git.sur5r.net Git - freertos/blob - Demo/CORTEX_STM32F103_GCC_Rowley/Drivers/CircularBuffer.c

   1 /*\r
   2     FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.\r
   3 \r
   4     ***************************************************************************\r
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  15     *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *\r
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  17     *                                                                         *\r
  18     * A pdf reference manual is also available.  Both are usually delivered   *\r
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  20     * and 8pm GMT (although please allow up to 24 hours in case of            *\r
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  22     *                                                                         *\r
  23     ***************************************************************************\r
  24 \r
  25     This file is part of the FreeRTOS distribution.\r
  26 \r
  27     FreeRTOS is free software; you can redistribute it and/or modify it under\r
  28     the terms of the GNU General Public License (version 2) as published by the\r
  29     Free Software Foundation AND MODIFIED BY the FreeRTOS exception.\r
  30     ***NOTE*** The exception to the GPL is included to allow you to distribute\r
  31     a combined work that includes FreeRTOS without being obliged to provide the\r
  32     source code for proprietary components outside of the FreeRTOS kernel.\r
  33     FreeRTOS is distributed in the hope that it will be useful, but WITHOUT\r
  34     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or\r
  35     FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for\r
  36     more details. You should have received a copy of the GNU General Public \r
  37     License and the FreeRTOS license exception along with FreeRTOS; if not it \r
  38     can be viewed here: http://www.freertos.org/a00114.html and also obtained \r
  39     by writing to Richard Barry, contact details for whom are available on the\r
  40     FreeRTOS WEB site.\r
  41 \r
  42     1 tab == 4 spaces!\r
  43 \r
  44     http://www.FreeRTOS.org - Documentation, latest information, license and\r
  45     contact details.\r
  46 \r
  47     http://www.SafeRTOS.com - A version that is certified for use in safety\r
  48     critical systems.\r
  49 \r
  50     http://www.OpenRTOS.com - Commercial support, development, porting,\r
  51     licensing and training services.\r
  52 */\r
  53 \r
  54 #include <string.h>\r
  55 \r
  56 #include "FreeRTOS.h"\r
  57 #include "CircularBuffer.h"\r
  58 \r
  59 /*-----------------------------------------------------------*/\r
  60 \r
  61 /* See the header file for function information. */\r
  62 void vInitialiseCircularBuffer( xCircularBuffer *pxBuffer,\r
  63                                                                 unsigned char *pucDataBuffer,\r
  64                                                                 unsigned long ulBufferSizeInBytes,\r
  65                                                                 unsigned long ulDataSizeInBytes,\r
  66                                                                 void *pvTag\r
  67                                                           )\r
  68 {\r
  69         pxBuffer->pucDataBuffer = pucDataBuffer;\r
  70         pxBuffer->ulBufferSizeInBytes = ulBufferSizeInBytes;\r
  71         pxBuffer->pucNextByteToRead = pucDataBuffer;\r
  72         pxBuffer->pucNextByteToWrite = pucDataBuffer;\r
  73         pxBuffer->ulDataSizeInBytes = ulDataSizeInBytes;\r
  74         pxBuffer->pvTag = pvTag;\r
  75 }\r
  76 /*-----------------------------------------------------------*/\r
  77 \r
  78 /* See the header file for function information. */\r
  79 unsigned long ulBytesInCircularBuffer( const xCircularBuffer * const pxBuffer )\r
  80 {\r
  81 unsigned char *pucNextByteToWrite;\r
  82 unsigned long ulReturn;\r
  83 \r
  84         if( pxBuffer->pvTag != NULL )\r
  85         {\r
  86                 /* Locate the position that the DMA will next write to. */\r
  87                 pucNextByteToWrite = ( unsigned char * ) *( ( unsigned long * ) pxBuffer->pvTag );\r
  88         }\r
  89         else\r
  90         {\r
  91                 /* Locate the position the application will next write to. */\r
  92                 pucNextByteToWrite = pxBuffer->pucNextByteToWrite;\r
  93         }\r
  94         \r
  95         /* Has the write pointer wrapped back to the start of the buffer\r
  96         compared to our read pointer? */\r
  97         if( ( unsigned long ) pucNextByteToWrite >= ( unsigned long ) pxBuffer->pucNextByteToRead )\r
  98         {\r
  99                 /* The write pointer is still ahead of us in the buffer.  The amount of\r
 100                 data available is simple the gap between the two pointers. */\r
 101                 ulReturn = ( unsigned long ) pucNextByteToWrite - ( unsigned long ) pxBuffer->pucNextByteToRead;\r
 102         }\r
 103         else\r
 104         {\r
 105                 /* The write pointer has wrapped back to the start.  The amount of data\r
 106                 available is equal to the data between the read pointer and the end of\r
 107                 the buffer...*/\r
 108                 ulReturn = ( unsigned long ) &( pxBuffer->pucDataBuffer[ pxBuffer->ulBufferSizeInBytes ] ) - ( unsigned long ) pxBuffer->pucNextByteToRead;\r
 109 \r
 110                 /*... plus the data between the start of the buffer and the write\r
 111                 pointer. */\r
 112                 ulReturn += ( unsigned long ) pucNextByteToWrite - ( unsigned long ) pxBuffer->pucDataBuffer;\r
 113         }\r
 114 \r
 115         return ulReturn;\r
 116 }\r
 117 /*-----------------------------------------------------------*/\r
 118 \r
 119 unsigned long ulCopyReceivedBytes( xCircularBuffer *pxBuffer, unsigned char * pucBuffer, unsigned long ulWantedBytes )\r
 120 {\r
 121 unsigned char *pucNextByteToWrite;\r
 122 unsigned long ulNumberOfBytesRead = 0, ulNumberOfBytesAvailable;\r
 123 \r
 124         if( pxBuffer->pvTag != NULL )\r
 125         {\r
 126                 /* Locate the position that the DMA will next write to. */\r
 127                 pucNextByteToWrite = ( unsigned char * ) *( ( unsigned long * ) pxBuffer->pvTag );\r
 128         }\r
 129         else\r
 130         {\r
 131                 /* Locate the position that the application will next write to. */\r
 132                 pucNextByteToWrite = pxBuffer->pucNextByteToWrite;\r
 133         }\r
 134         \r
 135         if( ( unsigned long ) pucNextByteToWrite >= ( unsigned long ) pxBuffer->pucNextByteToRead )\r
 136         {\r
 137                 /* The write pointer has not wrapped around from our read pointer.\r
 138         \r
 139                 Clip the number of bytes to read to the number available if the number\r
 140                 available is less than that wanted. */\r
 141                 ulNumberOfBytesAvailable = ( unsigned long ) pucNextByteToWrite - ( unsigned long ) ( pxBuffer->pucNextByteToRead );\r
 142                 \r
 143                 if( ulNumberOfBytesAvailable < ulWantedBytes )\r
 144                 {\r
 145                         ulWantedBytes = ulNumberOfBytesAvailable;\r
 146                 }\r
 147                 \r
 148                 /* Copy the data from ulRxBuffer into the application buffer. */\r
 149                 memcpy( pucBuffer, pxBuffer->pucNextByteToRead, ulWantedBytes );\r
 150 \r
 151                 /* Move up our read buffer. */\r
 152                 pxBuffer->pucNextByteToRead += ulWantedBytes;\r
 153                 ulNumberOfBytesRead = ulWantedBytes;\r
 154         }\r
 155         else\r
 156         {\r
 157                 /* The write pointer has wrapped around from our read pointer.  Is there\r
 158                 enough space from our read pointer to the end of the buffer without the\r
 159                 read pointer also wrapping around? */\r
 160                 ulNumberOfBytesAvailable = ( unsigned long ) &( pxBuffer->pucDataBuffer[ pxBuffer->ulBufferSizeInBytes ] ) - ( unsigned long ) pxBuffer->pucNextByteToRead;\r
 161                 \r
 162                 if( ulNumberOfBytesAvailable >= ulWantedBytes )\r
 163                 {\r
 164                         /* There is enough space from our current read pointer up to the end\r
 165                         of the buffer to obtain the number of bytes requested. */\r
 166                         memcpy( pucBuffer, pxBuffer->pucNextByteToRead, ulWantedBytes );\r
 167 \r
 168                         /* Move up our read buffer. */\r
 169                         pxBuffer->pucNextByteToRead += ulWantedBytes;\r
 170                         ulNumberOfBytesRead = ulWantedBytes;\r
 171                 }\r
 172                 else\r
 173                 {\r
 174                         /* There is not enough space up to the end of the buffer to obtain\r
 175                         the number of bytes requested.  Copy up to the end of the buffer. */\r
 176                         memcpy( pucBuffer, pxBuffer->pucNextByteToRead, ulNumberOfBytesAvailable );\r
 177                         ulNumberOfBytesRead = ulNumberOfBytesAvailable;\r
 178                         \r
 179                         /* Then wrap back to the beginning of the buffer to attempt to\r
 180                         read the remaining bytes. */\r
 181                         pxBuffer->pucNextByteToRead = pxBuffer->pucDataBuffer;\r
 182                         pucBuffer += ulNumberOfBytesAvailable;\r
 183                         \r
 184                         /* How many more bytes do we want to read? */\r
 185                         ulWantedBytes -= ulNumberOfBytesAvailable;\r
 186                         \r
 187                         /* Clip the number of bytes we are going to read to the number\r
 188                         available if this is less than the number we want. */\r
 189                         ulNumberOfBytesAvailable = ( unsigned long ) pucNextByteToWrite - ( unsigned long ) pxBuffer->pucNextByteToRead;\r
 190                         \r
 191                         if( ulNumberOfBytesAvailable < ulWantedBytes )\r
 192                         {\r
 193                                 ulWantedBytes = ulNumberOfBytesAvailable;\r
 194                         }\r
 195 \r
 196                         /* Copy these into the buffer. */\r
 197                         memcpy( pucBuffer, pxBuffer->pucNextByteToRead, ulWantedBytes );\r
 198 \r
 199                         /* Move up our read buffer. */\r
 200                         pxBuffer->pucNextByteToRead += ulWantedBytes;\r
 201                         ulNumberOfBytesRead += ulWantedBytes;\r
 202                 }\r
 203         }\r
 204         \r
 205         /* Check we have not moved our read pointer off the end of the buffer. */\r
 206         if( ( unsigned long ) pxBuffer->pucNextByteToRead >= ( unsigned long ) &( pxBuffer->pucDataBuffer[ pxBuffer->ulBufferSizeInBytes ] ) )\r
 207         {\r
 208                 pxBuffer->pucNextByteToRead = pxBuffer->pucDataBuffer;  \r
 209         }\r
 210         \r
 211         /* Return the number of bytes read. */\r
 212         return ulNumberOfBytesRead;\r
 213 }\r
 214 \r