mirror of
https://github.com/FreeRTOS/FreeRTOS-Plus-TCP
synced 2025-10-20 13:23:44 +08:00
426 lines
14 KiB
C
426 lines
14 KiB
C
/*
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* FreeRTOS+TCP V4.3.0
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* Copyright (C) 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* SPDX-License-Identifier: MIT
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* http://aws.amazon.com/freertos
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* http://www.FreeRTOS.org
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*/
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/**
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* @file FreeRTOS_Stream_Buffer.c
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* @brief Provides the API for managing/creating the stream buffers in the FreeRTOS+TCP network stack.
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*/
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/* Standard includes. */
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#include <stdint.h>
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#include <string.h>
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/* FreeRTOS includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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/* FreeRTOS+TCP includes. */
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#include "FreeRTOS_IP.h"
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/**
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* @brief Get the space between lower and upper value provided to the function.
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* @param[in] pxBuffer The circular stream buffer.
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* @param[in] uxLower The lower value.
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* @param[in] uxUpper The upper value.
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* @return The space between uxLower and uxUpper, which equals to the distance
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* minus 1.
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*/
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size_t uxStreamBufferSpace( const StreamBuffer_t * const pxBuffer,
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size_t uxLower,
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size_t uxUpper )
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{
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const size_t uxLength = pxBuffer->LENGTH;
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size_t uxCount = uxLength + uxUpper - uxLower - 1U;
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if( uxCount >= uxLength )
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{
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uxCount -= uxLength;
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}
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return uxCount;
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Get the distance between lower and upper value provided to the function.
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* @param[in] pxBuffer The circular stream buffer.
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* @param[in] uxLower The lower value.
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* @param[in] uxUpper The upper value.
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* @return The distance between uxLower and uxUpper.
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*/
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size_t uxStreamBufferDistance( const StreamBuffer_t * const pxBuffer,
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size_t uxLower,
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size_t uxUpper )
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{
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const size_t uxLength = pxBuffer->LENGTH;
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size_t uxCount = uxLength + uxUpper - uxLower;
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if( uxCount >= uxLength )
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{
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uxCount -= uxLength;
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}
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return uxCount;
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Get the number of items which can be added to the buffer at
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* the head before reaching the tail.
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* @param[in] pxBuffer The circular stream buffer.
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* @return The number of items which can still be added to uxHead
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* before hitting on uxTail
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*/
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size_t uxStreamBufferGetSpace( const StreamBuffer_t * const pxBuffer )
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{
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return uxStreamBufferSpace( pxBuffer, pxBuffer->uxHead, pxBuffer->uxTail );
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Get the distance between the pointer in free space and the tail.
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* @param[in] pxBuffer The circular stream buffer.
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* @return Distance between uxFront and uxTail or the number of items
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* which can still be added to uxFront, before hitting on uxTail.
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*/
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size_t uxStreamBufferFrontSpace( const StreamBuffer_t * const pxBuffer )
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{
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return uxStreamBufferSpace( pxBuffer, pxBuffer->uxFront, pxBuffer->uxTail );
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Get the number of items which can be read from the tail before
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* reaching the head.
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* @param[in] pxBuffer The circular stream buffer.
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* @return The number of items which can be read from the tail before
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* reaching the head.
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*/
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size_t uxStreamBufferGetSize( const StreamBuffer_t * const pxBuffer )
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{
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return uxStreamBufferDistance( pxBuffer, pxBuffer->uxTail, pxBuffer->uxHead );
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Get the space between the mid pointer and the head in the stream
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* buffer.
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* @param[in] pxBuffer The circular stream buffer.
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* @return The space between the mid pointer and the head.
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*/
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size_t uxStreamBufferMidSpace( const StreamBuffer_t * const pxBuffer )
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{
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return uxStreamBufferDistance( pxBuffer, pxBuffer->uxMid, pxBuffer->uxHead );
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Clear the stream buffer.
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* @param[in] pxBuffer The circular stream buffer.
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*/
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void vStreamBufferClear( StreamBuffer_t * const pxBuffer )
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{
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/* Make the circular buffer empty */
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pxBuffer->uxHead = 0U;
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pxBuffer->uxTail = 0U;
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pxBuffer->uxFront = 0U;
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pxBuffer->uxMid = 0U;
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Move the mid pointer forward by given byte count
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* @param[in] pxBuffer The circular stream buffer.
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* @param[in] uxCount The byte count by which the mid pointer is to be moved.
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*/
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void vStreamBufferMoveMid( StreamBuffer_t * const pxBuffer,
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const size_t uxCount )
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{
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/* Increment uxMid, but no further than uxHead */
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const size_t uxLength = pxBuffer->LENGTH;
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const size_t uxSize = uxStreamBufferMidSpace( pxBuffer );
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size_t uxMid = pxBuffer->uxMid;
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size_t uxMoveCount = uxCount;
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if( uxMoveCount > uxSize )
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{
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uxMoveCount = uxSize;
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}
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uxMid += uxMoveCount;
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if( uxMid >= uxLength )
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{
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uxMid -= uxLength;
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}
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pxBuffer->uxMid = uxMid;
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Check whether the value in left is less than or equal to the
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* value in right from the perspective of the circular stream
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* buffer.
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* @param[in] pxBuffer The circular stream buffer.
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* @param[in] uxLeft The left pointer in the stream buffer.
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* @param[in] uxRight The right value pointer in the stream buffer.
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* @return pdTRUE if uxLeft <= uxRight, else pdFALSE.
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*/
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BaseType_t xStreamBufferLessThenEqual( const StreamBuffer_t * const pxBuffer,
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size_t uxLeft,
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size_t uxRight )
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{
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BaseType_t xReturn = pdFALSE;
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const size_t uxTail = pxBuffer->uxTail;
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if( ( uxLeft - uxTail ) <= ( uxRight - uxTail ) )
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{
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xReturn = pdTRUE;
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}
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return xReturn;
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Get the pointer to data and the amount of data which can be read in one go.
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*
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* @param[in] pxBuffer The circular stream buffer.
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* @param[out] ppucData Pointer to the data pointer which will point to the
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* data which can be read.
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*
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* @return The number of bytes which can be read in one go (which might be less than
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* actual number of available bytes since this is a circular buffer and tail
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* can loop back to the start of the buffer).
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*/
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size_t uxStreamBufferGetPtr( StreamBuffer_t * const pxBuffer,
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uint8_t ** const ppucData )
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{
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const size_t uxNextTail = pxBuffer->uxTail;
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const size_t uxSize = uxStreamBufferGetSize( pxBuffer );
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/* MISRA Ref 18.4.1 [Usage of +, -, += and -= operators on expression of pointer type]. */
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/* More details at: https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/blob/main/MISRA.md#rule-184. */
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/* coverity[misra_c_2012_rule_18_4_violation] */
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*ppucData = pxBuffer->ucArray + uxNextTail;
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return FreeRTOS_min_size_t( uxSize, pxBuffer->LENGTH - uxNextTail );
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Adds data to a stream buffer.
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*
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* @param[in,out] pxBuffer The buffer to which the bytes will be added.
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* @param[in] uxOffset If uxOffset > 0, data will be written at an offset from uxHead
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* while uxHead will not be moved yet.
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* @param[in] pucData A pointer to the data to be added. If 'pucData' equals NULL,
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* the function is called to advance the 'Head' only.
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* @param[in] uxByteCount The number of bytes to add.
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*
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* @return The number of bytes added to the buffer.
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*/
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size_t uxStreamBufferAdd( StreamBuffer_t * const pxBuffer,
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size_t uxOffset,
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const uint8_t * const pucData,
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size_t uxByteCount )
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{
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size_t uxCount;
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size_t uxSpace = uxStreamBufferGetSpace( pxBuffer );
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/* If uxOffset > 0, items can be placed in front of uxHead */
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if( uxSpace > uxOffset )
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{
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uxSpace -= uxOffset;
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}
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else
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{
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uxSpace = 0U;
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}
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/* The number of bytes that can be written is the minimum of the number of
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* bytes requested and the number available. */
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uxCount = FreeRTOS_min_size_t( uxSpace, uxByteCount );
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if( uxCount != 0U )
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{
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const size_t uxLength = pxBuffer->LENGTH;
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size_t uxNextHead = pxBuffer->uxHead;
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if( uxOffset != 0U )
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{
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/* ( uxOffset > 0 ) means: write in front if the uxHead marker */
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uxNextHead += uxOffset;
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if( uxNextHead >= uxLength )
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{
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uxNextHead -= uxLength;
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}
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}
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if( pucData != NULL )
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{
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/* Calculate the number of bytes that can be added in the first
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* write - which may be less than the total number of bytes that need
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* to be added if the buffer will wrap back to the beginning. */
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const size_t uxFirst = FreeRTOS_min_size_t( uxLength - uxNextHead, uxCount );
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/* Write as many bytes as can be written in the first write. */
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( void ) memcpy( &( pxBuffer->ucArray[ uxNextHead ] ), pucData, uxFirst );
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/* If the number of bytes written was less than the number that
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* could be written in the first write... */
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if( uxCount > uxFirst )
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{
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/* ...then write the remaining bytes to the start of the
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* buffer. */
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( void ) memcpy( pxBuffer->ucArray, &( pucData[ uxFirst ] ), uxCount - uxFirst );
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}
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}
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/* The below update to the stream buffer members must happen
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* atomically. */
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taskENTER_CRITICAL();
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{
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if( uxOffset == 0U )
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{
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/* ( uxOffset == 0 ) means: write at uxHead position */
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uxNextHead += uxCount;
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if( uxNextHead >= uxLength )
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{
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uxNextHead -= uxLength;
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}
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pxBuffer->uxHead = uxNextHead;
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}
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if( xStreamBufferLessThenEqual( pxBuffer, pxBuffer->uxFront, uxNextHead ) != pdFALSE )
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{
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/* Advance the front pointer */
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pxBuffer->uxFront = uxNextHead;
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}
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}
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taskEXIT_CRITICAL();
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}
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return uxCount;
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}
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/*-----------------------------------------------------------*/
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/**
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* @brief Read bytes from stream buffer.
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*
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* @param[in] pxBuffer The buffer from which the bytes will be read.
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* @param[in] uxOffset can be used to read data located at a certain offset from 'lTail'.
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* @param[in,out] pucData If 'pucData' equals NULL, the function is called to advance 'lTail' only.
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* @param[in] uxMaxCount The number of bytes to read.
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* @param[in] xPeek if 'xPeek' is pdTRUE, or if 'uxOffset' is non-zero, the 'lTail' pointer will
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* not be advanced.
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*
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* @return The count of the bytes read.
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*/
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size_t uxStreamBufferGet( StreamBuffer_t * const pxBuffer,
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size_t uxOffset,
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uint8_t * const pucData,
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size_t uxMaxCount,
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BaseType_t xPeek )
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{
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size_t uxCount;
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/* How much data is available? */
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size_t uxSize = uxStreamBufferGetSize( pxBuffer );
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if( uxSize > uxOffset )
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{
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uxSize -= uxOffset;
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}
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else
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{
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uxSize = 0U;
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}
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/* Use the minimum of the wanted bytes and the available bytes. */
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uxCount = FreeRTOS_min_size_t( uxSize, uxMaxCount );
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if( uxCount != 0U )
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{
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const size_t uxLength = pxBuffer->LENGTH;
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size_t uxNextTail = pxBuffer->uxTail;
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if( uxOffset != 0U )
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{
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uxNextTail += uxOffset;
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if( uxNextTail >= uxLength )
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{
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uxNextTail -= uxLength;
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}
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}
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if( pucData != NULL )
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{
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/* Calculate the number of bytes that can be read - which may be
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* less than the number wanted if the data wraps around to the start of
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* the buffer. */
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const size_t uxFirst = FreeRTOS_min_size_t( uxLength - uxNextTail, uxCount );
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/* Obtain the number of bytes it is possible to obtain in the first
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* read. */
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( void ) memcpy( pucData, &( pxBuffer->ucArray[ uxNextTail ] ), uxFirst );
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/* If the total number of wanted bytes is greater than the number
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* that could be read in the first read... */
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if( uxCount > uxFirst )
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{
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/* ...then read the remaining bytes from the start of the buffer. */
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( void ) memcpy( &( pucData[ uxFirst ] ), pxBuffer->ucArray, uxCount - uxFirst );
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}
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}
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if( ( xPeek == pdFALSE ) && ( uxOffset == 0U ) )
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{
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/* Move the tail pointer to effectively remove the data read from
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* the buffer. */
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uxNextTail += uxCount;
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if( uxNextTail >= uxLength )
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{
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uxNextTail -= uxLength;
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}
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pxBuffer->uxTail = uxNextTail;
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}
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}
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return uxCount;
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}
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/*-----------------------------------------------------------*/
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