begriffs open source - cmsis-freertos/blob - Source/portable/MemMang/heap

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67 1 tab == 4 spaces!

68 */

69

70 /*

71 * A sample implementation of pvPortMalloc() that allows the heap to be defined

72 * across multiple non-contigous blocks and combines (coalescences) adjacent

73 * memory blocks as they are freed.

74 *

75 * See heap_1.c, heap_2.c, heap_3.c and heap_4.c for alternative

76 * implementations, and the memory management pages of http://www.FreeRTOS.org

77 * for more information.

78 *

79 * Usage notes:

80 *

81 * vPortDefineHeapRegions() ***must*** be called before pvPortMalloc().

82 * pvPortMalloc() will be called if any task objects (tasks, queues, event

83 * groups, etc.) are created, therefore vPortDefineHeapRegions() ***must*** be

84 * called before any other objects are defined.

85 *

86 * vPortDefineHeapRegions() takes a single parameter. The parameter is an array

87 * of HeapRegion_t structures. HeapRegion_t is defined in portable.h as

88 *

89 * typedef struct HeapRegion

90 * {

91 * uint8_t *pucStartAddress; << Start address of a block of memory that will be part of the heap.

92 * size_t xSizeInBytes; << Size of the block of memory.

93 * } HeapRegion_t;

94 *

95 * The array is terminated using a NULL zero sized region definition, and the

96 * memory regions defined in the array ***must*** appear in address order from

97 * low address to high address. So the following is a valid example of how

98 * to use the function.

99 *

100 * HeapRegion_t xHeapRegions[] =

101 * {

102 * { ( uint8_t * ) 0x80000000UL, 0x10000 }, << Defines a block of 0x10000 bytes starting at address 0x80000000

103 * { ( uint8_t * ) 0x90000000UL, 0xa0000 }, << Defines a block of 0xa0000 bytes starting at address of 0x90000000

104 * { NULL, 0 } << Terminates the array.

105 * };

106 *

107 * vPortDefineHeapRegions( xHeapRegions ); << Pass the array into vPortDefineHeapRegions().

108 *

109 * Note 0x80000000 is the lower address so appears in the array first.

110 *

111 */

112 #include <stdlib.h>

113

114 /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining

115 all the API functions to use the MPU wrappers. That should only be done when

116 task.h is included from an application file. */

117 #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE

118

119 #include "FreeRTOS.h"

120 #include "task.h"

121

122 #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE

123

124 #if( configSUPPORT_DYNAMIC_ALLOCATION == 0 )

125 #error This file must not be used if configSUPPORT_DYNAMIC_ALLOCATION is 0

126 #endif

127

128 /* Block sizes must not get too small. */

129 #define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( xHeapStructSize << 1 ) )

130

131 /* Assumes 8bit bytes! */

132 #define heapBITS_PER_BYTE ( ( size_t ) 8 )

133

134 /* Define the linked list structure. This is used to link free blocks in order

135 of their memory address. */

136 typedef struct A_BLOCK_LINK

137 {

138 struct A_BLOCK_LINK *pxNextFreeBlock; /*<< The next free block in the list. */

139 size_t xBlockSize; /*<< The size of the free block. */

140 } BlockLink_t;

141

142 /*-----------------------------------------------------------*/

143

144 /*

145 * Inserts a block of memory that is being freed into the correct position in

146 * the list of free memory blocks. The block being freed will be merged with

147 * the block in front it and/or the block behind it if the memory blocks are

148 * adjacent to each other.

149 */

150 static void prvInsertBlockIntoFreeList( BlockLink_t *pxBlockToInsert );

151

152 /*-----------------------------------------------------------*/

153

154 /* The size of the structure placed at the beginning of each allocated memory

155 block must by correctly byte aligned. */

156 static const size_t xHeapStructSize = ( sizeof( BlockLink_t ) + ( ( size_t ) ( portBYTE_ALIGNMENT - 1 ) ) ) & ~( ( size_t ) portBYTE_ALIGNMENT_MASK );

157

158 /* Create a couple of list links to mark the start and end of the list. */

159 static BlockLink_t xStart, *pxEnd = NULL;

160

161 /* Keeps track of the number of free bytes remaining, but says nothing about

162 fragmentation. */

163 static size_t xFreeBytesRemaining = 0U;

164 static size_t xMinimumEverFreeBytesRemaining = 0U;

165

166 /* Gets set to the top bit of an size_t type. When this bit in the xBlockSize

167 member of an BlockLink_t structure is set then the block belongs to the

168 application. When the bit is free the block is still part of the free heap

169 space. */

170 static size_t xBlockAllocatedBit = 0;

171

172 /*-----------------------------------------------------------*/

173

174 void *pvPortMalloc( size_t xWantedSize )

175 {

176 BlockLink_t *pxBlock, *pxPreviousBlock, *pxNewBlockLink;

177 void *pvReturn = NULL;

178

179 /* The heap must be initialised before the first call to

180 prvPortMalloc(). */

181 configASSERT( pxEnd );

182

183 vTaskSuspendAll();

184 {

185 /* Check the requested block size is not so large that the top bit is

186 set. The top bit of the block size member of the BlockLink_t structure

187 is used to determine who owns the block - the application or the

188 kernel, so it must be free. */

189 if( ( xWantedSize & xBlockAllocatedBit ) == 0 )

190 {

191 /* The wanted size is increased so it can contain a BlockLink_t

192 structure in addition to the requested amount of bytes. */

193 if( xWantedSize > 0 )

194 {

195 xWantedSize += xHeapStructSize;

196

197 /* Ensure that blocks are always aligned to the required number

198 of bytes. */

199 if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 )

200 {

201 /* Byte alignment required. */

202 xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );

203 }

204 else

205 {

206 mtCOVERAGE_TEST_MARKER();

207 }

208 }

209 else

210 {

211 mtCOVERAGE_TEST_MARKER();

212 }

213

214 if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )

215 {

216 /* Traverse the list from the start (lowest address) block until

217 one of adequate size is found. */

218 pxPreviousBlock = &xStart;

219 pxBlock = xStart.pxNextFreeBlock;

220 while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock != NULL ) )

221 {

222 pxPreviousBlock = pxBlock;

223 pxBlock = pxBlock->pxNextFreeBlock;

224 }

225

226 /* If the end marker was reached then a block of adequate size

227 was not found. */

228 if( pxBlock != pxEnd )

229 {

230 /* Return the memory space pointed to - jumping over the

231 BlockLink_t structure at its start. */

232 pvReturn = ( void * ) ( ( ( uint8_t * ) pxPreviousBlock->pxNextFreeBlock ) + xHeapStructSize );

233

234 /* This block is being returned for use so must be taken out

235 of the list of free blocks. */

236 pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;

237

238 /* If the block is larger than required it can be split into

239 two. */

240 if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )

241 {

242 /* This block is to be split into two. Create a new

243 block following the number of bytes requested. The void

244 cast is used to prevent byte alignment warnings from the

245 compiler. */

246 pxNewBlockLink = ( void * ) ( ( ( uint8_t * ) pxBlock ) + xWantedSize );

247

248 /* Calculate the sizes of two blocks split from the

249 single block. */

250 pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;

251 pxBlock->xBlockSize = xWantedSize;

252

253 /* Insert the new block into the list of free blocks. */

254 prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );

255 }

256 else

257 {

258 mtCOVERAGE_TEST_MARKER();

259 }

260

261 xFreeBytesRemaining -= pxBlock->xBlockSize;

262

263 if( xFreeBytesRemaining < xMinimumEverFreeBytesRemaining )

264 {

265 xMinimumEverFreeBytesRemaining = xFreeBytesRemaining;

266 }

267 else

268 {

269 mtCOVERAGE_TEST_MARKER();

270 }

271

272 /* The block is being returned - it is allocated and owned

273 by the application and has no "next" block. */

274 pxBlock->xBlockSize |= xBlockAllocatedBit;

275 pxBlock->pxNextFreeBlock = NULL;

276 }

277 else

278 {

279 mtCOVERAGE_TEST_MARKER();

280 }

281 }

282 else

283 {

284 mtCOVERAGE_TEST_MARKER();

285 }

286 }

287 else

288 {

289 mtCOVERAGE_TEST_MARKER();

290 }

291

292 traceMALLOC( pvReturn, xWantedSize );

293 }

294 ( void ) xTaskResumeAll();

295

296 #if( configUSE_MALLOC_FAILED_HOOK == 1 )

297 {

298 if( pvReturn == NULL )

299 {

300 extern void vApplicationMallocFailedHook( void );

301 vApplicationMallocFailedHook();

302 }

303 else

304 {

305 mtCOVERAGE_TEST_MARKER();

306 }

307 }

308 #endif

309

310 return pvReturn;

311 }

312 /*-----------------------------------------------------------*/

313

314 void vPortFree( void *pv )

315 {

316 uint8_t *puc = ( uint8_t * ) pv;

317 BlockLink_t *pxLink;

318

319 if( pv != NULL )

320 {

321 /* The memory being freed will have an BlockLink_t structure immediately

322 before it. */

323 puc -= xHeapStructSize;

324

325 /* This casting is to keep the compiler from issuing warnings. */

326 pxLink = ( void * ) puc;

327

328 /* Check the block is actually allocated. */

329 configASSERT( ( pxLink->xBlockSize & xBlockAllocatedBit ) != 0 );

330 configASSERT( pxLink->pxNextFreeBlock == NULL );

331

332 if( ( pxLink->xBlockSize & xBlockAllocatedBit ) != 0 )

333 {

334 if( pxLink->pxNextFreeBlock == NULL )

335 {

336 /* The block is being returned to the heap - it is no longer

337 allocated. */

338 pxLink->xBlockSize &= ~xBlockAllocatedBit;

339

340 vTaskSuspendAll();

341 {

342 /* Add this block to the list of free blocks. */

343 xFreeBytesRemaining += pxLink->xBlockSize;

344 traceFREE( pv, pxLink->xBlockSize );

345 prvInsertBlockIntoFreeList( ( ( BlockLink_t * ) pxLink ) );

346 }

347 ( void ) xTaskResumeAll();

348 }

349 else

350 {

351 mtCOVERAGE_TEST_MARKER();

352 }

353 }

354 else

355 {

356 mtCOVERAGE_TEST_MARKER();

357 }

358 }

359 }

360 /*-----------------------------------------------------------*/

361

362 size_t xPortGetFreeHeapSize( void )

363 {

364 return xFreeBytesRemaining;

365 }

366 /*-----------------------------------------------------------*/

367

368 size_t xPortGetMinimumEverFreeHeapSize( void )

369 {

370 return xMinimumEverFreeBytesRemaining;

371 }

372 /*-----------------------------------------------------------*/

373

374 static void prvInsertBlockIntoFreeList( BlockLink_t *pxBlockToInsert )

375 {

376 BlockLink_t *pxIterator;

377 uint8_t *puc;

378

379 /* Iterate through the list until a block is found that has a higher address

380 than the block being inserted. */

381 for( pxIterator = &xStart; pxIterator->pxNextFreeBlock < pxBlockToInsert; pxIterator = pxIterator->pxNextFreeBlock )

382 {

383 /* Nothing to do here, just iterate to the right position. */

384 }

385

386 /* Do the block being inserted, and the block it is being inserted after

387 make a contiguous block of memory? */

388 puc = ( uint8_t * ) pxIterator;

389 if( ( puc + pxIterator->xBlockSize ) == ( uint8_t * ) pxBlockToInsert )

390 {

391 pxIterator->xBlockSize += pxBlockToInsert->xBlockSize;

392 pxBlockToInsert = pxIterator;

393 }

394 else

395 {

396 mtCOVERAGE_TEST_MARKER();

397 }

398

399 /* Do the block being inserted, and the block it is being inserted before

400 make a contiguous block of memory? */

401 puc = ( uint8_t * ) pxBlockToInsert;

402 if( ( puc + pxBlockToInsert->xBlockSize ) == ( uint8_t * ) pxIterator->pxNextFreeBlock )

403 {

404 if( pxIterator->pxNextFreeBlock != pxEnd )

405 {

406 /* Form one big block from the two blocks. */

407 pxBlockToInsert->xBlockSize += pxIterator->pxNextFreeBlock->xBlockSize;

408 pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock->pxNextFreeBlock;

409 }

410 else

411 {

412 pxBlockToInsert->pxNextFreeBlock = pxEnd;

413 }

414 }

415 else

416 {

417 pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;

418 }

419

420 /* If the block being inserted plugged a gab, so was merged with the block

421 before and the block after, then it's pxNextFreeBlock pointer will have

422 already been set, and should not be set here as that would make it point

423 to itself. */

424 if( pxIterator != pxBlockToInsert )

425 {

426 pxIterator->pxNextFreeBlock = pxBlockToInsert;

427 }

428 else

429 {

430 mtCOVERAGE_TEST_MARKER();

431 }

432 }

433 /*-----------------------------------------------------------*/

434

435 void vPortDefineHeapRegions( const HeapRegion_t * const pxHeapRegions )

436 {

437 BlockLink_t *pxFirstFreeBlockInRegion = NULL, *pxPreviousFreeBlock;

438 size_t xAlignedHeap;

439 size_t xTotalRegionSize, xTotalHeapSize = 0;

440 BaseType_t xDefinedRegions = 0;

441 size_t xAddress;

442 const HeapRegion_t *pxHeapRegion;

443

444 /* Can only call once! */

445 configASSERT( pxEnd == NULL );

446

447 pxHeapRegion = &( pxHeapRegions[ xDefinedRegions ] );

448

449 while( pxHeapRegion->xSizeInBytes > 0 )

450 {

451 xTotalRegionSize = pxHeapRegion->xSizeInBytes;

452

453 /* Ensure the heap region starts on a correctly aligned boundary. */

454 xAddress = ( size_t ) pxHeapRegion->pucStartAddress;

455 if( ( xAddress & portBYTE_ALIGNMENT_MASK ) != 0 )

456 {

457 xAddress += ( portBYTE_ALIGNMENT - 1 );

458 xAddress &= ~portBYTE_ALIGNMENT_MASK;

459

460 /* Adjust the size for the bytes lost to alignment. */

461 xTotalRegionSize -= xAddress - ( size_t ) pxHeapRegion->pucStartAddress;

462 }

463

464 xAlignedHeap = xAddress;

465

466 /* Set xStart if it has not already been set. */

467 if( xDefinedRegions == 0 )

468 {

469 /* xStart is used to hold a pointer to the first item in the list of

470 free blocks. The void cast is used to prevent compiler warnings. */

471 xStart.pxNextFreeBlock = ( BlockLink_t * ) xAlignedHeap;

472 xStart.xBlockSize = ( size_t ) 0;

473 }

474 else

475 {

476 /* Should only get here if one region has already been added to the

477 heap. */

478 configASSERT( pxEnd != NULL );

479

480 /* Check blocks are passed in with increasing start addresses. */

481 configASSERT( xAddress > ( size_t ) pxEnd );

482 }

483

484 /* Remember the location of the end marker in the previous region, if

485 any. */

486 pxPreviousFreeBlock = pxEnd;

487

488 /* pxEnd is used to mark the end of the list of free blocks and is

489 inserted at the end of the region space. */

490 xAddress = xAlignedHeap + xTotalRegionSize;

491 xAddress -= xHeapStructSize;

492 xAddress &= ~portBYTE_ALIGNMENT_MASK;

493 pxEnd = ( BlockLink_t * ) xAddress;

494 pxEnd->xBlockSize = 0;

495 pxEnd->pxNextFreeBlock = NULL;

496

497 /* To start with there is a single free block in this region that is

498 sized to take up the entire heap region minus the space taken by the

499 free block structure. */

500 pxFirstFreeBlockInRegion = ( BlockLink_t * ) xAlignedHeap;

501 pxFirstFreeBlockInRegion->xBlockSize = xAddress - ( size_t ) pxFirstFreeBlockInRegion;

502 pxFirstFreeBlockInRegion->pxNextFreeBlock = pxEnd;

503

504 /* If this is not the first region that makes up the entire heap space

505 then link the previous region to this region. */

506 if( pxPreviousFreeBlock != NULL )

507 {

508 pxPreviousFreeBlock->pxNextFreeBlock = pxFirstFreeBlockInRegion;

509 }

510

511 xTotalHeapSize += pxFirstFreeBlockInRegion->xBlockSize;

512

513 /* Move onto the next HeapRegion_t structure. */

514 xDefinedRegions++;

515 pxHeapRegion = &( pxHeapRegions[ xDefinedRegions ] );

516 }

517

518 xMinimumEverFreeBytesRemaining = xTotalHeapSize;

519 xFreeBytesRemaining = xTotalHeapSize;

520

521 /* Check something was actually defined before it is accessed. */

522 configASSERT( xTotalHeapSize );

523

524 /* Work out the position of the top bit in a size_t variable. */

525 xBlockAllocatedBit = ( ( size_t ) 1 ) << ( ( sizeof( size_t ) * heapBITS_PER_BYTE ) - 1 );

526 }

527