1 /*
2 * FreeRTOS Kernel V10.6.2
3 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
4 *
5 * SPDX-License-Identifier: MIT
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy of
8 * this software and associated documentation files (the "Software"), to deal in
9 * the Software without restriction, including without limitation the rights to
10 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
11 * the Software, and to permit persons to whom the Software is furnished to do so,
12 * subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in all
15 * copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
19 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
20 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
21 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 *
24 * https://www.FreeRTOS.org
25 * https://github.com/FreeRTOS
26 *
27 */
28
29 /*
30 * A sample implementation of pvPortMalloc() and vPortFree() that permits
31 * allocated blocks to be freed, but does not combine adjacent free blocks
32 * into a single larger block (and so will fragment memory). See heap_4.c for
33 * an equivalent that does combine adjacent blocks into single larger blocks.
34 *
35 * See heap_1.c, heap_3.c and heap_4.c for alternative implementations, and the
36 * memory management pages of https://www.FreeRTOS.org for more information.
37 */
38 #include <stdlib.h>
39 #include <string.h>
40
41 /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
42 * all the API functions to use the MPU wrappers. That should only be done when
43 * task.h is included from an application file. */
44 #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE
45
46 #include "FreeRTOS.h"
47 #include "task.h"
48
49 #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE
50
51 #if ( configSUPPORT_DYNAMIC_ALLOCATION == 0 )
52 #error This file must not be used if configSUPPORT_DYNAMIC_ALLOCATION is 0
53 #endif
54
55 #ifndef configHEAP_CLEAR_MEMORY_ON_FREE
56 #define configHEAP_CLEAR_MEMORY_ON_FREE 0
57 #endif
58
59 /* A few bytes might be lost to byte aligning the heap start address. */
60 #define configADJUSTED_HEAP_SIZE ( configTOTAL_HEAP_SIZE - portBYTE_ALIGNMENT )
61
62 /* Assumes 8bit bytes! */
63 #define heapBITS_PER_BYTE ( ( size_t ) 8 )
64
65 /* Max value that fits in a size_t type. */
66 #define heapSIZE_MAX ( ~( ( size_t ) 0 ) )
67
68 /* Check if multiplying a and b will result in overflow. */
69 #define heapMULTIPLY_WILL_OVERFLOW( a, b ) ( ( ( a ) > 0 ) && ( ( b ) > ( heapSIZE_MAX / ( a ) ) ) )
70
71 /* Check if adding a and b will result in overflow. */
72 #define heapADD_WILL_OVERFLOW( a, b ) ( ( a ) > ( heapSIZE_MAX - ( b ) ) )
73
74 /* MSB of the xBlockSize member of an BlockLink_t structure is used to track
75 * the allocation status of a block. When MSB of the xBlockSize member of
76 * an BlockLink_t structure is set then the block belongs to the application.
77 * When the bit is free the block is still part of the free heap space. */
78 #define heapBLOCK_ALLOCATED_BITMASK ( ( ( size_t ) 1 ) << ( ( sizeof( size_t ) * heapBITS_PER_BYTE ) - 1 ) )
79 #define heapBLOCK_SIZE_IS_VALID( xBlockSize ) ( ( ( xBlockSize ) & heapBLOCK_ALLOCATED_BITMASK ) == 0 )
80 #define heapBLOCK_IS_ALLOCATED( pxBlock ) ( ( ( pxBlock->xBlockSize ) & heapBLOCK_ALLOCATED_BITMASK ) != 0 )
81 #define heapALLOCATE_BLOCK( pxBlock ) ( ( pxBlock->xBlockSize ) |= heapBLOCK_ALLOCATED_BITMASK )
82 #define heapFREE_BLOCK( pxBlock ) ( ( pxBlock->xBlockSize ) &= ~heapBLOCK_ALLOCATED_BITMASK )
83
84 /*-----------------------------------------------------------*/
85
86 /* Allocate the memory for the heap. */
87 #if ( configAPPLICATION_ALLOCATED_HEAP == 1 )
88
89 /* The application writer has already defined the array used for the RTOS
90 * heap - probably so it can be placed in a special segment or address. */
91 extern uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
92 #else
93 PRIVILEGED_DATA static uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
94 #endif /* configAPPLICATION_ALLOCATED_HEAP */
95
96
97 /* Define the linked list structure. This is used to link free blocks in order
98 * of their size. */
99 typedef struct A_BLOCK_LINK
100 {
101 struct A_BLOCK_LINK * pxNextFreeBlock; /*<< The next free block in the list. */
102 size_t xBlockSize; /*<< The size of the free block. */
103 } BlockLink_t;
104
105
106 static const uint16_t heapSTRUCT_SIZE = ( ( sizeof( BlockLink_t ) + ( portBYTE_ALIGNMENT - 1 ) ) & ~( ( size_t ) portBYTE_ALIGNMENT_MASK ) );
107 #define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )
108
109 /* Create a couple of list links to mark the start and end of the list. */
110 PRIVILEGED_DATA static BlockLink_t xStart, xEnd;
111
112 /* Keeps track of the number of free bytes remaining, but says nothing about
113 * fragmentation. */
114 PRIVILEGED_DATA static size_t xFreeBytesRemaining = configADJUSTED_HEAP_SIZE;
115
116 /*-----------------------------------------------------------*/
117
118 /*
119 * Initialises the heap structures before their first use.
120 */
121 static void prvHeapInit( void ) PRIVILEGED_FUNCTION;
122
123 /*-----------------------------------------------------------*/
124
125 /* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */
126
127 /*
128 * Insert a block into the list of free blocks - which is ordered by size of
129 * the block. Small blocks at the start of the list and large blocks at the end
130 * of the list.
131 */
132 #define prvInsertBlockIntoFreeList( pxBlockToInsert ) \
133 { \
134 BlockLink_t * pxIterator; \
135 size_t xBlockSize; \
136 \
137 xBlockSize = pxBlockToInsert->xBlockSize; \
138 \
139 /* Iterate through the list until a block is found that has a larger size */ \
140 /* than the block we are inserting. */ \
141 for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock ) \
142 { \
143 /* There is nothing to do here - just iterate to the correct position. */ \
144 } \
145 \
146 /* Update the list to include the block being inserted in the correct */ \
147 /* position. */ \
148 pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock; \
149 pxIterator->pxNextFreeBlock = pxBlockToInsert; \
150 }
151 /*-----------------------------------------------------------*/
152
pvPortMalloc(size_t xWantedSize)153 void * pvPortMalloc( size_t xWantedSize )
154 {
155 BlockLink_t * pxBlock;
156 BlockLink_t * pxPreviousBlock;
157 BlockLink_t * pxNewBlockLink;
158 PRIVILEGED_DATA static BaseType_t xHeapHasBeenInitialised = pdFALSE;
159 void * pvReturn = NULL;
160 size_t xAdditionalRequiredSize;
161
162 vTaskSuspendAll();
163 {
164 /* If this is the first call to malloc then the heap will require
165 * initialisation to setup the list of free blocks. */
166 if( xHeapHasBeenInitialised == pdFALSE )
167 {
168 prvHeapInit();
169 xHeapHasBeenInitialised = pdTRUE;
170 }
171
172 if( xWantedSize > 0 )
173 {
174 /* The wanted size must be increased so it can contain a BlockLink_t
175 * structure in addition to the requested amount of bytes. Some
176 * additional increment may also be needed for alignment. */
177 xAdditionalRequiredSize = heapSTRUCT_SIZE + portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK );
178
179 if( heapADD_WILL_OVERFLOW( xWantedSize, xAdditionalRequiredSize ) == 0 )
180 {
181 xWantedSize += xAdditionalRequiredSize;
182 }
183 else
184 {
185 xWantedSize = 0;
186 }
187 }
188
189 /* Check the block size we are trying to allocate is not so large that the
190 * top bit is set. The top bit of the block size member of the BlockLink_t
191 * structure is used to determine who owns the block - the application or
192 * the kernel, so it must be free. */
193 if( heapBLOCK_SIZE_IS_VALID( xWantedSize ) != 0 )
194 {
195 if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
196 {
197 /* Blocks are stored in byte order - traverse the list from the start
198 * (smallest) block until one of adequate size is found. */
199 pxPreviousBlock = &xStart;
200 pxBlock = xStart.pxNextFreeBlock;
201
202 while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock != NULL ) )
203 {
204 pxPreviousBlock = pxBlock;
205 pxBlock = pxBlock->pxNextFreeBlock;
206 }
207
208 /* If we found the end marker then a block of adequate size was not found. */
209 if( pxBlock != &xEnd )
210 {
211 /* Return the memory space - jumping over the BlockLink_t structure
212 * at its start. */
213 pvReturn = ( void * ) ( ( ( uint8_t * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );
214
215 /* This block is being returned for use so must be taken out of the
216 * list of free blocks. */
217 pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;
218
219 /* If the block is larger than required it can be split into two. */
220 if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )
221 {
222 /* This block is to be split into two. Create a new block
223 * following the number of bytes requested. The void cast is
224 * used to prevent byte alignment warnings from the compiler. */
225 pxNewBlockLink = ( void * ) ( ( ( uint8_t * ) pxBlock ) + xWantedSize );
226
227 /* Calculate the sizes of two blocks split from the single
228 * block. */
229 pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
230 pxBlock->xBlockSize = xWantedSize;
231
232 /* Insert the new block into the list of free blocks. */
233 prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );
234 }
235
236 xFreeBytesRemaining -= pxBlock->xBlockSize;
237
238 /* The block is being returned - it is allocated and owned
239 * by the application and has no "next" block. */
240 heapALLOCATE_BLOCK( pxBlock );
241 pxBlock->pxNextFreeBlock = NULL;
242 }
243 }
244 }
245
246 traceMALLOC( pvReturn, xWantedSize );
247 }
248 ( void ) xTaskResumeAll();
249
250 #if ( configUSE_MALLOC_FAILED_HOOK == 1 )
251 {
252 if( pvReturn == NULL )
253 {
254 vApplicationMallocFailedHook();
255 }
256 }
257 #endif
258
259 return pvReturn;
260 }
261 /*-----------------------------------------------------------*/
262
vPortFree(void * pv)263 void vPortFree( void * pv )
264 {
265 uint8_t * puc = ( uint8_t * ) pv;
266 BlockLink_t * pxLink;
267
268 if( pv != NULL )
269 {
270 /* The memory being freed will have an BlockLink_t structure immediately
271 * before it. */
272 puc -= heapSTRUCT_SIZE;
273
274 /* This unexpected casting is to keep some compilers from issuing
275 * byte alignment warnings. */
276 pxLink = ( void * ) puc;
277
278 configASSERT( heapBLOCK_IS_ALLOCATED( pxLink ) != 0 );
279 configASSERT( pxLink->pxNextFreeBlock == NULL );
280
281 if( heapBLOCK_IS_ALLOCATED( pxLink ) != 0 )
282 {
283 if( pxLink->pxNextFreeBlock == NULL )
284 {
285 /* The block is being returned to the heap - it is no longer
286 * allocated. */
287 heapFREE_BLOCK( pxLink );
288 #if ( configHEAP_CLEAR_MEMORY_ON_FREE == 1 )
289 {
290 ( void ) memset( puc + heapSTRUCT_SIZE, 0, pxLink->xBlockSize - heapSTRUCT_SIZE );
291 }
292 #endif
293
294 vTaskSuspendAll();
295 {
296 /* Add this block to the list of free blocks. */
297 prvInsertBlockIntoFreeList( ( ( BlockLink_t * ) pxLink ) );
298 xFreeBytesRemaining += pxLink->xBlockSize;
299 traceFREE( pv, pxLink->xBlockSize );
300 }
301 ( void ) xTaskResumeAll();
302 }
303 }
304 }
305 }
306 /*-----------------------------------------------------------*/
307
xPortGetFreeHeapSize(void)308 size_t xPortGetFreeHeapSize( void )
309 {
310 return xFreeBytesRemaining;
311 }
312 /*-----------------------------------------------------------*/
313
vPortInitialiseBlocks(void)314 void vPortInitialiseBlocks( void )
315 {
316 /* This just exists to keep the linker quiet. */
317 }
318 /*-----------------------------------------------------------*/
319
pvPortCalloc(size_t xNum,size_t xSize)320 void * pvPortCalloc( size_t xNum,
321 size_t xSize )
322 {
323 void * pv = NULL;
324
325 if( heapMULTIPLY_WILL_OVERFLOW( xNum, xSize ) == 0 )
326 {
327 pv = pvPortMalloc( xNum * xSize );
328
329 if( pv != NULL )
330 {
331 ( void ) memset( pv, 0, xNum * xSize );
332 }
333 }
334
335 return pv;
336 }
337 /*-----------------------------------------------------------*/
338
prvHeapInit(void)339 static void prvHeapInit( void ) /* PRIVILEGED_FUNCTION */
340 {
341 BlockLink_t * pxFirstFreeBlock;
342 uint8_t * pucAlignedHeap;
343
344 /* Ensure the heap starts on a correctly aligned boundary. */
345 pucAlignedHeap = ( uint8_t * ) ( ( ( portPOINTER_SIZE_TYPE ) & ucHeap[ portBYTE_ALIGNMENT - 1 ] ) & ( ~( ( portPOINTER_SIZE_TYPE ) portBYTE_ALIGNMENT_MASK ) ) );
346
347 /* xStart is used to hold a pointer to the first item in the list of free
348 * blocks. The void cast is used to prevent compiler warnings. */
349 xStart.pxNextFreeBlock = ( void * ) pucAlignedHeap;
350 xStart.xBlockSize = ( size_t ) 0;
351
352 /* xEnd is used to mark the end of the list of free blocks. */
353 xEnd.xBlockSize = configADJUSTED_HEAP_SIZE;
354 xEnd.pxNextFreeBlock = NULL;
355
356 /* To start with there is a single free block that is sized to take up the
357 * entire heap space. */
358 pxFirstFreeBlock = ( BlockLink_t * ) pucAlignedHeap;
359 pxFirstFreeBlock->xBlockSize = configADJUSTED_HEAP_SIZE;
360 pxFirstFreeBlock->pxNextFreeBlock = &xEnd;
361 }
362 /*-----------------------------------------------------------*/
363
