git.sur5r.net Git - freertos/blob - Source/portable/MemMang/heap_2.c

   1 /*\r
   2     FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.\r
   3 \r
   4     ***************************************************************************\r
   5     *                                                                         *\r
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  14     *                                                                         *\r
  15     *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *\r
  16     *                  http://www.FreeRTOS.org/Documentation                  *\r
  17     *                                                                         *\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 /*\r
  55  * A sample implementation of pvPortMalloc() and vPortFree() that permits\r
  56  * allocated blocks to be freed, but does not combine adjacent free blocks\r
  57  * into a single larger block.\r
  58  *\r
  59  * See heap_1.c and heap_3.c for alternative implementations, and the memory\r
  60  * management pages of http://www.FreeRTOS.org for more information.\r
  61  */\r
  62 #include <stdlib.h>\r
  63 \r
  64 /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining\r
  65 all the API functions to use the MPU wrappers.  That should only be done when\r
  66 task.h is included from an application file. */\r
  67 #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE\r
  68 \r
  69 #include "FreeRTOS.h"\r
  70 #include "task.h"\r
  71 \r
  72 #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE\r
  73 \r
  74 /* Allocate the memory for the heap.  The struct is used to force byte\r
  75 alignment without using any non-portable code. */\r
  76 static union xRTOS_HEAP\r
  77 {\r
  78         #if portBYTE_ALIGNMENT == 8\r
  79                 volatile portDOUBLE dDummy;\r
  80         #else\r
  81                 volatile unsigned long ulDummy;\r
  82         #endif\r
  83         unsigned char ucHeap[ configTOTAL_HEAP_SIZE ];\r
  84 } xHeap;\r
  85 \r
  86 /* Define the linked list structure.  This is used to link free blocks in order\r
  87 of their size. */\r
  88 typedef struct A_BLOCK_LINK\r
  89 {\r
  90         struct A_BLOCK_LINK *pxNextFreeBlock;   /*<< The next free block in the list. */\r
  91         size_t xBlockSize;                                              /*<< The size of the free block. */\r
  92 } xBlockLink;\r
  93 \r
  94 \r
  95 static const unsigned short  heapSTRUCT_SIZE    = ( sizeof( xBlockLink ) + portBYTE_ALIGNMENT - ( sizeof( xBlockLink ) % portBYTE_ALIGNMENT ) );\r
  96 #define heapMINIMUM_BLOCK_SIZE  ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )\r
  97 \r
  98 /* Create a couple of list links to mark the start and end of the list. */\r
  99 static xBlockLink xStart, xEnd;\r
 100 \r
 101 /* Keeps track of the number of free bytes remaining, but says nothing about\r
 102 fragmentation. */\r
 103 static size_t xFreeBytesRemaining = configTOTAL_HEAP_SIZE;\r
 104 \r
 105 /* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */\r
 106 \r
 107 /*\r
 108  * Insert a block into the list of free blocks - which is ordered by size of\r
 109  * the block.  Small blocks at the start of the list and large blocks at the end\r
 110  * of the list.\r
 111  */\r
 112 #define prvInsertBlockIntoFreeList( pxBlockToInsert )                                                           \\r
 113 {                                                                                                                                                                       \\r
 114 xBlockLink *pxIterator;                                                                                                                         \\r
 115 size_t xBlockSize;                                                                                                                                      \\r
 116                                                                                                                                                                         \\r
 117         xBlockSize = pxBlockToInsert->xBlockSize;                                                                               \\r
 118                                                                                                                                                                         \\r
 119         /* Iterate through the list until a block is found that has a larger size */    \\r
 120         /* than the block we are inserting. */                                                                                  \\r
 121         for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock )     \\r
 122         {                                                                                                                                                               \\r
 123                 /* There is nothing to do here - just iterate to the correct position. */       \\r
 124         }                                                                                                                                                               \\r
 125                                                                                                                                                                         \\r
 126         /* Update the list to include the block being inserted in the correct */                \\r
 127         /* position. */                                                                                                                                 \\r
 128         pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;                                 \\r
 129         pxIterator->pxNextFreeBlock = pxBlockToInsert;                                                                  \\r
 130 }\r
 131 /*-----------------------------------------------------------*/\r
 132 \r
 133 #define prvHeapInit()                                                                                                                           \\r
 134 {                                                                                                                                                                       \\r
 135 xBlockLink *pxFirstFreeBlock;                                                                                                           \\r
 136                                                                                                                                                                         \\r
 137         /* xStart is used to hold a pointer to the first item in the list of free */    \\r
 138         /* blocks.  The void cast is used to prevent compiler warnings. */                              \\r
 139         xStart.pxNextFreeBlock = ( void * ) xHeap.ucHeap;                                                               \\r
 140         xStart.xBlockSize = ( size_t ) 0;                                                                                               \\r
 141                                                                                                                                                                         \\r
 142         /* xEnd is used to mark the end of the list of free blocks. */                                  \\r
 143         xEnd.xBlockSize = configTOTAL_HEAP_SIZE;                                                                                \\r
 144         xEnd.pxNextFreeBlock = NULL;                                                                                                    \\r
 145                                                                                                                                                                         \\r
 146         /* To start with there is a single free block that is sized to take up the              \\r
 147         entire heap space. */                                                                                                                   \\r
 148         pxFirstFreeBlock = ( void * ) xHeap.ucHeap;                                                                             \\r
 149         pxFirstFreeBlock->xBlockSize = configTOTAL_HEAP_SIZE;                                                   \\r
 150         pxFirstFreeBlock->pxNextFreeBlock = &xEnd;                                                                              \\r
 151 }\r
 152 /*-----------------------------------------------------------*/\r
 153 \r
 154 void *pvPortMalloc( size_t xWantedSize )\r
 155 {\r
 156 xBlockLink *pxBlock, *pxPreviousBlock, *pxNewBlockLink;\r
 157 static portBASE_TYPE xHeapHasBeenInitialised = pdFALSE;\r
 158 void *pvReturn = NULL;\r
 159 \r
 160         vTaskSuspendAll();\r
 161         {\r
 162                 /* If this is the first call to malloc then the heap will require\r
 163                 initialisation to setup the list of free blocks. */\r
 164                 if( xHeapHasBeenInitialised == pdFALSE )\r
 165                 {\r
 166                         prvHeapInit();\r
 167                         xHeapHasBeenInitialised = pdTRUE;\r
 168                 }\r
 169 \r
 170                 /* The wanted size is increased so it can contain a xBlockLink\r
 171                 structure in addition to the requested amount of bytes. */\r
 172                 if( xWantedSize > 0 )\r
 173                 {\r
 174                         xWantedSize += heapSTRUCT_SIZE;\r
 175 \r
 176                         /* Ensure that blocks are always aligned to the required number of bytes. */\r
 177                         if( xWantedSize & portBYTE_ALIGNMENT_MASK )\r
 178                         {\r
 179                                 /* Byte alignment required. */\r
 180                                 xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );\r
 181                         }\r
 182                 }\r
 183 \r
 184                 if( ( xWantedSize > 0 ) && ( xWantedSize < configTOTAL_HEAP_SIZE ) )\r
 185                 {\r
 186                         /* Blocks are stored in byte order - traverse the list from the start\r
 187                         (smallest) block until one of adequate size is found. */\r
 188                         pxPreviousBlock = &xStart;\r
 189                         pxBlock = xStart.pxNextFreeBlock;\r
 190                         while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock ) )\r
 191                         {\r
 192                                 pxPreviousBlock = pxBlock;\r
 193                                 pxBlock = pxBlock->pxNextFreeBlock;\r
 194                         }\r
 195 \r
 196                         /* If we found the end marker then a block of adequate size was not found. */\r
 197                         if( pxBlock != &xEnd )\r
 198                         {\r
 199                                 /* Return the memory space - jumping over the xBlockLink structure\r
 200                                 at its start. */\r
 201                                 pvReturn = ( void * ) ( ( ( unsigned char * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );\r
 202 \r
 203                                 /* This block is being returned for use so must be taken our of the\r
 204                                 list of free blocks. */\r
 205                                 pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;\r
 206 \r
 207                                 /* If the block is larger than required it can be split into two. */\r
 208                                 if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )\r
 209                                 {\r
 210                                         /* This block is to be split into two.  Create a new block\r
 211                                         following the number of bytes requested. The void cast is\r
 212                                         used to prevent byte alignment warnings from the compiler. */\r
 213                                         pxNewBlockLink = ( void * ) ( ( ( unsigned char * ) pxBlock ) + xWantedSize );\r
 214 \r
 215                                         /* Calculate the sizes of two blocks split from the single\r
 216                                         block. */\r
 217                                         pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;\r
 218                                         pxBlock->xBlockSize = xWantedSize;\r
 219 \r
 220                                         /* Insert the new block into the list of free blocks. */\r
 221                                         prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );\r
 222                                 }\r
 223                                 \r
 224                                 xFreeBytesRemaining -= pxBlock->xBlockSize;\r
 225                         }\r
 226                 }\r
 227         }\r
 228         xTaskResumeAll();\r
 229 \r
 230         #if( configUSE_MALLOC_FAILED_HOOK == 1 )\r
 231         {\r
 232                 if( pvReturn == NULL )\r
 233                 {\r
 234                         extern void vApplicationMallocFailedHook( void );\r
 235                         vApplicationMallocFailedHook();\r
 236                 }\r
 237         }\r
 238         #endif\r
 239 \r
 240         return pvReturn;\r
 241 }\r
 242 /*-----------------------------------------------------------*/\r
 243 \r
 244 void vPortFree( void *pv )\r
 245 {\r
 246 unsigned char *puc = ( unsigned char * ) pv;\r
 247 xBlockLink *pxLink;\r
 248 \r
 249         if( pv )\r
 250         {\r
 251                 /* The memory being freed will have an xBlockLink structure immediately\r
 252                 before it. */\r
 253                 puc -= heapSTRUCT_SIZE;\r
 254 \r
 255                 /* This casting is to keep the compiler from issuing warnings. */\r
 256                 pxLink = ( void * ) puc;\r
 257 \r
 258                 vTaskSuspendAll();\r
 259                 {\r
 260                         /* Add this block to the list of free blocks. */\r
 261                         prvInsertBlockIntoFreeList( ( ( xBlockLink * ) pxLink ) );\r
 262                         xFreeBytesRemaining += pxLink->xBlockSize;\r
 263                 }\r
 264                 xTaskResumeAll();\r
 265         }\r
 266 }\r
 267 /*-----------------------------------------------------------*/\r
 268 \r
 269 size_t xPortGetFreeHeapSize( void )\r
 270 {\r
 271         return xFreeBytesRemaining;\r
 272 }\r
 273 /*-----------------------------------------------------------*/\r
 274 \r
 275 void vPortInitialiseBlocks( void )\r
 276 {\r
 277         /* This just exists to keep the linker quiet. */\r
 278 }\r