text: /*
   * FreeRTOS+TCP V2.0.3
   * Copyright (C) 2017 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
   */
  
  /* 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"
  
  /*
   * uxStreamBufferAdd( )
   * Adds data to a stream buffer.  If uxOffset > 0, data will be written at
   * an offset from uxHead while uxHead will not be moved yet.  This possibility
   * will be used when TCP data is received while earlier data is still missing.
   * If 'pucData' equals NULL, the function is called to advance 'uxHead' only.
   */
  size_t uxStreamBufferAdd( StreamBuffer_t *pxBuffer, size_t uxOffset, const uint8_t *pucData, size_t uxCount )
  {
  size_t uxSpace, uxNextHead, uxFirst;
  
  	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. */
  			memcpy( ( void* ) ( 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. */
  				memcpy( ( void * )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;
  }
  /*-----------------------------------------------------------*/
  
  /*
   * uxStreamBufferGet( )
   * 'uxOffset' can be used to read data located at a certain offset from 'lTail'.
   * If 'pucData' equals NULL, the function is called to advance 'lTail' only.
   * if 'xPeek' is pdTRUE, or if 'uxOffset' is non-zero, the 'lTail' pointer will
   * not be advanced.
   */
  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. */
  			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. */
  				memcpy( pucData + uxFirst, pxBuffer->ucArray, uxCount - uxFirst );
  			}
  		}
  
  		if( ( xPeek == pdFALSE ) && ( uxOffset == 0UL ) )
  		{
  			/* Move the tail pointer to effecively remove the data read from
  			the buffer. */
  			uxNextTail += uxCount;
  
  			if( uxNextTail >= pxBuffer->LENGTH )
  			{
  				uxNextTail -= pxBuffer->LENGTH;
  			}
  
  			pxBuffer->uxTail = uxNextTail;
  		}
  	}
  
  	return uxCount;
  }
  
  