From eb49582837b9d37193c1b9830f5cf0d05659b977 Mon Sep 17 00:00:00 2001
From: John Wellbelove <jwellbelove@users.noreply.github.com>
Date: Sat, 26 Mar 2022 18:30:33 +0000
Subject: [PATCH] Small optimisations for computing indexes for queues &
 cyclic_value.

---
 include/etl/circular_buffer.h   | 42 ++++++++++++++++++++++++++++-----
 include/etl/cyclic_value.h      |  4 ++--
 include/etl/queue.h             |  4 ++--
 include/etl/queue_lockable.h    |  2 +-
 include/etl/queue_mpmc_mutex.h  |  2 +-
 include/etl/queue_spsc_atomic.h |  2 +-
 include/etl/queue_spsc_isr.h    |  2 +-
 include/etl/queue_spsc_locked.h |  2 +-
 8 files changed, 45 insertions(+), 15 deletions(-)

diff --git a/include/etl/circular_buffer.h b/include/etl/circular_buffer.h
index f042f621..42abcc61 100644
--- a/include/etl/circular_buffer.h
+++ b/include/etl/circular_buffer.h
@@ -95,7 +95,15 @@ namespace etl
     //*************************************************************************
     bool full() const
     {
-      return (in + 1U) % BUFFER_SIZE == out;
+      size_t i = in;
+
+      ++i;
+      if (i == BUFFER_SIZE) ETL_UNLIKELY
+      {
+        i = 0U;
+      }
+
+      return i == out;
     }
 
     //*************************************************************************
@@ -126,6 +134,26 @@ namespace etl
     {
     }
 
+    //*************************************************************************
+    void increment_in()
+    {
+      ++in;
+      if (in == BUFFER_SIZE) ETL_UNLIKELY
+      {
+        in = 0U;
+      }
+    }
+
+    //*************************************************************************
+    void increment_out()
+    {
+      ++out;
+      if (out == BUFFER_SIZE) ETL_UNLIKELY
+      {
+        out = 0U;
+      }
+    }
+
     const size_type BUFFER_SIZE;
     size_type in;            ///< Index to the next write.
     size_type out;           ///< Index to the next read.
@@ -835,14 +863,14 @@ namespace etl
     void push(const_reference item)
     {
       ::new (&pbuffer[in]) T(item);
-      in = (in + 1U) % BUFFER_SIZE;
+      increment_in();
 
       // Did we catch up with the 'out' index?
       if (in == out)
       {
         // Forget about the oldest one.
         pbuffer[out].~T();
-        out = (out + 1U) % BUFFER_SIZE;
+        this->increment_out();
       }
       else
       {
@@ -859,14 +887,14 @@ namespace etl
     void push(rvalue_reference item)
     {
       ::new (&pbuffer[in]) T(etl::move(item));
-      in = (in + 1U) % BUFFER_SIZE;
+      increment_in();
 
       // Did we catch up with the 'out' index?
       if (in == out)
       {
         // Forget about the oldest item.
         pbuffer[out].~T();
-        out = (out + 1U) % BUFFER_SIZE;
+        increment_out();
       }
       else
       {
@@ -895,7 +923,7 @@ namespace etl
     {
       ETL_ASSERT(!empty(), ETL_ERROR(circular_buffer_empty));
       pbuffer[out].~T();
-      out = (out + 1U) % BUFFER_SIZE;
+      increment_out();
       ETL_DECREMENT_DEBUG_COUNT
     }
 
@@ -1013,6 +1041,8 @@ namespace etl
       }
     }
 
+
+
     pointer pbuffer;
 
   private:
diff --git a/include/etl/cyclic_value.h b/include/etl/cyclic_value.h
index 000b40ed..2c08f357 100644
--- a/include/etl/cyclic_value.h
+++ b/include/etl/cyclic_value.h
@@ -172,7 +172,7 @@ namespace etl
     //*************************************************************************
     cyclic_value& operator ++()
     {
-      if (value >= LAST)
+      if (value >= LAST) ETL_UNLIKELY
       {
         value = FIRST;
       }
@@ -201,7 +201,7 @@ namespace etl
     //*************************************************************************
     cyclic_value& operator --()
     {
-      if (value <= FIRST)
+      if (value <= FIRST) ETL_UNLIKELY
       {
         value = LAST;
       }
diff --git a/include/etl/queue.h b/include/etl/queue.h
index cc498b88..b9eb00b9 100644
--- a/include/etl/queue.h
+++ b/include/etl/queue.h
@@ -187,7 +187,7 @@ namespace etl
     //*************************************************************************
     void add_in()
     {
-      if (++in == CAPACITY)
+      if (++in == CAPACITY) ETL_UNLIKELY
       {
         in = 0;
       }
@@ -201,7 +201,7 @@ namespace etl
     //*************************************************************************
     void del_out()
     {
-      if (++out == CAPACITY)
+      if (++out == CAPACITY) ETL_UNLIKELY
       {
         out = 0;
       }
diff --git a/include/etl/queue_lockable.h b/include/etl/queue_lockable.h
index db795a7a..02ac59a8 100644
--- a/include/etl/queue_lockable.h
+++ b/include/etl/queue_lockable.h
@@ -185,7 +185,7 @@ namespace etl
     {
       ++index;
 
-      if (index == maximum)
+      if (index == maximum) ETL_UNLIKELY
       {
         index = 0;
       }
diff --git a/include/etl/queue_mpmc_mutex.h b/include/etl/queue_mpmc_mutex.h
index 16b2cc45..9b27179d 100644
--- a/include/etl/queue_mpmc_mutex.h
+++ b/include/etl/queue_mpmc_mutex.h
@@ -89,7 +89,7 @@ namespace etl
     {
       ++index;
 
-      if (index == maximum)
+      if (index == maximum) ETL_UNLIKELY
       {
         index = 0;
       }
diff --git a/include/etl/queue_spsc_atomic.h b/include/etl/queue_spsc_atomic.h
index 574e048c..c4dc9056 100644
--- a/include/etl/queue_spsc_atomic.h
+++ b/include/etl/queue_spsc_atomic.h
@@ -141,7 +141,7 @@ namespace etl
     {
       ++index;
 
-      if (index == maximum)
+      if (index == maximum) ETL_UNLIKELY
       {
         index = 0;
       }
diff --git a/include/etl/queue_spsc_isr.h b/include/etl/queue_spsc_isr.h
index 3e93fa8b..071ce2ee 100644
--- a/include/etl/queue_spsc_isr.h
+++ b/include/etl/queue_spsc_isr.h
@@ -421,7 +421,7 @@ namespace etl
     {
       ++index;
 
-      if (index == maximum)
+      if (index == maximum) ETL_UNLIKELY
       {
         index = 0;
       }
diff --git a/include/etl/queue_spsc_locked.h b/include/etl/queue_spsc_locked.h
index 185f64a6..facddeb5 100644
--- a/include/etl/queue_spsc_locked.h
+++ b/include/etl/queue_spsc_locked.h
@@ -118,7 +118,7 @@ namespace etl
     {
       ++index;
 
-      if (index == maximum)
+      if (index == maximum) ETL_UNLIKELY
       {
         index = 0;
       }