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

   1 /*\r
   2     FreeRTOS V6.0.0 - 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     * The FreeRTOS eBook and reference manual are available to purchase for a *\r
  29     * small fee. Help yourself get started quickly while also helping the     *\r
  30     * FreeRTOS project! See http://www.FreeRTOS.org/Documentation for details *\r
  31     *                                                                         *\r
  32     ***************************************************************************\r
  33 \r
  34     1 tab == 4 spaces!\r
  35 \r
  36     Please ensure to read the configuration and relevant port sections of the\r
  37     online documentation.\r
  38 \r
  39     http://www.FreeRTOS.org - Documentation, latest information, license and\r
  40     contact details.\r
  41 \r
  42     http://www.SafeRTOS.com - A version that is certified for use in safety\r
  43     critical systems.\r
  44 \r
  45     http://www.OpenRTOS.com - Commercial support, development, porting,\r
  46     licensing and training services.\r
  47 */\r
  48 \r
  49 /*\r
  50  * A sample implementation of pvPortMalloc() and vPortFree() that permits\r
  51  * allocated blocks to be freed, but does not combine adjacent free blocks\r
  52  * into a single larger block.\r
  53  *\r
  54  * See heap_1.c and heap_3.c for alternative implementations, and the memory\r
  55  * management pages of http://www.FreeRTOS.org for more information.\r
  56  */\r
  57 #include <stdlib.h>\r
  58 \r
  59 /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining\r
  60 all the API functions to use the MPU wrappers.  That should only be done when\r
  61 task.h is included from an application file. */\r
  62 #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE\r
  63 \r
  64 #include "FreeRTOS.h"\r
  65 #include "task.h"\r
  66 \r
  67 #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE\r
  68 \r
  69 /* Allocate the memory for the heap.  The struct is used to force byte\r
  70 alignment without using any non-portable code. */\r
  71 static union xRTOS_HEAP\r
  72 {\r
  73         #if portBYTE_ALIGNMENT == 8\r
  74                 volatile portDOUBLE dDummy;\r
  75         #else\r
  76                 volatile unsigned long ulDummy;\r
  77         #endif\r
  78         unsigned char ucHeap[ configTOTAL_HEAP_SIZE ];\r
  79 } xHeap;\r
  80 \r
  81 /* Define the linked list structure.  This is used to link free blocks in order\r
  82 of their size. */\r
  83 typedef struct A_BLOCK_LINK\r
  84 {\r
  85         struct A_BLOCK_LINK *pxNextFreeBlock;   /*<< The next free block in the list. */\r
  86         size_t xBlockSize;                                              /*<< The size of the free block. */\r
  87 } xBlockLink;\r
  88 \r
  89 \r
  90 static const unsigned short  heapSTRUCT_SIZE    = ( sizeof( xBlockLink ) + portBYTE_ALIGNMENT - ( sizeof( xBlockLink ) % portBYTE_ALIGNMENT ) );\r
  91 #define heapMINIMUM_BLOCK_SIZE  ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )\r
  92 \r
  93 /* Create a couple of list links to mark the start and end of the list. */\r
  94 static xBlockLink xStart, xEnd;\r
  95 \r
  96 /* Keeps track of the number of free bytes remaining, but says nothing about\r
  97 fragmentation. */\r
  98 static size_t xFreeBytesRemaining = configTOTAL_HEAP_SIZE;\r
  99 \r
 100 /* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */\r
 101 \r
 102 /*\r
 103  * Insert a block into the list of free blocks - which is ordered by size of\r
 104  * the block.  Small blocks at the start of the list and large blocks at the end\r
 105  * of the list.\r
 106  */\r
 107 #define prvInsertBlockIntoFreeList( pxBlockToInsert )                                                           \\r
 108 {                                                                                                                                                                       \\r
 109 xBlockLink *pxIterator;                                                                                                                         \\r
 110 size_t xBlockSize;                                                                                                                                      \\r
 111                                                                                                                                                                         \\r
 112         xBlockSize = pxBlockToInsert->xBlockSize;                                                                               \\r
 113                                                                                                                                                                         \\r
 114         /* Iterate through the list until a block is found that has a larger size */    \\r
 115         /* than the block we are inserting. */                                                                                  \\r
 116         for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock )     \\r
 117         {                                                                                                                                                               \\r
 118                 /* There is nothing to do here - just iterate to the correct position. */       \\r
 119         }                                                                                                                                                               \\r
 120                                                                                                                                                                         \\r
 121         /* Update the list to include the block being inserted in the correct */                \\r
 122         /* position. */                                                                                                                                 \\r
 123         pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;                                 \\r
 124         pxIterator->pxNextFreeBlock = pxBlockToInsert;                                                                  \\r
 125 }\r
 126 /*-----------------------------------------------------------*/\r
 127 \r
 128 #define prvHeapInit()                                                                                                                           \\r
 129 {                                                                                                                                                                       \\r
 130 xBlockLink *pxFirstFreeBlock;                                                                                                           \\r
 131                                                                                                                                                                         \\r
 132         /* xStart is used to hold a pointer to the first item in the list of free */    \\r
 133         /* blocks.  The void cast is used to prevent compiler warnings. */                              \\r
 134         xStart.pxNextFreeBlock = ( void * ) xHeap.ucHeap;                                                               \\r
 135         xStart.xBlockSize = ( size_t ) 0;                                                                                               \\r
 136                                                                                                                                                                         \\r
 137         /* xEnd is used to mark the end of the list of free blocks. */                                  \\r
 138         xEnd.xBlockSize = configTOTAL_HEAP_SIZE;                                                                                \\r
 139         xEnd.pxNextFreeBlock = NULL;                                                                                                    \\r
 140                                                                                                                                                                         \\r
 141         /* To start with there is a single free block that is sized to take up the              \\r
 142         entire heap space. */                                                                                                                   \\r
 143         pxFirstFreeBlock = ( void * ) xHeap.ucHeap;                                                                             \\r
 144         pxFirstFreeBlock->xBlockSize = configTOTAL_HEAP_SIZE;                                                   \\r
 145         pxFirstFreeBlock->pxNextFreeBlock = &xEnd;                                                                              \\r
 146 }\r
 147 /*-----------------------------------------------------------*/\r
 148 \r
 149 void *pvPortMalloc( size_t xWantedSize )\r
 150 {\r
 151 xBlockLink *pxBlock, *pxPreviousBlock, *pxNewBlockLink;\r
 152 static portBASE_TYPE xHeapHasBeenInitialised = pdFALSE;\r
 153 void *pvReturn = NULL;\r
 154 \r
 155         vTaskSuspendAll();\r
 156         {\r
 157                 /* If this is the first call to malloc then the heap will require\r
 158                 initialisation to setup the list of free blocks. */\r
 159                 if( xHeapHasBeenInitialised == pdFALSE )\r
 160                 {\r
 161                         prvHeapInit();\r
 162                         xHeapHasBeenInitialised = pdTRUE;\r
 163                 }\r
 164 \r
 165                 /* The wanted size is increased so it can contain a xBlockLink\r
 166                 structure in addition to the requested amount of bytes. */\r
 167                 if( xWantedSize > 0 )\r
 168                 {\r
 169                         xWantedSize += heapSTRUCT_SIZE;\r
 170 \r
 171                         /* Ensure that blocks are always aligned to the required number of bytes. */\r
 172                         if( xWantedSize & portBYTE_ALIGNMENT_MASK )\r
 173                         {\r
 174                                 /* Byte alignment required. */\r
 175                                 xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );\r
 176                         }\r
 177                 }\r
 178 \r
 179                 if( ( xWantedSize > 0 ) && ( xWantedSize < configTOTAL_HEAP_SIZE ) )\r
 180                 {\r
 181                         /* Blocks are stored in byte order - traverse the list from the start\r
 182                         (smallest) block until one of adequate size is found. */\r
 183                         pxPreviousBlock = &xStart;\r
 184                         pxBlock = xStart.pxNextFreeBlock;\r
 185                         while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock ) )\r
 186                         {\r
 187                                 pxPreviousBlock = pxBlock;\r
 188                                 pxBlock = pxBlock->pxNextFreeBlock;\r
 189                         }\r
 190 \r
 191                         /* If we found the end marker then a block of adequate size was not found. */\r
 192                         if( pxBlock != &xEnd )\r
 193                         {\r
 194                                 /* Return the memory space - jumping over the xBlockLink structure\r
 195                                 at its start. */\r
 196                                 pvReturn = ( void * ) ( ( ( unsigned char * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );\r
 197 \r
 198                                 /* This block is being returned for use so must be taken our of the\r
 199                                 list of free blocks. */\r
 200                                 pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;\r
 201 \r
 202                                 /* If the block is larger than required it can be split into two. */\r
 203                                 if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )\r
 204                                 {\r
 205                                         /* This block is to be split into two.  Create a new block\r
 206                                         following the number of bytes requested. The void cast is\r
 207                                         used to prevent byte alignment warnings from the compiler. */\r
 208                                         pxNewBlockLink = ( void * ) ( ( ( unsigned char * ) pxBlock ) + xWantedSize );\r
 209 \r
 210                                         /* Calculate the sizes of two blocks split from the single\r
 211                                         block. */\r
 212                                         pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;\r
 213                                         pxBlock->xBlockSize = xWantedSize;\r
 214 \r
 215                                         /* Insert the new block into the list of free blocks. */\r
 216                                         prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );\r
 217                                 }\r
 218                                 \r
 219                                 xFreeBytesRemaining -= xWantedSize;\r
 220                         }\r
 221                 }\r
 222         }\r
 223         xTaskResumeAll();\r
 224 \r
 225         #if( configUSE_MALLOC_FAILED_HOOK == 1 )\r
 226         {\r
 227                 if( pvReturn == NULL )\r
 228                 {\r
 229                         extern void vApplicationMallocFailedHook( void );\r
 230                         vApplicationMallocFailedHook();\r
 231                 }\r
 232         }\r
 233         #endif\r
 234 \r
 235         return pvReturn;\r
 236 }\r
 237 /*-----------------------------------------------------------*/\r
 238 \r
 239 void vPortFree( void *pv )\r
 240 {\r
 241 unsigned char *puc = ( unsigned char * ) pv;\r
 242 xBlockLink *pxLink;\r
 243 \r
 244         if( pv )\r
 245         {\r
 246                 /* The memory being freed will have an xBlockLink structure immediately\r
 247                 before it. */\r
 248                 puc -= heapSTRUCT_SIZE;\r
 249 \r
 250                 /* This casting is to keep the compiler from issuing warnings. */\r
 251                 pxLink = ( void * ) puc;\r
 252 \r
 253                 vTaskSuspendAll();\r
 254                 {\r
 255                         /* Add this block to the list of free blocks. */\r
 256                         prvInsertBlockIntoFreeList( ( ( xBlockLink * ) pxLink ) );\r
 257                         xFreeBytesRemaining += pxLink->xBlockSize;\r
 258                 }\r
 259                 xTaskResumeAll();\r
 260         }\r
 261 }\r
 262 /*-----------------------------------------------------------*/\r
 263 \r
 264 size_t xPortGetFreeHeapSize( void )\r
 265 {\r
 266         return xFreeBytesRemaining;\r
 267 }\r
 268 /*-----------------------------------------------------------*/\r
 269 \r