size_t xStreamBufferSend( StreamBufferHandle_t xStreamBuffer,
                          const void * pvTxData,
                          size_t xDataLengthBytes,
                          TickType_t xTicksToWait )
{
    StreamBuffer_t * const pxStreamBuffer = xStreamBuffer;
    size_t xReturn, xSpace = 0;
    size_t xRequiredSpace = xDataLengthBytes;
    TimeOut_t xTimeOut;

    /* The maximum amount of space a stream buffer will ever report is its length
     * minus 1. */
    const size_t xMaxReportedSpace = pxStreamBuffer->xLength - ( size_t ) 1;

    configASSERT( pvTxData );
    configASSERT( pxStreamBuffer );

    /* This send function is used to write to both message buffers and stream
     * buffers.  If this is a message buffer then the space needed must be
     * increased by the amount of bytes needed to store the length of the
     * message. */
    if( ( pxStreamBuffer->ucFlags & sbFLAGS_IS_MESSAGE_BUFFER ) != ( uint8_t ) 0 )
    {
        xRequiredSpace += sbBYTES_TO_STORE_MESSAGE_LENGTH;

        /* Overflow? */
        configASSERT( xRequiredSpace > xDataLengthBytes );

        /* If this is a message buffer then it must be possible to write the
         * whole message. */
        if( xRequiredSpace > xMaxReportedSpace )
        {
            /* The message would not fit even if the entire buffer was empty,
             * so don't wait for space. */
            xTicksToWait = ( TickType_t ) 0;
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }
    }
    else
    {
        /* If this is a stream buffer then it is acceptable to write only part
         * of the message to the buffer.  Cap the length to the total length of
         * the buffer. */
        if( xRequiredSpace > xMaxReportedSpace )
        {
            xRequiredSpace = xMaxReportedSpace;
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }
    }

    if( xTicksToWait != ( TickType_t ) 0 )
    {
        vTaskSetTimeOutState( &xTimeOut );

        do
        {
            /* Wait until the required number of bytes are free in the message
             * buffer. */
            taskENTER_CRITICAL();
            {
                xSpace = xStreamBufferSpacesAvailable( pxStreamBuffer );

                if( xSpace < xRequiredSpace )
                {
                    /* Clear notification state as going to wait for space. */
                    ( void ) xTaskNotifyStateClear( NULL );

                    /* Should only be one writer. */
                    configASSERT( pxStreamBuffer->xTaskWaitingToSend == NULL );
                    pxStreamBuffer->xTaskWaitingToSend = xTaskGetCurrentTaskHandle();
                }
                else
                {
                    taskEXIT_CRITICAL();
                    break;
                }
            }
            taskEXIT_CRITICAL();

            traceBLOCKING_ON_STREAM_BUFFER_SEND( xStreamBuffer );
            ( void ) xTaskNotifyWait( ( uint32_t ) 0, ( uint32_t ) 0, NULL, xTicksToWait );
            pxStreamBuffer->xTaskWaitingToSend = NULL;
        } while( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE );
    }
    else
    {
        mtCOVERAGE_TEST_MARKER();
    }

    if( xSpace == ( size_t ) 0 )
    {
        xSpace = xStreamBufferSpacesAvailable( pxStreamBuffer );
    }
    else
    {
        mtCOVERAGE_TEST_MARKER();
    }

    xReturn = prvWriteMessageToBuffer( pxStreamBuffer, pvTxData, xDataLengthBytes, xSpace, xRequiredSpace );

    if( xReturn > ( size_t ) 0 )
    {
        traceSTREAM_BUFFER_SEND( xStreamBuffer, xReturn );

        /* Was a task waiting for the data? */
        if( prvBytesInBuffer( pxStreamBuffer ) >= pxStreamBuffer->xTriggerLevelBytes )
        {
            sbSEND_COMPLETED( pxStreamBuffer );
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }
    }
    else
    {
        mtCOVERAGE_TEST_MARKER();
        traceSTREAM_BUFFER_SEND_FAILED( xStreamBuffer );
    }

    return xReturn;
}