mirror of
https://github.com/FreeRTOS/FreeRTOS-Kernel.git
synced 2025-04-19 21:11:57 -04:00
215 lines
8.9 KiB
C
215 lines
8.9 KiB
C
/*
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FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* If you are: *
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* *
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* + New to FreeRTOS, *
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* + Wanting to learn FreeRTOS or multitasking in general quickly *
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* + Looking for basic training, *
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* + Wanting to improve your FreeRTOS skills and productivity *
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* *
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* then take a look at the FreeRTOS eBook *
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* *
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* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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* http://www.FreeRTOS.org/Documentation *
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* *
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* A pdf reference manual is also available. Both are usually delivered *
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* to your inbox within 20 minutes to two hours when purchased between 8am *
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* and 8pm GMT (although please allow up to 24 hours in case of *
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* exceptional circumstances). Thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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***NOTE*** The exception to the GPL is included to allow you to distribute
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a combined work that includes FreeRTOS without being obliged to provide the
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source code for proprietary components outside of the FreeRTOS kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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#include <string.h>
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#include "FreeRTOS.h"
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#include "CircularBuffer.h"
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/*-----------------------------------------------------------*/
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/* See the header file for function information. */
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void vInitialiseCircularBuffer( xCircularBuffer *pxBuffer,
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unsigned char *pucDataBuffer,
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unsigned long ulBufferSizeInBytes,
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unsigned long ulDataSizeInBytes,
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void *pvTag
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)
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{
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pxBuffer->pucDataBuffer = pucDataBuffer;
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pxBuffer->ulBufferSizeInBytes = ulBufferSizeInBytes;
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pxBuffer->pucNextByteToRead = pucDataBuffer;
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pxBuffer->pucNextByteToWrite = pucDataBuffer;
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pxBuffer->ulDataSizeInBytes = ulDataSizeInBytes;
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pxBuffer->pvTag = pvTag;
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}
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/*-----------------------------------------------------------*/
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/* See the header file for function information. */
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unsigned long ulBytesInCircularBuffer( const xCircularBuffer * const pxBuffer )
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{
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unsigned char *pucNextByteToWrite;
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unsigned long ulReturn;
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if( pxBuffer->pvTag != NULL )
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{
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/* Locate the position that the DMA will next write to. */
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pucNextByteToWrite = ( unsigned char * ) *( ( unsigned long * ) pxBuffer->pvTag );
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}
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else
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{
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/* Locate the position the application will next write to. */
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pucNextByteToWrite = pxBuffer->pucNextByteToWrite;
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}
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/* Has the write pointer wrapped back to the start of the buffer
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compared to our read pointer? */
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if( ( unsigned long ) pucNextByteToWrite >= ( unsigned long ) pxBuffer->pucNextByteToRead )
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{
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/* The write pointer is still ahead of us in the buffer. The amount of
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data available is simple the gap between the two pointers. */
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ulReturn = ( unsigned long ) pucNextByteToWrite - ( unsigned long ) pxBuffer->pucNextByteToRead;
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}
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else
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{
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/* The write pointer has wrapped back to the start. The amount of data
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available is equal to the data between the read pointer and the end of
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the buffer...*/
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ulReturn = ( unsigned long ) &( pxBuffer->pucDataBuffer[ pxBuffer->ulBufferSizeInBytes ] ) - ( unsigned long ) pxBuffer->pucNextByteToRead;
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/*... plus the data between the start of the buffer and the write
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pointer. */
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ulReturn += ( unsigned long ) pucNextByteToWrite - ( unsigned long ) pxBuffer->pucDataBuffer;
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}
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return ulReturn;
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}
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/*-----------------------------------------------------------*/
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unsigned long ulCopyReceivedBytes( xCircularBuffer *pxBuffer, unsigned char * pucBuffer, unsigned long ulWantedBytes )
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{
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unsigned char *pucNextByteToWrite;
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unsigned long ulNumberOfBytesRead = 0, ulNumberOfBytesAvailable;
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if( pxBuffer->pvTag != NULL )
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{
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/* Locate the position that the DMA will next write to. */
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pucNextByteToWrite = ( unsigned char * ) *( ( unsigned long * ) pxBuffer->pvTag );
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}
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else
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{
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/* Locate the position that the application will next write to. */
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pucNextByteToWrite = pxBuffer->pucNextByteToWrite;
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}
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if( ( unsigned long ) pucNextByteToWrite >= ( unsigned long ) pxBuffer->pucNextByteToRead )
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{
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/* The write pointer has not wrapped around from our read pointer.
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Clip the number of bytes to read to the number available if the number
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available is less than that wanted. */
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ulNumberOfBytesAvailable = ( unsigned long ) pucNextByteToWrite - ( unsigned long ) ( pxBuffer->pucNextByteToRead );
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if( ulNumberOfBytesAvailable < ulWantedBytes )
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{
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ulWantedBytes = ulNumberOfBytesAvailable;
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}
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/* Copy the data from ulRxBuffer into the application buffer. */
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memcpy( pucBuffer, pxBuffer->pucNextByteToRead, ulWantedBytes );
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/* Move up our read buffer. */
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pxBuffer->pucNextByteToRead += ulWantedBytes;
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ulNumberOfBytesRead = ulWantedBytes;
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}
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else
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{
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/* The write pointer has wrapped around from our read pointer. Is there
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enough space from our read pointer to the end of the buffer without the
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read pointer also wrapping around? */
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ulNumberOfBytesAvailable = ( unsigned long ) &( pxBuffer->pucDataBuffer[ pxBuffer->ulBufferSizeInBytes ] ) - ( unsigned long ) pxBuffer->pucNextByteToRead;
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if( ulNumberOfBytesAvailable >= ulWantedBytes )
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{
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/* There is enough space from our current read pointer up to the end
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of the buffer to obtain the number of bytes requested. */
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memcpy( pucBuffer, pxBuffer->pucNextByteToRead, ulWantedBytes );
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/* Move up our read buffer. */
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pxBuffer->pucNextByteToRead += ulWantedBytes;
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ulNumberOfBytesRead = ulWantedBytes;
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}
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else
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{
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/* There is not enough space up to the end of the buffer to obtain
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the number of bytes requested. Copy up to the end of the buffer. */
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memcpy( pucBuffer, pxBuffer->pucNextByteToRead, ulNumberOfBytesAvailable );
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ulNumberOfBytesRead = ulNumberOfBytesAvailable;
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/* Then wrap back to the beginning of the buffer to attempt to
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read the remaining bytes. */
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pxBuffer->pucNextByteToRead = pxBuffer->pucDataBuffer;
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pucBuffer += ulNumberOfBytesAvailable;
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/* How many more bytes do we want to read? */
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ulWantedBytes -= ulNumberOfBytesAvailable;
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/* Clip the number of bytes we are going to read to the number
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available if this is less than the number we want. */
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ulNumberOfBytesAvailable = ( unsigned long ) pucNextByteToWrite - ( unsigned long ) pxBuffer->pucNextByteToRead;
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if( ulNumberOfBytesAvailable < ulWantedBytes )
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{
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ulWantedBytes = ulNumberOfBytesAvailable;
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}
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/* Copy these into the buffer. */
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memcpy( pucBuffer, pxBuffer->pucNextByteToRead, ulWantedBytes );
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/* Move up our read buffer. */
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pxBuffer->pucNextByteToRead += ulWantedBytes;
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ulNumberOfBytesRead += ulWantedBytes;
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}
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}
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/* Check we have not moved our read pointer off the end of the buffer. */
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if( ( unsigned long ) pxBuffer->pucNextByteToRead >= ( unsigned long ) &( pxBuffer->pucDataBuffer[ pxBuffer->ulBufferSizeInBytes ] ) )
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{
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pxBuffer->pucNextByteToRead = pxBuffer->pucDataBuffer;
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}
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/* Return the number of bytes read. */
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return ulNumberOfBytesRead;
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}
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