git.sur5r.net Git - freertos/blob - FreeRTOS/Source/portable/MemMang/heap_4.c

   1 /*\r
   2     FreeRTOS V8.1.2 - Copyright (C) 2014 Real Time Engineers Ltd.\r
   3     All rights reserved\r
   4 \r
   5     VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.\r
   6 \r
   7     ***************************************************************************\r
   8      *                                                                       *\r
   9      *    FreeRTOS provides completely free yet professionally developed,    *\r
  10      *    robust, strictly quality controlled, supported, and cross          *\r
  11      *    platform software that has become a de facto standard.             *\r
  12      *                                                                       *\r
  13      *    Help yourself get started quickly and support the FreeRTOS         *\r
  14      *    project by purchasing a FreeRTOS tutorial book, reference          *\r
  15      *    manual, or both from: http://www.FreeRTOS.org/Documentation        *\r
  16      *                                                                       *\r
  17      *    Thank you!                                                         *\r
  18      *                                                                       *\r
  19     ***************************************************************************\r
  20 \r
  21     This file is part of the FreeRTOS distribution.\r
  22 \r
  23     FreeRTOS is free software; you can redistribute it and/or modify it under\r
  24     the terms of the GNU General Public License (version 2) as published by the\r
  25     Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.\r
  26 \r
  27     >>!   NOTE: The modification to the GPL is included to allow you to     !<<\r
  28     >>!   distribute a combined work that includes FreeRTOS without being   !<<\r
  29     >>!   obliged to provide the source code for proprietary components     !<<\r
  30     >>!   outside of the FreeRTOS kernel.                                   !<<\r
  31 \r
  32     FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY\r
  33     WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS\r
  34     FOR A PARTICULAR PURPOSE.  Full license text is available from the following\r
  35     link: http://www.freertos.org/a00114.html\r
  36 \r
  37     1 tab == 4 spaces!\r
  38 \r
  39     ***************************************************************************\r
  40      *                                                                       *\r
  41      *    Having a problem?  Start by reading the FAQ "My application does   *\r
  42      *    not run, what could be wrong?"                                     *\r
  43      *                                                                       *\r
  44      *    http://www.FreeRTOS.org/FAQHelp.html                               *\r
  45      *                                                                       *\r
  46     ***************************************************************************\r
  47 \r
  48     http://www.FreeRTOS.org - Documentation, books, training, latest versions,\r
  49     license and Real Time Engineers Ltd. contact details.\r
  50 \r
  51     http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,\r
  52     including FreeRTOS+Trace - an indispensable productivity tool, a DOS\r
  53     compatible FAT file system, and our tiny thread aware UDP/IP stack.\r
  54 \r
  55     http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High\r
  56     Integrity Systems to sell under the OpenRTOS brand.  Low cost OpenRTOS\r
  57     licenses offer ticketed support, indemnification and middleware.\r
  58 \r
  59     http://www.SafeRTOS.com - High Integrity Systems also provide a safety\r
  60     engineered and independently SIL3 certified version for use in safety and\r
  61     mission critical applications that require provable dependability.\r
  62 \r
  63     1 tab == 4 spaces!\r
  64 */\r
  65 \r
  66 /*\r
  67  * A sample implementation of pvPortMalloc() and vPortFree() that combines\r
  68  * (coalescences) adjacent memory blocks as they are freed, and in so doing\r
  69  * limits memory fragmentation.\r
  70  *\r
  71  * See heap_1.c, heap_2.c and heap_3.c for alternative implementations, and the\r
  72  * memory management pages of http://www.FreeRTOS.org for more information.\r
  73  */\r
  74 #include <stdlib.h>\r
  75 \r
  76 /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining\r
  77 all the API functions to use the MPU wrappers.  That should only be done when\r
  78 task.h is included from an application file. */\r
  79 #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE\r
  80 \r
  81 #include "FreeRTOS.h"\r
  82 #include "task.h"\r
  83 \r
  84 #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE\r
  85 \r
  86 /* Block sizes must not get too small. */\r
  87 #define heapMINIMUM_BLOCK_SIZE  ( ( size_t ) ( xHeapStructSize * 2 ) )\r
  88 \r
  89 /* Assumes 8bit bytes! */\r
  90 #define heapBITS_PER_BYTE               ( ( size_t ) 8 )\r
  91 \r
  92 /* Allocate the memory for the heap. */\r
  93 #if( configAPPLICATION_ALLOCATED_HEAP == 1 )\r
  94         /* The application writer has already defined the array used for the RTOS\r
  95         heap - probably so it can be placed in a special segment or address. */\r
  96         extern uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];\r
  97 #else\r
  98         static uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];\r
  99 #endif /* configAPPLICATION_ALLOCATED_HEAP */\r
 100 \r
 101 /* Define the linked list structure.  This is used to link free blocks in order\r
 102 of their memory address. */\r
 103 typedef struct A_BLOCK_LINK\r
 104 {\r
 105         struct A_BLOCK_LINK *pxNextFreeBlock;   /*<< The next free block in the list. */\r
 106         size_t xBlockSize;                                              /*<< The size of the free block. */\r
 107 } BlockLink_t;\r
 108 \r
 109 /*-----------------------------------------------------------*/\r
 110 \r
 111 /*\r
 112  * Inserts a block of memory that is being freed into the correct position in\r
 113  * the list of free memory blocks.  The block being freed will be merged with\r
 114  * the block in front it and/or the block behind it if the memory blocks are\r
 115  * adjacent to each other.\r
 116  */\r
 117 static void prvInsertBlockIntoFreeList( BlockLink_t *pxBlockToInsert );\r
 118 \r
 119 /*\r
 120  * Called automatically to setup the required heap structures the first time\r
 121  * pvPortMalloc() is called.\r
 122  */\r
 123 static void prvHeapInit( void );\r
 124 \r
 125 /*-----------------------------------------------------------*/\r
 126 \r
 127 /* The size of the structure placed at the beginning of each allocated memory\r
 128 block must by correctly byte aligned. */\r
 129 static const size_t xHeapStructSize     = ( ( sizeof( BlockLink_t ) + ( portBYTE_ALIGNMENT - 1 ) ) & ~portBYTE_ALIGNMENT_MASK );\r
 130 \r
 131 /* Create a couple of list links to mark the start and end of the list. */\r
 132 static BlockLink_t xStart, *pxEnd = NULL;\r
 133 \r
 134 /* Keeps track of the number of free bytes remaining, but says nothing about\r
 135 fragmentation. */\r
 136 static size_t xFreeBytesRemaining = 0U;\r
 137 static size_t xMinimumEverFreeBytesRemaining = 0U;\r
 138 \r
 139 /* Gets set to the top bit of an size_t type.  When this bit in the xBlockSize\r
 140 member of an BlockLink_t structure is set then the block belongs to the\r
 141 application.  When the bit is free the block is still part of the free heap\r
 142 space. */\r
 143 static size_t xBlockAllocatedBit = 0;\r
 144 \r
 145 /*-----------------------------------------------------------*/\r
 146 \r
 147 void *pvPortMalloc( size_t xWantedSize )\r
 148 {\r
 149 BlockLink_t *pxBlock, *pxPreviousBlock, *pxNewBlockLink;\r
 150 void *pvReturn = NULL;\r
 151 \r
 152         vTaskSuspendAll();\r
 153         {\r
 154                 /* If this is the first call to malloc then the heap will require\r
 155                 initialisation to setup the list of free blocks. */\r
 156                 if( pxEnd == NULL )\r
 157                 {\r
 158                         prvHeapInit();\r
 159                 }\r
 160                 else\r
 161                 {\r
 162                         mtCOVERAGE_TEST_MARKER();\r
 163                 }\r
 164 \r
 165                 /* Check the requested block size is not so large that the top bit is\r
 166                 set.  The top bit of the block size member of the BlockLink_t structure\r
 167                 is used to determine who owns the block - the application or the\r
 168                 kernel, so it must be free. */\r
 169                 if( ( xWantedSize & xBlockAllocatedBit ) == 0 )\r
 170                 {\r
 171                         /* The wanted size is increased so it can contain a BlockLink_t\r
 172                         structure in addition to the requested amount of bytes. */\r
 173                         if( xWantedSize > 0 )\r
 174                         {\r
 175                                 xWantedSize += xHeapStructSize;\r
 176 \r
 177                                 /* Ensure that blocks are always aligned to the required number\r
 178                                 of bytes. */\r
 179                                 if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 )\r
 180                                 {\r
 181                                         /* Byte alignment required. */\r
 182                                         xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );\r
 183                                         configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 );\r
 184                                 }\r
 185                                 else\r
 186                                 {\r
 187                                         mtCOVERAGE_TEST_MARKER();\r
 188                                 }\r
 189                         }\r
 190                         else\r
 191                         {\r
 192                                 mtCOVERAGE_TEST_MARKER();\r
 193                         }\r
 194 \r
 195                         if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )\r
 196                         {\r
 197                                 /* Traverse the list from the start     (lowest address) block until\r
 198                                 one     of adequate size is found. */\r
 199                                 pxPreviousBlock = &xStart;\r
 200                                 pxBlock = xStart.pxNextFreeBlock;\r
 201                                 while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock != NULL ) )\r
 202                                 {\r
 203                                         pxPreviousBlock = pxBlock;\r
 204                                         pxBlock = pxBlock->pxNextFreeBlock;\r
 205                                 }\r
 206 \r
 207                                 /* If the end marker was reached then a block of adequate size\r
 208                                 was     not found. */\r
 209                                 if( pxBlock != pxEnd )\r
 210                                 {\r
 211                                         /* Return the memory space pointed to - jumping over the\r
 212                                         BlockLink_t structure at its start. */\r
 213                                         pvReturn = ( void * ) ( ( ( uint8_t * ) pxPreviousBlock->pxNextFreeBlock ) + xHeapStructSize );\r
 214 \r
 215                                         /* This block is being returned for use so must be taken out\r
 216                                         of the list of free blocks. */\r
 217                                         pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;\r
 218 \r
 219                                         /* If the block is larger than required it can be split into\r
 220                                         two. */\r
 221                                         if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )\r
 222                                         {\r
 223                                                 /* This block is to be split into two.  Create a new\r
 224                                                 block following the number of bytes requested. The void\r
 225                                                 cast is used to prevent byte alignment warnings from the\r
 226                                                 compiler. */\r
 227                                                 pxNewBlockLink = ( void * ) ( ( ( uint8_t * ) pxBlock ) + xWantedSize );\r
 228                                                 configASSERT( ( ( ( uint32_t ) pxNewBlockLink ) & portBYTE_ALIGNMENT_MASK ) == 0 );\r
 229 \r
 230                                                 /* Calculate the sizes of two blocks split from the\r
 231                                                 single block. */\r
 232                                                 pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;\r
 233                                                 pxBlock->xBlockSize = xWantedSize;\r
 234 \r
 235                                                 /* Insert the new block into the list of free blocks. */\r
 236                                                 prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );\r
 237                                         }\r
 238                                         else\r
 239                                         {\r
 240                                                 mtCOVERAGE_TEST_MARKER();\r
 241                                         }\r
 242 \r
 243                                         xFreeBytesRemaining -= pxBlock->xBlockSize;\r
 244 \r
 245                                         if( xFreeBytesRemaining < xMinimumEverFreeBytesRemaining )\r
 246                                         {\r
 247                                                 xMinimumEverFreeBytesRemaining = xFreeBytesRemaining;\r
 248                                         }\r
 249                                         else\r
 250                                         {\r
 251                                                 mtCOVERAGE_TEST_MARKER();\r
 252                                         }\r
 253 \r
 254                                         /* The block is being returned - it is allocated and owned\r
 255                                         by the application and has no "next" block. */\r
 256                                         pxBlock->xBlockSize |= xBlockAllocatedBit;\r
 257                                         pxBlock->pxNextFreeBlock = NULL;\r
 258                                 }\r
 259                                 else\r
 260                                 {\r
 261                                         mtCOVERAGE_TEST_MARKER();\r
 262                                 }\r
 263                         }\r
 264                         else\r
 265                         {\r
 266                                 mtCOVERAGE_TEST_MARKER();\r
 267                         }\r
 268                 }\r
 269                 else\r
 270                 {\r
 271                         mtCOVERAGE_TEST_MARKER();\r
 272                 }\r
 273 \r
 274                 traceMALLOC( pvReturn, xWantedSize );\r
 275         }\r
 276         ( void ) xTaskResumeAll();\r
 277 \r
 278         #if( configUSE_MALLOC_FAILED_HOOK == 1 )\r
 279         {\r
 280                 if( pvReturn == NULL )\r
 281                 {\r
 282                         extern void vApplicationMallocFailedHook( void );\r
 283                         vApplicationMallocFailedHook();\r
 284                 }\r
 285                 else\r
 286                 {\r
 287                         mtCOVERAGE_TEST_MARKER();\r
 288                 }\r
 289         }\r
 290         #endif\r
 291 \r
 292         configASSERT( ( ( ( uint32_t ) pvReturn ) & portBYTE_ALIGNMENT_MASK ) == 0 );\r
 293         return pvReturn;\r
 294 }\r
 295 /*-----------------------------------------------------------*/\r
 296 \r
 297 void vPortFree( void *pv )\r
 298 {\r
 299 uint8_t *puc = ( uint8_t * ) pv;\r
 300 BlockLink_t *pxLink;\r
 301 \r
 302         if( pv != NULL )\r
 303         {\r
 304                 /* The memory being freed will have an BlockLink_t structure immediately\r
 305                 before it. */\r
 306                 puc -= xHeapStructSize;\r
 307 \r
 308                 /* This casting is to keep the compiler from issuing warnings. */\r
 309                 pxLink = ( void * ) puc;\r
 310 \r
 311                 /* Check the block is actually allocated. */\r
 312                 configASSERT( ( pxLink->xBlockSize & xBlockAllocatedBit ) != 0 );\r
 313                 configASSERT( pxLink->pxNextFreeBlock == NULL );\r
 314 \r
 315                 if( ( pxLink->xBlockSize & xBlockAllocatedBit ) != 0 )\r
 316                 {\r
 317                         if( pxLink->pxNextFreeBlock == NULL )\r
 318                         {\r
 319                                 /* The block is being returned to the heap - it is no longer\r
 320                                 allocated. */\r
 321                                 pxLink->xBlockSize &= ~xBlockAllocatedBit;\r
 322 \r
 323                                 vTaskSuspendAll();\r
 324                                 {\r
 325                                         /* Add this block to the list of free blocks. */\r
 326                                         xFreeBytesRemaining += pxLink->xBlockSize;\r
 327                                         traceFREE( pv, pxLink->xBlockSize );\r
 328                                         prvInsertBlockIntoFreeList( ( ( BlockLink_t * ) pxLink ) );\r
 329                                 }\r
 330                                 ( void ) xTaskResumeAll();\r
 331                         }\r
 332                         else\r
 333                         {\r
 334                                 mtCOVERAGE_TEST_MARKER();\r
 335                         }\r
 336                 }\r
 337                 else\r
 338                 {\r
 339                         mtCOVERAGE_TEST_MARKER();\r
 340                 }\r
 341         }\r
 342 }\r
 343 /*-----------------------------------------------------------*/\r
 344 \r
 345 size_t xPortGetFreeHeapSize( void )\r
 346 {\r
 347         return xFreeBytesRemaining;\r
 348 }\r
 349 /*-----------------------------------------------------------*/\r
 350 \r
 351 size_t xPortGetMinimumEverFreeHeapSize( void )\r
 352 {\r
 353         return xMinimumEverFreeBytesRemaining;\r
 354 }\r
 355 /*-----------------------------------------------------------*/\r
 356 \r
 357 void vPortInitialiseBlocks( void )\r
 358 {\r
 359         /* This just exists to keep the linker quiet. */\r
 360 }\r
 361 /*-----------------------------------------------------------*/\r
 362 \r
 363 static void prvHeapInit( void )\r
 364 {\r
 365 BlockLink_t *pxFirstFreeBlock;\r
 366 uint8_t *pucAlignedHeap;\r
 367 uint32_t ulAddress;\r
 368 size_t xTotalHeapSize = configTOTAL_HEAP_SIZE;\r
 369 \r
 370         /* Ensure the heap starts on a correctly aligned boundary. */\r
 371         ulAddress = ( uint32_t ) ucHeap;\r
 372 \r
 373         if( ( ulAddress & portBYTE_ALIGNMENT_MASK ) != 0 )\r
 374         {\r
 375                 ulAddress += ( portBYTE_ALIGNMENT - 1 );\r
 376                 ulAddress &= ~portBYTE_ALIGNMENT_MASK;\r
 377                 xTotalHeapSize -= ulAddress - ( uint32_t ) ucHeap;\r
 378         }\r
 379 \r
 380         pucAlignedHeap = ( uint8_t * ) ulAddress;\r
 381 \r
 382         /* xStart is used to hold a pointer to the first item in the list of free\r
 383         blocks.  The void cast is used to prevent compiler warnings. */\r
 384         xStart.pxNextFreeBlock = ( void * ) pucAlignedHeap;\r
 385         xStart.xBlockSize = ( size_t ) 0;\r
 386 \r
 387         /* pxEnd is used to mark the end of the list of free blocks and is inserted\r
 388         at the end of the heap space. */\r
 389         ulAddress = ( ( uint32_t ) pucAlignedHeap ) + xTotalHeapSize;\r
 390         ulAddress -= xHeapStructSize;\r
 391         ulAddress &= ~portBYTE_ALIGNMENT_MASK;\r
 392         pxEnd = ( void * ) ulAddress;\r
 393         pxEnd->xBlockSize = 0;\r
 394         pxEnd->pxNextFreeBlock = NULL;\r
 395 \r
 396         /* To start with there is a single free block that is sized to take up the\r
 397         entire heap space, minus the space taken by pxEnd. */\r
 398         pxFirstFreeBlock = ( void * ) pucAlignedHeap;\r
 399         pxFirstFreeBlock->xBlockSize = ulAddress - ( uint32_t ) pxFirstFreeBlock;\r
 400         pxFirstFreeBlock->pxNextFreeBlock = pxEnd;\r
 401 \r
 402         /* Only one block exists - and it covers the entire usable heap space. */\r
 403         xMinimumEverFreeBytesRemaining = pxFirstFreeBlock->xBlockSize;\r
 404         xFreeBytesRemaining = pxFirstFreeBlock->xBlockSize;\r
 405 \r
 406         /* Work out the position of the top bit in a size_t variable. */\r
 407         xBlockAllocatedBit = ( ( size_t ) 1 ) << ( ( sizeof( size_t ) * heapBITS_PER_BYTE ) - 1 );\r
 408 }\r
 409 /*-----------------------------------------------------------*/\r
 410 \r
 411 static void prvInsertBlockIntoFreeList( BlockLink_t *pxBlockToInsert )\r
 412 {\r
 413 BlockLink_t *pxIterator;\r
 414 uint8_t *puc;\r
 415 \r
 416         /* Iterate through the list until a block is found that has a higher address\r
 417         than the block being inserted. */\r
 418         for( pxIterator = &xStart; pxIterator->pxNextFreeBlock < pxBlockToInsert; pxIterator = pxIterator->pxNextFreeBlock )\r
 419         {\r
 420                 /* Nothing to do here, just iterate to the right position. */\r
 421         }\r
 422 \r
 423         /* Do the block being inserted, and the block it is being inserted after\r
 424         make a contiguous block of memory? */\r
 425         puc = ( uint8_t * ) pxIterator;\r
 426         if( ( puc + pxIterator->xBlockSize ) == ( uint8_t * ) pxBlockToInsert )\r
 427         {\r
 428                 pxIterator->xBlockSize += pxBlockToInsert->xBlockSize;\r
 429                 pxBlockToInsert = pxIterator;\r
 430         }\r
 431         else\r
 432         {\r
 433                 mtCOVERAGE_TEST_MARKER();\r
 434         }\r
 435 \r
 436         /* Do the block being inserted, and the block it is being inserted before\r
 437         make a contiguous block of memory? */\r
 438         puc = ( uint8_t * ) pxBlockToInsert;\r
 439         if( ( puc + pxBlockToInsert->xBlockSize ) == ( uint8_t * ) pxIterator->pxNextFreeBlock )\r
 440         {\r
 441                 if( pxIterator->pxNextFreeBlock != pxEnd )\r
 442                 {\r
 443                         /* Form one big block from the two blocks. */\r
 444                         pxBlockToInsert->xBlockSize += pxIterator->pxNextFreeBlock->xBlockSize;\r
 445                         pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock->pxNextFreeBlock;\r
 446                 }\r
 447                 else\r
 448                 {\r
 449                         pxBlockToInsert->pxNextFreeBlock = pxEnd;\r
 450                 }\r
 451         }\r
 452         else\r
 453         {\r
 454                 pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;\r
 455         }\r
 456 \r
 457         /* If the block being inserted plugged a gab, so was merged with the block\r
 458         before and the block after, then it's pxNextFreeBlock pointer will have\r
 459         already been set, and should not be set here as that would make it point\r
 460         to itself. */\r
 461         if( pxIterator != pxBlockToInsert )\r
 462         {\r
 463                 pxIterator->pxNextFreeBlock = pxBlockToInsert;\r
 464         }\r
 465         else\r
 466         {\r
 467                 mtCOVERAGE_TEST_MARKER();\r
 468         }\r
 469 }\r
 470 \r