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Introduce sbBYTES_TO_STORE_MESSAGE_LENGTH to allow the number of bytes used to hold a message length in a message buffer to be reduced if 4 bytes is always too many (save a little RAM).

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This commit is contained in:
Richard Barry 2018-03-15 15:51:22 +00:00
parent aec45f2479
commit 3ec86b7a98
2 changed files with 14 additions and 1 deletions
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7
FreeRTOS/Source/include/FreeRTOS.h
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@ -826,6 +826,13 @@ extern "C" {
#define configSTACK_DEPTH_TYPE uint16_t
#endif
#ifndef configMESSAGE_BUFFER_LENGTH_TYPE
/* Defaults to size_t for backward compatibility, but can be overridden
in FreeRTOSConfig.h if lengths will always be less than the number of bytes
in a size_t. */
#define configMESSAGE_BUFFER_LENGTH_TYPE size_t
#endif
/* Sanity check the configuration. */
#if( configUSE_TICKLESS_IDLE != 0 )
#if( INCLUDE_vTaskSuspend != 1 )

8
FreeRTOS/Source/stream_buffer.c
View file

@ -129,7 +129,7 @@ that uses task notifications. */
/*lint -restore (9026) */
/* The number of bytes used to hold the length of a message in the buffer. */
#define sbBYTES_TO_STORE_MESSAGE_LENGTH ( sizeof( size_t ) )
#define sbBYTES_TO_STORE_MESSAGE_LENGTH ( sizeof( configMESSAGE_BUFFER_LENGTH_TYPE ) )
/* 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. */
@ -504,6 +504,9 @@ TimeOut_t xTimeOut;
if( ( pxStreamBuffer->ucFlags & sbFLAGS_IS_MESSAGE_BUFFER ) != ( uint8_t ) 0 )
{
xRequiredSpace += sbBYTES_TO_STORE_MESSAGE_LENGTH;
/* Overflow? */
configASSERT( xRequiredSpace > xDataLengthBytes );
}
else
{
@ -906,6 +909,9 @@ size_t xOriginalTail, xReceivedLength, xNextMessageLength;
returned to its prior state if the length of the message is too
large for the provided buffer. */
xOriginalTail = pxStreamBuffer->xTail;
/* Ensure xNextMessageLength is cleared to 0 in case
sizeof( configMESSAGE_BUFFER_LENGTH_TYPE ) != sizeof( size_t ). */
xNextMessageLength = 0;
( void ) prvReadBytesFromBuffer( pxStreamBuffer, ( uint8_t * ) &xNextMessageLength, xBytesToStoreMessageLength, xBytesAvailable );
/* Reduce the number of bytes available by the number of bytes just