From 0ab20dd78bac14963f3edc8c41679d443c9e5fa4 Mon Sep 17 00:00:00 2001
From: Kody Stribrny <kstribrn@amazon.com>
Date: Wed, 22 Apr 2026 10:45:02 -0700
Subject: [PATCH] Batching buffers read when reaching threshold

This change reduces the differences between traditional
stream/message buffers and batching stream buffers. Batching
stream buffers are updated to trigger and read data when
enough data is present to EQUAL the threshold rather than exceed
it.

Inspired by https://github.com/FreeRTOS/FreeRTOS-Kernel/issues/1375
---
 include/stream_buffer.h | 8 ++------
 stream_buffer.c         | 6 +++---
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/include/stream_buffer.h b/include/stream_buffer.h
index 577420c4465..3a6f0862234 100644
--- a/include/stream_buffer.h
+++ b/include/stream_buffer.h
@@ -292,10 +292,8 @@ typedef void (* StreamBufferCallbackFunction_t)( StreamBufferHandle_t xStreamBuf
  * - The task reading from a non-empty stream buffer returns immediately
  *   regardless of the amount of data in the buffer.
  * - The task reading from a non-empty steam batching buffer blocks until the
- *   amount of data in the buffer exceeds the trigger level or the block time
+ *   amount of data in the buffer reaches the trigger level or the block time
  *   expires.
- *
- * @param xBufferSizeBytes The total number of bytes the stream batching buffer
  * will be able to hold at any one time.
  *
  * @param xTriggerLevelBytes The number of bytes that must be in the stream
@@ -380,10 +378,8 @@ typedef void (* StreamBufferCallbackFunction_t)( StreamBufferHandle_t xStreamBuf
  * - The task reading from a non-empty stream buffer returns immediately
  *   regardless of the amount of data in the buffer.
  * - The task reading from a non-empty steam batching buffer blocks until the
- *   amount of data in the buffer exceeds the trigger level or the block time
+ *   amount of data in the buffer reaches the trigger level or the block time
  *   expires.
- *
- * @param xBufferSizeBytes The size, in bytes, of the buffer pointed to by the
  * pucStreamBufferStorageArea parameter.
  *
  * @param xTriggerLevelBytes The number of bytes that must be in the stream
diff --git a/stream_buffer.c b/stream_buffer.c
index 287bd073699..182437e260f 100644
--- a/stream_buffer.c
+++ b/stream_buffer.c
@@ -224,7 +224,7 @@
 /* Bits stored in the ucFlags field of the stream buffer. */
     #define sbFLAGS_IS_MESSAGE_BUFFER          ( ( uint8_t ) 1 ) /* Set if the stream buffer was created as a message buffer, in which case it holds discrete messages rather than a stream. */
     #define sbFLAGS_IS_STATICALLY_ALLOCATED    ( ( uint8_t ) 2 ) /* Set if the stream buffer was created using statically allocated memory. */
-    #define sbFLAGS_IS_BATCHING_BUFFER         ( ( uint8_t ) 4 ) /* Set if the stream buffer was created as a batching buffer, meaning the receiver task will only unblock when the trigger level exceededs. */
+    #define sbFLAGS_IS_BATCHING_BUFFER         ( ( uint8_t ) 4 ) /* Set if the stream buffer was created as a batching buffer, meaning the receiver task will only unblock when the trigger level is reached. */
 
 /*-----------------------------------------------------------*/
 
@@ -1077,9 +1077,9 @@ size_t xStreamBufferReceive( StreamBufferHandle_t xStreamBuffer,
     }
     else if( ( pxStreamBuffer->ucFlags & sbFLAGS_IS_BATCHING_BUFFER ) != ( uint8_t ) 0 )
     {
-        /* Force task to block if the batching buffer contains less bytes than
+        /* Force task to block if the batching buffer contains fewer bytes than
          * the trigger level. */
-        xBytesToStoreMessageLength = pxStreamBuffer->xTriggerLevelBytes;
+        xBytesToStoreMessageLength = pxStreamBuffer->xTriggerLevelBytes - 1U;
     }
     else
     {