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

   1 /*\r
   2         FreeRTOS V5.4.2 - Copyright (C) 2009 Real Time Engineers Ltd.\r
   3 \r
   4         This file is part of the FreeRTOS distribution.\r
   5 \r
   6         FreeRTOS is free software; you can redistribute it and/or modify it     under \r
   7         the terms of the GNU General Public License (version 2) as published by the \r
   8         Free Software Foundation and modified by the FreeRTOS exception.\r
   9         **NOTE** The exception to the GPL is included to allow you to distribute a\r
  10         combined work that includes FreeRTOS without being obliged to provide the \r
  11         source code for proprietary components outside of the FreeRTOS kernel.  \r
  12         Alternative commercial license and support terms are also available upon \r
  13         request.  See the licensing section of http://www.FreeRTOS.org for full \r
  14         license details.\r
  15 \r
  16         FreeRTOS is distributed in the hope that it will be useful,     but WITHOUT\r
  17         ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or\r
  18         FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for\r
  19         more details.\r
  20 \r
  21         You should have received a copy of the GNU General Public License along\r
  22         with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59\r
  23         Temple Place, Suite 330, Boston, MA  02111-1307  USA.\r
  24 \r
  25 \r
  26         ***************************************************************************\r
  27         *                                                                         *\r
  28         * Looking for a quick start?  Then check out the FreeRTOS eBook!          *\r
  29         * See http://www.FreeRTOS.org/Documentation for details                   *\r
  30         *                                                                         *\r
  31         ***************************************************************************\r
  32 \r
  33         1 tab == 4 spaces!\r
  34 \r
  35         Please ensure to read the configuration and relevant port sections of the\r
  36         online documentation.\r
  37 \r
  38         http://www.FreeRTOS.org - Documentation, latest information, license and\r
  39         contact details.\r
  40 \r
  41         http://www.SafeRTOS.com - A version that is certified for use in safety\r
  42         critical systems.\r
  43 \r
  44         http://www.OpenRTOS.com - Commercial support, development, porting,\r
  45         licensing and training services.\r
  46 */\r
  47 \r
  48 /*\r
  49  * A sample implementation of pvPortMalloc() and vPortFree() that permits\r
  50  * allocated blocks to be freed, but does not combine adjacent free blocks\r
  51  * into a single larger block.\r
  52  *\r
  53  * See heap_1.c and heap_3.c for alternative implementations, and the memory\r
  54  * management pages of http://www.FreeRTOS.org for more information.\r
  55  */\r
  56 #include <stdlib.h>\r
  57 \r
  58 #include "FreeRTOS.h"\r
  59 #include "task.h"\r
  60 \r
  61 /* Setup the correct byte alignment mask for the defined byte alignment. */\r
  62 \r
  63 #if portBYTE_ALIGNMENT == 8\r
  64         #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0007 )\r
  65 #endif\r
  66 \r
  67 #if portBYTE_ALIGNMENT == 4\r
  68         #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0003 )\r
  69 #endif\r
  70 \r
  71 #if portBYTE_ALIGNMENT == 2\r
  72         #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0001 )\r
  73 #endif\r
  74 \r
  75 #if portBYTE_ALIGNMENT == 1\r
  76         #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0000 )\r
  77 #endif\r
  78 \r
  79 #ifndef heapBYTE_ALIGNMENT_MASK\r
  80         #error "Invalid portBYTE_ALIGNMENT definition"\r
  81 #endif\r
  82 \r
  83 /* Allocate the memory for the heap.  The struct is used to force byte\r
  84 alignment without using any non-portable code. */\r
  85 static union xRTOS_HEAP\r
  86 {\r
  87         #if portBYTE_ALIGNMENT == 8\r
  88                 volatile portDOUBLE dDummy;\r
  89         #else\r
  90                 volatile unsigned portLONG ulDummy;\r
  91         #endif  \r
  92         unsigned portCHAR ucHeap[ configTOTAL_HEAP_SIZE ];\r
  93 } xHeap;\r
  94 \r
  95 /* Define the linked list structure.  This is used to link free blocks in order\r
  96 of their size. */\r
  97 typedef struct A_BLOCK_LINK\r
  98 {\r
  99         struct A_BLOCK_LINK *pxNextFreeBlock;   /*<< The next free block in the list. */\r
 100         size_t xBlockSize;                                              /*<< The size of the free block. */\r
 101 } xBlockLink;\r
 102 \r
 103 \r
 104 static const unsigned portSHORT  heapSTRUCT_SIZE        = ( sizeof( xBlockLink ) + portBYTE_ALIGNMENT - ( sizeof( xBlockLink ) % portBYTE_ALIGNMENT ) );\r
 105 #define heapMINIMUM_BLOCK_SIZE  ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )\r
 106 \r
 107 /* Create a couple of list links to mark the start and end of the list. */\r
 108 static xBlockLink xStart, xEnd;\r
 109 \r
 110 /* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */\r
 111 \r
 112 /*\r
 113  * Insert a block into the list of free blocks - which is ordered by size of\r
 114  * the block.  Small blocks at the start of the list and large blocks at the end\r
 115  * of the list.\r
 116  */\r
 117 #define prvInsertBlockIntoFreeList( pxBlockToInsert )                                                           \\r
 118 {                                                                                                                                                                       \\r
 119 xBlockLink *pxIterator;                                                                                                                         \\r
 120 size_t xBlockSize;                                                                                                                                      \\r
 121                                                                                                                                                                         \\r
 122         xBlockSize = pxBlockToInsert->xBlockSize;                                                                               \\r
 123                                                                                                                                                                         \\r
 124         /* Iterate through the list until a block is found that has a larger size */    \\r
 125         /* than the block we are inserting. */                                                                                  \\r
 126         for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock )     \\r
 127         {                                                                                                                                                               \\r
 128                 /* There is nothing to do here - just iterate to the correct position. */       \\r
 129         }                                                                                                                                                               \\r
 130                                                                                                                                                                         \\r
 131         /* Update the list to include the block being inserted in the correct */                \\r
 132         /* position. */                                                                                                                                 \\r
 133         pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;                                 \\r
 134         pxIterator->pxNextFreeBlock = pxBlockToInsert;                                                                  \\r
 135 }\r
 136 /*-----------------------------------------------------------*/\r
 137 \r
 138 #define prvHeapInit()                                                                                                                           \\r
 139 {                                                                                                                                                                       \\r
 140 xBlockLink *pxFirstFreeBlock;                                                                                                           \\r
 141                                                                                                                                                                         \\r
 142         /* xStart is used to hold a pointer to the first item in the list of free */    \\r
 143         /* blocks.  The void cast is used to prevent compiler warnings. */                              \\r
 144         xStart.pxNextFreeBlock = ( void * ) xHeap.ucHeap;                                                               \\r
 145         xStart.xBlockSize = ( size_t ) 0;                                                                                               \\r
 146                                                                                                                                                                         \\r
 147         /* xEnd is used to mark the end of the list of free blocks. */                                  \\r
 148         xEnd.xBlockSize = configTOTAL_HEAP_SIZE;                                                                                \\r
 149         xEnd.pxNextFreeBlock = NULL;                                                                                                    \\r
 150                                                                                                                                                                         \\r
 151         /* To start with there is a single free block that is sized to take up the              \\r
 152         entire heap space. */                                                                                                                   \\r
 153         pxFirstFreeBlock = ( void * ) xHeap.ucHeap;                                                                             \\r
 154         pxFirstFreeBlock->xBlockSize = configTOTAL_HEAP_SIZE;                                                   \\r
 155         pxFirstFreeBlock->pxNextFreeBlock = &xEnd;                                                                              \\r
 156 }\r
 157 /*-----------------------------------------------------------*/\r
 158 \r
 159 void *pvPortMalloc( size_t xWantedSize )\r
 160 {\r
 161 xBlockLink *pxBlock, *pxPreviousBlock, *pxNewBlockLink;\r
 162 static portBASE_TYPE xHeapHasBeenInitialised = pdFALSE;\r
 163 void *pvReturn = NULL;\r
 164 \r
 165         vTaskSuspendAll();\r
 166         {\r
 167                 /* If this is the first call to malloc then the heap will require\r
 168                 initialisation to setup the list of free blocks. */\r
 169                 if( xHeapHasBeenInitialised == pdFALSE )\r
 170                 {\r
 171                         prvHeapInit();\r
 172                         xHeapHasBeenInitialised = pdTRUE;\r
 173                 }\r
 174 \r
 175                 /* The wanted size is increased so it can contain a xBlockLink\r
 176                 structure in addition to the requested amount of bytes. */\r
 177                 if( xWantedSize > 0 )\r
 178                 {\r
 179                         xWantedSize += heapSTRUCT_SIZE;\r
 180 \r
 181                         /* Ensure that blocks are always aligned to the required number of bytes. */\r
 182                         if( xWantedSize & heapBYTE_ALIGNMENT_MASK )\r
 183                         {\r
 184                                 /* Byte alignment required. */\r
 185                                 xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & heapBYTE_ALIGNMENT_MASK ) );\r
 186                         }\r
 187                 }\r
 188 \r
 189                 if( ( xWantedSize > 0 ) && ( xWantedSize < configTOTAL_HEAP_SIZE ) )\r
 190                 {\r
 191                         /* Blocks are stored in byte order - traverse the list from the start\r
 192                         (smallest) block until one of adequate size is found. */\r
 193                         pxPreviousBlock = &xStart;\r
 194                         pxBlock = xStart.pxNextFreeBlock;\r
 195                         while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock ) )\r
 196                         {\r
 197                                 pxPreviousBlock = pxBlock;\r
 198                                 pxBlock = pxBlock->pxNextFreeBlock;\r
 199                         }\r
 200 \r
 201                         /* If we found the end marker then a block of adequate size was not found. */\r
 202                         if( pxBlock != &xEnd )\r
 203                         {\r
 204                                 /* Return the memory space - jumping over the xBlockLink structure\r
 205                                 at its start. */\r
 206                                 pvReturn = ( void * ) ( ( ( unsigned portCHAR * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );\r
 207 \r
 208                                 /* This block is being returned for use so must be taken our of the\r
 209                                 list of free blocks. */\r
 210                                 pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;\r
 211 \r
 212                                 /* If the block is larger than required it can be split into two. */\r
 213                                 if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )\r
 214                                 {\r
 215                                         /* This block is to be split into two.  Create a new block\r
 216                                         following the number of bytes requested. The void cast is\r
 217                                         used to prevent byte alignment warnings from the compiler. */\r
 218                                         pxNewBlockLink = ( void * ) ( ( ( unsigned portCHAR * ) pxBlock ) + xWantedSize );\r
 219                                         \r
 220                                         /* Calculate the sizes of two blocks split from the single\r
 221                                         block. */\r
 222                                         pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize; \r
 223                                         pxBlock->xBlockSize = xWantedSize;                      \r
 224                                         \r
 225                                         /* Insert the new block into the list of free blocks. */\r
 226                                         prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );\r
 227                                 }\r
 228                         }\r
 229                 }\r
 230         }\r
 231         xTaskResumeAll();\r
 232 \r
 233         #if( configUSE_MALLOC_FAILED_HOOK == 1 )\r
 234         {\r
 235                 if( pvReturn == NULL )\r
 236                 {\r
 237                         extern void vApplicationMallocFailedHook( void );\r
 238                         vApplicationMallocFailedHook();\r
 239                 }\r
 240         }\r
 241         #endif\r
 242         \r
 243         return pvReturn;\r
 244 }\r
 245 /*-----------------------------------------------------------*/\r
 246 \r
 247 void vPortFree( void *pv )\r
 248 {\r
 249 unsigned portCHAR *puc = ( unsigned portCHAR * ) pv;\r
 250 xBlockLink *pxLink;\r
 251 \r
 252         if( pv )\r
 253         {\r
 254                 /* The memory being freed will have an xBlockLink structure immediately\r
 255                 before it. */\r
 256                 puc -= heapSTRUCT_SIZE;\r
 257 \r
 258                 /* This casting is to keep the compiler from issuing warnings. */\r
 259                 pxLink = ( void * ) puc;\r
 260 \r
 261                 vTaskSuspendAll();\r
 262                 {                               \r
 263                         /* Add this block to the list of free blocks. */\r
 264                         prvInsertBlockIntoFreeList( ( ( xBlockLink * ) pxLink ) );\r
 265                 }\r
 266                 xTaskResumeAll();\r
 267         }\r
 268 }\r
 269 /*-----------------------------------------------------------*/\r
 270 \r