Merge remote-tracking branch 'origin/feature/random_hash' into development

include/etl/random.h

@@ -1,4 +1,4 @@
-///\file
+///\file
 
 /******************************************************************************
 The MIT License(MIT)
@@ -289,6 +289,7 @@ namespace etl
   //***************************************************************************
   /// A 32 bit random number generator.
   /// Uses a linear shift feedback register.
+  /// Polynomial 0x80200003
   /// https://en.wikipedia.org/wiki/Linear-feedback_shift_register
   //***************************************************************************
   class random_lsfr : public random
@@ -499,6 +500,73 @@ namespace etl
 
     uint64_t value;
   };
+
+#if ETL_8BIT_SUPPORT
+  //***************************************************************************
+  /// A 32 bit random number generator.
+  /// Applies a user supplied 32bit hash to a counter.
+  /// The hash must implement 'void add(uint8_t)' and 'uint8_t value()' member functions.
+  //***************************************************************************
+  template <typename THash>
+  class random_hash : public random
+  {
+  public:
+
+    random_hash()
+    {
+      // An attempt to come up with a unique non-zero seed,
+      // based on the address of the instance.
+      uintptr_t n = reinterpret_cast<uintptr_t>(this);
+      value = static_cast<uint32_t>(n);
+    }
+
+    //***************************************************************************
+    /// Constructor with seed value.
+    ///\param seed The new seed value.
+    //***************************************************************************
+    random_hash(uint32_t seed)
+    {
+      initialise(seed);
+    }
+
+    //***************************************************************************
+    /// Initialises the sequence with a new seed value.
+    ///\param seed The new seed value.
+    //***************************************************************************
+    void initialise(uint32_t seed)
+    {
+      value = seed;
+    }
+
+    //***************************************************************************
+    /// Get the next random_lsfr number.
+    //***************************************************************************
+    uint32_t operator()()
+    {
+      ++value;
+      hash.add(value);
+      return hash.value();
+    }
+
+    //***************************************************************************
+    /// Get the next random_lsfr number in a specified inclusive range.
+    //***************************************************************************
+    uint32_t range(uint32_t low, uint32_t high)
+    {
+      uint32_t r = high - low + 1;
+      uint32_t n = operator()();
+      n %= r;
+      n += low;
+
+      return n;
+    }
+
+  private:
+
+    THash   hash;
+    uint8_t value;
+  };
+#endif
 }
 
 #endif

include/etl/version.h

@@ -38,7 +38,7 @@ SOFTWARE.
 ///\ingroup utilities
 
 #define ETL_VERSION_MAJOR 14
-#define ETL_VERSION_MINOR  0
+#define ETL_VERSION_MINOR  1
 #define ETL_VERSION_PATCH  0
 
 #define ETL_VERSION       ETL_STRINGIFY(ETL_VERSION_MAJOR) ETL_STRINGIFY(ETL_VERSION_MINOR) ETL_STRINGIFY(ETL_VERSION_PATCH)

support/Release notes.txt

@@ -1,3 +1,7 @@
+===============================================================================
+14.1.0
+Added hash based random number generator
+
 ===============================================================================
 14.0.0
 The ETL is now 'all header'.

test/test_random.cpp

@@ -31,6 +31,7 @@ SOFTWARE.
 #include <stdint.h>
 
 #include "etl/random.h"
+#include "etl/crc32.h"
 
 #include <vector>
 #include <algorithm>
@@ -357,5 +358,59 @@ namespace
         CHECK(n <= high);
       }
     }
+
+    //=========================================================================
+    TEST(test_random_hash_sequence)
+    {
+      std::vector<uint32_t> out1(10000);
+      etl::random_hash<etl::crc32> r;
+
+      struct generator
+      {
+        generator(etl::random& r_)
+          : r(r_)
+        {
+        }
+
+        uint32_t operator()()
+        {
+          return r();
+        }
+
+        etl::random& r;
+      };
+
+      std::generate(out1.begin(), out1.end(), generator(r));
+
+      std::ofstream file("random_hash.csv");
+
+      if (!file.fail())
+      {
+        for (size_t i = 0; i < out1.size(); i += 2)
+        {
+          file << out1[i] << "," << out1[i + 1] << "\n";
+        }
+      }
+
+      file.close();
+    }
+
+    //=========================================================================
+    TEST(test_random_hash_range)
+    {
+      etl::random_hash<etl::crc32> r;
+
+      uint32_t low  = 1234;
+      uint32_t high = 9876;
+
+      for (int i = 0; i < 100000; ++i)
+      {
+        uint32_t n = r.range(low, high);
+
+        CHECK(n >= low);
+        CHECK(n <= high);
+      }
+    }
+
   };
 }

test/vs2017/.gitignore

@@ -4,3 +4,4 @@
 /random_mwc.csv
 /random_xorshift.csv
 /random_pcg.csv
+/random_hash.csv