mongoose/test/freertos-tcp/FreeRTOS_Stream_Buffer.c

/*
 * FreeRTOS+TCP V2.3.2
 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * http://aws.amazon.com/freertos
 * http://www.FreeRTOS.org
 */

/**
 * @file FreeRTOS_Stream_Buffer.c
 * @brief Provides the API for managing/creating the stream buffers in the FreeRTOS+TCP network stack.
 */

/* Standard includes. */
#include <stdint.h>

/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "semphr.h"

/* FreeRTOS+TCP includes. */
#include "FreeRTOS_UDP_IP.h"
#include "FreeRTOS_IP.h"
#include "FreeRTOS_Sockets.h"
#include "FreeRTOS_IP_Private.h"


/**
 * @brief Adds data to a stream buffer.
 *
 * @param[in,out] pxBuffer: The buffer to which the bytes will be added.
 * @param[in] uxOffset: If uxOffset > 0, data will be written at an offset from uxHead
 *                      while uxHead will not be moved yet.
 * @param[in] pucData: A pointer to the data to be added.
 * @param[in] uxByteCount: The number of bytes to add.
 *
 * @return The number of bytes added to the buffer.
 */
size_t uxStreamBufferAdd( StreamBuffer_t * pxBuffer,
                          size_t uxOffset,
                          const uint8_t * pucData,
                          size_t uxByteCount )
{
    size_t uxSpace, uxNextHead, uxFirst;
    size_t uxCount = uxByteCount;

    uxSpace = uxStreamBufferGetSpace( pxBuffer );

    /* If uxOffset > 0, items can be placed in front of uxHead */
    if( uxSpace > uxOffset )
    {
        uxSpace -= uxOffset;
    }
    else
    {
        uxSpace = 0U;
    }

    /* The number of bytes that can be written is the minimum of the number of
     * bytes requested and the number available. */
    uxCount = FreeRTOS_min_uint32( uxSpace, uxCount );

    if( uxCount != 0U )
    {
        uxNextHead = pxBuffer->uxHead;

        if( uxOffset != 0U )
        {
            /* ( uxOffset > 0 ) means: write in front if the uxHead marker */
            uxNextHead += uxOffset;

            if( uxNextHead >= pxBuffer->LENGTH )
            {
                uxNextHead -= pxBuffer->LENGTH;
            }
        }

        if( pucData != NULL )
        {
            /* Calculate the number of bytes that can be added in the first
            * write - which may be less than the total number of bytes that need
            * to be added if the buffer will wrap back to the beginning. */
            uxFirst = FreeRTOS_min_uint32( pxBuffer->LENGTH - uxNextHead, uxCount );

            /* Write as many bytes as can be written in the first write. */
            ( void ) memcpy( &( pxBuffer->ucArray[ uxNextHead ] ), pucData, uxFirst );

            /* If the number of bytes written was less than the number that
             * could be written in the first write... */
            if( uxCount > uxFirst )
            {
                /* ...then write the remaining bytes to the start of the
                 * buffer. */
                ( void ) memcpy( pxBuffer->ucArray, &( pucData[ uxFirst ] ), uxCount - uxFirst );
            }
        }

        if( uxOffset == 0U )
        {
            /* ( uxOffset == 0 ) means: write at uxHead position */
            uxNextHead += uxCount;

            if( uxNextHead >= pxBuffer->LENGTH )
            {
                uxNextHead -= pxBuffer->LENGTH;
            }

            pxBuffer->uxHead = uxNextHead;
        }

        if( xStreamBufferLessThenEqual( pxBuffer, pxBuffer->uxFront, uxNextHead ) != pdFALSE )
        {
            /* Advance the front pointer */
            pxBuffer->uxFront = uxNextHead;
        }
    }

    return uxCount;
}
/*-----------------------------------------------------------*/

/**
 * @brief Read bytes from stream buffer.
 *
 * @param[in] pxBuffer: The buffer from which the bytes will be read.
 * @param[in] uxOffset: can be used to read data located at a certain offset from 'lTail'.
 * @param[in,out] pucData: If 'pucData' equals NULL, the function is called to advance 'lTail' only.
 * @param[in] uxMaxCount: The number of bytes to read.
 * @param[in] xPeek: if 'xPeek' is pdTRUE, or if 'uxOffset' is non-zero, the 'lTail' pointer will
 *                   not be advanced.
 *
 * @return The count of the bytes read.
 */
size_t uxStreamBufferGet( StreamBuffer_t * pxBuffer,
                          size_t uxOffset,
                          uint8_t * pucData,
                          size_t uxMaxCount,
                          BaseType_t xPeek )
{
    size_t uxSize, uxCount, uxFirst, uxNextTail;

    /* How much data is available? */
    uxSize = uxStreamBufferGetSize( pxBuffer );

    if( uxSize > uxOffset )
    {
        uxSize -= uxOffset;
    }
    else
    {
        uxSize = 0U;
    }

    /* Use the minimum of the wanted bytes and the available bytes. */
    uxCount = FreeRTOS_min_uint32( uxSize, uxMaxCount );

    if( uxCount > 0U )
    {
        uxNextTail = pxBuffer->uxTail;

        if( uxOffset != 0U )
        {
            uxNextTail += uxOffset;

            if( uxNextTail >= pxBuffer->LENGTH )
            {
                uxNextTail -= pxBuffer->LENGTH;
            }
        }

        if( pucData != NULL )
        {
            /* Calculate the number of bytes that can be read - which may be
             * less than the number wanted if the data wraps around to the start of
             * the buffer. */
            uxFirst = FreeRTOS_min_uint32( pxBuffer->LENGTH - uxNextTail, uxCount );

            /* Obtain the number of bytes it is possible to obtain in the first
             * read. */
            ( void ) memcpy( pucData, &( pxBuffer->ucArray[ uxNextTail ] ), uxFirst );

            /* If the total number of wanted bytes is greater than the number
             * that could be read in the first read... */
            if( uxCount > uxFirst )
            {
                /*...then read the remaining bytes from the start of the buffer. */
                ( void ) memcpy( &( pucData[ uxFirst ] ), pxBuffer->ucArray, uxCount - uxFirst );
            }
        }

        if( ( xPeek == pdFALSE ) && ( uxOffset == 0UL ) )
        {
            /* Move the tail pointer to effectively remove the data read from
             * the buffer. */
            uxNextTail += uxCount;

            if( uxNextTail >= pxBuffer->LENGTH )
            {
                uxNextTail -= pxBuffer->LENGTH;
            }

            pxBuffer->uxTail = uxNextTail;
        }
    }

    return uxCount;
}