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

1 /*

4

5 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

6

7 This file is part of the FreeRTOS distribution.

8

9 FreeRTOS is free software; you can redistribute it and/or modify it under

10 the terms of the GNU General Public License (version 2) as published by the

11 Free Software Foundation >>>> AND MODIFIED BY <<<< the FreeRTOS exception.

12

13 ***************************************************************************

14 >>! NOTE: The modification to the GPL is included to allow you to !<<

15 >>! distribute a combined work that includes FreeRTOS without being !<<

16 >>! obliged to provide the source code for proprietary components !<<

17 >>! outside of the FreeRTOS kernel. !<<

18 ***************************************************************************

19

20 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY

21 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

22 FOR A PARTICULAR PURPOSE. Full license text is available on the following

23 link: http://www.freertos.org/a00114.html

24

25 ***************************************************************************

26 * *

27 * FreeRTOS provides completely free yet professionally developed, *

28 * robust, strictly quality controlled, supported, and cross *

29 * platform software that is more than just the market leader, it *

30 * is the industry's de facto standard. *

31 * *

32 * Help yourself get started quickly while simultaneously helping *

33 * to support the FreeRTOS project by purchasing a FreeRTOS *

34 * tutorial book, reference manual, or both: *

35 * http://www.FreeRTOS.org/Documentation *

36 * *

37 ***************************************************************************

38

39 http://www.FreeRTOS.org/FAQHelp.html - Having a problem? Start by reading

40 the FAQ page "My application does not run, what could be wrong?". Have you

41 defined configASSERT()?

42

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59 http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High

60 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS

61 licenses offer ticketed support, indemnification and commercial middleware.

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63 http://www.SafeRTOS.com - High Integrity Systems also provide a safety

64 engineered and independently SIL3 certified version for use in safety and

65 mission critical applications that require provable dependability.

66

67 1 tab == 4 spaces!

68 */

69

70 /*

71 * A sample implementation of pvPortMalloc() and vPortFree() that permits

72 * allocated blocks to be freed, but does not combine adjacent free blocks

73 * into a single larger block (and so will fragment memory). See heap_4.c for

74 * an equivalent that does combine adjacent blocks into single larger blocks.

75 *

76 * See heap_1.c, heap_3.c and heap_4.c for alternative implementations, and the

77 * memory management pages of http://www.FreeRTOS.org for more information.

78 */

79 #include <stdlib.h>

80

81 /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining

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

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

84 #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE

85

86 #include "FreeRTOS.h"

87 #include "task.h"

88

89 #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE

90

91 #if( configSUPPORT_DYNAMIC_ALLOCATION == 0 )

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

93 #endif

94

95 /* A few bytes might be lost to byte aligning the heap start address. */

96 #define configADJUSTED_HEAP_SIZE ( configTOTAL_HEAP_SIZE - portBYTE_ALIGNMENT )

97

98 /*

99 * Initialises the heap structures before their first use.

100 */

101 static void prvHeapInit( void );

102

103 /* Allocate the memory for the heap. */

104 #if( configAPPLICATION_ALLOCATED_HEAP == 1 )

105 /* The application writer has already defined the array used for the RTOS

106 heap - probably so it can be placed in a special segment or address. */

107 extern uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];

108 #else

109 static uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];

110 #endif /* configAPPLICATION_ALLOCATED_HEAP */

111

112

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

114 of their size. */

115 typedef struct A_BLOCK_LINK

116 {

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

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

119 } BlockLink_t;

120

121

122 static const uint16_t heapSTRUCT_SIZE = ( ( sizeof ( BlockLink_t ) + ( portBYTE_ALIGNMENT - 1 ) ) & ~portBYTE_ALIGNMENT_MASK );

123 #define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )

124

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

126 static BlockLink_t xStart, xEnd;

127

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

129 fragmentation. */

130 static size_t xFreeBytesRemaining = configADJUSTED_HEAP_SIZE;

131

132 /* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */

133

134 /*

135 * Insert a block into the list of free blocks - which is ordered by size of

136 * the block. Small blocks at the start of the list and large blocks at the end

137 * of the list.

138 */

139 #define prvInsertBlockIntoFreeList( pxBlockToInsert ) \

140 { \

141 BlockLink_t *pxIterator; \

142 size_t xBlockSize; \

143 \

144 xBlockSize = pxBlockToInsert->xBlockSize; \

145 \

146 /* Iterate through the list until a block is found that has a larger size */ \

147 /* than the block we are inserting. */ \

148 for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock ) \

149 { \

150 /* There is nothing to do here - just iterate to the correct position. */ \

151 } \

152 \

153 /* Update the list to include the block being inserted in the correct */ \

154 /* position. */ \

155 pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock; \

156 pxIterator->pxNextFreeBlock = pxBlockToInsert; \

157 }

158 /*-----------------------------------------------------------*/

159

160 void *pvPortMalloc( size_t xWantedSize )

161 {

162 BlockLink_t *pxBlock, *pxPreviousBlock, *pxNewBlockLink;

163 static BaseType_t xHeapHasBeenInitialised = pdFALSE;

164 void *pvReturn = NULL;

165

166 vTaskSuspendAll();

167 {

168 /* If this is the first call to malloc then the heap will require

169 initialisation to setup the list of free blocks. */

170 if( xHeapHasBeenInitialised == pdFALSE )

171 {

172 prvHeapInit();

173 xHeapHasBeenInitialised = pdTRUE;

174 }

175

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

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

178 if( xWantedSize > 0 )

179 {

180 xWantedSize += heapSTRUCT_SIZE;

181

182 /* Ensure that blocks are always aligned to the required number of bytes. */

183 if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0 )

184 {

185 /* Byte alignment required. */

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

187 }

188 }

189

190 if( ( xWantedSize > 0 ) && ( xWantedSize < configADJUSTED_HEAP_SIZE ) )

191 {

192 /* Blocks are stored in byte order - traverse the list from the start

193 (smallest) block until one of adequate size is found. */

194 pxPreviousBlock = &xStart;

195 pxBlock = xStart.pxNextFreeBlock;

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

197 {

198 pxPreviousBlock = pxBlock;

199 pxBlock = pxBlock->pxNextFreeBlock;

200 }

201

202 /* If we found the end marker then a block of adequate size was not found. */

203 if( pxBlock != &xEnd )

204 {

205 /* Return the memory space - jumping over the BlockLink_t structure

206 at its start. */

207 pvReturn = ( void * ) ( ( ( uint8_t * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );

208

209 /* This block is being returned for use so must be taken out of the

210 list of free blocks. */

211 pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;

212

213 /* If the block is larger than required it can be split into two. */

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

215 {

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

217 following the number of bytes requested. The void cast is

218 used to prevent byte alignment warnings from the compiler. */

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

220

221 /* Calculate the sizes of two blocks split from the single

222 block. */

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

224 pxBlock->xBlockSize = xWantedSize;

225

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

227 prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );

228 }

229

230 xFreeBytesRemaining -= pxBlock->xBlockSize;

231 }

232 }

233

234 traceMALLOC( pvReturn, xWantedSize );

235 }

236 ( void ) xTaskResumeAll();

237

238 #if( configUSE_MALLOC_FAILED_HOOK == 1 )

239 {

240 if( pvReturn == NULL )

241 {

242 extern void vApplicationMallocFailedHook( void );

243 vApplicationMallocFailedHook();

244 }

245 }

246 #endif

247

248 return pvReturn;

249 }

250 /*-----------------------------------------------------------*/

251

252 void vPortFree( void *pv )

253 {

254 uint8_t *puc = ( uint8_t * ) pv;

255 BlockLink_t *pxLink;

256

257 if( pv != NULL )

258 {

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

260 before it. */

261 puc -= heapSTRUCT_SIZE;

262

263 /* This unexpected casting is to keep some compilers from issuing

264 byte alignment warnings. */

265 pxLink = ( void * ) puc;

266

267 vTaskSuspendAll();

268 {

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

270 prvInsertBlockIntoFreeList( ( ( BlockLink_t * ) pxLink ) );

271 xFreeBytesRemaining += pxLink->xBlockSize;

272 traceFREE( pv, pxLink->xBlockSize );

273 }

274 ( void ) xTaskResumeAll();

275 }

276 }

277 /*-----------------------------------------------------------*/

278

279 size_t xPortGetFreeHeapSize( void )

280 {

281 return xFreeBytesRemaining;

282 }

283 /*-----------------------------------------------------------*/

284

285 void vPortInitialiseBlocks( void )

286 {

287 /* This just exists to keep the linker quiet. */

288 }

289 /*-----------------------------------------------------------*/

290

291 static void prvHeapInit( void )

292 {

293 BlockLink_t *pxFirstFreeBlock;

294 uint8_t *pucAlignedHeap;

295

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

297 pucAlignedHeap = ( uint8_t * ) ( ( ( portPOINTER_SIZE_TYPE ) &ucHeap[ portBYTE_ALIGNMENT ] ) & ( ~( ( portPOINTER_SIZE_TYPE ) portBYTE_ALIGNMENT_MASK ) ) );

298

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

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

301 xStart.pxNextFreeBlock = ( void * ) pucAlignedHeap;

302 xStart.xBlockSize = ( size_t ) 0;

303

304 /* xEnd is used to mark the end of the list of free blocks. */

305 xEnd.xBlockSize = configADJUSTED_HEAP_SIZE;

306 xEnd.pxNextFreeBlock = NULL;

307

308 /* To start with there is a single free block that is sized to take up the

309 entire heap space. */

310 pxFirstFreeBlock = ( void * ) pucAlignedHeap;

311 pxFirstFreeBlock->xBlockSize = configADJUSTED_HEAP_SIZE;

312 pxFirstFreeBlock->pxNextFreeBlock = &xEnd;

313 }

314 /*-----------------------------------------------------------*/