as larger or larger than the specified type.
+  /// Will return the specified type is there is not a larger type.
+  ///\ingroup largest
+  //***************************************************************************
+  template <typename T>
+  struct larger_int_type
+  {
+    STATIC_ASSERT(etl::is_integral<T>::value, "Must be an integral type");
+
+    typedef typename etl::smallest_int_for_bits<etl::integral_limits<typename etl::make_signed<T>::type>::bits + 1>::type type;
+  };
+
+  //***************************************************************************
+  /// Defines a type that is as larger or larger than the specified type.
+  /// Will return the specified type is there is not a larger type.
+  ///\ingroup largest
+  //***************************************************************************
+  template <typename T>
+  struct larger_uint_type
+  {
+    STATIC_ASSERT(etl::is_integral<T>::value, "Must be an integral type");
+
+    typedef typename etl::smallest_uint_for_bits<etl::integral_limits<typename etl::make_unsigned<T>::type>::bits + 1>::type type;
+  };
+
+  //***************************************************************************
+  /// Defines a type that is as larger or larger than the specified type.
+  /// Will return the specified type is there is not a larger type.
+  /// The returned type will be of the same sign.
+  ///\ingroup largest
+  //***************************************************************************
+  template <typename T, bool IS_SIGNED = etl::is_signed<T>::value>
+  struct larger_type;
+
+  template <typename T>
+  struct larger_type<T, false>
+  {
+    STATIC_ASSERT(etl::is_integral<T>::value, "Must be an integral type");
+
+    typedef typename etl::smallest_uint_for_bits<etl::integral_limits<T>::bits + 1>::type type;
+  };
+
+  template <typename T>
+  struct larger_type<T, true>
+  {
+    STATIC_ASSERT(etl::is_integral<T>::value, "Must be an integral type");
+
+    typedef typename etl::smallest_int_for_bits<etl::integral_limits<T>::bits + 1>::type type;
+  };
+
+  /*[[[cog
+  import cog
+  cog.outl("//***************************************************************************")
+  cog.outl("/// Template to determine the largest type, size and alignment.")
+  cog.outl("/// Supports up to %s types." % NTypes)
+  cog.outl("/// Defines <b>value</b> which is the largest type, size and alignment of all the parameters.")
+  cog.outl("///\ingroup largest")
+  cog.outl("//***************************************************************************")
+  cog.out("template <typename T1, ")
+  for n in range(2, int(NTypes)):
+      cog.out("typename T%s = void, " % n)
+      if n % 4 == 0:
+          cog.outl("")
+          cog.out("          ")
+  cog.outl("typename T%s = void>" % NTypes)
+  cog.outl("struct largest")
+  cog.outl("{")
+  cog.out("  typedef typename etl::largest_type<")
+  for n in range(1, int(NTypes)):
+      cog.out("T%s, " % n)
+      if n % 16 == 0:
+          cog.outl("")
+          cog.out("                                     ")
+  cog.outl("T%s>::type type;" % NTypes)
+  cog.outl("")
+  cog.outl("  enum")
+  cog.outl("  {")
+  cog.out("    size      = etl::largest_type<")
+  for n in range(1, int(NTypes)):
+      cog.out("T%s, " % n)
+      if n % 16 == 0:
+          cog.outl("")
+          cog.out("                                  ")
+  cog.outl("T%s>::size," % NTypes)
+  cog.out("    alignment = etl::largest_alignment<")
+  for n in range(1, int(NTypes)):
+      cog.out("T%s, " % n)
+      if n % 16 == 0:
+          cog.outl("")
+          cog.out("                                       ")
+  cog.outl("T%s>::value" % NTypes)
+  cog.outl("  };")
+  cog.outl("};")
+  ]]]*/
+  /*[[[end]]]*/
+}
+
+#endif
diff --git a/src/memory.h b/src/memory.h
index 947c1124..1920f0b2 100644
--- a/src/memory.h
+++ b/src/memory.h
@@ -662,6 +662,27 @@ namespace etl
 
     return i_begin;
   }
+
+  //*****************************************************************************
+  /// Copy constructs a derived class to an address.
+  ///\tparam T The derived type.
+  ///\ingroup memory
+  //*****************************************************************************
+  template <typename T>
+  struct create_copy
+  {
+    void create_copy_at(void* p)
+    {
+      new (p) T(static_cast<const T&>(*this));
+    }
+
+    template <typename TCounter>
+    void create_copy_at(void* p, TCounter& count)
+    {
+      new (p) T(static_cast<const T&>(*this));
+      ++count;
+    }
+  };
 }
 
 #endif
diff --git a/src/message.h b/src/message.h
new file mode 100644
index 00000000..d422e7b5
--- /dev/null
+++ b/src/message.h
@@ -0,0 +1,96 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_MESSAGE__
+#define __ETL_MESSAGE__
+
+#include <stdint.h>
+
+#include "error_handler.h"
+#include "exception.h"
+#include "message_types.h"
+
+#undef ETL_FILE
+#define ETL_FILE "38"
+
+namespace etl
+{
+  //***************************************************************************
+  class message_exception : public etl::exception
+  {
+  public:
+
+    message_exception(string_type what, string_type file_name, numeric_type line_number)
+      : exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  class unhandled_message_exception : public etl::message_exception
+  {
+  public:
+
+    unhandled_message_exception(string_type file_name, numeric_type line_number)
+      : message_exception(ETL_ERROR_TEXT("message:unknown", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  class imessage
+  {
+  public:
+
+    //********************************************
+    virtual ~imessage() {}
+    virtual etl::message_id_t get_message_id() const = 0;
+  };
+
+  //***************************************************************************
+  template <const etl::message_id_t ID_>
+  class message : public imessage
+  {
+  public:
+
+    enum
+    {
+      ID = ID_
+    };
+
+    //********************************************
+    etl::message_id_t get_message_id() const
+    {
+      return ID;
+    }
+  };
+}
+
+#undef ETL_FILE
+
+#endif
diff --git a/src/message_bus.h b/src/message_bus.h
new file mode 100644
index 00000000..ef8c811b
--- /dev/null
+++ b/src/message_bus.h
@@ -0,0 +1,389 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_MESSAGE_BUS_
+#define __ETL_MESSAGE_BUS_
+
+#include <stdint.h>
+#include <algorithm>
+
+#include "algorithm.h"
+#include "vector.h"
+#include "nullptr.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "message_types.h"
+#include "message.h"
+#include "message_router.h"
+
+#undef ETL_FILE
+#define ETL_FILE "39"
+
+namespace etl
+{
+  //***************************************************************************
+  /// Base exception class for message bus
+  //***************************************************************************
+  class message_bus_exception : public etl::exception
+  {
+  public:
+
+    message_bus_exception(string_type what, string_type file_name, numeric_type line_number)
+      : etl::exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Too many subscribers.
+  //***************************************************************************
+  class message_bus_too_many_subscribers : public etl::message_bus_exception
+  {
+  public:
+
+    message_bus_too_many_subscribers(string_type file_name, numeric_type line_number)
+      : message_bus_exception(ETL_ERROR_TEXT("message bus:too many subscribers", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Interface for message bus
+  //***************************************************************************
+  class imessage_bus : public etl::imessage_router
+  {
+  private:
+
+    typedef etl::ivector<etl::imessage_router*> router_list_t;
+
+  public:
+
+    using etl::imessage_router::receive;
+
+    //*******************************************
+    /// Subscribe to the bus.
+    //*******************************************
+    bool subscribe(etl::imessage_router& router)
+    {
+      bool ok = true;
+
+      // There's no point actually adding null routers.
+      if (router.get_message_router_id() != etl::imessage_router::NULL_MESSAGE_ROUTER)
+      {
+        ok = !router_list.full();
+
+        ETL_ASSERT(ok, ETL_ERROR(etl::message_bus_too_many_subscribers));
+
+        if (ok)
+        {
+          if (router.get_message_router_id() == etl::imessage_router::MESSAGE_BUS)
+          {
+            // Message busses get added to the end.
+            router_list.push_back(&router);
+          }
+          else
+          {
+            // Routers get added in id order.
+            router_list_t::iterator irouter = std::upper_bound(router_list.begin(),
+                                                               router_list.end(),
+                                                               router.get_message_router_id(),
+                                                               compare_router_id());
+
+            router_list.insert(irouter, &router);
+          }
+        }
+      }
+
+      return ok;
+    }
+
+    //*******************************************
+    /// Unsubscribe from the bus.
+    //*******************************************
+    void unsubscribe(etl::message_router_id_t id)
+    {
+      if (id == etl::imessage_bus::ALL_MESSAGE_ROUTERS)
+      {
+        clear();
+      }
+      else
+      {
+        std::pair<router_list_t::iterator, router_list_t::iterator> range = std::equal_range(router_list.begin(),
+                                                                                             router_list.end(),
+                                                                                             id,
+                                                                                             compare_router_id());
+
+        router_list.erase(range.first, range.second);
+      }
+    }
+
+    //*******************************************
+    void unsubscribe(etl::imessage_router& router)
+    {
+      router_list_t::iterator irouter = std::find(router_list.begin(),
+                                                  router_list.end(),
+                                                  &router);
+
+      if (irouter != router_list.end())
+      {
+        router_list.erase(irouter);
+      }
+    }
+
+    //*******************************************
+    void receive(const etl::imessage& message)
+    {
+      etl::null_message_router nmr;
+      receive(nmr, etl::imessage_router::ALL_MESSAGE_ROUTERS, message);
+    }
+
+    //*******************************************
+    void receive(etl::message_router_id_t destination_router_id,
+                 const etl::imessage&     message)
+    {
+      etl::null_message_router nmr;
+      receive(nmr, destination_router_id, message);
+    }
+
+    //*******************************************
+    void receive(etl::imessage_router& source,
+                 const etl::imessage&  message)
+    {
+      receive(source, etl::imessage_router::ALL_MESSAGE_ROUTERS, message);
+    }
+
+    //*******************************************
+    void receive(etl::imessage_router&    source,
+                 etl::message_router_id_t destination_router_id,
+                 const etl::imessage&     message)
+    {
+      switch (destination_router_id)
+      {
+        //*****************************
+        // Null message router. These routers can never be subscribed.
+        case etl::imessage_router::NULL_MESSAGE_ROUTER:
+        {
+          break;
+        }
+
+        //*****************************
+        // Broadcast to all routers.
+        case etl::imessage_router::ALL_MESSAGE_ROUTERS:
+        {
+          router_list_t::iterator irouter = router_list.begin();
+
+          // Broadcast to everyone.
+          while (irouter != router_list.end())
+          {
+            etl::imessage_router& router = **irouter;
+
+            if (router.get_message_router_id() == etl::imessage_router::MESSAGE_BUS)
+            {
+              // The router is actually a bus.
+              etl::imessage_bus& bus = static_cast<etl::imessage_bus&>(router);
+
+              // So pass it on.
+              bus.receive(source, destination_router_id, message);
+            }
+            else if (router.accepts(message.get_message_id()))
+            {
+              router.receive(source, message);
+            }
+
+            ++irouter;
+          }
+
+          break;
+        }
+
+        //*****************************
+        // Must be an addressed message.
+        default:
+        {
+          router_list_t::iterator irouter = router_list.begin();
+
+          // Find routers with the id.
+          std::pair<router_list_t::iterator, router_list_t::iterator> range = std::equal_range(router_list.begin(),
+                                                                                               router_list.end(),
+                                                                                               destination_router_id,
+                                                                                               compare_router_id());
+
+          // Call all of them.
+          while (range.first != range.second)
+          {
+            if ((*(range.first))->accepts(message.get_message_id()))
+            {
+              (*(range.first))->receive(source, message);
+            }
+
+            ++range.first;
+          }
+
+          // Do any message buses.
+          // These are always at the end of the list.
+          irouter = std::lower_bound(router_list.begin(),
+                                     router_list.end(),
+                                     etl::imessage_bus::MESSAGE_BUS,
+                                     compare_router_id());
+
+          while (irouter != router_list.end())
+          {
+            // The router is actually a bus.
+            etl::imessage_bus& bus = static_cast<etl::imessage_bus&>(**irouter);
+
+            // So pass it on.
+            bus.receive(source, destination_router_id, message);
+
+            ++irouter;
+          }
+
+          break;
+        }
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //*******************************************
+    /// Does this message bus accept the message id?
+    /// Yes!, it accepts everything!
+    //*******************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      return true;
+    }
+
+    //*******************************************
+    size_t size() const
+    {
+      return router_list.size();
+    }
+
+    //*******************************************
+    void clear()
+    {
+      return router_list.clear();
+    }
+
+  protected:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    imessage_bus(router_list_t& list)
+      : imessage_router(etl::imessage_router::MESSAGE_BUS),
+        router_list(list)
+    {
+    }
+
+  private:
+
+    //*******************************************
+    // How to compare routers to router ids.
+    //*******************************************
+    struct compare_router_id
+    {
+      bool operator()(const etl::imessage_router* prouter, etl::message_router_id_t id) const
+      {
+        return prouter->get_message_router_id() < id;
+      }
+
+      bool operator()(etl::message_router_id_t id, const etl::imessage_router* prouter) const
+      {
+        return id < prouter->get_message_router_id();
+      }
+    };
+
+    router_list_t& router_list;
+  };
+
+  //***************************************************************************
+  /// The message bus
+  //***************************************************************************
+  template <uint_least8_t MAX_ROUTERS_>
+  class message_bus : public etl::imessage_bus
+  {
+  public:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    message_bus()
+      : imessage_bus(router_list)
+    {
+    }
+
+  private:
+
+    etl::vector<etl::imessage_router*, MAX_ROUTERS_> router_list;
+  };
+
+  //***************************************************************************
+  /// Send a message to a bus.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_bus&   bus,
+                                  const etl::imessage& message)
+  {
+    bus.receive(message);
+  }
+
+  //***************************************************************************
+  /// Send a message to a bus.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_bus&       bus,
+                                  etl::message_router_id_t id,
+                                  const etl::imessage&     message)
+  {
+    bus.receive(id, message);
+  }
+
+  //***************************************************************************
+  /// Send a message to a bus.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_router& source,
+                                  etl::imessage_bus&    bus,
+                                  const etl::imessage&  message)
+  {
+    bus.receive(source, message);
+  }
+
+  //***************************************************************************
+  /// Send a message to a bus.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_router&    source,
+                                  etl::imessage_bus&       bus,
+                                  etl::message_router_id_t id,
+                                  const etl::imessage&     message)
+  {
+    bus.receive(source, id, message);
+  }
+}
+
+#undef ETL_FILE
+
+#endif
diff --git a/src/message_router.h b/src/message_router.h
new file mode 100644
index 00000000..c024391b
--- /dev/null
+++ b/src/message_router.h
@@ -0,0 +1,2200 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#if 0
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+#endif
+
+//***************************************************************************
+// This file has been auto generated. Do not edit this file.
+//***************************************************************************
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -omessage_router.h -DHandlers=<n> message_router_generator.h 
+// Where <n> is the number of messages to support.
+//
+// e.g.
+// To generate handlers for up to 16 messages...
+// python -m cogapp -d -e -omessage_router.h -DHandlers=16 message_router_generator.h 
+//
+// See generate.bat
+//***************************************************************************
+
+#ifndef __ETL_MESSAGE_ROUTER__
+#define __ETL_MESSAGE_ROUTER__
+
+#include <stdint.h>
+
+#include "message.h"
+#include "message_types.h"
+#include "alignment.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "largest.h"
+
+#undef ETL_FILE
+#define ETL_FILE "35"
+
+namespace etl
+{
+  //***************************************************************************
+  /// Base exception class for message router
+  //***************************************************************************
+  class message_router_exception : public etl::exception
+  {
+  public:
+
+    message_router_exception(string_type what, string_type file_name, numeric_type line_number)
+      : etl::exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Router id is out of the legal range.
+  //***************************************************************************
+  class message_router_illegal_id : public etl::message_router_exception
+  {
+  public:
+
+    message_router_illegal_id(string_type file_name, numeric_type line_number)
+      : message_router_exception(ETL_ERROR_TEXT("message router:illegal id", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  class imessage_router
+  {
+  public:
+
+    virtual ~imessage_router() {}
+    virtual void receive(const etl::imessage& message) = 0;
+    virtual void receive(imessage_router& source, const etl::imessage& message) = 0;
+    virtual bool accepts(etl::message_id_t id) const = 0;
+
+    //********************************************
+    bool accepts(const etl::imessage& msg) const
+    {
+      return accepts(msg.get_message_id());
+    }
+
+    //********************************************
+    etl::message_router_id_t get_message_router_id() const
+    {
+      return message_router_id;
+    }
+
+    enum
+    {
+      NULL_MESSAGE_ROUTER = 255,
+      MESSAGE_BUS         = 254,
+      ALL_MESSAGE_ROUTERS = 253,
+      MAX_MESSAGE_ROUTER  = 249
+    };
+
+  protected:
+
+    imessage_router(etl::message_router_id_t id)
+      : message_router_id(id)
+    {
+    }
+
+  private:
+
+    // Disabled.
+    imessage_router(const imessage_router&);
+    imessage_router& operator =(const imessage_router&);
+
+    etl::message_router_id_t  message_router_id;
+  };
+
+  //***************************************************************************
+  /// This router can be used either as a sink for messages
+  /// or as a producer-only of messages such an interrupt routine.
+  //***************************************************************************
+  class null_message_router : public imessage_router
+  {
+  public:
+
+    null_message_router()
+      : imessage_router(imessage_router::NULL_MESSAGE_ROUTER)
+    {
+    }
+
+    //********************************************
+    void receive(const etl::imessage& message)
+    {
+    }
+
+    //********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& message)
+    {
+    }
+
+    //********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      return false;
+    }
+
+    //********************************************
+    static null_message_router& instance()
+    {
+      static null_message_router nmr;
+      return nmr;
+    }
+  };
+
+  //***************************************************************************
+  /// Send a message to a router.
+  /// Sets the 'sender' to etl::null_message_router type.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_router& destination, 
+                                  const etl::imessage&  message)
+  {
+    destination.receive(message);
+  }
+
+  //***************************************************************************
+  /// Send a message to a router.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_router& source, 
+                                  etl::imessage_router& destination, 
+                                  const etl::imessage&  message)
+  {
+    destination.receive(source, message);
+  }
+  
+  //***************************************************************************
+  // The definition for all 16 message types.
+  //***************************************************************************
+  template <typename TDerived,
+            typename T1, typename T2 = void, typename T3 = void, typename T4 = void, 
+            typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, 
+            typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void, 
+            typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
+  class message_router  : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          case T8::ID: ::new (p) T8(static_cast<const T8&>(msg)); break;
+          case T9::ID: ::new (p) T9(static_cast<const T9&>(msg)); break;
+          case T10::ID: ::new (p) T10(static_cast<const T10&>(msg)); break;
+          case T11::ID: ::new (p) T11(static_cast<const T11&>(msg)); break;
+          case T12::ID: ::new (p) T12(static_cast<const T12&>(msg)); break;
+          case T13::ID: ::new (p) T13(static_cast<const T13&>(msg)); break;
+          case T14::ID: ::new (p) T14(static_cast<const T14&>(msg)); break;
+          case T15::ID: ::new (p) T15(static_cast<const T15&>(msg)); break;
+          case T16::ID: ::new (p) T16(static_cast<const T16&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const etl::message_id_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        case T14::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T14&>(msg)); break;
+        case T15::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T15&>(msg)); break;
+        case T16::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T16&>(msg)); break;
+        default:  static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID: 
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID: case T13::ID: case T14::ID: case T15::ID: case T16::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 15 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13, typename T14, typename T15>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          case T8::ID: ::new (p) T8(static_cast<const T8&>(msg)); break;
+          case T9::ID: ::new (p) T9(static_cast<const T9&>(msg)); break;
+          case T10::ID: ::new (p) T10(static_cast<const T10&>(msg)); break;
+          case T11::ID: ::new (p) T11(static_cast<const T11&>(msg)); break;
+          case T12::ID: ::new (p) T12(static_cast<const T12&>(msg)); break;
+          case T13::ID: ::new (p) T13(static_cast<const T13&>(msg)); break;
+          case T14::ID: ::new (p) T14(static_cast<const T14&>(msg)); break;
+          case T15::ID: ::new (p) T15(static_cast<const T15&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        case T14::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T14&>(msg)); break;
+        case T15::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T15&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID: 
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID: case T13::ID: case T14::ID: case T15::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 14 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13, typename T14>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          case T8::ID: ::new (p) T8(static_cast<const T8&>(msg)); break;
+          case T9::ID: ::new (p) T9(static_cast<const T9&>(msg)); break;
+          case T10::ID: ::new (p) T10(static_cast<const T10&>(msg)); break;
+          case T11::ID: ::new (p) T11(static_cast<const T11&>(msg)); break;
+          case T12::ID: ::new (p) T12(static_cast<const T12&>(msg)); break;
+          case T13::ID: ::new (p) T13(static_cast<const T13&>(msg)); break;
+          case T14::ID: ::new (p) T14(static_cast<const T14&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        case T14::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T14&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID: 
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID: case T13::ID: case T14::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 13 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          case T8::ID: ::new (p) T8(static_cast<const T8&>(msg)); break;
+          case T9::ID: ::new (p) T9(static_cast<const T9&>(msg)); break;
+          case T10::ID: ::new (p) T10(static_cast<const T10&>(msg)); break;
+          case T11::ID: ::new (p) T11(static_cast<const T11&>(msg)); break;
+          case T12::ID: ::new (p) T12(static_cast<const T12&>(msg)); break;
+          case T13::ID: ::new (p) T13(static_cast<const T13&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID: 
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID: case T13::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 12 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          case T8::ID: ::new (p) T8(static_cast<const T8&>(msg)); break;
+          case T9::ID: ::new (p) T9(static_cast<const T9&>(msg)); break;
+          case T10::ID: ::new (p) T10(static_cast<const T10&>(msg)); break;
+          case T11::ID: ::new (p) T11(static_cast<const T11&>(msg)); break;
+          case T12::ID: ::new (p) T12(static_cast<const T12&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID: 
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 11 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          case T8::ID: ::new (p) T8(static_cast<const T8&>(msg)); break;
+          case T9::ID: ::new (p) T9(static_cast<const T9&>(msg)); break;
+          case T10::ID: ::new (p) T10(static_cast<const T10&>(msg)); break;
+          case T11::ID: ::new (p) T11(static_cast<const T11&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID: 
+        case T9::ID: case T10::ID: case T11::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 10 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          case T8::ID: ::new (p) T8(static_cast<const T8&>(msg)); break;
+          case T9::ID: ::new (p) T9(static_cast<const T9&>(msg)); break;
+          case T10::ID: ::new (p) T10(static_cast<const T10&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID: 
+        case T9::ID: case T10::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 9 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, T7, T8, T9, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          case T8::ID: ::new (p) T8(static_cast<const T8&>(msg)); break;
+          case T9::ID: ::new (p) T9(static_cast<const T9&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7, T8, T9>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8, T9>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID: 
+        case T9::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 8 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, T7, T8, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          case T8::ID: ::new (p) T8(static_cast<const T8&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7, T8>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7, T8>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID: 
+        
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 7 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, T7, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          case T7::ID: ::new (p) T7(static_cast<const T7&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6, T7>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6, T7>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6, T7>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 6 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6>
+  class message_router<TDerived, T1, T2, T3, T4, T5, T6, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          case T6::ID: ::new (p) T6(static_cast<const T6&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5, T6>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5, T6>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5, T6>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 5 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5>
+  class message_router<TDerived, T1, T2, T3, T4, T5, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          case T5::ID: ::new (p) T5(static_cast<const T5&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4, T5>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4, T5>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4, T5>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 4 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3, typename T4>
+  class message_router<TDerived, T1, T2, T3, T4, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          case T4::ID: ::new (p) T4(static_cast<const T4&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3, T4>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3, T4>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3, T4>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 3 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2, typename T3>
+  class message_router<TDerived, T1, T2, T3, void, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: ::new (p) T3(static_cast<const T3&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2, T3>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2, T3>::size,
+        ALIGNMENT = etl::largest<T1, T2, T3>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 2 message types.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1, typename T2>
+  class message_router<TDerived, T1, T2, void, void, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: ::new (p) T2(static_cast<const T2&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1, T2>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1, T2>::size,
+        ALIGNMENT = etl::largest<T1, T2>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 1 message type.
+  //***************************************************************************
+  template <typename TDerived, 
+            typename T1>
+  class message_router<TDerived, T1, void, void, void, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    //**********************************************
+    class message_packet
+    {
+    public:
+
+      //********************************************
+      explicit message_packet(const etl::imessage& msg)
+      {
+        const size_t id = msg.get_message_id();
+
+        void* p = data;
+
+        switch (id)
+        {
+          case T1::ID: ::new (p) T1(static_cast<const T1&>(msg)); break;
+          default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;
+        }
+      }
+
+      //********************************************
+      template <typename T>
+      explicit message_packet(const T& msg)
+      {
+        STATIC_ASSERT((etl::is_one_of<T, T1>::value), "Unsupported type for this message packet");
+
+        void* p = data;
+        ::new (p) T(static_cast<const T&>(msg));
+      }
+
+      //********************************************
+      ~message_packet()
+      {
+        static_cast<etl::imessage*>(data)->~imessage();
+      }
+
+      //********************************************
+      etl::imessage& get()
+      {
+        return *static_cast<etl::imessage*>(data);
+      }
+
+      //********************************************
+      const etl::imessage& get() const
+      {
+        return *static_cast<const etl::imessage*>(data);
+      }
+
+      enum
+      {
+        SIZE      = etl::largest<T1>::size,
+        ALIGNMENT = etl::largest<T1>::alignment
+      };
+
+    private:
+
+      typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+    };
+
+    //**********************************************
+    message_router(etl::message_router_id_t id)
+      : imessage_router(id)
+    {
+      ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));
+    }
+
+    //**********************************************
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::instance(), msg);
+    }
+
+    //**********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TDerived*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        default: static_cast<TDerived*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    using imessage_router::accepts;
+
+    //**********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: 
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+}
+
+#undef ETL_FILE
+
+#endif
diff --git a/src/message_router_generator.h b/src/message_router_generator.h
new file mode 100644
index 00000000..cf1c3685
--- /dev/null
+++ b/src/message_router_generator.h
@@ -0,0 +1,514 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+/*[[[cog
+import cog
+cog.outl("#if 0")
+]]]*/
+/*[[[end]]]*/
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+/*[[[cog
+import cog
+cog.outl("#endif")
+]]]*/
+/*[[[end]]]*/
+
+/*[[[cog
+import cog
+cog.outl("//***************************************************************************")
+cog.outl("// This file has been auto generated. Do not edit this file.")
+cog.outl("//***************************************************************************")
+]]]*/
+/*[[[end]]]*/
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -omessage_router.h -DHandlers=<n> message_router_generator.h 
+// Where <n> is the number of messages to support.
+//
+// e.g.
+// To generate handlers for up to 16 messages...
+// python -m cogapp -d -e -omessage_router.h -DHandlers=16 message_router_generator.h 
+//
+// See generate.bat
+//***************************************************************************
+
+#ifndef __ETL_MESSAGE_ROUTER__
+#define __ETL_MESSAGE_ROUTER__
+
+#include <stdint.h>
+
+#include "message.h"
+#include "message_types.h"
+#include "alignment.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "largest.h"
+
+#undef ETL_FILE
+#define ETL_FILE "35"
+
+namespace etl
+{
+  //***************************************************************************
+  /// Base exception class for message router
+  //***************************************************************************
+  class message_router_exception : public etl::exception
+  {
+  public:
+
+    message_router_exception(string_type what, string_type file_name, numeric_type line_number)
+      : etl::exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Router id is out of the legal range.
+  //***************************************************************************
+  class message_router_illegal_id : public etl::message_router_exception
+  {
+  public:
+
+    message_router_illegal_id(string_type file_name, numeric_type line_number)
+      : message_router_exception(ETL_ERROR_TEXT("message router:illegal id", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  class imessage_router
+  {
+  public:
+
+    virtual ~imessage_router() {}
+    virtual void receive(const etl::imessage& message) = 0;
+    virtual void receive(imessage_router& source, const etl::imessage& message) = 0;
+    virtual bool accepts(etl::message_id_t id) const = 0;
+
+    //********************************************
+    bool accepts(const etl::imessage& msg) const
+    {
+      return accepts(msg.get_message_id());
+    }
+
+    //********************************************
+    etl::message_router_id_t get_message_router_id() const
+    {
+      return message_router_id;
+    }
+
+    enum
+    {
+      NULL_MESSAGE_ROUTER = 255,
+      MESSAGE_BUS         = 254,
+      ALL_MESSAGE_ROUTERS = 253,
+      MAX_MESSAGE_ROUTER  = 249
+    };
+
+  protected:
+
+    imessage_router(etl::message_router_id_t id)
+      : message_router_id(id)
+    {
+    }
+
+  private:
+
+    // Disabled.
+    imessage_router(const imessage_router&);
+    imessage_router& operator =(const imessage_router&);
+
+    etl::message_router_id_t  message_router_id;
+  };
+
+  //***************************************************************************
+  /// This router can be used either as a sink for messages
+  /// or as a producer-only of messages such an interrupt routine.
+  //***************************************************************************
+  class null_message_router : public imessage_router
+  {
+  public:
+
+    null_message_router()
+      : imessage_router(imessage_router::NULL_MESSAGE_ROUTER)
+    {
+    }
+
+    //********************************************
+    void receive(const etl::imessage& message)
+    {
+    }
+
+    //********************************************
+    void receive(etl::imessage_router& source, const etl::imessage& message)
+    {
+    }
+
+    //********************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      return false;
+    }
+
+    //********************************************
+    static null_message_router& instance()
+    {
+      static null_message_router nmr;
+      return nmr;
+    }
+  };
+
+  //***************************************************************************
+  /// Send a message to a router.
+  /// Sets the 'sender' to etl::null_message_router type.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_router& destination, 
+                                  const etl::imessage&  message)
+  {
+    destination.receive(message);
+  }
+
+  //***************************************************************************
+  /// Send a message to a router.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_router& source, 
+                                  etl::imessage_router& destination, 
+                                  const etl::imessage&  message)
+  {
+    destination.receive(source, message);
+  }
+  
+  /*[[[cog
+      import cog
+      ################################################
+      # The first definition for all of the messages.
+      ################################################
+      cog.outl("//***************************************************************************")
+      cog.outl("// The definition for all %s message types." % Handlers)
+      cog.outl("//***************************************************************************")
+      cog.outl("template <typename TDerived,")
+      cog.out("          ")
+      cog.out("typename T1, ")
+      for n in range(2, int(Handlers)):
+          cog.out("typename T%s = void, " % n)
+          if n % 4 == 0:
+              cog.outl("")
+              cog.out("          ")
+      cog.outl("typename T%s = void>" % int(Handlers))
+      cog.out("class message_router")
+      cog.outl("  : public imessage_router")
+      cog.outl("{")
+      cog.outl("public:")
+      cog.outl("")
+      cog.outl("  //**********************************************")
+      cog.outl("  class message_packet")
+      cog.outl("  {")
+      cog.outl("  public:")
+      cog.outl("")
+      cog.outl("    //********************************************")
+      cog.outl("    explicit message_packet(const etl::imessage& msg)")
+      cog.outl("    {")
+      cog.outl("      const size_t id = msg.get_message_id();")
+      cog.outl("")
+      cog.outl("      void* p = data;")
+      cog.outl("")
+      cog.outl("      switch (id)")
+      cog.outl("      {")
+      for n in range(1, int(Handlers) + 1):
+          cog.outl("        case T%s::ID: ::new (p) T%s(static_cast<const T%s&>(msg)); break;" % (n, n, n))
+      cog.outl("        default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;")
+      cog.outl("      }")
+      cog.outl("    }")
+      cog.outl("")      
+      cog.outl("    //********************************************")
+      cog.outl("    template <typename T>")
+      cog.outl("    explicit message_packet(const T& msg)")
+      cog.outl("    {")
+      cog.out("      STATIC_ASSERT((etl::is_one_of<T, ")
+      for n in range(1, int(Handlers)):
+          cog.out("T%s, " % n)
+          if n % 16 == 0:
+              cog.outl("")
+              cog.out("                                       ")
+      cog.outl("""T%s>::value), "Unsupported type for this message packet");""" % int(Handlers))
+      cog.outl("")
+      cog.outl("      void* p = data;")
+      cog.outl("      ::new (p) T(static_cast<const T&>(msg));")
+      cog.outl("    }")
+      cog.outl("")
+      cog.outl("    //********************************************")
+      cog.outl("    ~message_packet()")
+      cog.outl("    {")
+      cog.outl("      static_cast<etl::imessage*>(data)->~imessage();")
+      cog.outl("    }")
+      cog.outl("")
+      cog.outl("    //********************************************")
+      cog.outl("    etl::imessage& get()")
+      cog.outl("    {")
+      cog.outl("      return *static_cast<etl::imessage*>(data);")
+      cog.outl("    }")
+      cog.outl("")
+      cog.outl("    //********************************************")
+      cog.outl("    const etl::imessage& get() const")
+      cog.outl("    {")
+      cog.outl("      return *static_cast<const etl::imessage*>(data);")
+      cog.outl("    }")
+      cog.outl("")
+      cog.outl("    enum")
+      cog.outl("    {")
+      cog.out("      SIZE      = etl::largest<")
+      for n in range(1, int(Handlers)):
+          cog.out("T%s, " % n)
+      cog.outl("T%s>::size," % int(Handlers))
+      cog.out("      ALIGNMENT = etl::largest<")
+      for n in range(1, int(Handlers)):
+          cog.out("T%s, " % n)
+      cog.outl("T%s>::alignment" % int(Handlers))
+      cog.outl("    };")
+      cog.outl("")
+      cog.outl("  private:")
+      cog.outl("")
+      cog.outl("    typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;")
+      cog.outl("  };")
+      cog.outl("")
+      cog.outl("  //**********************************************")
+      cog.outl("  message_router(etl::message_router_id_t id)")
+      cog.outl("    : imessage_router(id)")
+      cog.outl("  {")
+      cog.outl("    ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));")
+      cog.outl("  }")
+      cog.outl("")
+      cog.outl("  //**********************************************")
+      cog.outl("  void receive(const etl::imessage& msg)")
+      cog.outl("  {")
+      cog.outl("    receive(etl::null_message_router::instance(), msg);")
+      cog.outl("  }")
+      cog.outl("")
+      cog.outl("  //**********************************************")
+      cog.outl("  void receive(etl::imessage_router& source, const etl::imessage& msg)")
+      cog.outl("  {")
+      cog.outl("    const etl::message_id_t id = msg.get_message_id();")
+      cog.outl("")
+      cog.outl("    switch (id)")
+      cog.outl("    {")
+      for n in range(1, int(Handlers) + 1):
+          cog.out("      case T%d::ID:" % n)
+          cog.out(" static_cast<TDerived*>(this)->on_receive(source, static_cast<const T%d&>(msg));" % n)
+          cog.outl(" break;")
+      cog.out("      default:")
+      cog.out("  static_cast<TDerived*>(this)->on_receive_unknown(source, msg);")
+      cog.outl(" break;")
+      cog.outl("    }")
+      cog.outl("  }")
+      cog.outl("")
+      cog.outl("  using imessage_router::accepts;")
+      cog.outl("")
+      cog.outl("  //**********************************************")
+      cog.outl("  bool accepts(etl::message_id_t id) const")
+      cog.outl("  {")
+      cog.outl("    switch (id)")
+      cog.outl("    {")
+      cog.out("      ")
+      for n in range(1, int(Handlers) + 1):
+          cog.out("case T%d::ID: " % n)
+          if n % 8 == 0:
+              cog.outl("")
+              cog.out("      ")
+      cog.outl("  return true; break;")
+      cog.outl("      default:")
+      cog.outl("        return false; break;")
+      cog.outl("    }")
+      cog.outl("  }")
+      cog.outl("};")
+
+      ####################################
+      # All of the other specialisations.
+      ####################################
+      for n in range(int(Handlers) - 1, 0, -1):
+          cog.outl("")
+          cog.outl("//***************************************************************************")
+          if n == 1:
+              cog.outl("// Specialisation for %d message type." % n)
+          else:
+              cog.outl("// Specialisation for %d message types." % n)
+          cog.outl("//***************************************************************************")
+          cog.outl("template <typename TDerived, ")
+          cog.out("          ")
+          for t in range(1, n):
+              cog.out("typename T%d, " % t)
+              if t % 4 == 0:
+                  cog.outl("")
+                  cog.out("          ")
+          cog.outl("typename T%d>" % n)
+          cog.out("class message_router<TDerived, ")
+          for t in range(1, n + 1):
+              cog.out("T%d, " % t)
+              if t % 16 == 0:
+                  cog.outl("")
+                  cog.out("               ")
+          for t in range(n + 1, int(Handlers)):
+              cog.out("void, ")
+              if t % 16 == 0:
+                  cog.outl("")
+                  cog.out("               ")
+          cog.outl("void>")
+          cog.outl(" : public imessage_router")
+          cog.outl("{")
+          cog.outl("public:")
+          cog.outl("")
+          cog.outl("  //**********************************************")
+          cog.outl("  class message_packet")
+          cog.outl("  {")
+          cog.outl("  public:")
+          cog.outl("")
+          cog.outl("    //********************************************")
+          cog.outl("    explicit message_packet(const etl::imessage& msg)")
+          cog.outl("    {")
+          cog.outl("      const size_t id = msg.get_message_id();")
+          cog.outl("")
+          cog.outl("      void* p = data;")
+          cog.outl("")
+          cog.outl("      switch (id)")
+          cog.outl("      {")
+          for t in range(1, n + 1):
+              cog.outl("        case T%s::ID: ::new (p) T%s(static_cast<const T%s&>(msg)); break;" % (t, t, t))
+          cog.outl("        default: ETL_ASSERT(false, ETL_ERROR(unhandled_message_exception)); break;")
+          cog.outl("      }")
+          cog.outl("    }")
+          cog.outl("")
+          cog.outl("    //********************************************")
+          cog.outl("    template <typename T>")
+          cog.outl("    explicit message_packet(const T& msg)")
+          cog.outl("    {")
+          cog.out("      STATIC_ASSERT((etl::is_one_of<T, ")
+          for t in range(1, n):
+              cog.out("T%s, " % t)
+              if t % 16 == 0:
+                  cog.outl("")
+                  cog.out("                                       ")
+          cog.outl("""T%s>::value), "Unsupported type for this message packet");""" % n)
+          cog.outl("")
+          cog.outl("      void* p = data;")
+          cog.outl("      ::new (p) T(static_cast<const T&>(msg));")
+          cog.outl("    }")
+          cog.outl("")
+          cog.outl("    //********************************************")
+          cog.outl("    ~message_packet()")
+          cog.outl("    {")
+          cog.outl("      static_cast<etl::imessage*>(data)->~imessage();")
+          cog.outl("    }")
+          cog.outl("")
+          cog.outl("    //********************************************")
+          cog.outl("    etl::imessage& get()")
+          cog.outl("    {")
+          cog.outl("      return *static_cast<etl::imessage*>(data);")
+          cog.outl("    }")
+          cog.outl("")
+          cog.outl("    //********************************************")
+          cog.outl("    const etl::imessage& get() const")
+          cog.outl("    {")
+          cog.outl("      return *static_cast<const etl::imessage*>(data);")
+          cog.outl("    }")
+          cog.outl("")
+          cog.outl("    enum")
+          cog.outl("    {")
+          cog.out("      SIZE      = etl::largest<")
+          for t in range(1, n):
+              cog.out("T%s, " % t)
+          cog.outl("T%s>::size," % n)
+          cog.out("      ALIGNMENT = etl::largest<")
+          for t in range(1, n):
+              cog.out("T%s, " % t)
+          cog.outl("T%s>::alignment" % n)
+          cog.outl("    };")
+          cog.outl("")
+          cog.outl("  private:")
+          cog.outl("")
+          cog.outl("    typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;")
+          cog.outl("  };")
+          cog.outl("")
+          cog.outl("  //**********************************************")
+          cog.outl("  message_router(etl::message_router_id_t id)")
+          cog.outl("    : imessage_router(id)")
+          cog.outl("  {")
+          cog.outl("    ETL_ASSERT(id <= etl::imessage_router::MAX_MESSAGE_ROUTER, ETL_ERROR(etl::message_router_illegal_id));")
+          cog.outl("  }")
+          cog.outl("")
+          cog.outl("  //**********************************************")
+          cog.outl("  void receive(const etl::imessage& msg)")
+          cog.outl("  {")
+          cog.outl("    receive(etl::null_message_router::instance(), msg);")
+          cog.outl("  }")
+          cog.outl("")
+          cog.outl("  //**********************************************")
+          cog.outl("  void receive(etl::imessage_router& source, const etl::imessage& msg)")
+          cog.outl("  {")
+          cog.outl("    const size_t id = msg.get_message_id();")
+          cog.outl("")
+          cog.outl("    switch (id)")
+          cog.outl("    {")
+          for t in range(1, n + 1):
+              cog.out("      case T%d::ID:" % t)
+              cog.out(" static_cast<TDerived*>(this)->on_receive(source, static_cast<const T%d&>(msg));" % t)
+              cog.outl(" break;")
+          cog.out("      default:")
+          cog.out(" static_cast<TDerived*>(this)->on_receive_unknown(source, msg);")
+          cog.outl(" break;")
+          cog.outl("    }")
+          cog.outl("  }")
+          cog.outl("")
+          cog.outl("  using imessage_router::accepts;")
+          cog.outl("")
+          cog.outl("  //**********************************************")
+          cog.outl("  bool accepts(etl::message_id_t id) const")
+          cog.outl("  {")
+          cog.outl("    switch (id)")
+          cog.outl("    {")
+          cog.out("      ")
+          for t in range(1, n + 1):
+              cog.out("case T%d::ID: " % t)
+              if t % 8 == 0:
+                  cog.outl("")
+                  cog.out("      ")
+          cog.outl("")
+          cog.outl("        return true; break;")
+          cog.outl("      default:")
+          cog.outl("        return false; break;")
+          cog.outl("    }")
+          cog.outl("  }")
+          cog.outl("};")
+  ]]]*/
+  /*[[[end]]]*/
+}
+
+#undef ETL_FILE
+
+#endif
diff --git a/src/message_types.h b/src/message_types.h
new file mode 100644
index 00000000..a049dae9
--- /dev/null
+++ b/src/message_types.h
@@ -0,0 +1,46 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_MESSAGE_DEFS__
+#define __ETL_MESSAGE_DEFS__
+
+#include <stdint.h>
+
+namespace etl
+{
+  /// Allow alternative type for message id.
+#if !defined(ETL_MESSAGE_ID_TYPE)
+  typedef uint_least8_t message_id_t;
+#else
+  typedef ETL_MESSAGE_ID_TYPE message_id_t;
+#endif
+
+  typedef uint_least8_t message_router_id_t;
+}
+
+#endif
diff --git a/src/packet.h b/src/packet.h
new file mode 100644
index 00000000..ef0e2d79
--- /dev/null
+++ b/src/packet.h
@@ -0,0 +1,128 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_PACKET__
+#define __ETL_PACKET__
+
+#include "platform.h"
+#include "static_assert.h"
+#include "alignment.h"
+
+#undef ETL_FILE
+#define ETL_FILE "38"
+
+//*****************************************************************************
+///\defgroup packet packet
+/// A class that can contain one a several related types.
+///\ingroup containers
+//*****************************************************************************
+
+namespace etl
+{
+  //***************************************************************************
+  /// A template class that can store any types derived from TBase that conform
+  /// to the size and alignment requirements.
+  ///\ingroup packet
+  //***************************************************************************
+  template <typename TBase, size_t SIZE, size_t ALIGNMENT>            
+  class packet
+  {
+  public:
+
+    //***************************************************************************
+    /// Constructor that static asserts any types that do not conform to the max size and alignment.
+    //***************************************************************************
+    template <typename T>
+    explicit packet(const T& value)
+    {
+      STATIC_ASSERT((etl::is_base_of<TBase, T>::value), "Unsupported type");
+      STATIC_ASSERT(sizeof(T) <= SIZE, "Unsupported size");
+      STATIC_ASSERT(etl::alignment_of<T>::value <= ALIGNMENT, "Unsupported alignment");
+
+      ::new (static_cast<T*>(data)) T(value);
+    }
+
+    //***************************************************************************
+    /// Destructor
+    //***************************************************************************
+    ~packet()
+    {
+      static_cast<TBase*>(data)->~TBase();
+    }
+
+    //***************************************************************************
+    /// Assignment operator for type.
+    ///\param value The value to assign.
+    //***************************************************************************
+    template <typename T>
+    packet& operator =(const T& value)
+    {
+      STATIC_ASSERT((etl::is_base_of<TBase, T>::value), "Unsupported type");
+      STATIC_ASSERT(sizeof(T) <= SIZE, "Unsupported size");
+      STATIC_ASSERT(etl::alignment_of<T>::value <= ALIGNMENT, "Unsupported alignment");
+
+      static_cast<TBase*>(data)->~TBase();
+      ::new (static_cast<T*>(data)) T(value);
+
+      return *this;
+    }
+
+    //***************************************************************************
+    /// Get access to the contained object.
+    //***************************************************************************
+    TBase& get()
+    {
+      return *static_cast<TBase*>(data);
+    }
+
+    //***************************************************************************
+    /// Get access to the contained object.
+    //***************************************************************************
+    const TBase& get() const
+    {
+      return *static_cast<const TBase*>(data);
+    }
+
+  private:
+    
+    packet(const packet& other);
+    packet& operator =(const packet& other);
+
+    //***************************************************************************
+    /// The internal storage.
+    /// Aligned on a suitable boundary, which should be good for all types.
+    //***************************************************************************
+    typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
+  };
+}
+
+#undef ETL_FILE
+
+#endif
diff --git a/src/scheduler.h b/src/scheduler.h
new file mode 100644
index 00000000..388b0a8c
--- /dev/null
+++ b/src/scheduler.h
@@ -0,0 +1,410 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_SCHEDULER__
+#define __ETL_SCHEDULER__
+
+#include <stdint.h>
+
+#include "vector.h"
+#include "nullptr.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "task.h"
+#include "type_traits.h"
+#include "function.h"
+
+#undef ETL_FILE
+#define ETL_FILE "36"
+
+namespace etl
+{
+  //***************************************************************************
+  /// Base exception class for scheduler.
+  //***************************************************************************
+  class scheduler_exception : public etl::exception
+  {
+  public:
+
+    scheduler_exception(string_type what, string_type file_name, numeric_type line_number)
+      : etl::exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// 'No tasks' exception.
+  //***************************************************************************
+  class scheduler_no_tasks_exception : public etl::scheduler_exception
+  {
+  public:
+
+    scheduler_no_tasks_exception(string_type file_name, numeric_type line_number)
+      : etl::scheduler_exception(ETL_ERROR_TEXT("scheduler:no tasks", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// 'Null tasks' exception.
+  //***************************************************************************
+  class scheduler_null_task_exception : public etl::scheduler_exception
+  {
+  public:
+
+    scheduler_null_task_exception(string_type file_name, numeric_type line_number)
+      : etl::scheduler_exception(ETL_ERROR_TEXT("scheduler:null task", ETL_FILE"B"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// 'Too many tasks' exception.
+  //***************************************************************************
+  class scheduler_too_many_tasks_exception : public etl::scheduler_exception
+  {
+  public:
+
+    scheduler_too_many_tasks_exception(string_type file_name, numeric_type line_number)
+      : etl::scheduler_exception(ETL_ERROR_TEXT("scheduler:too many tasks", ETL_FILE"C"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Sequencial Single.
+  /// A policy the scheduler can use to decide what to do next.
+  /// Only calls the task to process work once, if it has work to do.
+  //***************************************************************************
+  struct scheduler_policy_sequencial_single
+  {
+    bool schedule_tasks(etl::ivector<etl::task*>& task_list)
+    {
+      bool idle = true;
+
+      for (size_t index = 0; index < task_list.size(); ++index)
+      {
+        etl::task& task = *(task_list[index]);
+
+        if (task.task_request_work() > 0)
+        {
+          task.task_process_work();
+          idle = false;
+        }
+      }
+
+      return idle;
+    }
+  };
+
+  //***************************************************************************
+  /// Sequencial Multiple.
+  /// A policy the scheduler can use to decide what to do next.
+  /// Calls the task to process work until it reports that it has no more.
+  //***************************************************************************
+  struct scheduler_policy_sequencial_multiple
+  {
+    bool schedule_tasks(etl::ivector<etl::task*>& task_list)
+    {
+      bool idle = true;
+
+      for (size_t index = 0; index < task_list.size(); ++index)
+      {
+        etl::task& task = *(task_list[index]);
+
+        while (task.task_request_work() > 0)
+        {
+          task.task_process_work();
+          idle = false;
+        }
+      }
+
+      return idle;
+    }
+  };
+
+  //***************************************************************************
+  /// Highest Priority.
+  /// A policy the scheduler can use to decide what to do next.
+  /// Calls the highest priority task that has work.
+  //***************************************************************************
+  struct scheduler_policy_highest_priority
+  {
+    bool schedule_tasks(etl::ivector<etl::task*>& task_list)
+    {
+      bool idle = true;
+
+      size_t index = 0;
+      while (index < task_list.size())
+      {
+        etl::task& task = *(task_list[index]);
+
+        if (task.task_request_work() > 0)
+        {
+          task.task_process_work();
+          idle = false;
+          break;
+        }
+        else
+        {
+          ++index;
+        }
+      }
+
+      return idle;
+    }
+  };
+
+  //***************************************************************************
+  /// Most Work.
+  /// A policy the scheduler can use to decide what to do next.
+  /// Calls the task that has the most work.
+  /// Starts looking from the task with the highest priority.
+  //***************************************************************************
+  struct scheduler_policy_most_work
+  {
+    bool schedule_tasks(etl::ivector<etl::task*>& task_list)
+    {
+      bool idle = true;
+
+      size_t most_index = 0;
+      uint_least8_t most_work = 0;
+
+      for (size_t index = 0; index < task_list.size(); ++index)
+      {
+        etl::task& task = *(task_list[index]);
+
+        uint_least8_t n_work = task.task_request_work();
+
+        if (n_work > most_work)
+        {
+          most_index = index;
+          most_work = n_work;
+          idle = false;
+        }
+      }
+
+      if (!idle)
+      {
+        task_list[most_index]->task_process_work();
+      }
+
+      return idle;
+    }
+  };
+
+  //***************************************************************************
+  /// Scheduler base.
+  //***************************************************************************
+  class ischeduler
+  {
+  public:
+
+    //*******************************************
+    // Virtuals.
+    //*******************************************
+    virtual void start() = 0;
+
+    virtual ~ischeduler()
+    {
+    }
+
+    //*******************************************
+    /// Set the idle callback.
+    //*******************************************
+    void set_idle_callback(etl::ifunction<void>& callback)
+    {
+      p_idle_callback = &callback;
+    }
+
+    //*******************************************
+    /// Set the watchdog callback.
+    //*******************************************
+    void set_watchdog_callback(etl::ifunction<void>& callback)
+    {
+      p_watchdog_callback = &callback;
+    }
+
+    //*******************************************
+    /// Set the running state for the scheduler.
+    //*******************************************
+    void set_scheduler_running(bool scheduler_running_)
+    {
+      scheduler_running = scheduler_running_;
+    }
+
+    //*******************************************
+    /// Get the running state for the scheduler.
+    //*******************************************
+    bool scheduler_is_running() const
+    {
+      return scheduler_running;
+    }
+
+    //*******************************************
+    /// Force the scheduler to exit.
+    //*******************************************
+    void exit_scheduler()
+    {
+      scheduler_exit = true;
+    }
+
+    //*******************************************
+    /// Add a task.
+    /// Add to the task list in priority order.
+    //*******************************************
+    void add_task(etl::task& task)
+    {
+      ETL_ASSERT(!task_list.full(), ETL_ERROR(etl::scheduler_too_many_tasks_exception))
+
+      if (!task_list.full())
+      {
+        typename task_list_t::iterator itask = std::upper_bound(task_list.begin(),
+                                                                task_list.end(),
+                                                                task.get_task_priority(),
+                                                                compare_priority());
+
+        task_list.insert(itask, &task);
+      }
+    }
+
+    //*******************************************
+    /// Add a task list.
+    /// Adds to the tasks to the internal task list in priority order.
+    /// Input order is ignored.
+    //*******************************************
+    template <typename TSize>
+    void add_task_list(etl::task** p_tasks, TSize size)
+    {
+      for (TSize i = 0; i < size; ++i)
+      {
+        ETL_ASSERT((p_tasks[i] != nullptr), ETL_ERROR(etl::scheduler_null_task_exception));
+        add_task(*(p_tasks[i]));
+      }
+    }
+
+  protected:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    ischeduler(etl::ivector<etl::task*>& task_list_)
+      : scheduler_running(false),
+        scheduler_exit(false),
+        p_idle_callback(nullptr),
+        p_watchdog_callback(nullptr),
+        task_list(task_list_)
+    {
+    }
+
+    bool scheduler_running;
+    bool scheduler_exit;
+    etl::ifunction<void>* p_idle_callback;
+    etl::ifunction<void>* p_watchdog_callback;
+
+  private:
+
+    //*******************************************
+    // Used to order tasks in descending priority.
+    //*******************************************
+    struct compare_priority
+    {
+      bool operator()(etl::task* ptask, etl::task_priority_t priority) const
+      {
+        return ptask->get_task_priority() > priority;
+      }
+
+      bool operator()(etl::task_priority_t priority, etl::task* ptask) const
+      {
+        return priority > ptask->get_task_priority();
+      }
+    };
+
+    typedef etl::ivector<etl::task*> task_list_t;
+    task_list_t& task_list;
+  };
+
+  //***************************************************************************
+  /// Scheduler.
+  //***************************************************************************
+  template <typename TSchedulerPolicy, size_t MAX_TASKS_>
+  class scheduler : public etl::ischeduler, protected TSchedulerPolicy
+  {
+  public:
+
+    enum
+    {
+      MAX_TASKS = MAX_TASKS_,
+    };
+
+    scheduler()
+      : ischeduler(task_list)
+    {
+    }
+
+    //*******************************************
+    /// Start the scheduler. SEQUENCIAL_SINGLE
+    /// Only calls the task to process work once, if it has work to do.
+    //*******************************************
+    void start()
+    {
+      ETL_ASSERT(task_list.size() > 0, ETL_ERROR(etl::scheduler_no_tasks_exception));
+
+      const size_t task_list_size = task_list.size();
+
+      scheduler_running = true;
+
+      while (!scheduler_exit)
+      {
+        if (scheduler_running)
+        {
+          bool idle = TSchedulerPolicy::schedule_tasks(task_list);
+
+          if (p_watchdog_callback)
+          {
+            (*p_watchdog_callback)();
+          }
+
+          if (idle && p_idle_callback)
+          {
+            (*p_idle_callback)();
+          }
+        }
+      }
+    }
+
+  private:
+
+    typedef etl::vector<etl::task*, MAX_TASKS> task_list_t;
+    task_list_t task_list;
+  };
+}
+
+#undef ETL_FILE
+
+#endif
diff --git a/src/smallest.h b/src/smallest.h
index b9ac9e22..16a2ed7c 100644
--- a/src/smallest.h
+++ b/src/smallest.h
@@ -5,7 +5,7 @@ The MIT License(MIT)
 
 Embedded Template Library.
 https://github.com/ETLCPP/etl
-http://www.etlcpp.com
+https://www.etlcpp.com
 
 Copyright(c) 2014 jwellbelove
 
@@ -28,6 +28,28 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 ******************************************************************************/
 
+#if 0
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+#endif
+
+//***************************************************************************
+// This file has been auto generated. Do not edit this file.
+//***************************************************************************
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -osmallest.h -DNTypes=<n> smallest_generator.h
+// Where <n> is the number of types to support.
+//
+// e.g.
+// To generate handlers for up to 16 types...
+// python -m cogapp -d -e -osmallest.h -DNTypes=16 smallest_generator.h
+//
+// See generate.bat
+//***************************************************************************
+
 #ifndef __ETL_SMALLEST__
 #define __ETL_SMALLEST__
 
@@ -47,9 +69,9 @@ namespace etl
   /// Defines 'size' which is the size of the smallest parameter.
   ///\ingroup smallest
   //***************************************************************************
-  template <typename T1,         typename T2  = void, typename T3  = void, typename T4  = void,
-            typename T5  = void, typename T6  = void, typename T7  = void, typename T8  = void,
-            typename T9  = void, typename T10 = void, typename T11 = void, typename T12 = void,
+  template <typename T1, typename T2 = void, typename T3 = void, typename T4 = void, 
+            typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, 
+            typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void, 
             typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
   struct smallest_type
   {
@@ -82,10 +104,10 @@ namespace etl
 
     // Set 'type' to be the smallest of the first parameter and any of the others.
     // This is recursive.
-    typedef typename choose_type<(sizeof(T1) < sizeof(smallest_other)),// Boolean
-                                  T1,                                  // TrueType
-                                  smallest_other>                      // FalseType
-                                  ::type type;                         // The smallest type of the two.
+    typedef typename choose_type<(sizeof(T1) < sizeof(smallest_other)), // Boolean
+                                  T1,                                   // TrueType
+                                  smallest_other>                       // FalseType
+                                  ::type type;                          // The smallest type of the two.
 
     // The size of the smallest type.
     enum
@@ -98,10 +120,8 @@ namespace etl
   // Specialisation for one template parameter.
   //***************************************************************************
   template <typename T1>
-  struct smallest_type <T1,   void, void, void,
-                        void, void, void, void,
-                        void, void, void, void,
-                        void, void, void, void>
+  struct smallest_type<T1,   void, void, void, void, void, void, void, 
+                       void, void, void, void, void, void, void, void>
   {
     typedef T1 type;
 
diff --git a/src/smallest_generator.h b/src/smallest_generator.h
new file mode 100644
index 00000000..1c99c09c
--- /dev/null
+++ b/src/smallest_generator.h
@@ -0,0 +1,336 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2014 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+/*[[[cog
+import cog
+cog.outl("#if 0")
+]]]*/
+/*[[[end]]]*/
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+/*[[[cog
+import cog
+cog.outl("#endif")
+]]]*/
+/*[[[end]]]*/
+
+/*[[[cog
+import cog
+cog.outl("//***************************************************************************")
+cog.outl("// This file has been auto generated. Do not edit this file.")
+cog.outl("//***************************************************************************")
+]]]*/
+/*[[[end]]]*/
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -osmallest.h -DNTypes=<n> smallest_generator.h
+// Where <n> is the number of types to support.
+//
+// e.g.
+// To generate handlers for up to 16 types...
+// python -m cogapp -d -e -osmallest.h -DNTypes=16 smallest_generator.h
+//
+// See generate.bat
+//***************************************************************************
+
+#ifndef __ETL_SMALLEST__
+#define __ETL_SMALLEST__
+
+#include <stdint.h>
+
+#include "integral_limits.h"
+
+///\defgroup smallest smallest
+///\ingroup utilities
+
+namespace etl
+{
+  /*[[[cog
+  import cog
+  cog.outl("//***************************************************************************")
+  cog.outl("/// Template to determine the smallest type and size.")
+  cog.outl("/// Supports up to %s types." % NTypes)
+  cog.outl("/// Defines 'value_type' which is the type of the smallest parameter.")
+  cog.outl("/// Defines 'size' which is the size of the smallest parameter.")
+  cog.outl("///\ingroup smallest")
+  cog.outl("//***************************************************************************")
+  cog.out("template <typename T1, ")
+  for n in range(2, int(NTypes)):
+      cog.out("typename T%s = void, " % n)
+      if n % 4 == 0:
+          cog.outl("")
+          cog.out("          ")
+  cog.outl("typename T%s = void>" % int(NTypes))
+  cog.outl("struct smallest_type")
+  cog.outl("{")
+  cog.outl("private:")
+  cog.outl("")
+  cog.outl("  // Declaration.")
+  cog.outl("  template <const bool Boolean, typename TrueType, typename FalseType>")
+  cog.outl("  struct choose_type;")
+  cog.outl("")
+  cog.outl("  // Specialisation for 'true'.")
+  cog.outl("  // Defines 'type' as 'TrueType'.")
+  cog.outl("  template <typename TrueType, typename FalseType>")
+  cog.outl("  struct choose_type<true, TrueType, FalseType>")
+  cog.outl("  {")
+  cog.outl("    typedef TrueType type;")
+  cog.outl("  };")
+  cog.outl("")
+  cog.outl("  // Specialisation for 'false'. ")
+  cog.outl("  // Defines 'type' as 'FalseType'.")
+  cog.outl("  template <typename TrueType, typename FalseType>")
+  cog.outl("  struct choose_type<false, TrueType, FalseType>")
+  cog.outl("  {")
+  cog.outl("    typedef FalseType type;")
+  cog.outl("  };")
+  cog.outl("")
+  cog.outl("public:")
+  cog.outl("")
+  cog.outl("  // Define 'smallest_other' as 'smallest_type' with all but the first parameter. ")
+  cog.out("  typedef typename smallest_type<")
+  for n in range(2, int(NTypes)):
+      cog.out("T%s, " % n)
+      if n % 16 == 0:
+          cog.outl("")
+          cog.out("                                ")
+  cog.outl("T%s>::type smallest_other;" % int(NTypes))
+  cog.outl("")
+  cog.outl("  // Set 'type' to be the smallest of the first parameter and any of the others.")
+  cog.outl("  // This is recursive.")
+  cog.outl("  typedef typename choose_type<(sizeof(T1) < sizeof(smallest_other)), // Boolean")
+  cog.outl("                                T1,                                   // TrueType")
+  cog.outl("                                smallest_other>                       // FalseType")
+  cog.outl("                                ::type type;                          // The smallest type of the two.")
+  cog.outl("")
+  cog.outl("  // The size of the smallest type.")
+  cog.outl("  enum")
+  cog.outl("  {")
+  cog.outl("    size = sizeof(type)")
+  cog.outl("  };")
+  cog.outl("};")
+  cog.outl("")
+  cog.outl("//***************************************************************************")
+  cog.outl("// Specialisation for one template parameter.")
+  cog.outl("//***************************************************************************")
+  cog.outl("template <typename T1>")
+  cog.out("struct smallest_type<T1,   ")
+  for n in range(2, int(NTypes)):
+      cog.out("void, ")
+      if n % 8 == 0:
+          cog.outl("")
+          cog.out("                     ")
+  cog.outl("void>")
+  cog.outl("{")
+  cog.outl("  typedef T1 type;")
+  cog.outl("")
+  cog.outl("  enum")
+  cog.outl("  {")
+  cog.outl("    size = sizeof(type)")
+  cog.outl("  };")
+  cog.outl("};")
+  ]]]*/
+  /*[[[end]]]*/
+  
+  namespace __private_smallest__
+  {
+    //*************************************************************************
+    // Determine the type to hold the number of bits based on the index.
+    //*************************************************************************
+    template <const int index>
+    struct best_fit_uint_type;
+    
+    //*************************************************************************
+    // Less than or equal to 8 bits.
+    //*************************************************************************
+    template <>
+    struct best_fit_uint_type<0>
+    {
+      typedef uint_least8_t type;
+    };
+
+    //*************************************************************************
+    // 9 to 16 bits.
+    //*************************************************************************
+    template <>
+    struct best_fit_uint_type<1>
+    {
+      typedef uint_least16_t type;
+    };
+
+    //*************************************************************************
+    // 17 to 31 bits.
+    //*************************************************************************
+    template <>
+    struct best_fit_uint_type<2>
+    {
+      typedef uint_least32_t type;
+    };
+
+    //*************************************************************************
+    // Greater than 32 bits.
+    //*************************************************************************
+    template <>
+    struct best_fit_uint_type<3>
+    {
+      typedef uint_least64_t type;
+    };
+
+    //*************************************************************************
+    // Determine the type to hold the number of bits based on the index.
+    //*************************************************************************
+    template <const int index>
+    struct best_fit_int_type;
+
+    //*************************************************************************
+    // Less than or equal to 8 bits.
+    //*************************************************************************
+    template <>
+    struct best_fit_int_type<0>
+    {
+      typedef int_least8_t type;
+    };
+
+    //*************************************************************************
+    // 9 to 16 bits.
+    //*************************************************************************
+    template <>
+    struct best_fit_int_type<1>
+    {
+      typedef int_least16_t type;
+    };
+
+    //*************************************************************************
+    // 17 to 31 bits.
+    //*************************************************************************
+    template <>
+    struct best_fit_int_type<2>
+    {
+      typedef int_least32_t type;
+    };
+
+    //*************************************************************************
+    // Greater than 32 bits.
+    //*************************************************************************
+    template <>
+    struct best_fit_int_type<3>
+    {
+      typedef int_least64_t type;
+    };
+  }
+
+  //***************************************************************************
+  /// Template to determine the smallest unsigned int type that can contain a 
+  /// value with the specified number of bits.
+  /// Defines 'type' which is the type of the smallest unsigned integer.
+  ///\ingroup smallest
+  //***************************************************************************
+  template <const size_t NBITS>
+  struct smallest_uint_for_bits
+  {
+  private:
+    
+    // Determines the index of the best unsigned type for the required number of bits.
+    static const int TYPE_INDEX = ((NBITS >  8) ? 1 : 0) + 
+                                  ((NBITS > 16) ? 1 : 0) +
+                                  ((NBITS > 32) ? 1 : 0);
+
+  public:
+
+    typedef typename __private_smallest__::best_fit_uint_type<TYPE_INDEX>::type type;
+  };
+
+  //***************************************************************************
+  /// Template to determine the smallest signed int type that can contain a 
+  /// value with the specified number of bits.
+  /// Defines 'type' which is the type of the smallest signed integer.
+  ///\ingroup smallest
+  //***************************************************************************
+  template <const size_t NBITS>
+  struct smallest_int_for_bits
+  {
+  private:
+
+    // Determines the index of the best unsigned type for the required number of bits.
+    static const int TYPE_INDEX = ((NBITS >  8) ? 1 : 0) +
+                                  ((NBITS > 16) ? 1 : 0) +
+                                  ((NBITS > 32) ? 1 : 0);
+
+  public:
+
+    typedef typename __private_smallest__::best_fit_int_type<TYPE_INDEX>::type type;
+  };
+
+  //***************************************************************************
+  /// Template to determine the smallest unsigned int type that can contain the
+  /// specified unsigned value.
+  /// Defines 'type' which is the type of the smallest unsigned integer.
+  ///\ingroup smallest
+  //***************************************************************************
+  template <const uintmax_t VALUE>
+  struct smallest_uint_for_value
+  {
+  private:
+
+    // Determines the index of the best unsigned type for the required value.
+    static const int TYPE_INDEX = ((VALUE > UINT_LEAST8_MAX)  ? 1 : 0) +
+                                  ((VALUE > UINT16_MAX) ? 1 : 0) + 
+                                  ((VALUE > UINT32_MAX) ? 1 : 0);
+
+  public:
+
+    typedef typename __private_smallest__::best_fit_uint_type<TYPE_INDEX>::type type;
+  };
+
+  //***************************************************************************
+  /// Template to determine the smallest int type that can contain the
+  /// specified signed value.
+  /// Defines 'type' which is the type of the smallest signed integer.
+  ///\ingroup smallest
+  //***************************************************************************
+  template <const intmax_t VALUE>
+  struct smallest_int_for_value
+  {
+  private:
+
+    // Determines the index of the best signed type for the required value.
+    static const int TYPE_INDEX = (((VALUE > INT_LEAST8_MAX)  || (VALUE < INT_LEAST8_MIN))  ? 1 : 0) + 
+                                  (((VALUE > INT16_MAX) || (VALUE < INT16_MIN)) ? 1 : 0) +
+                                  (((VALUE > INT32_MAX) || (VALUE < INT32_MIN)) ? 1 : 0);
+
+  public:
+
+    typedef typename __private_smallest__::best_fit_int_type<TYPE_INDEX>::type type;
+  };
+}
+
+#endif
diff --git a/src/task.h b/src/task.h
new file mode 100644
index 00000000..dbe410f1
--- /dev/null
+++ b/src/task.h
@@ -0,0 +1,125 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_TASK__
+#define __ETL_TASK__
+
+#include <stdint.h>
+
+#include "error_handler.h"
+#include "exception.h"
+
+#undef ETL_FILE
+#define ETL_FILE "37"
+
+namespace etl
+{
+  //***************************************************************************
+  /// Base exception class for task.
+  //***************************************************************************
+  class task_exception : public etl::exception
+  {
+  public:
+
+    task_exception(string_type what, string_type file_name, numeric_type line_number)
+      : etl::exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  typedef uint_least8_t task_priority_t;
+
+  //***************************************************************************
+  /// Scheduler.
+  //***************************************************************************
+  class task
+  {
+  public:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    task(task_priority_t priority)
+      : task_running(true),
+        task_priority(priority)
+    {
+    }
+
+    //*******************************************
+    /// Destructor.
+    //*******************************************
+    virtual ~task()
+    {
+    }
+
+    //*******************************************
+    /// Called to check if the task has work.
+    /// Returns a score as to the amount of work it has to do.
+    //*******************************************
+    virtual uint32_t task_request_work() const = 0;
+
+    //*******************************************
+    /// Called to get the task to do work.
+    //*******************************************
+    virtual void task_process_work() = 0;
+
+    //*******************************************
+    /// Set the running state for the task.
+    //*******************************************
+    void set_task_running(bool task_running_)
+    {
+      task_running = task_running_;
+    }
+
+    //*******************************************
+    /// Get the running state for the task.
+    //*******************************************
+    bool task_is_running() const
+    {
+      return task_running;
+    }
+
+    //*******************************************
+    /// Get the priority of the task.
+    /// Higher value = higher priority.
+    //*******************************************
+    etl::task_priority_t get_task_priority() const
+    {
+      return task_priority;
+    }
+
+  private:
+
+    bool task_running;
+    etl::task_priority_t task_priority;
+  };
+}
+
+#undef ETL_FILE
+
+#endif
diff --git a/src/type_traits.h b/src/type_traits.h
index 5c9876a5..afd8be8d 100644
--- a/src/type_traits.h
+++ b/src/type_traits.h
@@ -5,7 +5,7 @@ The MIT License(MIT)
 
 Embedded Template Library.
 https://github.com/ETLCPP/etl
-http://www.etlcpp.com
+https://www.etlcpp.com
 
 Copyright(c) 2014 jwellbelove
 
@@ -28,6 +28,28 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 ******************************************************************************/
 
+#if 0
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+#endif
+
+//***************************************************************************
+// This file has been auto generated. Do not edit this file.
+//***************************************************************************
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -otypes.h -DHandlers=<n> types_generator.h
+// Where <n> is the number of types to support.
+//
+// e.g.
+// To generate handlers for up to 16 types...
+// python -m cogapp -d -e -otype_traits.h -DIsOneOf=16 type_traits_generator.h
+//
+// See generate.bat
+//***************************************************************************
+
 #ifndef __ETL_TYPE_TRAITS__
 #define __ETL_TYPE_TRAITS__
 
@@ -152,7 +174,6 @@ namespace etl
   template <typename T> struct is_integral<volatile T> : is_integral<T> {};
   template <typename T> struct is_integral<const volatile T> : is_integral<T> {};
 
-
   /// is_signed
   ///\ingroup type_traits
   template <typename T> struct is_signed : false_type {};
@@ -237,15 +258,15 @@ namespace etl
   template <typename T> struct is_reference<T&> : true_type {};
 
   /// is_pod
+  /// For C++03, only fundamental and pointers types are recognised.
   ///\ingroup type_traits
-
 #if defined(ETL_C11_TYPE_TRAITS_SUPPORTED)// && !defined(ETL_IN_UNIT_TEST)
   // For compilers that support C++11
   template <typename T> struct is_pod : std::is_pod<T> {};
 #else
   /// For C++03, only fundamental and pointers types are recognised.
   template <typename T> struct is_pod : etl::integral_constant<bool, etl::is_fundamental<T>::value ||
-                                                                     etl::is_pointer<T>::value> {};
+    etl::is_pointer<T>::value> {};
 #endif
 
 #if defined(ETL_C11_TYPE_TRAITS_SUPPORTED) && defined(ETL_C11_TYPE_TRAITS_IS_TRIVIAL_SUPPORTED)// && !defined(ETL_IN_UNIT_TEST)
@@ -290,6 +311,7 @@ namespace etl
   template <typename T> struct is_trivially_copy_assignable : etl::is_pod<T> {};
 #endif
 
+
   /// conditional
   ///\ingroup type_traits
   template <bool B, typename T, typename F>  struct conditional { typedef T type; };
@@ -392,29 +414,80 @@ namespace etl
                                       typename etl::remove_cv<U>::type>::type type;
   };
 
+  /// is_base_of
+  ///\ingroup type_traits
+  template<class TBase, class TDerived>
+  struct is_base_of
+  {
+  private:
+
+    template<typename T> struct dummy {};
+    struct internal: TDerived, dummy<int>{};
+
+    static TBase* check(TBase*);
+    template<typename T> static char check(dummy<T>*);
+
+  public:
+
+    static const bool value = (sizeof(check((internal*)0)) == sizeof(TBase*));
+  };
+
   /// Alignment templates.
   /// These require compiler specific intrinsics.
   ///\ingroup type_traits
-#if defined(ETL_C11_ALIGNOF_SUPPORTED)
-  template <typename T> struct alignment_of : integral_constant<size_t, size_t(alignof(T))> {};
-#elif defined(ETL_COMPILER_MICROSOFT)
+#ifdef ETL_COMPILER_MICROSOFT
   template <typename T> struct alignment_of : integral_constant<size_t, size_t(__alignof(T))> {};
-#elif defined(ETL_COMPILER_GCC)
+#endif
+
+#ifdef ETL_COMPILER_GCC
   template <typename T> struct alignment_of : integral_constant<size_t, size_t(__alignof__(T))> {};
-#elif defined(ETL_COMPILER_KEIL)
+#endif
+
+#ifdef ETL_COMPILER_KEIL
   template <typename T> struct alignment_of : integral_constant<size_t, size_t(__alignof__(T))> {};
-#elif defined(ETL_COMPILER_IAR)
+#endif
+
+#ifdef ETL_COMPILER_IAR
   template <typename T> struct alignment_of : integral_constant<size_t, size_t(__ALIGNOF__(T))> {};
-#elif defined(ETL_COMPILER_TI)
+#endif
+
+#ifdef ETL_COMPILER_TI
   template <typename T> struct alignment_of : integral_constant<size_t, size_t(__ALIGNOF__(T))> {};
-#else
-  // Best guess!
-  template <typename T> struct alignment_of : integral_constant<size_t, size_t(__alignof__(T))> {};
 #endif
 
   /// Specialisation of 'alignment_of' for 'void'.
   ///\ingroup type_traits
   template <> struct alignment_of<void> : integral_constant <size_t, 0>{};
+
+  //***************************************************************************
+  /// Template to determine if a type is one of a specified list.
+  ///\ingroup types
+  //***************************************************************************
+  template <typename T,
+            typename T1, typename T2 = void, typename T3 = void, typename T4 = void, 
+            typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, 
+            typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void, 
+            typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
+  struct is_one_of
+  {
+    static const bool value = 
+        etl::is_same<T, T1>::value ||
+        etl::is_same<T, T2>::value ||
+        etl::is_same<T, T3>::value ||
+        etl::is_same<T, T4>::value ||
+        etl::is_same<T, T5>::value ||
+        etl::is_same<T, T6>::value ||
+        etl::is_same<T, T7>::value ||
+        etl::is_same<T, T8>::value ||
+        etl::is_same<T, T9>::value ||
+        etl::is_same<T, T10>::value ||
+        etl::is_same<T, T11>::value ||
+        etl::is_same<T, T12>::value ||
+        etl::is_same<T, T13>::value ||
+        etl::is_same<T, T14>::value ||
+        etl::is_same<T, T15>::value ||
+        etl::is_same<T, T16>::value;
+  };
 }
 
 #endif
diff --git a/src/type_traits_generator.h b/src/type_traits_generator.h
new file mode 100644
index 00000000..68a2202d
--- /dev/null
+++ b/src/type_traits_generator.h
@@ -0,0 +1,500 @@
+///\file
+
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2014 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+/*[[[cog
+import cog
+cog.outl("#if 0")
+]]]*/
+/*[[[end]]]*/
+#error THIS HEADER IS A GENERATOR. DO NOT INCLUDE.
+/*[[[cog
+import cog
+cog.outl("#endif")
+]]]*/
+/*[[[end]]]*/
+
+/*[[[cog
+import cog
+cog.outl("//***************************************************************************")
+cog.outl("// This file has been auto generated. Do not edit this file.")
+cog.outl("//***************************************************************************")
+]]]*/
+/*[[[end]]]*/
+
+//***************************************************************************
+// To generate to header file, run this at the command line.
+// Note: You will need Python and COG installed.
+//
+// python -m cogapp -d -e -otypes.h -DHandlers=<n> types_generator.h
+// Where <n> is the number of types to support.
+//
+// e.g.
+// To generate handlers for up to 16 types...
+// python -m cogapp -d -e -otype_traits.h -DIsOneOf=16 type_traits_generator.h
+//
+// See generate.bat
+//***************************************************************************
+
+#ifndef __ETL_TYPE_TRAITS__
+#define __ETL_TYPE_TRAITS__
+
+#include <stddef.h>
+
+#include "platform.h"
+#include "nullptr.h"
+
+#if defined(ETL_C11_TYPE_TRAITS_SUPPORTED)
+  #include <type_traits>
+#endif
+
+///\defgroup type_traits type_traits
+/// A set of type traits definitions for compilers that do not support the standard header.
+/// \ingroup utilities
+
+namespace etl
+{
+  /// integral_constant
+  ///\ingroup type_traits
+  template <typename T, const T VALUE>
+  struct integral_constant
+  {
+    static const T value = VALUE;
+
+    typedef T value_type;
+    typedef integral_constant<T, VALUE> type;
+
+    operator value_type() const
+    {
+       return value;
+    }
+  };
+
+  /// integral_constant specialisations
+  ///\ingroup type_traits
+  typedef integral_constant<bool, false> false_type;
+  typedef integral_constant<bool, true>  true_type;
+
+  /// remove_reference
+  ///\ingroup type_traits
+  template <typename T> struct remove_reference { typedef T type; };
+  template <typename T> struct remove_reference<T&> { typedef T type; };
+
+  /// add_reference
+  ///\ingroup type_traits
+  template <typename T> struct add_reference { typedef T& type; };
+  template <typename T> struct add_reference<T&> { typedef T& type; };
+
+  /// remove_pointer
+  ///\ingroup type_traits
+  template <typename T> struct remove_pointer { typedef T type; };
+  template <typename T> struct remove_pointer<T*> { typedef T type; };
+
+  /// add_pointer
+  ///\ingroup type_traits
+  template <typename T> struct add_pointer { typedef typename remove_reference<T>::type* type; };
+
+  /// is_const
+  ///\ingroup type_traits
+  template <typename T> struct is_const : false_type {};
+  template <typename T> struct is_const<const T> : true_type {};
+  template <typename T> struct is_const<const volatile T> : true_type {};
+
+  /// remove_const
+  ///\ingroup type_traits
+  template <typename T> struct remove_const { typedef T type; };
+  template <typename T> struct remove_const<const T> { typedef T type; };
+
+  /// add_const
+  ///\ingroup type_traits
+  template <typename T> struct add_const { typedef const T type; };
+  template <typename T> struct add_const<const T> { typedef const T type; };
+
+  /// is_volatile
+  ///\ingroup type_traits
+  template <typename T> struct is_volatile : false_type {};
+  template <typename T> struct is_volatile<volatile T> : true_type {};
+  template <typename T> struct is_volatile<const volatile T> : true_type {};
+
+  /// remove_volatile
+  ///\ingroup type_traits
+  template <typename T> struct remove_volatile { typedef T type; };
+  template <typename T> struct remove_volatile<volatile T> { typedef T type; };
+
+  /// add_volatile
+  ///\ingroup type_traits
+  template <typename T> struct add_volatile { typedef volatile T type; };
+  template <typename T> struct add_volatile<volatile T> { typedef volatile T type; };
+
+  /// remove_cv
+  ///\ingroup type_traits
+  template <typename T> struct remove_cv
+  {
+    typedef typename remove_volatile<typename remove_const<T>::type>::type type;
+  };
+
+  /// add_cv
+  ///\ingroup type_traits
+  template <typename T> struct add_cv
+  {
+    typedef typename add_volatile<typename add_const<T>::type>::type type;
+  };
+
+  /// is_integral
+  ///\ingroup type_traits
+  template <typename T> struct is_integral : false_type {};
+  template <> struct is_integral<bool> : true_type {};
+  template <> struct is_integral<char> : true_type {};
+  template <> struct is_integral<unsigned char> : true_type {};
+  template <> struct is_integral<signed char> : true_type {};
+  template <> struct is_integral<wchar_t> : true_type {};
+  template <> struct is_integral<short> : true_type {};
+  template <> struct is_integral<unsigned short> : true_type {};
+  template <> struct is_integral<int> : true_type {};
+  template <> struct is_integral<unsigned int> : true_type {};
+  template <> struct is_integral<long> : true_type {};
+  template <> struct is_integral<unsigned long> : true_type {};
+  template <> struct is_integral<long long> : true_type {};
+  template <> struct is_integral<unsigned long long> : true_type {};
+  template <typename T> struct is_integral<const T> : is_integral<T> {};
+  template <typename T> struct is_integral<volatile T> : is_integral<T> {};
+  template <typename T> struct is_integral<const volatile T> : is_integral<T> {};
+
+  /// is_signed
+  ///\ingroup type_traits
+  template <typename T> struct is_signed : false_type {};
+  template <> struct is_signed<char> : integral_constant<bool, (char(255) < 0)> {};
+  template <> struct is_signed<wchar_t> : public etl::integral_constant<bool, static_cast<bool>(wchar_t(-1) < wchar_t(0))> {};
+  template <> struct is_signed<signed char> : true_type {};
+  template <> struct is_signed<short> : true_type {};
+  template <> struct is_signed<int> : true_type {};
+  template <> struct is_signed<long> : true_type {};
+  template <> struct is_signed<long long> : true_type {};
+  template <> struct is_signed<float> : true_type{};
+  template <> struct is_signed<double> : true_type{};
+  template <> struct is_signed<long double> : true_type{};
+  template <typename T> struct is_signed<const T> : is_signed<T> {};
+  template <typename T> struct is_signed<volatile T> : is_signed<T> {};
+  template <typename T> struct is_signed<const volatile T> : is_signed<T> {};
+
+  /// is_unsigned
+  ///\ingroup type_traits
+  template <typename T> struct is_unsigned : false_type {};
+  template <> struct is_unsigned<bool> : true_type {};
+  template <> struct is_unsigned<char> : integral_constant<bool, (char(255) > 0)> {};
+  template <> struct is_unsigned<unsigned char> : true_type {};
+  template <> struct is_unsigned<wchar_t> : public etl::integral_constant<bool, (wchar_t(-1) > wchar_t(0))> {};
+  template <> struct is_unsigned<unsigned short> : true_type {};
+  template <> struct is_unsigned<unsigned int> : true_type {};
+  template <> struct is_unsigned<unsigned long> : true_type {};
+  template <> struct is_unsigned<unsigned long long> : true_type {};
+  template <typename T> struct is_unsigned<const T> : is_unsigned<T> {};
+  template <typename T> struct is_unsigned<volatile T> : is_unsigned<T> {};
+  template <typename T> struct is_unsigned<const volatile T> : is_unsigned<T> {};
+
+  /// is_floating_point
+  ///\ingroup type_traits
+  template <typename T> struct is_floating_point : false_type {};
+  template <> struct is_floating_point<float> : true_type {};
+  template <> struct is_floating_point<double> : true_type {};
+  template <> struct is_floating_point<long double> : true_type {};
+  template <typename T> struct is_floating_point<const T> : is_floating_point<T> {};
+  template <typename T> struct is_floating_point<volatile T> : is_floating_point<T> {};
+  template <typename T> struct is_floating_point<const volatile T> : is_floating_point<T> {};
+
+  /// is_same
+  ///\ingroup type_traits
+  template <typename T1, typename T2> struct is_same : public false_type {};
+  template <typename T> struct is_same<T, T> : public true_type {};
+
+  /// is_void
+  ///\ingroup type_traits
+  template<typename T> struct is_void : false_type {};
+  template<> struct is_void<void> : true_type {};
+
+  /// is_arithmetic
+  ///\ingroup type_traits
+  template<typename T> struct is_arithmetic : integral_constant<bool, is_integral<T>::value || is_floating_point<T>::value> {};
+
+  /// is_fundamental
+  ///\ingroup type_traits
+  template <typename T> struct is_fundamental : integral_constant<bool, is_arithmetic<T>::value ||
+                                                                        is_void<T>::value  ||
+                                                                        is_same<std::nullptr_t,
+                                                                  typename remove_cv<T>::type>::value> {};
+
+  /// is_compound
+  ///\ingroup type_traits
+  template <typename T> struct is_compound : integral_constant<bool, !is_fundamental<T>::value> {};
+
+  /// is_array
+  ///\ingroup type_traits
+  template <typename T> struct is_array : false_type {};
+  template <typename T> struct is_array<T[]> : true_type {};
+  template <typename T, size_t MAXN> struct is_array<T[MAXN]> : true_type {};
+
+  /// is_pointer
+  ///\ingroup type_traits
+  template <typename T> struct is_pointer : false_type {};
+  template <typename T> struct is_pointer<T*> : true_type {};
+
+  /// is_reference
+  ///\ingroup type_traits
+  template <typename T> struct is_reference : false_type {};
+  template <typename T> struct is_reference<T&> : true_type {};
+
+  /// is_pod
+  /// For C++03, only fundamental and pointers types are recognised.
+  ///\ingroup type_traits
+#if defined(ETL_C11_TYPE_TRAITS_SUPPORTED)// && !defined(ETL_IN_UNIT_TEST)
+  // For compilers that support C++11
+  template <typename T> struct is_pod : std::is_pod<T> {};
+#else
+  /// For C++03, only fundamental and pointers types are recognised.
+  template <typename T> struct is_pod : etl::integral_constant<bool, etl::is_fundamental<T>::value ||
+    etl::is_pointer<T>::value> {};
+#endif
+
+#if defined(ETL_C11_TYPE_TRAITS_SUPPORTED) && defined(ETL_C11_TYPE_TRAITS_IS_TRIVIAL_SUPPORTED)// && !defined(ETL_IN_UNIT_TEST)
+  /// is_trivially_constructible
+  /// For C++03, only POD types are recognised.
+  ///\ingroup type_traits
+  template <typename T> struct is_trivially_constructible : std::is_trivially_constructible<T> {};
+
+  /// is_trivially_copy_constructible
+  /// For C++03, only POD types are recognised.
+  ///\ingroup type_traits
+  template <typename T> struct is_trivially_copy_constructible : std::is_trivially_copy_constructible<T> {};
+
+  /// is_trivially_destructible
+  /// For C++03, only POD types are recognised.
+  ///\ingroup type_traits
+  template <typename T> struct is_trivially_destructible : std::is_trivially_destructible<T> {};
+
+  /// is_trivially_copy_assignable
+  /// For C++03, only POD types are recognised.
+  ///\ingroup type_traits
+  template <typename T> struct is_trivially_copy_assignable : std::is_trivially_copy_assignable<T> {};
+#else
+  /// is_trivially_constructible
+  /// For C++03, only POD types are recognised.
+  ///\ingroup type_traits
+  template <typename T> struct is_trivially_constructible : etl::is_pod<T> {};
+
+  /// is_trivially_copy_constructible
+  /// For C++03, only POD types are recognised.
+  ///\ingroup type_traits
+  template <typename T> struct is_trivially_copy_constructible : etl::is_pod<T> {};
+
+  /// is_trivially_destructible
+  /// For C++03, only POD types are recognised.
+  ///\ingroup type_traits
+  template <typename T> struct is_trivially_destructible : etl::is_pod<T> {};
+
+  /// is_trivially_copy_assignable
+  /// For C++03, only POD types are recognised.
+  ///\ingroup type_traits
+  template <typename T> struct is_trivially_copy_assignable : etl::is_pod<T> {};
+#endif
+
+
+  /// conditional
+  ///\ingroup type_traits
+  template <bool B, typename T, typename F>  struct conditional { typedef T type; };
+  template <typename T, typename F> struct conditional<false, T, F> { typedef F type; };
+
+  /// make_signed
+  ///\ingroup type_traits
+  template <typename T> struct make_signed { typedef  T type; };
+  template <> struct make_signed<char> { typedef  signed char type; };
+  template <> struct make_signed<unsigned char> { typedef  signed char type; };
+
+  template <> struct make_signed<wchar_t>
+  {
+    typedef etl::conditional<sizeof(wchar_t) == sizeof(int16_t),
+                                    int16_t,
+                                    etl::conditional<sizeof(wchar_t) == sizeof(int32_t),
+                                                            int32_t,
+                                                            void>::type>::type type;
+  };
+
+  template <> struct make_signed<unsigned short> { typedef  short type; };
+  template <> struct make_signed<unsigned int> { typedef int type; };
+  template <> struct make_signed<unsigned long> { typedef  long type; };
+  template <> struct make_signed<unsigned long long> { typedef long long type; };
+  template <typename T> struct make_signed<const T> : add_const<typename make_signed<T>::type> {};
+  template <typename T> struct make_signed<volatile T> : add_volatile<typename make_signed<T>::type> {};
+  template <typename T> struct make_signed<const volatile T> : add_const<typename add_volatile<typename make_signed<T>::type>::type> {};
+
+  /// make_unsigned
+  ///\ingroup type_traits
+  template <typename T> struct make_unsigned { typedef  T type; };
+  template <> struct make_unsigned<char> { typedef unsigned char type; };
+  template <> struct make_unsigned<signed char> { typedef unsigned char type; };
+  template <> struct make_unsigned<short> { typedef unsigned short type; };
+
+  template <> struct make_unsigned<wchar_t>
+  {
+    typedef etl::conditional<sizeof(wchar_t) == sizeof(uint16_t),
+                                    uint16_t,
+                                    etl::conditional<sizeof(wchar_t) == sizeof(uint32_t),
+                                                     uint32_t,
+                                                     void>::type>::type type;
+  };
+
+  template <> struct make_unsigned<int> { typedef unsigned int type; };
+  template <> struct make_unsigned<long> { typedef unsigned long type; };
+  template <> struct make_unsigned<long long> { typedef unsigned long long type; };
+  template <typename T> struct make_unsigned<const T> : add_const<typename make_unsigned<T>::type> {};
+  template <typename T> struct make_unsigned<volatile T> : add_volatile<typename make_unsigned<T>::type> {};
+  template <typename T> struct make_unsigned<const volatile T> : add_const<typename add_volatile<typename make_unsigned<T>::type>::type> {};
+
+  /// enable_if
+  ///\ingroup type_traits
+  template <bool B, typename T = void> struct enable_if {};
+  template <typename T> struct enable_if<true, T> { typedef T type; };
+
+  /// extent
+  ///\ingroup type_traits
+  template <typename T, size_t MAXN = 0>
+  struct extent : integral_constant<size_t, 0> {};
+
+  template <typename T>
+  struct extent<T[], 0> : integral_constant<size_t, 0> {};
+
+  template <typename T, size_t MAXN>
+  struct extent<T[], MAXN> : integral_constant<size_t, extent<T, MAXN - 1>::value> {};
+
+  template <typename T, size_t MAXN>
+  struct extent<T[MAXN], 0> : integral_constant<size_t, MAXN> {};
+
+  template <typename T, size_t I, size_t MAXN>
+  struct extent<T[I], MAXN> : integral_constant<size_t, extent<T, MAXN - 1>::value> {};
+
+  /// remove_extent
+  ///\ingroup type_traits
+  template <typename T> struct remove_extent { typedef T type; };
+  template <typename T> struct remove_extent<T[]> { typedef T type; };
+  template <typename T, size_t MAXN> struct remove_extent<T[MAXN]> { typedef T type;};
+
+  /// remove_all_extents
+  ///\ingroup type_traits
+  template <typename T> struct remove_all_extents { typedef T type;};
+  template <typename T> struct remove_all_extents<T[]> { typedef typename remove_all_extents<T>::type type; };
+  template <typename T, size_t MAXN> struct remove_all_extents<T[MAXN]> { typedef typename remove_all_extents<T>::type type; };
+
+  /// rank
+  ///\ingroup type_traits
+  template <typename T>struct rank : integral_constant<size_t, 0> {};
+  template <typename T> struct rank<T[]> : public integral_constant<size_t, rank<T>::value + 1> {};
+  template <typename T, size_t MAXN> struct rank<T[MAXN]> : public integral_constant<size_t, rank<T>::value + 1> {};
+
+  /// decay
+  ///\ingroup type_traits
+  template <typename T>
+  struct decay
+  {
+    typedef typename etl::remove_reference<T>::type U;
+    typedef typename etl::conditional<etl::is_array<U>::value,
+                                      typename etl::remove_extent<U>::type*,
+                                      typename etl::remove_cv<U>::type>::type type;
+  };
+
+  /// is_base_of
+  ///\ingroup type_traits
+  template<class TBase, class TDerived>
+  struct is_base_of
+  {
+  private:
+
+    template<typename T> struct dummy {};
+    struct internal: TDerived, dummy<int>{};
+
+    static TBase* check(TBase*);
+    template<typename T> static char check(dummy<T>*);
+
+  public:
+
+    static const bool value = (sizeof(check((internal*)0)) == sizeof(TBase*));
+  };
+
+  /// Alignment templates.
+  /// These require compiler specific intrinsics.
+  ///\ingroup type_traits
+#ifdef ETL_COMPILER_MICROSOFT
+  template <typename T> struct alignment_of : integral_constant<size_t, size_t(__alignof(T))> {};
+#endif
+
+#ifdef ETL_COMPILER_GCC
+  template <typename T> struct alignment_of : integral_constant<size_t, size_t(__alignof__(T))> {};
+#endif
+
+#ifdef ETL_COMPILER_KEIL
+  template <typename T> struct alignment_of : integral_constant<size_t, size_t(__alignof__(T))> {};
+#endif
+
+#ifdef ETL_COMPILER_IAR
+  template <typename T> struct alignment_of : integral_constant<size_t, size_t(__ALIGNOF__(T))> {};
+#endif
+
+#ifdef ETL_COMPILER_TI
+  template <typename T> struct alignment_of : integral_constant<size_t, size_t(__ALIGNOF__(T))> {};
+#endif
+
+  /// Specialisation of 'alignment_of' for 'void'.
+  ///\ingroup type_traits
+  template <> struct alignment_of<void> : integral_constant <size_t, 0>{};
+
+  /*[[[cog
+  import cog
+  cog.outl("//***************************************************************************")
+  cog.outl("/// Template to determine if a type is one of a specified list.")
+  cog.outl("///\ingroup types")
+  cog.outl("//***************************************************************************")
+  cog.outl("template <typename T,")
+  cog.out("          ")
+  cog.out("typename T1, ")
+  for n in range(2, int(IsOneOf)):
+      cog.out("typename T%s = void, " % n)
+      if n % 4 == 0:
+          cog.outl("")
+          cog.out("          ")
+  cog.outl("typename T%s = void>" % IsOneOf)
+  cog.outl("struct is_one_of")
+  cog.outl("{")
+  cog.outl("  static const bool value = ")
+  for n in range(1, int(IsOneOf)):
+      cog.outl("      etl::is_same<T, T%s>::value ||" % n)
+  cog.outl("      etl::is_same<T, T%s>::value;" % IsOneOf)
+  cog.outl("};")
+  ]]]*/
+  /*[[[end]]]*/
+}
+
+#endif
diff --git a/src/user_type.h b/src/user_type.h
index 98837a92..4ecb193c 100644
--- a/src/user_type.h
+++ b/src/user_type.h
@@ -89,43 +89,16 @@ SOFTWARE.
     TypeName operator ++(int) { TypeName temp(*this); TypeName::operator ++(); return temp; } \
     TypeName& operator --() { --value; return *this; } \
     TypeName operator --(int) { TypeName temp(*this); TypeName::operator --(); return temp; } \
-    TypeName& operator +=(const TypeName& rhs) { value += rhs.value; return *this; } \
-    TypeName& operator -=(const TypeName& rhs) { value -= rhs.value; return *this; } \
-    TypeName& operator *=(const TypeName& rhs) { value *= rhs.value; return *this; } \
-    TypeName& operator /=(const TypeName& rhs) { value /= rhs.value; return *this; } \
-    TypeName& operator %=(const TypeName& rhs) { value %= rhs.value; return *this; } \
-    TypeName& operator &=(const TypeName& rhs) { value &= rhs.value; return *this; } \
-    TypeName& operator &=(ValueType mask) { value &= mask; return *this; } \
-    TypeName& operator |=(const TypeName& rhs) { value |= rhs.value; return *this; } \
-    TypeName& operator |=(ValueType mask) { value &= mask; return *this; } \
-    TypeName& operator ^=(const TypeName& rhs) { value ^= rhs.value; return *this; } \
-    TypeName& operator ^=(ValueType mask) { value ^= mask; return *this; } \
+    TypeName& operator +=(const ValueType& rhs) { value += rhs; return *this; } \
+    TypeName& operator -=(const ValueType& rhs) { value -= rhs; return *this; } \
+    TypeName& operator *=(const ValueType& rhs) { value *= rhs; return *this; } \
+    TypeName& operator /=(const ValueType& rhs) { value /= rhs; return *this; } \
+    TypeName& operator %=(const ValueType& rhs) { value %= rhs; return *this; } \
+    TypeName& operator &=(const ValueType& rhs) { value &= rhs; return *this; } \
+    TypeName& operator |=(const ValueType& rhs) { value |= rhs; return *this; } \
+    TypeName& operator ^=(const ValueType& rhs) { value ^= rhs; return *this; } \
     TypeName& operator <<=(ValueType distance) { value <<= distance; return *this; } \
     TypeName& operator >>=(ValueType distance) { value >>= distance; return *this; } \
-    \
-    /* Volatile definitions.*/ \
-    TypeName(const volatile TypeName &other) : value(other.value) {} \
-    void operator=(const volatile TypeName &other) volatile { value = other.value; } \
-    operator ValueType() volatile const { return value; } \
-    volatile ValueType& get() volatile { return value; } \
-    const volatile ValueType& get() volatile const { return value; } \
-    void operator ++() volatile { ++value; } \
-    volatile TypeName operator ++(int) volatile { volatile TypeName temp(*this); TypeName::operator ++(); return temp; } \
-    void operator --() volatile { --value; } \
-    volatile TypeName operator --(int) volatile { volatile TypeName temp(*this); TypeName::operator --(); return temp; } \
-    void operator +=(const volatile TypeName& rhs) volatile { value += rhs.value; } \
-    void operator -=(const volatile TypeName& rhs) volatile { value -= rhs.value; } \
-    void operator *=(const volatile TypeName& rhs) volatile { value *= rhs.value; } \
-    void operator /=(const volatile TypeName& rhs) volatile { value /= rhs.value; } \
-    void operator %=(const volatile TypeName& rhs) volatile { value %= rhs.value; } \
-    void operator &=(const volatile TypeName& rhs) volatile { value &= rhs.value; } \
-    void operator &=(ValueType mask) volatile { value &= mask; } \
-    void operator |=(const volatile TypeName& rhs) volatile { value |= rhs.value; } \
-    void operator |=(ValueType mask) volatile { value &= mask; } \
-    void operator ^=(const volatile TypeName& rhs) volatile { value ^= rhs.value; } \
-    void operator ^=(ValueType mask) volatile { value ^= mask; } \
-    void operator <<=(ValueType distance) volatile { value <<= distance; } \
-    void operator >>=(ValueType distance) volatile { value >>= distance; } \
   private: \
     ValueType value; \
   public: \
diff --git a/src/variant.h b/src/variant.h
index 6b2931eb..0d57a4a4 100644
--- a/src/variant.h
+++ b/src/variant.h
@@ -5,7 +5,7 @@ The MIT License(MIT)
 
 Embedded Template Library.
 https://github.com/ETLCPP/etl
-http://www.etlcpp.com
+https://www.etlcpp.com
 
 Copyright(c) 2014 jwellbelove
 
@@ -42,7 +42,6 @@ SOFTWARE.
 #include "static_assert.h"
 #include "alignment.h"
 #include "error_handler.h"
-#include "largest.h"
 
 #if defined(ETL_COMPILER_KEIL)
   #pragma diag_suppress 940
@@ -124,6 +123,11 @@ namespace etl
     //***************************************************************************
     typedef typename largest_type<T1, T2, T3, T4, T5, T6, T7, T8>::type largest_t;
 
+    //***************************************************************************
+    /// The largest size.
+    //***************************************************************************
+    static const size_t SIZE = sizeof(largest_t);
+
     //***************************************************************************
     /// The largest alignment.
     //***************************************************************************
@@ -139,46 +143,6 @@ namespace etl
     //***************************************************************************
     static const type_id_t UNSUPPORTED_TYPE_ID = integral_limits<type_id_t>::max;
 
-    //***************************************************************************
-    /// Do we pass this type by value?
-    //***************************************************************************
-    template <typename T>
-    struct pass_by_value : integral_constant<bool, etl::is_fundamental<T>::value || etl::is_pointer<T>::value>
-    {
-    };
-
-    //***************************************************************************
-    /// Define the type for a parameter.
-    //***************************************************************************
-    template <typename T, bool>
-    struct type_definition;
-
-    //***************************************************************************
-    /// Pass by value.
-    //***************************************************************************
-    template <typename T>
-    struct type_definition<T, true>
-    {
-      typedef T type;
-    };
-
-    //***************************************************************************
-    /// Pass by const reference.
-    //***************************************************************************
-    template <typename T>
-    struct type_definition<T, false>
-    {
-      typedef const T& type;
-    };
-
-    //***************************************************************************
-    /// Determines the type for parameters.
-    //***************************************************************************
-    template <typename T>
-    struct parameter_type : public type_definition<T, pass_by_value<T>::value>
-    {
-    };
-
     //***************************************************************************
     /// Short form of no_type placeholders.
     //***************************************************************************
@@ -249,14 +213,14 @@ namespace etl
 
       friend class variant;
 
-      virtual void read(typename parameter_type<R1>::type value) = 0;
-      virtual void read(typename parameter_type<R2>::type value) = 0;
-      virtual void read(typename parameter_type<R3>::type value) = 0;
-      virtual void read(typename parameter_type<R4>::type value) = 0;
-      virtual void read(typename parameter_type<R5>::type value) = 0;
-      virtual void read(typename parameter_type<R6>::type value) = 0;
-      virtual void read(typename parameter_type<R7>::type value) = 0;
-      virtual void read(typename parameter_type<R8>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R1>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R2>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R3>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R4>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R5>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R6>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R7>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R8>::type value) = 0;
     };
 
     //*************************************************************************
@@ -269,13 +233,13 @@ namespace etl
 
       friend class variant;
 
-      virtual void read(typename parameter_type<R1>::type value) = 0;
-      virtual void read(typename parameter_type<R2>::type value) = 0;
-      virtual void read(typename parameter_type<R3>::type value) = 0;
-      virtual void read(typename parameter_type<R4>::type value) = 0;
-      virtual void read(typename parameter_type<R5>::type value) = 0;
-      virtual void read(typename parameter_type<R6>::type value) = 0;
-      virtual void read(typename parameter_type<R7>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R1>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R2>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R3>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R4>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R5>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R6>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R7>::type value) = 0;
 
     private:
 
@@ -292,12 +256,12 @@ namespace etl
 
       friend class variant;
 
-      virtual void read(typename parameter_type<R1>::type value) = 0;
-      virtual void read(typename parameter_type<R2>::type value) = 0;
-      virtual void read(typename parameter_type<R3>::type value) = 0;
-      virtual void read(typename parameter_type<R4>::type value) = 0;
-      virtual void read(typename parameter_type<R5>::type value) = 0;
-      virtual void read(typename parameter_type<R6>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R1>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R2>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R3>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R4>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R5>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R6>::type value) = 0;
 
     private:
 
@@ -315,11 +279,11 @@ namespace etl
 
       friend class variant;
 
-      virtual void read(typename parameter_type<R1>::type value) = 0;
-      virtual void read(typename parameter_type<R2>::type value) = 0;
-      virtual void read(typename parameter_type<R3>::type value) = 0;
-      virtual void read(typename parameter_type<R4>::type value) = 0;
-      virtual void read(typename parameter_type<R5>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R1>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R2>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R3>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R4>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R5>::type value) = 0;
 
     private:
 
@@ -338,10 +302,10 @@ namespace etl
 
       friend class variant;
 
-      virtual void read(typename parameter_type<R1>::type value) = 0;
-      virtual void read(typename parameter_type<R2>::type value) = 0;
-      virtual void read(typename parameter_type<R3>::type value) = 0;
-      virtual void read(typename parameter_type<R4>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R1>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R2>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R3>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R4>::type value) = 0;
 
     private:
 
@@ -361,9 +325,9 @@ namespace etl
 
       friend class variant;
 
-      virtual void read(typename parameter_type<R1>::type value) = 0;
-      virtual void read(typename parameter_type<R2>::type value) = 0;
-      virtual void read(typename parameter_type<R3>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R1>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R2>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R3>::type value) = 0;
 
     private:
 
@@ -384,8 +348,8 @@ namespace etl
 
       friend class variant;
 
-      virtual void read(typename parameter_type<R1>::type value) = 0;
-      virtual void read(typename parameter_type<R2>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R1>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R2>::type value) = 0;
 
     private:
 
@@ -407,7 +371,7 @@ namespace etl
 
       friend class variant;
 
-      virtual void read(typename parameter_type<R1>::type value) = 0;
+      virtual void read(typename etl::parameter_type<R1>::type value) = 0;
 
     private:
 
@@ -862,7 +826,7 @@ namespace etl
     //***************************************************************************
     void clear()
     {
-      type_id = UNSUPPORTED_TYPE_ID;
+      destruct_current();
     }
 
     //***************************************************************************
@@ -962,7 +926,7 @@ namespace etl
     /// The internal storage.
     /// Aligned on a suitable boundary, which should be good for all types.
     //***************************************************************************
-    typename etl::aligned_storage<sizeof(largest_t), etl::largest_alignment<T1, T2, T3, T4, T5, T6, T7, T8>::value>::type data;
+    typename etl::aligned_storage<SIZE, ALIGNMENT>::type data;
 
     //***************************************************************************
     /// The id of the current stored type.
diff --git a/temp/message_router.h b/temp/message_router.h
new file mode 100644
index 00000000..85d95fe0
--- /dev/null
+++ b/temp/message_router.h
@@ -0,0 +1,984 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_MESSAGE_ROUTER__
+#define __ETL_MESSAGE_ROUTER__
+
+#include <stdint.h>
+
+namespace etl
+{
+  /// Allow alternative type for message id.
+#if !defined(ETL_MESSAGE_ID_TYPE)
+    typedef uint_least8_t message_id_t;
+#else
+    typedef ETL_MESSAGE_ID_TYPE message_id_t;
+#endif
+
+  //***************************************************************************
+  class imessage
+  {
+  public:
+
+    virtual ~imessage() {}
+    virtual etl::message_id_t get_message_id() const = 0;
+  };
+
+  //***************************************************************************
+  template <const size_t ID_>
+  class message : public imessage
+  {
+  public:
+
+    enum
+    {
+      ID = ID_
+    };
+
+    //*******************************************
+    etl::message_id_t get_message_id() const
+    {
+      return etl::message_id_t(ID);
+    }
+  };
+
+  //***************************************************************************
+  class imessage_router
+  {
+  public:
+
+    virtual ~imessage_router() {}
+    virtual void receive(const etl::imessage& message) = 0;
+    virtual void receive(imessage_router& source, const etl::imessage& message) = 0;
+    virtual bool accepts(etl::message_id_t id) const = 0;
+
+    //*******************************************
+    bool accepts(const etl::imessage& msg) const
+    {
+      return accepts(msg.get_message_id());
+    }
+
+    //*******************************************
+    void send_message(imessage_router& destination,
+                      const etl::imessage& message)
+    {
+      destination.receive(*this, message);
+    }
+  };
+
+  //***************************************************************************
+  /// This router can be used either as a sink for messages
+  /// or as a producer-only of messages such an interrupt routine.
+  //***************************************************************************
+  class null_message_router : public imessage_router
+  {
+  public:
+
+    //*******************************************
+    void receive(const etl::imessage& message)
+    {
+    }
+
+    //*******************************************
+    void receive(etl::imessage_router& source, const etl::imessage& message)
+    {
+    }
+
+    //*******************************************
+    bool accepts(etl::message_id_t id) const
+    {
+      return false;
+    }
+
+    //*******************************************
+    static null_message_router& get()
+    {
+      static null_message_router instance;
+      return instance;
+    }
+  };
+
+  //***************************************************************************
+  /// Send a message to a router.
+  /// Sets the 'sender' to etl::null_message_router type.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_router& destination,
+                                  const etl::imessage&  message)
+  {
+    destination.receive(message);
+  }
+
+  //***************************************************************************
+  /// Send a message to a router.
+  //***************************************************************************
+  inline static void send_message(etl::imessage_router& source,
+                                  etl::imessage_router& destination,
+                                  const etl::imessage&  message)
+  {
+    destination.receive(source, message);
+  }
+
+  //***************************************************************************
+  // To generate to header file, run this at the command line.
+  // Note: You will need Python and COG installed.
+  //
+  // python -m cogapp -d -e -omessage_router.h -DHandlers=<n> message_router_generator.h
+  // Where <n> is the number of messages to support.
+  //
+  // e.g.
+  // To generate handlers for up to 16 messages...
+  // python -m cogapp -d -e -omessage_router.h -DHandlers=16 message_router_generator.h
+  //
+  // See CreateMessageProcessor.bat
+  //***************************************************************************
+
+  //***************************************************************************
+  // The code below has been auto generated. Do not manually edit.
+  //***************************************************************************
+
+  //***************************************************************************
+  // The definition for all 16 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2 = void, typename T3 = void, typename T4 = void,
+            typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void,
+            typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void,
+            typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
+  class message_router  : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const etl::message_id_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        case T14::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T14&>(msg)); break;
+        case T15::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T15&>(msg)); break;
+        case T16::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T16&>(msg)); break;
+        default:  static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID:
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID: case T13::ID: case T14::ID: case T15::ID: case T16::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 15 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6, typename T7, typename T8,
+            typename T9, typename T10, typename T11, typename T12,
+            typename T13, typename T14, typename T15>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        case T14::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T14&>(msg)); break;
+        case T15::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T15&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID:
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID: case T13::ID: case T14::ID: case T15::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 14 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6, typename T7, typename T8,
+            typename T9, typename T10, typename T11, typename T12,
+            typename T13, typename T14>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        case T14::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T14&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID:
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID: case T13::ID: case T14::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 13 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6, typename T7, typename T8,
+            typename T9, typename T10, typename T11, typename T12,
+            typename T13>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID:
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID: case T13::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 12 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6, typename T7, typename T8,
+            typename T9, typename T10, typename T11, typename T12>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID:
+        case T9::ID: case T10::ID: case T11::ID: case T12::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 11 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6, typename T7, typename T8,
+            typename T9, typename T10, typename T11>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID:
+        case T9::ID: case T10::ID: case T11::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 10 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6, typename T7, typename T8,
+            typename T9, typename T10>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID:
+        case T9::ID: case T10::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 9 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6, typename T7, typename T8,
+            typename T9>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID:
+        case T9::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 8 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6, typename T7, typename T8>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID: case T8::ID:
+
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 7 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6, typename T7>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID: case T7::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 6 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5, typename T6>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID: case T6::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 5 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4,
+            typename T5>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID: case T5::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 4 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3, typename T4>
+  class message_router<TProcessor, T1, T2, T3, T4, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID: case T4::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 3 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2, typename T3>
+  class message_router<TProcessor, T1, T2, T3, void, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID: case T3::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+
+    class message_packet
+    {
+    public:
+
+      explicit message_packet(const imessage& msg)
+      {
+        const etl::message_id_t id = msg.get_message_id();
+
+        switch (id)
+        {
+          case T1::ID: new (&storage) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: new (&storage) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: new (&storage) T3(static_cast<const T3&>(msg)); break;
+          default: break;
+        }
+      }
+
+      ~message_packet()
+      {
+        static_cast<const etl::imessage*>(storage).~imessage();
+      }
+
+      message_packet(const message_packet& other)
+      {
+        const etl::message_id_t id = other.get_imessage().get_message_id();
+
+        switch (id)
+        {
+          case T1::ID: new (&storage) T1(static_cast<const T1&>(msg)); break;
+          case T2::ID: new (&storage) T2(static_cast<const T2&>(msg)); break;
+          case T3::ID: new (&storage) T3(static_cast<const T3&>(msg)); break;
+          default: break;
+        }
+      }
+
+      message_packet& operator = (const message_packet& other)
+      {
+        if (this != &other)
+        {
+          static_cast<const etl::imessage*>(storage).~imessage();
+          new (this) message_packet(other);
+        }
+      }
+
+      const etl::imessage& get_imessage() const
+      {
+        return *reiniterpret_cast<const imessage*>(storage);
+      }
+
+      operator const imessage&() const
+      {
+        return get_imessage();
+      }
+
+    private:
+
+      etl::aligned_storage<etl::largest<T1, T2, T3>::size, etl::largest_alignment<T1, T2, T3>::value>::type storage;
+    };
+  };
+
+  //***************************************************************************
+  // Specialisation for 2 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2>
+  class message_router<TProcessor, T1, T2, void, void, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID: case T2::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 1 message type.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1>
+  class message_router<TProcessor, T1, void, void, void, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const etl::imessage& msg)
+    {
+      receive(etl::null_message_router::get(), msg);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+
+    bool accepts(etl::message_id_t id) const
+    {
+      switch (id)
+      {
+        case T1::ID:
+          return true; break;
+        default:
+          return false; break;
+      }
+    }
+  };
+}
+
+#endif
diff --git a/test/codeblocks/ETL.cbp b/test/codeblocks/ETL.cbp
index 963db74b..60485a23 100644
--- a/test/codeblocks/ETL.cbp
+++ b/test/codeblocks/ETL.cbp
@@ -172,6 +172,8 @@
 		<Unit filename="../../src/fnv_1.h" />
 		<Unit filename="../../src/forward_list.h" />
 		<Unit filename="../../src/frame_check_sequence.h" />
+		<Unit filename="../../src/fsm.h" />
+		<Unit filename="../../src/fsm_generator.h" />
 		<Unit filename="../../src/function.h" />
 		<Unit filename="../../src/functional.h" />
 		<Unit filename="../../src/functors.h" />
@@ -193,12 +195,17 @@
 		<Unit filename="../../src/iterator.h" />
 		<Unit filename="../../src/jenkins.h" />
 		<Unit filename="../../src/largest.h" />
+		<Unit filename="../../src/largest_generator.h" />
 		<Unit filename="../../src/list.h" />
 		<Unit filename="../../src/log.h" />
 		<Unit filename="../../src/map.h" />
 		<Unit filename="../../src/memory.h" />
+		<Unit filename="../../src/message_bus.h" />
 		<Unit filename="../../src/message_processor.h" />
 		<Unit filename="../../src/message_processor_generator.h" />
+		<Unit filename="../../src/message_router.h" />
+		<Unit filename="../../src/message_router_generator.h" />
+		<Unit filename="../../src/message_types.h" />
 		<Unit filename="../../src/multimap.h" />
 		<Unit filename="../../src/multiset.h" />
 		<Unit filename="../../src/murmur3.h" />
@@ -206,6 +213,7 @@
 		<Unit filename="../../src/numeric.h" />
 		<Unit filename="../../src/observer.h" />
 		<Unit filename="../../src/optional.h" />
+		<Unit filename="../../src/packet.h" />
 		<Unit filename="../../src/parameter_type.h" />
 		<Unit filename="../../src/pearson.cpp" />
 		<Unit filename="../../src/pearson.h" />
@@ -226,12 +234,16 @@
 		<Unit filename="../../src/reference_flat_multimap.h" />
 		<Unit filename="../../src/reference_flat_multiset.h" />
 		<Unit filename="../../src/reference_flat_set.h" />
+		<Unit filename="../../src/scheduler.h" />
 		<Unit filename="../../src/set.h" />
 		<Unit filename="../../src/smallest.h" />
+		<Unit filename="../../src/smallest_generator.h" />
 		<Unit filename="../../src/stack.h" />
 		<Unit filename="../../src/static_assert.h" />
+		<Unit filename="../../src/task.h" />
 		<Unit filename="../../src/type_def.h" />
 		<Unit filename="../../src/type_traits.h" />
+		<Unit filename="../../src/type_traits_generator.h" />
 		<Unit filename="../../src/u16string.h" />
 		<Unit filename="../../src/u32string.h" />
 		<Unit filename="../../src/unordered_map.h" />
@@ -273,6 +285,7 @@
 		<Unit filename="../test_flat_set.cpp" />
 		<Unit filename="../test_fnv_1.cpp" />
 		<Unit filename="../test_forward_list.cpp" />
+		<Unit filename="../test_fsm.cpp" />
 		<Unit filename="../test_function.cpp" />
 		<Unit filename="../test_functional.cpp" />
 		<Unit filename="../test_hash.cpp" />
@@ -291,12 +304,15 @@
 		<Unit filename="../test_map.cpp" />
 		<Unit filename="../test_maths.cpp" />
 		<Unit filename="../test_memory.cpp" />
+		<Unit filename="../test_message_bus.cpp" />
+		<Unit filename="../test_message_router.cpp" />
 		<Unit filename="../test_multimap.cpp" />
 		<Unit filename="../test_multiset.cpp" />
 		<Unit filename="../test_murmur3.cpp" />
 		<Unit filename="../test_numeric.cpp" />
 		<Unit filename="../test_observer.cpp" />
 		<Unit filename="../test_optional.cpp" />
+		<Unit filename="../test_packet.cpp" />
 		<Unit filename="../test_pearson.cpp" />
 		<Unit filename="../test_pool.cpp" />
 		<Unit filename="../test_priority_queue.cpp" />
@@ -314,12 +330,14 @@
 		<Unit filename="../test_string_u16.cpp" />
 		<Unit filename="../test_string_u32.cpp" />
 		<Unit filename="../test_string_wchar_t.cpp" />
+		<Unit filename="../test_task_scheduler.cpp" />
 		<Unit filename="../test_type_def.cpp" />
 		<Unit filename="../test_type_traits.cpp" />
 		<Unit filename="../test_unordered_map.cpp" />
 		<Unit filename="../test_unordered_multimap.cpp" />
 		<Unit filename="../test_unordered_multiset.cpp" />
 		<Unit filename="../test_unordered_set.cpp" />
+		<Unit filename="../test_user_type.cpp" />
 		<Unit filename="../test_utility.cpp" />
 		<Unit filename="../test_variant.cpp" />
 		<Unit filename="../test_vector.cpp" />
diff --git a/test/codeblocks/ETL.depend b/test/codeblocks/ETL.depend
index c4e17a7b..1b6a961c 100644
--- a/test/codeblocks/ETL.depend
+++ b/test/codeblocks/ETL.depend
@@ -3289,7 +3289,7 @@
 	"CurrentTest.h"
 	"ReportAssertImpl.h"
 
-1501066687 source:d:\users\john\documents\programming\github\etl\test\test_algorithm.cpp
+1501803139 source:d:\users\john\documents\programming\github\etl\test\test_algorithm.cpp
 	"UnitTest++.h"
 	"algorithm.h"
 	"container.h"
@@ -3538,7 +3538,7 @@
 	"static_assert.h"
 	"exception.h"
 
-1501067284 source:d:\users\john\documents\programming\github\etl\test\test_deque.cpp
+1501803126 source:d:\users\john\documents\programming\github\etl\test\test_deque.cpp
 	"UnitTest++.h"
 	"ExtraCheckMacros.h"
 	"deque.h"
@@ -3727,7 +3727,7 @@
 
 1482623723 v_1.h"
 
-1497713618 source:d:\users\john\documents\programming\github\etl\test\test_forward_list.cpp
+1501803126 source:d:\users\john\documents\programming\github\etl\test\test_forward_list.cpp
 	"UnitTest++.h"
 	"ExtraCheckMacros.h"
 	"data.h"
@@ -4151,12 +4151,12 @@
 	"../exception.h"
 	"../error_handler.h"
 
-1500986416 source:d:\users\john\documents\programming\github\etl\test\test_type_traits.cpp
+1501803140 source:d:\users\john\documents\programming\github\etl\test\test_type_traits.cpp
 	"UnitTest++.h"
 	"type_traits.h"
 	<type_traits>
 
-1500986416 source:d:\users\john\documents\programming\github\etl\test\test_variant.cpp
+1501803140 source:d:\users\john\documents\programming\github\etl\test\test_variant.cpp
 	"UnitTest++.h"
 	"ExtraCheckMacros.h"
 	"variant.h"
@@ -5302,7 +5302,7 @@
 	"platform.h"
 	"static_assert.h"
 
-1501066686 d:\users\john\documents\programming\github\etl\src\algorithm.h
+1502118978 d:\users\john\documents\programming\github\etl\src\algorithm.h
 	<algorithm>
 	<iterator>
 	<utility>
@@ -5312,7 +5312,7 @@
 	"iterator.h"
 	"type_traits.h"
 
-1501066686 d:\users\john\documents\programming\github\etl\src\type_traits.h
+1502118978 d:\users\john\documents\programming\github\etl\src\type_traits.h
 	<stddef.h>
 	"platform.h"
 	"nullptr.h"
@@ -5322,7 +5322,7 @@
 	<stddef.h>
 	<iterator>
 
-1500986416 d:\users\john\documents\programming\github\etl\src\alignment.h
+1502118978 d:\users\john\documents\programming\github\etl\src\alignment.h
 	<stdint.h>
 	"type_traits.h"
 	"static_assert.h"
@@ -5370,7 +5370,7 @@
 	<stdint.h>
 	"log.h"
 
-1501066686 d:\users\john\documents\programming\github\etl\src\smallest.h
+1502118978 d:\users\john\documents\programming\github\etl\src\smallest.h
 	<stdint.h>
 	"integral_limits.h"
 
@@ -5484,7 +5484,7 @@
 	"static_assert.h"
 	"exception.h"
 
-1501067284 d:\users\john\documents\programming\github\etl\src\deque.h
+1501803126 d:\users\john\documents\programming\github\etl\src\deque.h
 	<stddef.h>
 	<stdint.h>
 	<iterator>
@@ -5561,7 +5561,7 @@
 	"../error_handler.h"
 	"../debug_count.h"
 
-1501067284 d:\users\john\documents\programming\github\etl\src\vector.h
+1501803126 d:\users\john\documents\programming\github\etl\src\vector.h
 	<type_traits>
 	<stddef.h>
 	<stdint.h>
@@ -5606,7 +5606,7 @@
 	"../ivector.h"
 	"../error_handler.h"
 
-1497713617 d:\users\john\documents\programming\github\etl\src\forward_list.h
+1501803126 d:\users\john\documents\programming\github\etl\src\forward_list.h
 	<iterator>
 	<algorithm>
 	<functional>
@@ -5703,12 +5703,12 @@
 	"nullptr.h"
 	"parameter_type.h"
 
-1501067284 d:\users\john\documents\programming\github\etl\src\largest.h
+1502118978 d:\users\john\documents\programming\github\etl\src\largest.h
 	"type_traits.h"
 	"smallest.h"
 	"static_assert.h"
 
-1501067284 d:\users\john\documents\programming\github\etl\src\list.h
+1502118941 d:\users\john\documents\programming\github\etl\src\list.h
 	<iterator>
 	<algorithm>
 	<functional>
@@ -5930,7 +5930,7 @@
 	"exception.h"
 	"error_handler.h"
 
-1500986416 d:\users\john\documents\programming\github\etl\src\variant.h
+1501803139 d:\users\john\documents\programming\github\etl\src\variant.h
 	<stdint.h>
 	"platform.h"
 	"array.h"
@@ -5941,7 +5941,6 @@
 	"static_assert.h"
 	"alignment.h"
 	"error_handler.h"
-	"largest.h"
 
 1479515291 d:\users\john\documents\programming\github\etl\src\visitor.h
 
@@ -7825,7 +7824,7 @@
 	<iterator>
 	"type_traits.h"
 
-1501066686 d:\users\john\documents\programming\github\etl\src\memory.h
+1502118978 d:\users\john\documents\programming\github\etl\src\memory.h
 	<iterator>
 	<algorithm>
 	"type_traits.h"
@@ -7835,10 +7834,10 @@
 	<assert.h>
 	"platform.h"
 
-1501067284 source:d:\users\john\documents\programming\github\etl\src\random.cpp
+1501803126 source:d:\users\john\documents\programming\github\etl\src\random.cpp
 	"random.h"
 
-1501067284 d:\users\john\documents\programming\github\etl\src\random.h
+1501803126 d:\users\john\documents\programming\github\etl\src\random.h
 	<stdint.h>
 
 1494277861 source:d:\users\john\documents\programming\github\etl\test\test_intrusive_flat_map.cpp
@@ -7933,7 +7932,7 @@
 	"UnitTest++.h"
 	"iterator.h"
 
-1500986416 source:d:\users\john\documents\programming\github\etl\test\test_memory.cpp
+1501803139 source:d:\users\john\documents\programming\github\etl\test\test_memory.cpp
 	"UnitTest++.h"
 	"memory.h"
 	"debug_count.h"
@@ -7944,7 +7943,7 @@
 	<stdint.h>
 	<vector>
 
-1501067284 source:d:\users\john\documents\programming\github\etl\test\test_random.cpp
+1501803126 source:d:\users\john\documents\programming\github\etl\test\test_random.cpp
 	"UnitTest++.h"
 	<stdint.h>
 	"random.h"
@@ -7952,7 +7951,7 @@
 	<algorithm>
 	<fstream>
 
-1501067284 source:d:\users\john\documents\programming\github\etl\test\test_vector_non_trivial.cpp
+1501803126 source:d:\users\john\documents\programming\github\etl\test\test_vector_non_trivial.cpp
 	"UnitTest++.h"
 	<vector>
 	<array>
@@ -8229,3 +8228,133 @@
 	"exception.h"
 	"vector.h"
 
+1479515291 source:d:\users\john\documents\programming\github\etl\test\test_compile.cpp
+	"algorithm.h"
+	"alignment.h"
+	"array.h"
+	"bitset.h"
+	"container.h"
+	"crc8_ccitt.h"
+	"crc16.h"
+	"crc16_ccitt.h"
+	"crc16_kermit.h"
+	"crc32.h"
+	"crc64_ecma.h"
+	"cyclic_value.h"
+	"deque.h"
+	"io_port.h"
+	"vector.h"
+	"variant.h"
+	"list.h"
+	"map.h"
+	<algorithm>
+
+1501803139 source:d:\users\john\documents\programming\github\etl\test\test_fsm.cpp
+	"UnitTest++.h"
+	"fsm.h"
+	"enum_type.h"
+	"container.h"
+	<iostream>
+
+1501803139 d:\users\john\documents\programming\github\etl\src\fsm.h
+	<stdint.h>
+	"array.h"
+	"nullptr.h"
+	"error_handler.h"
+	"exception.h"
+	"user_type.h"
+	"message_router.h"
+	"integral_limits.h"
+	"largest.h"
+
+1501803139 d:\users\john\documents\programming\github\etl\src\user_type.h
+
+1501803139 d:\users\john\documents\programming\github\etl\src\message_router.h
+	<stdint.h>
+	"message.h"
+	"message_types.h"
+	"alignment.h"
+	"error_handler.h"
+	"exception.h"
+	"largest.h"
+
+1501803140 source:d:\users\john\documents\programming\github\etl\test\test_message_router.cpp
+	"UnitTest++.h"
+	"ExtraCheckMacros.h"
+	"message_router.h"
+	"queue.h"
+	"largest.h"
+	"packet.h"
+
+1501803139 d:\users\john\documents\programming\github\etl\src\packet.h
+	"platform.h"
+	"static_assert.h"
+	"alignment.h"
+
+1501803140 source:d:\users\john\documents\programming\github\etl\test\test_packet.cpp
+	"UnitTest++.h"
+	"ExtraCheckMacros.h"
+	"packet.h"
+	"largest.h"
+	"queue.h"
+	"pool.h"
+
+1501803140 source:d:\users\john\documents\programming\github\etl\test\test_task_scheduler.cpp
+	"UnitTest++.h"
+	<stdint.h>
+	<string>
+	<vector>
+	"task.h"
+	"scheduler.h"
+	"container.h"
+
+1501803139 d:\users\john\documents\programming\github\etl\src\task.h
+	<stdint.h>
+	"error_handler.h"
+	"exception.h"
+
+1501803139 d:\users\john\documents\programming\github\etl\src\scheduler.h
+	<stdint.h>
+	"vector.h"
+	"nullptr.h"
+	"error_handler.h"
+	"exception.h"
+	"task.h"
+	"type_traits.h"
+	"function.h"
+
+1501803139 d:\users\john\documents\programming\github\etl\src\message.h
+	<stdint.h>
+	"error_handler.h"
+	"exception.h"
+	"message_types.h"
+
+1501803139 d:\users\john\documents\programming\github\etl\src\message_types.h
+	<stdint.h>
+
+1501803139 source:d:\users\john\documents\programming\github\etl\test\test_message_bus.cpp
+	"UnitTest++.h"
+	"ExtraCheckMacros.h"
+	"message_router.h"
+	"message_bus.h"
+	"queue.h"
+	"largest.h"
+	"packet.h"
+
+1501803139 d:\users\john\documents\programming\github\etl\src\message_bus.h
+	<stdint.h>
+	<algorithm>
+	"algorithm.h"
+	"vector.h"
+	"nullptr.h"
+	"error_handler.h"
+	"exception.h"
+	"message_types.h"
+	"message.h"
+	"message_router.h"
+
+1501803140 source:d:\users\john\documents\programming\github\etl\test\test_user_type.cpp
+	"UnitTest++.h"
+	<string>
+	"user_type.h"
+
diff --git a/test/codeblocks/ETL.layout b/test/codeblocks/ETL.layout
index 613556e7..7fc9cd9e 100644
--- a/test/codeblocks/ETL.layout
+++ b/test/codeblocks/ETL.layout
@@ -2,269 +2,24 @@
 <CodeBlocks_layout_file>
 	<FileVersion major="1" minor="0" />
 	<ActiveTarget name="Windows" />
-	<File name="..\test_memory.cpp" open="0" top="0" tabpos="25" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="15446" topLine="391" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\vector.h" open="0" top="0" tabpos="6" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="15560" topLine="342" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\error_handler.h" open="0" top="0" tabpos="4" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="4288" topLine="74" />
-		</Cursor>
-	</File>
-	<File name="..\test_list.cpp" open="0" top="0" tabpos="27" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="17914" topLine="493" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\queue.h" open="0" top="0" tabpos="17" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="11193" topLine="229" />
-		</Cursor>
-	</File>
-	<File name="..\test_algorithm.cpp" open="0" top="0" tabpos="8" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="11590" topLine="274" />
-		</Cursor>
-	</File>
-	<File name="..\test_type_traits.cpp" open="0" top="0" tabpos="11" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="37662" topLine="472" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\unordered_multimap.h" open="0" top="0" tabpos="10" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="22871" topLine="625" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\private\pvoidvector.h" open="0" top="0" tabpos="19" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="7770" topLine="137" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\deque.h" open="0" top="0" tabpos="3" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="54765" topLine="1616" />
-		</Cursor>
-	</File>
-	<File name="..\main.cpp" open="0" top="0" tabpos="18" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="141" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\test_vector.cpp" open="0" top="0" tabpos="9" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="1450" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\unordered_multiset.h" open="0" top="0" tabpos="9" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="22451" topLine="619" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\Test.cpp" open="0" top="0" tabpos="19" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="699" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\integral_limits.h" open="0" top="0" tabpos="1" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="7252" topLine="152" />
-		</Cursor>
-	</File>
-	<File name="..\test_flat_multimap.cpp" open="0" top="0" tabpos="6" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="3425" topLine="85" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\alignment.h" open="0" top="0" tabpos="16" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="1527" topLine="15" />
-		</Cursor>
-	</File>
-	<File name="..\test_flat_multiset.cpp" open="0" top="0" tabpos="21" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="3011" topLine="58" />
-		</Cursor>
-	</File>
-	<File name="..\test_flat_map.cpp" open="0" top="0" tabpos="20" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="18781" topLine="559" />
-		</Cursor>
-	</File>
 	<File name="..\..\src\intrusive_flat_map.h" open="0" top="0" tabpos="4" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
 		<Cursor>
 			<Cursor1 position="4065" topLine="242" />
 		</Cursor>
 	</File>
-	<File name="..\test_io_port.cpp" open="0" top="0" tabpos="14" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="1452" topLine="3" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\Checks.h" open="0" top="0" tabpos="5" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="469" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\test_map.cpp" open="0" top="0" tabpos="19" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="6368" topLine="164" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\TestReporterStdout.cpp" open="0" top="0" tabpos="25" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="883" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\TestRunner.cpp" open="0" top="0" tabpos="20" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="2279" topLine="25" />
-		</Cursor>
-	</File>
-	<File name="..\test_vector_pointer.cpp" open="0" top="0" tabpos="10" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="1450" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\test_deque.cpp" open="0" top="0" tabpos="5" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="1445" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\Config.h" open="0" top="0" tabpos="5" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="792" topLine="7" />
-		</Cursor>
-	</File>
-	<File name="..\test_intrusive_list.cpp" open="0" top="0" tabpos="24" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="27580" topLine="735" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\flat_map.h" open="0" top="0" tabpos="8" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="2722" topLine="43" />
-		</Cursor>
-	</File>
-	<File name="..\test_integral_limits.cpp" open="0" top="0" tabpos="18" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="0" topLine="49" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\forward_list.h" open="0" top="0" tabpos="11" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="31509" topLine="979" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\TestMacros.h" open="0" top="0" tabpos="13" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="1865" topLine="28" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\TestRunner.h" open="0" top="0" tabpos="21" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="156" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\test_flat_set.cpp" open="0" top="0" tabpos="7" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="11541" topLine="359" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\Win32\TimeHelpers.cpp" open="0" top="0" tabpos="9" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="103" topLine="6" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\variant.h" open="0" top="0" tabpos="7" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="36839" topLine="839" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\flat_multimap.h" open="0" top="0" tabpos="0" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="0" topLine="87" />
-		</Cursor>
-	</File>
-	<File name="..\test_intrusive_forward_list.cpp" open="0" top="0" tabpos="1" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="29068" topLine="703" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\TestResults.cpp" open="0" top="0" tabpos="24" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="537" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\unordered_set.h" open="0" top="0" tabpos="8" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="22041" topLine="620" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\static_assert.h" open="0" top="0" tabpos="7" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="1477" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\intrusive_flat_multiset.h" open="0" top="0" tabpos="11" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="7605" topLine="248" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\intrusive_flat_multimap.h" open="0" top="0" tabpos="9" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="3269" topLine="248" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\iterator.h" open="0" top="0" tabpos="17" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="1557" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\test_forward_list.cpp" open="1" top="1" tabpos="1" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="8719" topLine="184" />
-		</Cursor>
-	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\CurrentTest.cpp" open="0" top="0" tabpos="26" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="368" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\algorithm.h" open="0" top="0" tabpos="3" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="0" topLine="0" />
-		</Cursor>
-	</File>
 	<File name="..\..\src\type_traits.h" open="0" top="0" tabpos="12" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
 		<Cursor>
 			<Cursor1 position="16936" topLine="334" />
 		</Cursor>
 	</File>
-	<File name="..\test_iterator.cpp" open="0" top="0" tabpos="16" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+	<File name="..\..\..\unittest-cpp\UnitTest++\TestReporterStdout.cpp" open="0" top="0" tabpos="25" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
 		<Cursor>
-			<Cursor1 position="6722" topLine="118" />
+			<Cursor1 position="883" topLine="0" />
 		</Cursor>
 	</File>
-	<File name="..\..\..\unittest-cpp\UnitTest++\ExecuteTest.h" open="0" top="0" tabpos="18" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+	<File name="..\..\..\unittest-cpp\UnitTest++\Checks.h" open="0" top="0" tabpos="5" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
 		<Cursor>
-			<Cursor1 position="426" topLine="0" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\list.h" open="0" top="0" tabpos="22" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="35098" topLine="1063" />
-		</Cursor>
-	</File>
-	<File name="..\..\src\binary.h" open="0" top="0" tabpos="2" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
-		<Cursor>
-			<Cursor1 position="14624" topLine="373" />
+			<Cursor1 position="469" topLine="0" />
 		</Cursor>
 	</File>
 	<File name="..\..\src\intrusive_flat_set.h" open="0" top="0" tabpos="13" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
@@ -272,4 +27,64 @@
 			<Cursor1 position="7487" topLine="243" />
 		</Cursor>
 	</File>
+	<File name="..\..\src\flat_map.h" open="0" top="0" tabpos="8" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="2722" topLine="43" />
+		</Cursor>
+	</File>
+	<File name="..\..\src\error_handler.h" open="0" top="0" tabpos="4" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="4288" topLine="74" />
+		</Cursor>
+	</File>
+	<File name="..\main.cpp" open="0" top="0" tabpos="18" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="141" topLine="0" />
+		</Cursor>
+	</File>
+	<File name="..\..\src\flat_multimap.h" open="0" top="0" tabpos="0" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="0" topLine="87" />
+		</Cursor>
+	</File>
+	<File name="..\..\src\queue.h" open="0" top="0" tabpos="17" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="11193" topLine="229" />
+		</Cursor>
+	</File>
+	<File name="..\..\..\unittest-cpp\UnitTest++\TestRunner.h" open="0" top="0" tabpos="21" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="156" topLine="0" />
+		</Cursor>
+	</File>
+	<File name="..\..\src\message_bus.h" open="1" top="1" tabpos="2" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="10784" topLine="332" />
+		</Cursor>
+	</File>
+	<File name="..\test_type_traits.cpp" open="0" top="0" tabpos="11" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="37662" topLine="472" />
+		</Cursor>
+	</File>
+	<File name="..\test_map.cpp" open="0" top="0" tabpos="19" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="6368" topLine="164" />
+		</Cursor>
+	</File>
+	<File name="..\test_forward_list.cpp" open="1" top="0" tabpos="1" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="16670" topLine="442" />
+		</Cursor>
+	</File>
+	<File name="..\test_flat_multimap.cpp" open="0" top="0" tabpos="6" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="3425" topLine="85" />
+		</Cursor>
+	</File>
+	<File name="..\..\src\vector.h" open="0" top="0" tabpos="6" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="15560" topLine="342" />
+		</Cursor>
+	</File>
 </CodeBlocks_layout_file>
diff --git a/test/test_algorithm.cpp b/test/test_algorithm.cpp
index 6403aa23..eb631739 100644
--- a/test/test_algorithm.cpp
+++ b/test/test_algorithm.cpp
@@ -42,6 +42,39 @@ namespace
   typedef std::vector<int> Data;
   Data data = { 2, 1, 4, 3, 6, 5, 8, 7, 10, 9 };
 
+  struct StructData
+  {
+    int a;
+    int b;
+  };
+
+  bool operator ==(const StructData& lhs, const StructData& rhs)
+  {
+    return (lhs.a == rhs.a) && (lhs.b == rhs.b);
+  }
+
+  struct StructDataPredicate
+  {
+    bool operator ()(const StructData& lhs, const StructData& rhs) const
+    {
+      return lhs.a < rhs.a;
+    }
+  };
+
+  struct StructDataEquality
+  {
+    bool operator ()(const StructData& lhs, const StructData& rhs) const
+    {
+      return lhs.a == rhs.a;
+    }
+  };
+
+  std::ostream& operator << (std::ostream& os, const StructData& data)
+  {
+    os << data.a << "," << data.b;
+    return os;
+  }
+
   SUITE(test_algorithm)
   {
     //=========================================================================
@@ -543,10 +576,40 @@ namespace
       int data1[] = { 1, 2, 3, 5, 6, 7, 8 };
 
       // Find the element not less than 4.
-      int* p = std::find_if_not(std::begin(data1), std::end(data1), std::bind2nd(std::less<int>(), 4));
+      int* p = etl::find_if_not(std::begin(data1), std::end(data1), std::bind2nd(std::less<int>(), 4));
       CHECK_EQUAL(5, *p);
     }
 
+    //=========================================================================
+    TEST(binary_find)
+    {
+      int data1[] = { 1, 2, 3, 5, 6, 7, 8 };
+
+      // Find the element of value 5.
+      int* p = etl::binary_find(std::begin(data1), std::end(data1), 5);
+      CHECK_EQUAL(5, *p);
+
+      // Find the element of value 4.
+      p = etl::binary_find(std::begin(data1), std::end(data1), 4);
+      CHECK_EQUAL(std::end(data1), p);
+    }
+
+    //=========================================================================
+    TEST(binary_find_StructDataPredicate_StructDataEquality)
+    {
+      StructData data1[] = { { 1, 8 }, { 2, 7 }, { 3, 6 },{ 4, 5 },{ 5, 4 },{ 6, 3 },{ 7, 2 },{ 8, 1 } };
+      StructData test1   = { 4, 5 };
+      StructData test2   = { 9, 0 };
+
+      // Find the element of value 5.
+      StructData* p = etl::binary_find(std::begin(data1), std::end(data1), test1, StructDataPredicate(), StructDataEquality());
+      CHECK_EQUAL(test1, *p);
+
+      // Find the element of value 4.
+      p = etl::binary_find(std::begin(data1), std::end(data1), test2, StructDataPredicate(), StructDataEquality());
+      CHECK_EQUAL(std::end(data1), p);
+    }
+
     //=========================================================================
     TEST(for_each_if)
     {
diff --git a/test/test_fsm.cpp b/test/test_fsm.cpp
new file mode 100644
index 00000000..71a78263
--- /dev/null
+++ b/test/test_fsm.cpp
@@ -0,0 +1,503 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include "UnitTest++.h"
+
+#include "fsm.h"
+#include "enum_type.h"
+#include "container.h"
+
+#include <iostream>
+
+namespace
+{
+  const etl::message_router_id_t MOTOR_CONTROL = 0;
+
+
+  //***************************************************************************
+  // Events
+  struct EventId
+  {
+    enum enum_type
+    {
+      START,
+      STOP,
+      STOPPED,
+      SET_SPEED,
+      UNSUPPORTED
+    };
+
+    ETL_DECLARE_ENUM_TYPE(EventId, etl::message_id_t)
+    ETL_ENUM_TYPE(START,       "Start")
+    ETL_ENUM_TYPE(STOP,        "Stop")
+    ETL_ENUM_TYPE(STOPPED,     "Stopped")
+    ETL_ENUM_TYPE(SET_SPEED,   "Set Speed")
+    ETL_ENUM_TYPE(UNSUPPORTED, "Unsupported")
+    ETL_END_ENUM_TYPE
+  };
+
+  //***********************************
+  class Start : public etl::message<EventId::START>
+  {
+  };
+
+  //***********************************
+  class Stop : public etl::message<EventId::STOP>
+  {
+  public:
+
+    Stop() : isEmergencyStop(false) {}
+    Stop(bool emergency) : isEmergencyStop(emergency) {}
+
+    const bool isEmergencyStop;
+  };
+
+  //***********************************
+  class SetSpeed : public etl::message<EventId::SET_SPEED>
+  {
+  public:
+
+    SetSpeed(int speed) : speed(speed) {}
+
+    const int speed;
+  };
+
+  //***********************************
+  class Stopped : public etl::message<EventId::STOPPED>
+  {
+  };
+
+  //***********************************
+  class Unsupported : public etl::message<EventId::UNSUPPORTED>
+  {
+  };
+
+  //***************************************************************************
+  // States
+  struct StateId
+  {
+    enum enum_type
+    {
+      IDLE,
+      RUNNING,
+      WINDING_DOWN,
+      LOCKED,
+      NUMBER_OF_STATES
+    };
+
+    ETL_DECLARE_ENUM_TYPE(StateId, etl::fsm_state_id_t)
+    ETL_ENUM_TYPE(IDLE,         "Idle")
+    ETL_ENUM_TYPE(RUNNING,      "Running")
+    ETL_ENUM_TYPE(WINDING_DOWN, "Winding Down")
+    ETL_ENUM_TYPE(LOCKED,       "Locked")
+    ETL_END_ENUM_TYPE
+  };
+
+  //***********************************
+  // The motor control FSM.
+  //***********************************
+  class MotorControl : public etl::fsm
+  {
+  public:
+
+    MotorControl(etl::ifsm_state** p_states, size_t size)
+      : fsm(MOTOR_CONTROL)
+    {
+      set_states(p_states, size);
+      ClearStatistics();
+    }
+
+    //***********************************
+    void ClearStatistics()
+    {
+      startCount = 0;
+      stopCount = 0;
+      setSpeedCount = 0;
+      unknownCount = 0;
+      stoppedCount = 0;
+      isLampOn = false;
+      speed = 0;
+    }
+
+    //***********************************
+    void SetSpeed(int speed_)
+    {
+      speed = speed_;
+    }
+
+    //***********************************
+    void TurnRunningLampOn()
+    {
+      isLampOn = true;
+    }
+
+    //***********************************
+    void TurnRunningLampOff()
+    {
+      isLampOn = false;
+    }
+
+    int startCount;
+    int stopCount;
+    int setSpeedCount;
+    int unknownCount;
+    int stoppedCount;
+    bool isLampOn;
+    int speed;
+  };
+  
+  //***********************************
+  // The idle state.
+  //***********************************
+  class Idle : public etl::fsm_state<MotorControl, Idle, StateId::IDLE, Start>
+  {
+  public:
+
+    //***********************************
+    etl::fsm_state_id_t on_event(etl::imessage_router& sender, const Start& event)
+    {
+      ++get_fsm_context().startCount;
+      return StateId::RUNNING;
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event_unknown(etl::imessage_router& sender, const etl::imessage& event)
+    {
+      ++get_fsm_context().unknownCount;
+      return STATE_ID;
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_enter_state()
+    {
+      get_fsm_context().TurnRunningLampOff();
+      return StateId::LOCKED;
+    }
+  };
+
+  //***********************************
+  // The running state.
+  //***********************************
+  class Running : public etl::fsm_state<MotorControl, Running, StateId::RUNNING, Stop, SetSpeed>
+  {
+  public:
+
+    //***********************************
+    etl::fsm_state_id_t on_event(etl::imessage_router& sender, const Stop& event)
+    {
+      ++get_fsm_context().stopCount;
+
+      if (event.isEmergencyStop)
+      {
+        return StateId::IDLE;
+      }
+      else
+      {
+        return StateId::WINDING_DOWN;
+      }
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event(etl::imessage_router& sender, const SetSpeed& event)
+    {
+      ++get_fsm_context().setSpeedCount;
+      get_fsm_context().SetSpeed(event.speed);
+      return STATE_ID;
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event_unknown(etl::imessage_router& sender, const etl::imessage& event)
+    {
+      ++get_fsm_context().unknownCount;
+      return STATE_ID;
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_enter_state()
+    {
+      get_fsm_context().TurnRunningLampOn();
+
+      return STATE_ID;
+    }
+  };
+
+  //***********************************
+  // The winding down state.
+  //***********************************
+  class WindingDown : public etl::fsm_state<MotorControl, WindingDown, StateId::WINDING_DOWN, Stopped>
+  {
+  public:
+
+    //***********************************
+    etl::fsm_state_id_t on_event(etl::imessage_router& source, const Stopped& event)
+    {
+      ++get_fsm_context().stoppedCount;
+      return StateId::IDLE;
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event_unknown(etl::imessage_router& source, const etl::imessage& event)
+    {
+      ++get_fsm_context().unknownCount;
+      return STATE_ID;
+    }
+  };
+
+  //***********************************
+  // The locked state.
+  //***********************************
+  class Locked : public etl::fsm_state<MotorControl, Locked, StateId::LOCKED>
+  {
+  public:
+
+    //***********************************
+    etl::fsm_state_id_t on_event_unknown(etl::imessage_router& source, const etl::imessage& event)
+    {
+      ++get_fsm_context().unknownCount;
+      return STATE_ID;
+    }
+  };
+
+  // The states.
+  Idle        idle;
+  Running     running;
+  WindingDown windingDown;
+  Locked      locked;
+
+  etl::ifsm_state* stateList[StateId::NUMBER_OF_STATES] =
+  {
+    &idle, &running, &windingDown, &locked
+  };
+
+  MotorControl motorControl(stateList, etl::size(stateList));
+
+  SUITE(test_map)
+  {
+    //*************************************************************************
+    TEST(test_fsm)
+    {
+      etl::null_message_router nmr;
+
+      motorControl.reset();
+      motorControl.ClearStatistics();
+
+      CHECK(!motorControl.is_started());
+
+      // Start the FSM.
+      motorControl.start();
+      CHECK(motorControl.is_started());
+
+      // Now in Idle state.
+
+      CHECK_EQUAL(StateId::IDLE, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::IDLE, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(false, motorControl.isLampOn);
+      CHECK_EQUAL(0, motorControl.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.speed);
+      CHECK_EQUAL(0, motorControl.startCount);
+      CHECK_EQUAL(0, motorControl.stopCount);
+      CHECK_EQUAL(0, motorControl.stoppedCount);
+      CHECK_EQUAL(0, motorControl.unknownCount);
+
+      // Send unhandled events.
+      motorControl.receive(nmr, Stop());
+      motorControl.receive(nmr, Stopped());
+      motorControl.receive(nmr, SetSpeed(10));
+
+      CHECK_EQUAL(StateId::IDLE, motorControl.get_state_id());
+      CHECK_EQUAL(StateId::IDLE, motorControl.get_state().get_state_id());
+
+      CHECK_EQUAL(false, motorControl.isLampOn);
+      CHECK_EQUAL(0, motorControl.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.speed);
+      CHECK_EQUAL(0, motorControl.startCount);
+      CHECK_EQUAL(0, motorControl.stopCount);
+      CHECK_EQUAL(0, motorControl.stoppedCount);
+      CHECK_EQUAL(3, motorControl.unknownCount);
+
+      // Send Start event.
+      motorControl.receive(nmr, Start());
+
+      // Now in Running state.
+
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.isLampOn);
+      CHECK_EQUAL(0, motorControl.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.speed);
+      CHECK_EQUAL(1, motorControl.startCount);
+      CHECK_EQUAL(0, motorControl.stopCount);
+      CHECK_EQUAL(0, motorControl.stoppedCount);
+      CHECK_EQUAL(3, motorControl.unknownCount);
+
+      // Send unhandled events.
+      motorControl.receive(nmr, Start());
+      motorControl.receive(nmr, Stopped());
+
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.isLampOn);
+      CHECK_EQUAL(0, motorControl.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.speed);
+      CHECK_EQUAL(1, motorControl.startCount);
+      CHECK_EQUAL(0, motorControl.stopCount);
+      CHECK_EQUAL(0, motorControl.stoppedCount);
+      CHECK_EQUAL(5, motorControl.unknownCount);
+
+      // Send SetSpeed event.
+      motorControl.receive(nmr, SetSpeed(100));
+
+      // Still in Running state.
+
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.isLampOn);
+      CHECK_EQUAL(1, motorControl.setSpeedCount);
+      CHECK_EQUAL(100, motorControl.speed);
+      CHECK_EQUAL(1, motorControl.startCount);
+      CHECK_EQUAL(0, motorControl.stopCount);
+      CHECK_EQUAL(0, motorControl.stoppedCount);
+      CHECK_EQUAL(5, motorControl.unknownCount);
+
+      // Send Stop event.
+      motorControl.receive(nmr, Stop());
+
+      // Now in WindingDown state.
+
+      CHECK_EQUAL(StateId::WINDING_DOWN, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::WINDING_DOWN, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.isLampOn);
+      CHECK_EQUAL(1, motorControl.setSpeedCount);
+      CHECK_EQUAL(100, motorControl.speed);
+      CHECK_EQUAL(1, motorControl.startCount);
+      CHECK_EQUAL(1, motorControl.stopCount);
+      CHECK_EQUAL(0, motorControl.stoppedCount);
+      CHECK_EQUAL(5, motorControl.unknownCount);
+
+      // Send unhandled events.
+      motorControl.receive(nmr, Start());
+      motorControl.receive(nmr, Stop());
+      motorControl.receive(nmr, SetSpeed(100));
+
+      CHECK_EQUAL(StateId::WINDING_DOWN, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::WINDING_DOWN, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.isLampOn);
+      CHECK_EQUAL(1, motorControl.setSpeedCount);
+      CHECK_EQUAL(100, motorControl.speed);
+      CHECK_EQUAL(1, motorControl.startCount);
+      CHECK_EQUAL(1, motorControl.stopCount);
+      CHECK_EQUAL(0, motorControl.stoppedCount);
+      CHECK_EQUAL(8, motorControl.unknownCount);
+
+      // Send Stopped event.
+      motorControl.receive(nmr, Stopped());
+
+      // Now in Locked state via Idle state.
+      CHECK_EQUAL(StateId::LOCKED, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::LOCKED, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(false, motorControl.isLampOn);
+      CHECK_EQUAL(1, motorControl.setSpeedCount);
+      CHECK_EQUAL(100, motorControl.speed);
+      CHECK_EQUAL(1, motorControl.startCount);
+      CHECK_EQUAL(1, motorControl.stopCount);
+      CHECK_EQUAL(1, motorControl.stoppedCount);
+      CHECK_EQUAL(8, motorControl.unknownCount);
+    }
+
+    //*************************************************************************
+    TEST(test_fsm_emergency_stop)
+    {
+      etl::null_message_router nmr;
+
+      motorControl.reset();
+      motorControl.ClearStatistics();
+
+      CHECK(!motorControl.is_started());
+
+      // Start the FSM.
+      motorControl.start();
+      CHECK(motorControl.is_started());
+
+      // Now in Idle state.
+
+      // Send Start event.
+      motorControl.receive(nmr, Start());
+
+      // Now in Running state.
+
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.isLampOn);
+      CHECK_EQUAL(0, motorControl.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.speed);
+      CHECK_EQUAL(1, motorControl.startCount);
+      CHECK_EQUAL(0, motorControl.stopCount);
+      CHECK_EQUAL(0, motorControl.stoppedCount);
+      CHECK_EQUAL(0, motorControl.unknownCount);
+
+      // Send emergency Stop event.
+      motorControl.receive(nmr, Stop(true));
+
+      // Now in Locked state via Idle state.
+      CHECK_EQUAL(StateId::LOCKED, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::LOCKED, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(false, motorControl.isLampOn);
+      CHECK_EQUAL(0, motorControl.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.speed);
+      CHECK_EQUAL(1, motorControl.startCount);
+      CHECK_EQUAL(1, motorControl.stopCount);
+      CHECK_EQUAL(0, motorControl.stoppedCount);
+      CHECK_EQUAL(0, motorControl.unknownCount);
+    }
+
+    //*************************************************************************
+    TEST(test_fsm_supported)
+    {
+      CHECK(motorControl.accepts(EventId::SET_SPEED));
+      CHECK(motorControl.accepts(EventId::START));
+      CHECK(motorControl.accepts(EventId::STOP));
+      CHECK(motorControl.accepts(EventId::STOPPED));
+      CHECK(motorControl.accepts(EventId::UNSUPPORTED));
+
+      CHECK(motorControl.accepts(SetSpeed(0)));
+      CHECK(motorControl.accepts(Start()));
+      CHECK(motorControl.accepts(Stop()));
+      CHECK(motorControl.accepts(Stopped()));
+      CHECK(motorControl.accepts(Unsupported()));
+    }
+  };
+}
diff --git a/test/test_memory.cpp b/test/test_memory.cpp
index 44b5f0d6..1e237565 100644
--- a/test/test_memory.cpp
+++ b/test/test_memory.cpp
@@ -445,5 +445,31 @@ namespace
       etl::destroy(p, p + SIZE, count);
       CHECK_EQUAL(0U, count);
     }
+
+    //*************************************************************************
+    TEST(test_create_copy)
+    {
+      struct Test : etl::create_copy<Test>
+      {
+        std::string text;
+      };
+
+      char buffer[sizeof(Test)];
+
+      Test test1;
+      test1.text = "12345678";
+      test1.create_copy_at(buffer);
+      test1.text = "87654321";
+
+      Test& test2 = *reinterpret_cast<Test*>(buffer);
+
+      CHECK_EQUAL(std::string("87654321"), test1.text);
+      CHECK_EQUAL(std::string("12345678"), test2.text);
+
+      int count = 0;
+      test1.create_copy_at(buffer, count);
+
+      CHECK_EQUAL(1, count);
+    }
   };
 }
diff --git a/test/test_message_bus.cpp b/test/test_message_bus.cpp
new file mode 100644
index 00000000..66e079f5
--- /dev/null
+++ b/test/test_message_bus.cpp
@@ -0,0 +1,729 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include "UnitTest++.h"
+#include "ExtraCheckMacros.h"
+
+#include "message_router.h"
+#include "message_bus.h"
+#include "queue.h"
+#include "largest.h"
+#include "packet.h"
+
+//***************************************************************************
+// The set of messages.
+//***************************************************************************
+namespace
+{
+  enum
+  {
+    MESSAGE1,
+    MESSAGE2,
+    MESSAGE3,
+    MESSAGE4,
+    MESSAGE5
+  };
+
+  enum
+  {
+    ROUTER1 = 1,
+    ROUTER2 = 2,
+    ROUTER3 = 3,
+    ROUTER4 = 4,
+    ROUTER5 = 5
+  };
+
+  struct Message1 : public etl::message<MESSAGE1>
+  {
+  };
+
+  struct Message2 : public etl::message<MESSAGE2>
+  {
+  };
+
+  struct Message3 : public etl::message<MESSAGE3>
+  {
+    int value[10];
+  };
+
+  struct Message4 : public etl::message<MESSAGE4>
+  {
+  };
+
+  struct Message5 : public etl::message<MESSAGE5>
+  {
+  };
+
+  Message1 message1;
+  Message2 message2;
+  Message3 message3;
+  Message4 message4;
+  Message5 message5;
+
+  int call_order;
+
+  //***************************************************************************
+  // Router that handles messages 1, 2, 3, 4, 5.
+  //***************************************************************************
+  class RouterA : public etl::message_router<RouterA, Message1, Message2, Message3, Message4, Message5>
+  {
+  public:
+
+    RouterA(etl::message_router_id_t id)
+      : message_router(id),
+        message1_count(0),
+        message2_count(0),
+        message3_count(0),
+        message4_count(0),
+        message5_count(0),
+        message_unknown_count(0)
+    {
+
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message1& msg)
+    {
+      ++message1_count;
+      etl::send_message(sender, message5);
+
+      order = call_order++;
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message2& msg)
+    {
+      ++message2_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message3& msg)
+    {
+      ++message3_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message4& msg)
+    {
+      ++message4_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message5& msg)
+    {
+      ++message5_count;
+    }
+
+    void on_receive_unknown(etl::imessage_router& sender, const etl::imessage& msg)
+    {
+      ++message_unknown_count;
+    }
+
+    int message1_count;
+    int message2_count;
+    int message3_count;
+    int message4_count;
+    int message5_count;
+    int message_unknown_count;
+    int order;
+  };
+
+  //***************************************************************************
+  // Router that handles messages 1, 2, 4 and 5 and returns nothing.
+  //***************************************************************************
+  class RouterB : public etl::message_router<RouterB, Message1, Message2, Message4, Message5>
+  {
+  public:
+
+    RouterB(etl::message_router_id_t id)
+      : message_router(id),
+        message1_count(0),
+        message2_count(0),
+        message4_count(0),
+        message5_count(0),
+        message_unknown_count(0)
+    {
+
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message1& msg)
+    {
+      ++message1_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message2& msg)
+    {
+      ++message2_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message4& msg)
+    {
+      ++message4_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message5& msg)
+    {
+      ++message5_count;
+    }
+
+    void on_receive_unknown(etl::imessage_router& sender, const etl::imessage& msg)
+    {
+      ++message_unknown_count;
+      etl::send_message(sender, message5);
+    }
+
+    int message1_count;
+    int message2_count;
+    int message4_count;
+    int message5_count;
+    int message_unknown_count;
+  };
+
+  etl::imessage_router* p_router;
+  etl::imessage_bus*    p_bus;
+
+  SUITE(test_message_router)
+  {
+    //=========================================================================
+    TEST(message_bus_subscribe_unsubscribe)
+    {
+      etl::message_bus<2> bus1;
+
+      RouterA router1(0);
+      RouterB router2(1);
+      RouterA router3(2);
+
+      CHECK_EQUAL(0U, bus1.size());
+
+      CHECK_NO_THROW(bus1.subscribe(router1));
+      CHECK_EQUAL(1U, bus1.size());
+
+      CHECK_NO_THROW(bus1.subscribe(router2));
+      CHECK_EQUAL(2U, bus1.size());
+
+      CHECK_THROW(bus1.subscribe(router3), etl::message_bus_too_many_subscribers);
+      CHECK_EQUAL(2U, bus1.size());
+
+      bus1.unsubscribe(router1);
+      CHECK_EQUAL(1U, bus1.size());
+
+      // Erase router not in list.
+      bus1.unsubscribe(router3);
+      CHECK_EQUAL(1U, bus1.size());
+
+      // Erase using id.
+      bus1.unsubscribe(router2.get_message_router_id());
+      CHECK_EQUAL(0U, bus1.size());
+
+      // Erase router from empty list.
+      bus1.unsubscribe(router2);
+      CHECK_EQUAL(0U, bus1.size());
+    }
+
+    //=========================================================================
+    TEST(message_bus_subscribe_unsubscribe_sub_bus)
+    {
+      etl::message_bus<4> bus1;
+      etl::message_bus<2> bus2;
+      etl::message_bus<3> bus3;
+
+      RouterA router1(ROUTER1);
+      RouterA router2(ROUTER2);
+      RouterA router3(ROUTER3);
+      RouterA router4(ROUTER4);
+
+      bus1.subscribe(router1);
+      bus1.subscribe(router2);
+      bus1.subscribe(bus2);
+      bus1.subscribe(bus3);
+
+      bus2.subscribe(router3);
+      bus3.subscribe(router4);
+
+      CHECK_EQUAL(4U, bus1.size());
+
+      bus1.unsubscribe(etl::imessage_bus::MESSAGE_BUS);
+      CHECK_EQUAL(2U, bus1.size());
+
+      bus1.unsubscribe(etl::imessage_bus::ALL_MESSAGE_ROUTERS);
+      CHECK_EQUAL(0U, bus1.size());
+    }
+
+    //=========================================================================
+    TEST(message_bus_broadcast)
+    {
+      etl::message_bus<2> bus1;
+
+      RouterA router1(ROUTER1);
+      RouterB router2(ROUTER2);
+      RouterA sender(ROUTER3);
+
+      bus1.subscribe(router1);
+      bus1.subscribe(router2);
+
+      bus1.receive(sender, message1);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(0, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(2, sender.message5_count);
+
+      bus1.receive(sender, message2);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(1, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(4, sender.message5_count);
+
+      bus1.receive(sender, message3);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(1, router1.message2_count);
+      CHECK_EQUAL(1, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(5, sender.message5_count);
+
+      // Use global function.
+      etl::send_message(sender, bus1, message4);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(1, router1.message2_count);
+      CHECK_EQUAL(1, router1.message3_count);
+      CHECK_EQUAL(1, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(1, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(7, sender.message5_count);
+    }
+
+    //=========================================================================
+    TEST(message_bus_broadcast_as_router)
+    {
+      etl::message_bus<2> bus1;
+
+      RouterA router1(ROUTER1);
+      RouterB router2(ROUTER2);
+      RouterA sender(ROUTER3);
+
+      bus1.subscribe(router1);
+      bus1.subscribe(router2);
+
+      // Reference to router sub-type
+      etl::imessage_router& irouter = bus1;
+
+      irouter.receive(sender, message1);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(0, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(2, sender.message5_count);
+
+      irouter.receive(sender, message2);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(1, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(4, sender.message5_count);
+
+      irouter.receive(sender, message3);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(1, router1.message2_count);
+      CHECK_EQUAL(1, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(5, sender.message5_count);
+
+      // Use global function.
+      etl::send_message(sender, irouter, message4);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(1, router1.message2_count);
+      CHECK_EQUAL(1, router1.message3_count);
+      CHECK_EQUAL(1, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(1, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(7, sender.message5_count);
+    }
+
+    //=========================================================================
+    TEST(message_bus_addressed)
+    {
+      etl::message_bus<2> bus1;
+
+      RouterA router1(ROUTER1);
+      RouterB router2(ROUTER2);
+      RouterA sender(ROUTER3);
+
+      bus1.subscribe(router1);
+      bus1.subscribe(router2);
+
+      bus1.receive(sender, ROUTER1, message1);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(0, router2.message1_count);
+      CHECK_EQUAL(0, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(1, sender.message5_count);
+
+      bus1.receive(sender, ROUTER2, message2);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(0, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(2, sender.message5_count);
+
+      bus1.receive(sender, ROUTER1, message3);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(1, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(0, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(3, sender.message5_count);
+
+      // Use global function.
+      etl::send_message(sender, bus1, ROUTER2, message4);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(1, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(0, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(1, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(4, sender.message5_count);
+
+      // Send to a router not subscribed to the bus.
+      bus1.receive(sender, ROUTER5, message1);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(1, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(0, router2.message1_count);
+      CHECK_EQUAL(1, router2.message2_count);
+      CHECK_EQUAL(1, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(4, sender.message5_count);
+    }
+
+    //=========================================================================
+    TEST(message_bus_addressed_duplicate_router_id)
+    {
+      etl::message_bus<3> bus1;
+
+      RouterA router1(ROUTER1);
+      RouterB router2(ROUTER1);
+      RouterB router3(ROUTER2);
+      RouterA sender(ROUTER3);
+
+      bus1.subscribe(router1);
+      bus1.subscribe(router2);
+      bus1.subscribe(router3);
+
+      bus1.receive(sender, ROUTER1, message1);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(0, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(0, router3.message1_count);
+      CHECK_EQUAL(0, router3.message2_count);
+      CHECK_EQUAL(0, router3.message4_count);
+      CHECK_EQUAL(0, router3.message5_count);
+      CHECK_EQUAL(0, router3.message_unknown_count);
+
+      CHECK_EQUAL(2, sender.message5_count);
+    }
+
+    //=========================================================================
+    TEST(message_bus_broadcast_addressed_sub_bus)
+    {
+      etl::message_bus<3> bus1;
+      etl::message_bus<2> bus2;
+
+      RouterA router1(ROUTER1);
+      RouterA router2(ROUTER2);
+      RouterA router3(ROUTER3);
+      RouterA router4(ROUTER4);
+
+      RouterA sender(ROUTER5);
+
+      bus1.subscribe(router1);
+      bus1.subscribe(router2);
+      bus1.subscribe(bus2);
+
+      bus2.subscribe(router3);
+      bus2.subscribe(router4);
+
+      // Broadcast to bus1
+      bus1.receive(sender, message1);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(1, router2.message1_count);
+      CHECK_EQUAL(0, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(1, router3.message1_count);
+      CHECK_EQUAL(0, router3.message2_count);
+      CHECK_EQUAL(0, router3.message4_count);
+      CHECK_EQUAL(0, router3.message5_count);
+      CHECK_EQUAL(0, router3.message_unknown_count);
+
+      CHECK_EQUAL(1, router4.message1_count);
+      CHECK_EQUAL(0, router4.message2_count);
+      CHECK_EQUAL(0, router4.message4_count);
+      CHECK_EQUAL(0, router4.message5_count);
+      CHECK_EQUAL(0, router4.message_unknown_count);
+
+      CHECK_EQUAL(4, sender.message5_count);
+
+      // Addressed to ROUTER2
+      bus1.receive(sender, ROUTER2, message1);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(2, router2.message1_count);
+      CHECK_EQUAL(0, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(1, router3.message1_count);
+      CHECK_EQUAL(0, router3.message2_count);
+      CHECK_EQUAL(0, router3.message4_count);
+      CHECK_EQUAL(0, router3.message5_count);
+      CHECK_EQUAL(0, router3.message_unknown_count);
+
+      CHECK_EQUAL(1, router4.message1_count);
+      CHECK_EQUAL(0, router4.message2_count);
+      CHECK_EQUAL(0, router4.message4_count);
+      CHECK_EQUAL(0, router4.message5_count);
+      CHECK_EQUAL(0, router4.message_unknown_count);
+
+      CHECK_EQUAL(5, sender.message5_count);
+
+      // Addressed to ROUTER3 via bus2
+      bus1.receive(sender, ROUTER3, message1);
+
+      CHECK_EQUAL(1, router1.message1_count);
+      CHECK_EQUAL(0, router1.message2_count);
+      CHECK_EQUAL(0, router1.message3_count);
+      CHECK_EQUAL(0, router1.message4_count);
+      CHECK_EQUAL(0, router1.message5_count);
+      CHECK_EQUAL(0, router1.message_unknown_count);
+
+      CHECK_EQUAL(2, router2.message1_count);
+      CHECK_EQUAL(0, router2.message2_count);
+      CHECK_EQUAL(0, router2.message4_count);
+      CHECK_EQUAL(0, router2.message5_count);
+      CHECK_EQUAL(0, router2.message_unknown_count);
+
+      CHECK_EQUAL(2, router3.message1_count);
+      CHECK_EQUAL(0, router3.message2_count);
+      CHECK_EQUAL(0, router3.message4_count);
+      CHECK_EQUAL(0, router3.message5_count);
+      CHECK_EQUAL(0, router3.message_unknown_count);
+
+      CHECK_EQUAL(1, router4.message1_count);
+      CHECK_EQUAL(0, router4.message2_count);
+      CHECK_EQUAL(0, router4.message4_count);
+      CHECK_EQUAL(0, router4.message5_count);
+      CHECK_EQUAL(0, router4.message_unknown_count);
+
+      CHECK_EQUAL(6, sender.message5_count);
+    }
+
+    //=========================================================================
+    TEST(message_bus_broadcast_order)
+    {
+      etl::message_bus<4> bus1;
+      etl::message_bus<2> bus2;
+      etl::message_bus<2> bus3;
+
+      RouterA router1(ROUTER1);
+      RouterA router2(ROUTER2);
+      RouterA router3(ROUTER3);
+      RouterA router4a(ROUTER4);
+      RouterA router4b(ROUTER4);
+
+      RouterA sender(ROUTER5);
+
+      bus1.subscribe(router1);
+      bus1.subscribe(bus3);
+      bus1.subscribe(bus2);
+      bus1.subscribe(router2);
+
+      bus2.subscribe(router3);
+      bus3.subscribe(router4b);
+      bus3.subscribe(router4a);
+
+      call_order = 0;
+
+      bus1.receive(sender, message1);
+
+      CHECK_EQUAL(0, router1.order);
+      CHECK_EQUAL(1, router2.order);
+      CHECK_EQUAL(2, router4b.order);
+      CHECK_EQUAL(3, router4a.order);
+      CHECK_EQUAL(4, router3.order);
+    }
+  };
+}
diff --git a/test/test_message_router.cpp b/test/test_message_router.cpp
new file mode 100644
index 00000000..c2890fb0
--- /dev/null
+++ b/test/test_message_router.cpp
@@ -0,0 +1,421 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include "UnitTest++.h"
+#include "ExtraCheckMacros.h"
+
+#include "message_router.h"
+#include "queue.h"
+#include "largest.h"
+#include "packet.h"
+
+//***************************************************************************
+// The set of messages.
+//***************************************************************************
+namespace
+{
+  enum
+  {
+    MESSAGE1,
+    MESSAGE2,
+    MESSAGE3,
+    MESSAGE4,
+    MESSAGE5
+  };
+
+  enum
+  {
+    ROUTER1,
+    ROUTER2
+  };
+
+  struct Message1 : public etl::message<MESSAGE1>
+  {
+  };
+
+  struct Message2 : public etl::message<MESSAGE2>
+  {
+  };
+
+  struct Message3 : public etl::message<MESSAGE3>
+  {
+    int value[10];
+  };
+
+  struct Message4 : public etl::message<MESSAGE4>
+  {
+  };
+
+  struct Message5 : public etl::message<MESSAGE5>
+  {
+  };
+
+  Message1 message1;
+  Message2 message2;
+  Message3 message3;
+  Message4 message4;
+  Message5 message5;
+
+  //***************************************************************************
+  // Router that handles messages 1, 2, 3, 4 and 5 and returns nothing.
+  //***************************************************************************
+  class Router1 : public etl::message_router<Router1, Message1, Message2, Message3, Message4, Message5>
+  {
+  public:
+
+    Router1()
+      : message_router(ROUTER1),
+        message1_count(0),
+        message2_count(0),
+        message3_count(0),
+        message4_count(0),
+        message_unknown_count(0),
+        callback_count(0)
+    {
+
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message1& msg)
+    {
+      ++message1_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message2& msg)
+    {
+      ++message2_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message3& msg)
+    {
+      ++message3_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message4& msg)
+    {
+      ++message4_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message5& msg)
+    {
+      ++callback_count;
+    }
+
+    void on_receive_unknown(etl::imessage_router& sender, const etl::imessage& msg)
+    {
+      ++message_unknown_count;
+    }
+
+    int message1_count;
+    int message2_count;
+    int message3_count;
+    int message4_count;
+    int message_unknown_count;
+    int callback_count;
+  };
+
+  //***************************************************************************
+  // Router that handles messages 1, 2, 4 and 5 and returns nothing.
+  //***************************************************************************
+  class Router2 : public etl::message_router<Router2, Message1, Message2, Message4, Message5>
+  {
+  public:
+
+    Router2()
+      : message_router(ROUTER2),
+        message1_count(0),
+        message2_count(0),
+        message4_count(0),
+        message_unknown_count(0),
+        callback_count(0)
+    {
+
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message1& msg)
+    {
+      ++message1_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message2& msg)
+    {
+      ++message2_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message4& msg)
+    {
+      ++message4_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message5& msg)
+    {
+      ++callback_count;
+    }
+
+    void on_receive_unknown(etl::imessage_router& sender, const etl::imessage& msg)
+    {
+      ++message_unknown_count;
+      etl::send_message(sender, message5);
+    }
+
+    int message1_count;
+    int message2_count;
+    int message4_count;
+    int message_unknown_count;
+    int callback_count;
+  };
+
+
+  etl::imessage_router* p_router;
+
+  SUITE(test_message_router)
+  {
+    //=========================================================================
+    TEST(message_router)
+    {
+      Router1 r1;
+      Router2 r2;
+
+      p_router = &r1;
+
+      p_router->receive(r2, message1);
+      CHECK_EQUAL(1, r1.message1_count);
+      CHECK_EQUAL(0, r1.message2_count);
+      CHECK_EQUAL(0, r1.message3_count);
+      CHECK_EQUAL(0, r1.message4_count);
+      CHECK_EQUAL(0, r1.message_unknown_count);
+      CHECK_EQUAL(1, r2.callback_count);
+
+      p_router->receive(r2, message2);
+      CHECK_EQUAL(1, r1.message1_count);
+      CHECK_EQUAL(1, r1.message2_count);
+      CHECK_EQUAL(0, r1.message3_count);
+      CHECK_EQUAL(0, r1.message4_count);
+      CHECK_EQUAL(0, r1.message_unknown_count);
+      CHECK_EQUAL(2, r2.callback_count);
+
+      p_router->receive(r2, message3);
+      CHECK_EQUAL(1, r1.message1_count);
+      CHECK_EQUAL(1, r1.message2_count);
+      CHECK_EQUAL(1, r1.message3_count);
+      CHECK_EQUAL(0, r1.message4_count);
+      CHECK_EQUAL(0, r1.message_unknown_count);
+      CHECK_EQUAL(3, r2.callback_count);
+
+      p_router->receive(r2, message4);
+      CHECK_EQUAL(1, r1.message1_count);
+      CHECK_EQUAL(1, r1.message2_count);
+      CHECK_EQUAL(1, r1.message3_count);
+      CHECK_EQUAL(1, r1.message4_count);
+      CHECK_EQUAL(0, r1.message_unknown_count);
+      CHECK_EQUAL(4, r2.callback_count);
+
+      p_router = &r2;
+
+      p_router->receive(r1, message1);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(0, r2.message2_count);
+      CHECK_EQUAL(0, r2.message4_count);
+      CHECK_EQUAL(0, r2.message_unknown_count);
+      CHECK_EQUAL(1, r1.callback_count);
+
+      p_router->receive(r1, message2);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(1, r2.message2_count);
+      CHECK_EQUAL(0, r2.message4_count);
+      CHECK_EQUAL(0, r2.message_unknown_count);
+      CHECK_EQUAL(2, r1.callback_count);
+
+      p_router->receive(r1, message3);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(1, r2.message2_count);
+      CHECK_EQUAL(0, r2.message4_count);
+      CHECK_EQUAL(1, r2.message_unknown_count);
+      CHECK_EQUAL(3, r1.callback_count);
+
+      p_router->receive(r1, message4);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(1, r2.message2_count);
+      CHECK_EQUAL(1, r2.message4_count);
+      CHECK_EQUAL(1, r2.message_unknown_count);
+      CHECK_EQUAL(4, r1.callback_count);
+    }
+
+    //=========================================================================
+    TEST(message_null_router)
+    {
+      Router2 router;
+      etl::null_message_router null_router;
+
+      // Send from the null router.
+      etl::send_message(router, message1);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(0, router.message2_count);
+      CHECK_EQUAL(0, router.message4_count);
+      CHECK_EQUAL(0, router.message_unknown_count);
+
+      etl::send_message(router, message2);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(0, router.message4_count);
+      CHECK_EQUAL(0, router.message_unknown_count);
+
+      etl::send_message(router, message3);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(0, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      etl::send_message(router, message4);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      // Send to the null router.
+      etl::send_message(null_router, message1);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      etl::send_message(null_router, message2);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      etl::send_message(null_router, message3);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      etl::send_message(null_router, message4);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+    }
+
+    //=========================================================================
+    TEST(message_router_accepts)
+    {
+      Router2 r2;
+
+      CHECK(r2.accepts(message1));
+      CHECK(r2.accepts(message1.get_message_id()));
+
+      CHECK(r2.accepts(message2));
+      CHECK(r2.accepts(message2.get_message_id()));
+
+      CHECK(!r2.accepts(message3));
+      CHECK(!r2.accepts(message3.get_message_id()));
+
+      CHECK(r2.accepts(message4));
+      CHECK(r2.accepts(message4.get_message_id()));
+
+      CHECK(r2.accepts(message5));
+      CHECK(r2.accepts(message5.get_message_id()));
+    }
+
+    //=========================================================================
+    TEST(message_router_queue)
+    {
+      Router1 r1;
+      Router2 r2;
+
+      typedef Router2::message_packet Packet;
+      typedef etl::queue<Packet, 4> Queue;
+
+      Queue queue;
+
+      etl::imessage* im;
+
+      // Queue some messages in the message packet queue.
+      im = &message1;
+      queue.emplace(*im);
+
+      im = &message2;
+      queue.emplace(*im);
+
+      // The router2 queue doesn't accept Message3 types.
+      im = &message3;
+      CHECK_THROW(queue.emplace(*im), etl::unhandled_message_exception);
+
+      im = &message4;
+      queue.emplace(*im);
+
+      im = &message4;
+      queue.emplace(*im);
+
+      etl::imessage& imr1 = queue.front().get();
+      r2.receive(r1, imr1);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(0, r2.message2_count);
+      CHECK_EQUAL(0, r2.message4_count);
+      CHECK_EQUAL(0, r2.message_unknown_count);
+      CHECK_EQUAL(1, r1.callback_count);
+      queue.pop();
+
+      etl::imessage& imr2 = queue.front().get();
+      r2.receive(r1, imr2);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(1, r2.message2_count);
+      CHECK_EQUAL(0, r2.message4_count);
+      CHECK_EQUAL(0, r2.message_unknown_count);
+      CHECK_EQUAL(2, r1.callback_count);
+      queue.pop();
+
+      const etl::imessage& imr3 = queue.front().get();
+      r2.receive(r1, imr3);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(1, r2.message2_count);
+      CHECK_EQUAL(1, r2.message4_count);
+      CHECK_EQUAL(0, r2.message_unknown_count);
+      CHECK_EQUAL(3, r1.callback_count);
+      queue.pop();
+
+      const Queue& crqueue = queue;
+      const etl::imessage& imr4 = crqueue.front().get();
+      r2.receive(r1, imr4);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(1, r2.message2_count);
+      CHECK_EQUAL(2, r2.message4_count);
+      CHECK_EQUAL(0, r2.message_unknown_count);
+      CHECK_EQUAL(4, r1.callback_count);
+      queue.pop();
+    }
+  };
+}
diff --git a/test/test_packet.cpp b/test/test_packet.cpp
new file mode 100644
index 00000000..90f70c67
--- /dev/null
+++ b/test/test_packet.cpp
@@ -0,0 +1,183 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include "UnitTest++.h"
+#include "ExtraCheckMacros.h"
+
+#include "packet.h"
+#include "largest.h"
+#include "queue.h"
+#include "pool.h"
+
+namespace
+{
+  // Test classes for polymorphic tests.
+  struct base
+  {
+    base(int v_)
+      : v(v_)
+    {
+    }
+
+    virtual ~base()
+    {
+    }
+
+    virtual int value() const = 0;
+
+  protected:
+
+    const int v;
+  };
+
+  struct not_base
+  {
+    not_base()
+    {
+    }
+  };
+
+  struct derived_1 : public base
+  {
+    derived_1(int value)
+      : base(value)
+    {
+    }
+
+    int value() const
+    {
+      return v;
+    }
+
+    static int count;
+  };
+
+  struct derived_2 : public base
+  {
+    derived_2(int value)
+      : base(value)
+    {
+    }
+
+    int value() const
+    {
+      return v;
+    }
+  };
+
+  typedef etl::largest<derived_1, derived_2> types;
+  //
+  //// Test packet types.
+  typedef etl::packet<base, types::size, types::alignment> packet1_t;
+  typedef etl::packet<not_base, types::size, types::alignment> packet2_t;
+
+  SUITE(test_packet)
+  {
+    //*************************************************************************
+    TEST(test_constructor_value)
+    {
+      derived_1 d1(1);
+      derived_2 d2(2);
+
+      packet1_t p11(d1);
+      packet1_t p12(d2);
+
+      base* b;
+      b = &p11.get();
+      CHECK_EQUAL(d1.value(), b->value());
+
+      b = &p12.get();
+      CHECK_EQUAL(d2.value(), b->value());
+
+      // These lines should fail to compile.
+      //p11 = p12;
+      //packet2_t p21(d1);
+      //packet2_t p22(d1);
+    }
+
+    //*************************************************************************
+    TEST(test_assignment)
+    {
+      derived_1 d1(1);
+      derived_2 d2(2);
+
+      packet1_t p(d1);
+
+      base* b;
+      b = &p.get();
+      CHECK_EQUAL(d1.value(), b->value());
+
+      p = d2;
+      CHECK_EQUAL(d2.value(), b->value());
+    }
+
+    //*************************************************************************
+    TEST(test_packet_queueing)
+    {
+      derived_1 da(1);
+      derived_2 db(2);
+      derived_1 dc(3);
+      derived_2 dd(4);
+      
+      etl::queue<packet1_t, 4> queue;
+
+      queue.emplace(da);
+      queue.emplace(db);
+      queue.emplace(dc);
+      queue.emplace(dd);
+      
+      CHECK_EQUAL(da.value(), queue.front().get().value());
+      queue.pop();
+
+      CHECK_EQUAL(db.value(), queue.front().get().value());
+      queue.pop();
+
+      CHECK_EQUAL(dc.value(), queue.front().get().value());
+      queue.pop();
+
+      CHECK_EQUAL(dd.value(), queue.front().get().value());
+      queue.pop();
+    }
+
+    //*************************************************************************
+    TEST(test_packet_get)
+    {
+      derived_1 da(1);
+
+      // Non-const.
+      packet1_t p1(da);
+      base& rb = p1.get();
+      CHECK_EQUAL(da.value(), rb.value());
+
+      // Const.
+      const packet1_t p2(da);
+      const base& crb = p2.get();
+      CHECK_EQUAL(da.value(), crb.value());
+    }
+  }
+}
diff --git a/test/test_task_scheduler.cpp b/test/test_task_scheduler.cpp
new file mode 100644
index 00000000..7680e37f
--- /dev/null
+++ b/test/test_task_scheduler.cpp
@@ -0,0 +1,263 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include "UnitTest++.h"
+
+#include <stdint.h>
+#include <string>
+#include <vector>
+
+#include "task.h"
+#include "scheduler.h"
+#include "container.h"
+
+typedef std::vector<std::string> WorkList_t;
+
+//*****************************************************************************
+struct Common
+{
+  //*********************************************
+  Common()
+    : idle_callback(*this, &Common::IdleCallback),
+      watchdog_callback(*this, &Common::WatchdogCallback),
+      watchdog_called(false)
+  {
+  }
+
+  //*********************************************
+  void Clear()
+  {
+    workList.clear();
+  }
+
+  //*********************************************
+  void IdleCallback()
+  {
+    pScheduler->exit_scheduler();
+  }
+
+  //*********************************************
+  void WatchdogCallback()
+  {
+    watchdog_called = true;
+  }
+
+  WorkList_t workList;
+  etl::function<Common, void> idle_callback;
+  etl::function<Common, void> watchdog_callback;
+  etl::ischeduler* pScheduler;
+  bool watchdog_called;
+};
+
+//*****************************************************************************
+class Task : public etl::task
+{
+public:
+
+  //*********************************************
+  Task(etl::task_priority_t priority, WorkList_t& work, Common& common)
+    : task(priority),
+      work(work),
+      common(common),
+      workIndex(0),
+      addAtIndex(0),
+      workToAdd(""),
+      pTaskToAddTo(nullptr)
+  {
+    workCopy = work;
+  }
+
+  //*********************************************
+  void Reset()
+  {
+    workIndex    = 0;
+    addAtIndex   = 0;
+    workToAdd    = "";
+    pTaskToAddTo = nullptr;
+    work         = workCopy;
+  }
+
+  //*********************************************
+  void WorkToAdd(int addAtIndex_, const std::string& workToAdd_, Task& taskToAddTo_)
+  {
+    addAtIndex   = addAtIndex_;
+    workToAdd    = workToAdd_;
+    pTaskToAddTo = &taskToAddTo_;
+  }
+
+  //*********************************************
+  uint32_t task_request_work() const
+  {
+    return uint_least8_t(work.size() - workIndex);
+  }
+
+  //*********************************************
+  void task_process_work()
+  {
+    common.workList.push_back(work[workIndex]);
+    ++workIndex;
+
+    if (workIndex == addAtIndex)
+    {
+      pTaskToAddTo->work.push_back(workToAdd);
+    }
+  }
+
+private:
+
+  WorkList_t work;
+  WorkList_t workCopy;
+  Common &common;
+  uint_least8_t workIndex;
+  int addAtIndex;
+  std::string workToAdd;
+  Task* pTaskToAddTo;
+};
+
+Common common;
+
+WorkList_t work1 = { "T1W1", "T1W2", "T1W3" };
+WorkList_t work2 = { "T2W1", "T2W2", "T2W3", "T2W4" };
+WorkList_t work3 = { "T3W1", "T3W2" };
+
+Task task1(1, work1, common);
+Task task2(2, work2, common);
+Task task3(3, work3, common);
+
+etl::task* taskList[] = { &task1, &task2, &task3 };
+
+typedef etl::scheduler<etl::scheduler_policy_sequencial_single,   sizeof(etl::array_size(taskList))> SchedulerSequencialSingle;
+typedef etl::scheduler<etl::scheduler_policy_sequencial_multiple, sizeof(etl::array_size(taskList))> SchedulerSequencialMultiple;
+typedef etl::scheduler<etl::scheduler_policy_highest_priority,    sizeof(etl::array_size(taskList))> SchedulerHighestPriority;
+typedef etl::scheduler<etl::scheduler_policy_most_work,           sizeof(etl::array_size(taskList))> SchedulerMostWork;
+
+namespace
+{
+  SUITE(test_task_scheduler)
+  {
+    //=========================================================================
+    TEST(test_scheduler_sequencial_single)
+    {
+      SchedulerSequencialSingle s;
+
+      task1.Reset();
+      task2.Reset();
+      task3.Reset();
+
+      task2.WorkToAdd(2, "T3W3", task3);
+
+      common.Clear();
+      common.pScheduler = &s;
+
+      s.set_idle_callback(common.idle_callback);
+      s.set_watchdog_callback(common.watchdog_callback);
+      s.add_task_list(taskList, etl::size(taskList));
+      s.start(); // If 'start' returns then the idle callback was sucessfully called.
+
+      WorkList_t expected = { "T3W1", "T2W1", "T1W1", "T3W2", "T2W2", "T1W2", "T3W3", "T2W3", "T1W3", "T2W4" };
+
+      CHECK(expected == common.workList);
+      CHECK(common.watchdog_called);
+    }
+
+    //=========================================================================
+    TEST(test_scheduler_sequencial_multiple)
+    {
+      SchedulerSequencialMultiple s;
+
+      task1.Reset();
+      task2.Reset();
+      task3.Reset();
+
+      task2.WorkToAdd(2, "T3W3", task3);
+
+      common.Clear();
+      common.pScheduler = &s;
+
+      s.set_idle_callback(common.idle_callback);
+      s.set_watchdog_callback(common.watchdog_callback);
+      s.add_task_list(taskList, etl::size(taskList));
+      s.start(); // If 'start' returns then the idle callback was sucessfully called.
+
+      WorkList_t expected = { "T3W1", "T3W2", "T2W1", "T2W2", "T2W3", "T2W4", "T1W1", "T1W2", "T1W3", "T3W3" };
+
+      CHECK(expected == common.workList);
+      CHECK(common.watchdog_called);
+    }
+
+    //=========================================================================
+    TEST(test_scheduler_highest_priority)
+    {
+      SchedulerHighestPriority s;
+
+      task1.Reset();
+      task2.Reset();
+      task3.Reset();
+
+      task2.WorkToAdd(2, "T3W3", task3);
+
+      common.Clear();
+      common.pScheduler = &s;
+
+      s.set_idle_callback(common.idle_callback);
+      s.set_watchdog_callback(common.watchdog_callback);
+      s.add_task_list(taskList, etl::size(taskList));
+      s.start(); // If 'start' returns then the idle callback was sucessfully called.
+
+      WorkList_t expected = { "T3W1", "T3W2", "T2W1", "T2W2", "T3W3", "T2W3", "T2W4", "T1W1", "T1W2", "T1W3" };
+
+      CHECK(expected == common.workList);
+      CHECK(common.watchdog_called);
+    }
+
+    //=========================================================================
+    TEST(test_scheduler_most_work)
+    {
+      SchedulerMostWork s;
+
+      task1.Reset();
+      task2.Reset();
+      task3.Reset();
+
+      task2.WorkToAdd(3, "T3W3", task3);
+
+      common.Clear();
+      common.pScheduler = &s;
+
+      s.set_idle_callback(common.idle_callback);
+      s.set_watchdog_callback(common.watchdog_callback);
+      s.add_task_list(taskList, etl::size(taskList));
+      s.start(); // If 'start' returns then the idle callback was sucessfully called.
+
+      WorkList_t expected = { "T2W1", "T2W2", "T1W1", "T3W1", "T2W3", "T3W2", "T1W2", "T3W3", "T2W4", "T1W3" };
+
+      CHECK(expected == common.workList);
+      CHECK(common.watchdog_called);
+    }
+  };
+}
diff --git a/test/test_type_traits.cpp b/test/test_type_traits.cpp
index b9e624d7..5f80210e 100644
--- a/test/test_type_traits.cpp
+++ b/test/test_type_traits.cpp
@@ -41,14 +41,20 @@ namespace std
 #include "type_traits.h"
 #include <type_traits>
 
-// A class to test non-fundamental types.
-struct Test
-{
-  int a;
-};
-
 namespace
 {
+  // A class to test non-fundamental types.
+  struct Test
+  {
+    int a;
+  };
+
+  // A class to test etl::is_one_of
+  template <const int I>
+  struct Type
+  {
+  };
+
   SUITE(test_type_traits)
   {
     //*************************************************************************
@@ -525,5 +531,55 @@ namespace
       CHECK(std::alignment_of<double>::value             == etl::alignment_of<double>::value);
       CHECK(std::alignment_of<Test>::value               == etl::alignment_of<Test>::value);
     }
+
+    //*************************************************************************
+    TEST(test_is_one_of)
+    {
+      typedef Type<0> T0;
+      typedef Type<1> T1;
+      typedef Type<2> T2;
+      typedef Type<3> T3;
+      typedef Type<4> T4;
+
+      CHECK(bool(etl::is_one_of<char, char>::value));
+      CHECK(!(etl::is_one_of<char, T0>::value));
+
+      CHECK(bool(etl::is_one_of<char, T0, char>::value));
+      CHECK(!(etl::is_one_of<char, T0, T1>::value));
+
+      CHECK(bool(etl::is_one_of<char, T0, T1, char>::value));
+      CHECK(!(etl::is_one_of<char, T0, T1, T2>::value));
+
+      CHECK(bool(etl::is_one_of<char, T0, T1, T2, char>::value));
+      CHECK(!(etl::is_one_of<char, T0, T1, T2, T3>::value));
+
+      CHECK(bool(etl::is_one_of<char, T0, T1, T2, char>::value));
+      CHECK(!(etl::is_one_of<char, T0, T1, T2, T3>::value));
+
+      CHECK(bool(etl::is_one_of<char, char, T0, T1, T2, T3>::value));
+      CHECK(bool(etl::is_one_of<char, T0, char, T1, T2, T3>::value));
+      CHECK(bool(etl::is_one_of<char, T0, T1, char, T2, T3>::value));
+      CHECK(bool(etl::is_one_of<char, T0, T1, T2, char, T3>::value));
+      CHECK(bool(etl::is_one_of<char, T0, T1, T2, T3, char>::value));
+      CHECK(!(etl::is_one_of<char, T0, T1, T2, T3, T4>::value));
+    }
+
+    //*************************************************************************
+    TEST(test_is_base_of)
+    {
+      struct A { };
+      struct B : public A { };
+      struct C { };
+
+      CHECK((std::is_base_of<A, A>::value) == (etl::is_base_of<A, A>::value));
+      CHECK((std::is_base_of<A, B>::value) == (etl::is_base_of<A, B>::value));
+      CHECK((std::is_base_of<A, C>::value) == (etl::is_base_of<A, C>::value));
+      CHECK((std::is_base_of<B, A>::value) == (etl::is_base_of<B, A>::value));
+      CHECK((std::is_base_of<B, B>::value) == (etl::is_base_of<B, B>::value));
+      CHECK((std::is_base_of<B, C>::value) == (etl::is_base_of<B, C>::value));
+      CHECK((std::is_base_of<C, A>::value) == (etl::is_base_of<C, A>::value));
+      CHECK((std::is_base_of<C, B>::value) == (etl::is_base_of<C, B>::value));
+      CHECK((std::is_base_of<C, C>::value) == (etl::is_base_of<C, C>::value));
+    }
   };
 }
diff --git a/test/test_user_type.cpp b/test/test_user_type.cpp
new file mode 100644
index 00000000..0e3e5da7
--- /dev/null
+++ b/test/test_user_type.cpp
@@ -0,0 +1,224 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include "UnitTest++.h"
+#include <string>
+
+#include "user_type.h"
+
+ETL_DECLARE_USER_TYPE(CompassDirection, int)
+ETL_USER_TYPE(North, 0)
+ETL_USER_TYPE(South, 180)
+ETL_USER_TYPE(East,  90)
+ETL_USER_TYPE(West,  270)
+ETL_END_USER_TYPE(CompassDirection)
+
+namespace 
+{		
+  SUITE(test_user_type)
+  {
+    //*************************************************************************
+    TEST(Values)
+    {
+      CHECK_EQUAL(0,   CompassDirection::North);
+      CHECK_EQUAL(180, CompassDirection::South);
+      CHECK_EQUAL(90,  CompassDirection::East);
+      CHECK_EQUAL(270, CompassDirection::West);
+    }
+
+    //*************************************************************************
+    TEST(test_assignment)
+    {
+      CompassDirection value1 = CompassDirection::North;
+      CompassDirection value2 = CompassDirection(135);
+
+      value1 = value2;
+
+      CHECK_EQUAL(135, value1);
+    }
+
+    //*************************************************************************
+    TEST(test_equality)
+    {
+      CompassDirection value1 = CompassDirection::North;
+      CompassDirection value2 = CompassDirection::South;
+      CompassDirection value3 = CompassDirection::South;
+
+      CHECK(value1 != value2);
+      CHECK(value2 == value3);
+    }
+
+    //*************************************************************************
+    TEST(test_get_value)
+    {
+      CompassDirection actual   = CompassDirection::North;
+      CompassDirection expected = CompassDirection::North;
+
+      CHECK_EQUAL(expected, actual.get());
+    }
+
+    //*************************************************************************
+    TEST(test_pre_increment)
+    {
+      CompassDirection value = CompassDirection::North;
+      CompassDirection expected = CompassDirection(CompassDirection::North + 1);
+
+      CHECK_EQUAL(expected, ++value);
+    }
+
+    //*************************************************************************
+    TEST(test_post_increment)
+    {
+      CompassDirection value = CompassDirection::North;
+      CompassDirection expected = CompassDirection(CompassDirection::North + 1);
+
+      CHECK_EQUAL(CompassDirection::North, value++);
+      CHECK_EQUAL(expected, value);
+    }
+
+
+    //*************************************************************************
+    TEST(test_pre_decrement)
+    {
+      CompassDirection value = CompassDirection::North;
+      CompassDirection expected = CompassDirection(CompassDirection::North - 1);
+
+      CHECK_EQUAL(expected, --value);
+    }
+
+    //*************************************************************************
+    TEST(test_post_decrement)
+    {
+      CompassDirection value = CompassDirection::North;
+      CompassDirection expected = CompassDirection(CompassDirection::North - 1);
+
+      CHECK_EQUAL(CompassDirection::North, value--);
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_add_equal)
+    {
+      CompassDirection value = CompassDirection::North;
+      value += 3;
+      CompassDirection expected = CompassDirection(CompassDirection::North + 3);
+
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_subtract_equal)
+    {
+      CompassDirection value = CompassDirection::North;
+      value -= 3;
+      CompassDirection expected = CompassDirection(CompassDirection::North - 3);
+
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_muliply_equal)
+    {
+      CompassDirection value = CompassDirection::North;
+      value *= 3;
+      CompassDirection expected = CompassDirection(CompassDirection::North * 3);
+
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_divide_equal)
+    {
+      CompassDirection value = CompassDirection::North;
+      value /= 3;
+      CompassDirection expected = CompassDirection(CompassDirection::North / 3);
+
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_mod_equal)
+    {
+      CompassDirection value = CompassDirection::North;
+      value %= 3;
+      CompassDirection expected = CompassDirection(CompassDirection::North % 3);
+
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_and_equal)
+    {
+      CompassDirection value = CompassDirection::North;
+      value &= 0xAAAAAAAA;
+      CompassDirection expected = CompassDirection(CompassDirection::North & 0xAAAAAAAA);
+
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_or_equal)
+    {
+      CompassDirection value = CompassDirection::North;
+      value |= 0xAAAAAAAA;
+      CompassDirection expected = CompassDirection(CompassDirection::North | 0xAAAAAAAA);
+
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_xor_equal)
+    {
+      CompassDirection value = CompassDirection::North;
+      value ^= 0xAAAAAAAA;
+      CompassDirection expected = CompassDirection(CompassDirection::North ^ 0xAAAAAAAA);
+
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_shift_left)
+    {
+      CompassDirection value = CompassDirection::North;
+      value <<= 2;
+      CompassDirection expected = CompassDirection(CompassDirection::North << 2);
+
+      CHECK_EQUAL(expected, value);
+    }
+
+    //*************************************************************************
+    TEST(test_shift_right)
+    {
+      CompassDirection value = CompassDirection::North;
+      value >>= 2;
+      CompassDirection expected = CompassDirection(CompassDirection::North >> 2);
+
+      CHECK_EQUAL(expected, value);
+    }
+  };
+}
\ No newline at end of file
diff --git a/test/test_variant.cpp b/test/test_variant.cpp
index 0430c7f6..5b3324e9 100644
--- a/test/test_variant.cpp
+++ b/test/test_variant.cpp
@@ -35,70 +35,70 @@ SOFTWARE.
 #include <vector>
 #include <algorithm>
 
-// Test classes for polymorphic tests.
-struct base
-{
-  virtual ~base()
-  {
-  }
-
-  base()
-    : value(0)
-  {
-  }
-
-  virtual void set() = 0;
-  int value;
-};
-
-struct not_base
-{
-  not_base()
-    : value(0)
-  {
-  }
-
-  virtual void set() = 0;
-  int value;
-};
-
-struct derived_1 : public base
-{
-  void set()
-  {
-    value = 1;
-  }
-};
-
-struct derived_2 : public base
-{
-  void set()
-  {
-    value = 2;
-  }
-};
-
-// Test variant types.
-typedef etl::variant<char, int, std::string> test_variant_3a;
-typedef etl::variant<int, short, double> test_variant_3b;
-
-typedef etl::variant<int8_t> test_variant_1;
-typedef etl::variant<int8_t, uint8_t> test_variant_2;
-typedef etl::variant<int8_t, uint8_t, int16_t> test_variant_3;
-typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t> test_variant_4;
-typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t, int32_t> test_variant_5;
-typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t> test_variant_6;
-typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, int64_t> test_variant_7;
-typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, int64_t, uint64_t> test_variant_8;
-
-typedef etl::variant<derived_1, derived_2> test_variant_polymorphic;
-typedef etl::variant<char, unsigned char, short, unsigned short, int, unsigned int, long, unsigned long> test_variant_max_types;
-
-// This line should compile with no errors.
-test_variant_max_types variant_max;
-
 namespace
 {
+  // Test classes for polymorphic tests.
+  struct base
+  {
+    virtual ~base()
+    {
+    }
+
+    base()
+      : value(0)
+    {
+    }
+
+    virtual void set() = 0;
+    int value;
+  };
+
+  struct not_base
+  {
+    not_base()
+      : value(0)
+    {
+    }
+
+    virtual void set() = 0;
+    int value;
+  };
+
+  struct derived_1 : public base
+  {
+    void set()
+    {
+      value = 1;
+    }
+  };
+
+  struct derived_2 : public base
+  {
+    void set()
+    {
+      value = 2;
+    }
+  };
+
+  // Test variant types.
+  typedef etl::variant<char, int, std::string> test_variant_3a;
+  typedef etl::variant<int, short, double> test_variant_3b;
+
+  typedef etl::variant<int8_t> test_variant_1;
+  typedef etl::variant<int8_t, uint8_t> test_variant_2;
+  typedef etl::variant<int8_t, uint8_t, int16_t> test_variant_3;
+  typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t> test_variant_4;
+  typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t, int32_t> test_variant_5;
+  typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t> test_variant_6;
+  typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, int64_t> test_variant_7;
+  typedef etl::variant<int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, int64_t, uint64_t> test_variant_8;
+
+  typedef etl::variant<derived_1, derived_2> test_variant_polymorphic;
+  typedef etl::variant<char, unsigned char, short, unsigned short, int, unsigned int, long, unsigned long> test_variant_max_types;
+
+  // This line should compile with no errors.
+  test_variant_max_types variant_max;
+
   SUITE(test_variant)
   {
     TEST(test_alignment)
diff --git a/test/vs2017/etl.vcxproj b/test/vs2017/etl.vcxproj
index e2eddc14..a1356245 100644
--- a/test/vs2017/etl.vcxproj
+++ b/test/vs2017/etl.vcxproj
@@ -128,6 +128,19 @@
     </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemGroup>
+    <ClInclude Include="..\..\src\fsm.h" />
+    <ClInclude Include="..\..\src\fsm_generator.h" />
+    <ClInclude Include="..\..\src\largest_generator.h" />
+    <ClInclude Include="..\..\src\message.h" />
+    <ClInclude Include="..\..\src\message_bus.h" />
+    <ClInclude Include="..\..\src\message_types.h" />
+    <ClInclude Include="..\..\src\message_router.h" />
+    <ClInclude Include="..\..\src\message_router_generator.h" />
+    <ClInclude Include="..\..\src\packet.h" />
+    <ClInclude Include="..\..\src\scheduler.h" />
+    <ClInclude Include="..\..\src\smallest_generator.h" />
+    <ClInclude Include="..\..\src\task.h" />
+    <ClInclude Include="..\..\src\type_traits_generator.h" />
     <ClInclude Include="..\..\unittest-cpp\UnitTest++\AssertException.h" />
     <ClInclude Include="..\..\unittest-cpp\UnitTest++\CheckMacros.h" />
     <ClInclude Include="..\..\unittest-cpp\UnitTest++\Checks.h" />
@@ -212,7 +225,6 @@
     <ClInclude Include="..\..\src\flat_map.h" />
     <ClInclude Include="..\..\src\map.h" />
     <ClInclude Include="..\..\src\memory.h" />
-    <ClInclude Include="..\..\src\mru_cache.h" />
     <ClInclude Include="..\..\src\multimap.h" />
     <ClInclude Include="..\..\src\multiset.h" />
     <ClInclude Include="..\..\src\multi_array.h" />
@@ -236,7 +248,6 @@
     <ClInclude Include="..\..\src\reference_flat_multimap.h" />
     <ClInclude Include="..\..\src\reference_flat_multiset.h" />
     <ClInclude Include="..\..\src\reference_flat_set.h" />
-    <ClInclude Include="..\..\src\rr_cache.h" />
     <ClInclude Include="..\..\src\set.h" />
     <ClInclude Include="..\..\src\smallest.h" />
     <ClInclude Include="..\..\src\stack.h" />
@@ -329,6 +340,7 @@
     </ClCompile>
     <ClCompile Include="..\test_fnv_1.cpp" />
     <ClCompile Include="..\test_forward_list.cpp" />
+    <ClCompile Include="..\test_fsm.cpp" />
     <ClCompile Include="..\test_function.cpp" />
     <ClCompile Include="..\test_functional.cpp" />
     <ClCompile Include="..\test_hash.cpp" />
@@ -364,6 +376,8 @@
     </ClCompile>
     <ClCompile Include="..\test_maths.cpp" />
     <ClCompile Include="..\test_memory.cpp" />
+    <ClCompile Include="..\test_message_bus.cpp" />
+    <ClCompile Include="..\test_message_router.cpp" />
     <ClCompile Include="..\test_multimap.cpp" />
     <ClCompile Include="..\test_multiset.cpp" />
     <ClCompile Include="..\test_murmur3.cpp" />
@@ -373,6 +387,7 @@
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug No Unit Tests|Win32'">false</ExcludedFromBuild>
     </ClCompile>
     <ClCompile Include="..\test_optional.cpp" />
+    <ClCompile Include="..\test_packet.cpp" />
     <ClCompile Include="..\test_pearson.cpp" />
     <ClCompile Include="..\test_pool.cpp" />
     <ClCompile Include="..\test_priority_queue.cpp" />
@@ -393,12 +408,14 @@
     <ClCompile Include="..\test_string_u16.cpp" />
     <ClCompile Include="..\test_string_u32.cpp" />
     <ClCompile Include="..\test_string_wchar_t.cpp" />
+    <ClCompile Include="..\test_task_scheduler.cpp" />
     <ClCompile Include="..\test_type_def.cpp" />
     <ClCompile Include="..\test_type_traits.cpp" />
     <ClCompile Include="..\test_unordered_map.cpp" />
     <ClCompile Include="..\test_unordered_multimap.cpp" />
     <ClCompile Include="..\test_unordered_multiset.cpp" />
     <ClCompile Include="..\test_unordered_set.cpp" />
+    <ClCompile Include="..\test_user_type.cpp" />
     <ClCompile Include="..\test_utility.cpp" />
     <ClCompile Include="..\test_variant.cpp" />
     <ClCompile Include="..\test_vector.cpp" />
@@ -410,6 +427,9 @@
   <ItemGroup>
     <None Include="..\..\Doxyfile" />
     <None Include="..\..\library.properties" />
+    <None Include="..\..\src\generate.bat" />
+    <None Include="..\..\src\generate_fsm.bat" />
+    <None Include="..\..\src\generate_message_router.bat" />
   </ItemGroup>
   <ItemGroup>
     <Text Include="..\..\src\file_error_numbers.txt" />
diff --git a/test/vs2017/etl.vcxproj.filters b/test/vs2017/etl.vcxproj.filters
index 6c40bcc4..df04c8df 100644
--- a/test/vs2017/etl.vcxproj.filters
+++ b/test/vs2017/etl.vcxproj.filters
@@ -38,7 +38,13 @@
       <UniqueIdentifier>{7028012c-30c4-4993-b2d9-3b1521a610ae}</UniqueIdentifier>
     </Filter>
     <Filter Include="ETL\Frameworks">
-      <UniqueIdentifier>{5de50c3d-4679-4eb3-9b76-e43e1aad6a66}</UniqueIdentifier>
+      <UniqueIdentifier>{6be3bc76-e17c-4be0-8b0b-d1053e1a1761}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="ETL\Frameworks\Generators">
+      <UniqueIdentifier>{c1264f38-22fa-4fcb-8cab-f254b1290eab}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="ETL\Utilities\Generators">
+      <UniqueIdentifier>{39015d44-a7cb-47f0-a7dd-27714f852363}</UniqueIdentifier>
     </Filter>
   </ItemGroup>
   <ItemGroup>
@@ -261,12 +267,6 @@
     <ClInclude Include="..\..\src\icache.h">
       <Filter>ETL\Containers</Filter>
     </ClInclude>
-    <ClInclude Include="..\..\src\mru_cache.h">
-      <Filter>ETL\Containers</Filter>
-    </ClInclude>
-    <ClInclude Include="..\..\src\rr_cache.h">
-      <Filter>ETL\Containers</Filter>
-    </ClInclude>
     <ClInclude Include="..\..\src\intrusive_links.h">
       <Filter>ETL\Containers</Filter>
     </ClInclude>
@@ -438,6 +438,45 @@
     <ClInclude Include="..\..\unittest-cpp\UnitTest++\XmlTestReporter.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\src\fsm.h">
+      <Filter>ETL\Frameworks</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\message_router.h">
+      <Filter>ETL\Frameworks</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\packet.h">
+      <Filter>ETL\Containers</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\fsm_generator.h">
+      <Filter>ETL\Frameworks\Generators</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\message_router_generator.h">
+      <Filter>ETL\Frameworks\Generators</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\largest_generator.h">
+      <Filter>ETL\Utilities\Generators</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\type_traits_generator.h">
+      <Filter>ETL\Utilities\Generators</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\smallest_generator.h">
+      <Filter>ETL\Utilities\Generators</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\message.h">
+      <Filter>ETL\Frameworks</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\message_bus.h">
+      <Filter>ETL\Frameworks</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\message_types.h">
+      <Filter>ETL\Frameworks</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\scheduler.h">
+      <Filter>ETL\Frameworks</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\task.h">
+      <Filter>ETL\Frameworks</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\main.cpp">
@@ -761,6 +800,24 @@
     <ClCompile Include="..\..\unittest-cpp\UnitTest++\XmlTestReporter.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="..\test_fsm.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="..\test_message_router.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="..\test_packet.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="..\test_task_scheduler.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="..\test_message_bus.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="..\test_user_type.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <None Include="..\..\Doxyfile">
@@ -769,8 +826,14 @@
     <None Include="..\..\library.properties">
       <Filter>Resource Files</Filter>
     </None>
-    <None Include="..\..\src\CreateMessageProcessor.bat">
-      <Filter>Source Files</Filter>
+    <None Include="..\..\src\generate.bat">
+      <Filter>Resource Files</Filter>
+    </None>
+    <None Include="..\..\src\generate_message_router.bat">
+      <Filter>Resource Files</Filter>
+    </None>
+    <None Include="..\..\src\generate_fsm.bat">
+      <Filter>Resource Files</Filter>
     </None>
   </ItemGroup>
   <ItemGroup>
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diff --git a/uml/source/FSM example.zargo b/uml/source/FSM example.zargo
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