- Fix the stupid mess we created when making this from the cmake branch
[reactos.git] / lib / drivers / lwip / src / core / mem.c
1 /**
2 * @file
3 * Dynamic memory manager
4 *
5 * This is a lightweight replacement for the standard C library malloc().
6 *
7 * If you want to use the standard C library malloc() instead, define
8 * MEM_LIBC_MALLOC to 1 in your lwipopts.h
9 *
10 * To let mem_malloc() use pools (prevents fragmentation and is much faster than
11 * a heap but might waste some memory), define MEM_USE_POOLS to 1, define
12 * MEM_USE_CUSTOM_POOLS to 1 and create a file "lwippools.h" that includes a list
13 * of pools like this (more pools can be added between _START and _END):
14 *
15 * Define three pools with sizes 256, 512, and 1512 bytes
16 * LWIP_MALLOC_MEMPOOL_START
17 * LWIP_MALLOC_MEMPOOL(20, 256)
18 * LWIP_MALLOC_MEMPOOL(10, 512)
19 * LWIP_MALLOC_MEMPOOL(5, 1512)
20 * LWIP_MALLOC_MEMPOOL_END
21 */
22
23 /*
24 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
25 * All rights reserved.
26 *
27 * Redistribution and use in source and binary forms, with or without modification,
28 * are permitted provided that the following conditions are met:
29 *
30 * 1. Redistributions of source code must retain the above copyright notice,
31 * this list of conditions and the following disclaimer.
32 * 2. Redistributions in binary form must reproduce the above copyright notice,
33 * this list of conditions and the following disclaimer in the documentation
34 * and/or other materials provided with the distribution.
35 * 3. The name of the author may not be used to endorse or promote products
36 * derived from this software without specific prior written permission.
37 *
38 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
39 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
40 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
41 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
42 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
43 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
44 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
45 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
46 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
47 * OF SUCH DAMAGE.
48 *
49 * This file is part of the lwIP TCP/IP stack.
50 *
51 * Author: Adam Dunkels <adam@sics.se>
52 * Simon Goldschmidt
53 *
54 */
55
56 #include "lwip/opt.h"
57
58 #if !MEM_LIBC_MALLOC /* don't build if not configured for use in lwipopts.h */
59
60 #include "lwip/def.h"
61 #include "lwip/mem.h"
62 #include "lwip/sys.h"
63 #include "lwip/stats.h"
64 #include "lwip/err.h"
65
66 #include <string.h>
67
68 #if MEM_USE_POOLS
69 /* lwIP head implemented with different sized pools */
70
71 /**
72 * Allocate memory: determine the smallest pool that is big enough
73 * to contain an element of 'size' and get an element from that pool.
74 *
75 * @param size the size in bytes of the memory needed
76 * @return a pointer to the allocated memory or NULL if the pool is empty
77 */
78 void *
79 mem_malloc(mem_size_t size)
80 {
81 struct memp_malloc_helper *element;
82 memp_t poolnr;
83 mem_size_t required_size = size + sizeof(struct memp_malloc_helper);
84
85 for (poolnr = MEMP_POOL_FIRST; poolnr <= MEMP_POOL_LAST; poolnr = (memp_t)(poolnr + 1)) {
86 #if MEM_USE_POOLS_TRY_BIGGER_POOL
87 again:
88 #endif /* MEM_USE_POOLS_TRY_BIGGER_POOL */
89 /* is this pool big enough to hold an element of the required size
90 plus a struct memp_malloc_helper that saves the pool this element came from? */
91 if (required_size <= memp_sizes[poolnr]) {
92 break;
93 }
94 }
95 if (poolnr > MEMP_POOL_LAST) {
96 LWIP_ASSERT("mem_malloc(): no pool is that big!", 0);
97 return NULL;
98 }
99 element = (struct memp_malloc_helper*)memp_malloc(poolnr);
100 if (element == NULL) {
101 /* No need to DEBUGF or ASSERT: This error is already
102 taken care of in memp.c */
103 #if MEM_USE_POOLS_TRY_BIGGER_POOL
104 /** Try a bigger pool if this one is empty! */
105 if (poolnr < MEMP_POOL_LAST) {
106 poolnr++;
107 goto again;
108 }
109 #endif /* MEM_USE_POOLS_TRY_BIGGER_POOL */
110 return NULL;
111 }
112
113 /* save the pool number this element came from */
114 element->poolnr = poolnr;
115 /* and return a pointer to the memory directly after the struct memp_malloc_helper */
116 element++;
117
118 return element;
119 }
120
121 /**
122 * Free memory previously allocated by mem_malloc. Loads the pool number
123 * and calls memp_free with that pool number to put the element back into
124 * its pool
125 *
126 * @param rmem the memory element to free
127 */
128 void
129 mem_free(void *rmem)
130 {
131 struct memp_malloc_helper *hmem = (struct memp_malloc_helper*)rmem;
132
133 LWIP_ASSERT("rmem != NULL", (rmem != NULL));
134 LWIP_ASSERT("rmem == MEM_ALIGN(rmem)", (rmem == LWIP_MEM_ALIGN(rmem)));
135
136 /* get the original struct memp_malloc_helper */
137 hmem--;
138
139 LWIP_ASSERT("hmem != NULL", (hmem != NULL));
140 LWIP_ASSERT("hmem == MEM_ALIGN(hmem)", (hmem == LWIP_MEM_ALIGN(hmem)));
141 LWIP_ASSERT("hmem->poolnr < MEMP_MAX", (hmem->poolnr < MEMP_MAX));
142
143 /* and put it in the pool we saved earlier */
144 memp_free(hmem->poolnr, hmem);
145 }
146
147 #else /* MEM_USE_POOLS */
148 /* lwIP replacement for your libc malloc() */
149
150 /**
151 * The heap is made up as a list of structs of this type.
152 * This does not have to be aligned since for getting its size,
153 * we only use the macro SIZEOF_STRUCT_MEM, which automatically alignes.
154 */
155 struct mem {
156 /** index (-> ram[next]) of the next struct */
157 mem_size_t next;
158 /** index (-> ram[prev]) of the previous struct */
159 mem_size_t prev;
160 /** 1: this area is used; 0: this area is unused */
161 u8_t used;
162 };
163
164 /** All allocated blocks will be MIN_SIZE bytes big, at least!
165 * MIN_SIZE can be overridden to suit your needs. Smaller values save space,
166 * larger values could prevent too small blocks to fragment the RAM too much. */
167 #ifndef MIN_SIZE
168 #define MIN_SIZE 12
169 #endif /* MIN_SIZE */
170 /* some alignment macros: we define them here for better source code layout */
171 #define MIN_SIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(MIN_SIZE)
172 #define SIZEOF_STRUCT_MEM LWIP_MEM_ALIGN_SIZE(sizeof(struct mem))
173 #define MEM_SIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(MEM_SIZE)
174
175 /** If you want to relocate the heap to external memory, simply define
176 * LWIP_RAM_HEAP_POINTER as a void-pointer to that location.
177 * If so, make sure the memory at that location is big enough (see below on
178 * how that space is calculated). */
179 #ifndef LWIP_RAM_HEAP_POINTER
180 /** the heap. we need one struct mem at the end and some room for alignment */
181 u8_t ram_heap[MEM_SIZE_ALIGNED + (2*SIZEOF_STRUCT_MEM) + MEM_ALIGNMENT];
182 #define LWIP_RAM_HEAP_POINTER ram_heap
183 #endif /* LWIP_RAM_HEAP_POINTER */
184
185 /** pointer to the heap (ram_heap): for alignment, ram is now a pointer instead of an array */
186 static u8_t *ram;
187 /** the last entry, always unused! */
188 static struct mem *ram_end;
189 /** pointer to the lowest free block, this is used for faster search */
190 static struct mem *lfree;
191
192 /** concurrent access protection */
193 static sys_mutex_t mem_mutex;
194
195 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
196
197 static volatile u8_t mem_free_count;
198
199 /* Allow mem_free from other (e.g. interrupt) context */
200 #define LWIP_MEM_FREE_DECL_PROTECT() SYS_ARCH_DECL_PROTECT(lev_free)
201 #define LWIP_MEM_FREE_PROTECT() SYS_ARCH_PROTECT(lev_free)
202 #define LWIP_MEM_FREE_UNPROTECT() SYS_ARCH_UNPROTECT(lev_free)
203 #define LWIP_MEM_ALLOC_DECL_PROTECT() SYS_ARCH_DECL_PROTECT(lev_alloc)
204 #define LWIP_MEM_ALLOC_PROTECT() SYS_ARCH_PROTECT(lev_alloc)
205 #define LWIP_MEM_ALLOC_UNPROTECT() SYS_ARCH_UNPROTECT(lev_alloc)
206
207 #else /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
208
209 /* Protect the heap only by using a semaphore */
210 #define LWIP_MEM_FREE_DECL_PROTECT()
211 #define LWIP_MEM_FREE_PROTECT() sys_mutex_lock(&mem_mutex)
212 #define LWIP_MEM_FREE_UNPROTECT() sys_mutex_unlock(&mem_mutex)
213 /* mem_malloc is protected using semaphore AND LWIP_MEM_ALLOC_PROTECT */
214 #define LWIP_MEM_ALLOC_DECL_PROTECT()
215 #define LWIP_MEM_ALLOC_PROTECT()
216 #define LWIP_MEM_ALLOC_UNPROTECT()
217
218 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
219
220
221 /**
222 * "Plug holes" by combining adjacent empty struct mems.
223 * After this function is through, there should not exist
224 * one empty struct mem pointing to another empty struct mem.
225 *
226 * @param mem this points to a struct mem which just has been freed
227 * @internal this function is only called by mem_free() and mem_trim()
228 *
229 * This assumes access to the heap is protected by the calling function
230 * already.
231 */
232 static void
233 plug_holes(struct mem *mem)
234 {
235 struct mem *nmem;
236 struct mem *pmem;
237
238 LWIP_ASSERT("plug_holes: mem >= ram", (u8_t *)mem >= ram);
239 LWIP_ASSERT("plug_holes: mem < ram_end", (u8_t *)mem < (u8_t *)ram_end);
240 LWIP_ASSERT("plug_holes: mem->used == 0", mem->used == 0);
241
242 /* plug hole forward */
243 LWIP_ASSERT("plug_holes: mem->next <= MEM_SIZE_ALIGNED", mem->next <= MEM_SIZE_ALIGNED);
244
245 nmem = (struct mem *)(void *)&ram[mem->next];
246 if (mem != nmem && nmem->used == 0 && (u8_t *)nmem != (u8_t *)ram_end) {
247 /* if mem->next is unused and not end of ram, combine mem and mem->next */
248 if (lfree == nmem) {
249 lfree = mem;
250 }
251 mem->next = nmem->next;
252 ((struct mem *)(void *)&ram[nmem->next])->prev = (mem_size_t)((u8_t *)mem - ram);
253 }
254
255 /* plug hole backward */
256 pmem = (struct mem *)(void *)&ram[mem->prev];
257 if (pmem != mem && pmem->used == 0) {
258 /* if mem->prev is unused, combine mem and mem->prev */
259 if (lfree == mem) {
260 lfree = pmem;
261 }
262 pmem->next = mem->next;
263 ((struct mem *)(void *)&ram[mem->next])->prev = (mem_size_t)((u8_t *)pmem - ram);
264 }
265 }
266
267 /**
268 * Zero the heap and initialize start, end and lowest-free
269 */
270 void
271 mem_init(void)
272 {
273 struct mem *mem;
274
275 LWIP_ASSERT("Sanity check alignment",
276 (SIZEOF_STRUCT_MEM & (MEM_ALIGNMENT-1)) == 0);
277
278 /* align the heap */
279 ram = (u8_t *)LWIP_MEM_ALIGN(LWIP_RAM_HEAP_POINTER);
280 /* initialize the start of the heap */
281 mem = (struct mem *)(void *)ram;
282 mem->next = MEM_SIZE_ALIGNED;
283 mem->prev = 0;
284 mem->used = 0;
285 /* initialize the end of the heap */
286 ram_end = (struct mem *)(void *)&ram[MEM_SIZE_ALIGNED];
287 ram_end->used = 1;
288 ram_end->next = MEM_SIZE_ALIGNED;
289 ram_end->prev = MEM_SIZE_ALIGNED;
290
291 /* initialize the lowest-free pointer to the start of the heap */
292 lfree = (struct mem *)(void *)ram;
293
294 MEM_STATS_AVAIL(avail, MEM_SIZE_ALIGNED);
295
296 if(sys_mutex_new(&mem_mutex) != ERR_OK) {
297 LWIP_ASSERT("failed to create mem_mutex", 0);
298 }
299 }
300
301 /**
302 * Put a struct mem back on the heap
303 *
304 * @param rmem is the data portion of a struct mem as returned by a previous
305 * call to mem_malloc()
306 */
307 void
308 mem_free(void *rmem)
309 {
310 struct mem *mem;
311 LWIP_MEM_FREE_DECL_PROTECT();
312
313 if (rmem == NULL) {
314 LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("mem_free(p == NULL) was called.\n"));
315 return;
316 }
317 LWIP_ASSERT("mem_free: sanity check alignment", (((mem_ptr_t)rmem) & (MEM_ALIGNMENT-1)) == 0);
318
319 LWIP_ASSERT("mem_free: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
320 (u8_t *)rmem < (u8_t *)ram_end);
321
322 if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
323 SYS_ARCH_DECL_PROTECT(lev);
324 LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("mem_free: illegal memory\n"));
325 /* protect mem stats from concurrent access */
326 SYS_ARCH_PROTECT(lev);
327 MEM_STATS_INC(illegal);
328 SYS_ARCH_UNPROTECT(lev);
329 return;
330 }
331 /* protect the heap from concurrent access */
332 LWIP_MEM_FREE_PROTECT();
333 /* Get the corresponding struct mem ... */
334 mem = (struct mem *)(void *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);
335 /* ... which has to be in a used state ... */
336 LWIP_ASSERT("mem_free: mem->used", mem->used);
337 /* ... and is now unused. */
338 mem->used = 0;
339
340 if (mem < lfree) {
341 /* the newly freed struct is now the lowest */
342 lfree = mem;
343 }
344
345 MEM_STATS_DEC_USED(used, mem->next - (mem_size_t)(((u8_t *)mem - ram)));
346
347 /* finally, see if prev or next are free also */
348 plug_holes(mem);
349 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
350 mem_free_count = 1;
351 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
352 LWIP_MEM_FREE_UNPROTECT();
353 }
354
355 /**
356 * Shrink memory returned by mem_malloc().
357 *
358 * @param rmem pointer to memory allocated by mem_malloc the is to be shrinked
359 * @param newsize required size after shrinking (needs to be smaller than or
360 * equal to the previous size)
361 * @return for compatibility reasons: is always == rmem, at the moment
362 * or NULL if newsize is > old size, in which case rmem is NOT touched
363 * or freed!
364 */
365 void *
366 mem_trim(void *rmem, mem_size_t newsize)
367 {
368 mem_size_t size;
369 mem_size_t ptr, ptr2;
370 struct mem *mem, *mem2;
371 /* use the FREE_PROTECT here: it protects with sem OR SYS_ARCH_PROTECT */
372 LWIP_MEM_FREE_DECL_PROTECT();
373
374 /* Expand the size of the allocated memory region so that we can
375 adjust for alignment. */
376 newsize = LWIP_MEM_ALIGN_SIZE(newsize);
377
378 if(newsize < MIN_SIZE_ALIGNED) {
379 /* every data block must be at least MIN_SIZE_ALIGNED long */
380 newsize = MIN_SIZE_ALIGNED;
381 }
382
383 if (newsize > MEM_SIZE_ALIGNED) {
384 return NULL;
385 }
386
387 LWIP_ASSERT("mem_trim: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
388 (u8_t *)rmem < (u8_t *)ram_end);
389
390 if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
391 SYS_ARCH_DECL_PROTECT(lev);
392 LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("mem_trim: illegal memory\n"));
393 /* protect mem stats from concurrent access */
394 SYS_ARCH_PROTECT(lev);
395 MEM_STATS_INC(illegal);
396 SYS_ARCH_UNPROTECT(lev);
397 return rmem;
398 }
399 /* Get the corresponding struct mem ... */
400 mem = (struct mem *)(void *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);
401 /* ... and its offset pointer */
402 ptr = (mem_size_t)((u8_t *)mem - ram);
403
404 size = mem->next - ptr - SIZEOF_STRUCT_MEM;
405 LWIP_ASSERT("mem_trim can only shrink memory", newsize <= size);
406 if (newsize > size) {
407 /* not supported */
408 return NULL;
409 }
410 if (newsize == size) {
411 /* No change in size, simply return */
412 return rmem;
413 }
414
415 /* protect the heap from concurrent access */
416 LWIP_MEM_FREE_PROTECT();
417
418 mem2 = (struct mem *)(void *)&ram[mem->next];
419 if(mem2->used == 0) {
420 /* The next struct is unused, we can simply move it at little */
421 mem_size_t next;
422 /* remember the old next pointer */
423 next = mem2->next;
424 /* create new struct mem which is moved directly after the shrinked mem */
425 ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
426 if (lfree == mem2) {
427 lfree = (struct mem *)(void *)&ram[ptr2];
428 }
429 mem2 = (struct mem *)(void *)&ram[ptr2];
430 mem2->used = 0;
431 /* restore the next pointer */
432 mem2->next = next;
433 /* link it back to mem */
434 mem2->prev = ptr;
435 /* link mem to it */
436 mem->next = ptr2;
437 /* last thing to restore linked list: as we have moved mem2,
438 * let 'mem2->next->prev' point to mem2 again. but only if mem2->next is not
439 * the end of the heap */
440 if (mem2->next != MEM_SIZE_ALIGNED) {
441 ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
442 }
443 MEM_STATS_DEC_USED(used, (size - newsize));
444 /* no need to plug holes, we've already done that */
445 } else if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED <= size) {
446 /* Next struct is used but there's room for another struct mem with
447 * at least MIN_SIZE_ALIGNED of data.
448 * Old size ('size') must be big enough to contain at least 'newsize' plus a struct mem
449 * ('SIZEOF_STRUCT_MEM') with some data ('MIN_SIZE_ALIGNED').
450 * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty
451 * region that couldn't hold data, but when mem->next gets freed,
452 * the 2 regions would be combined, resulting in more free memory */
453 ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
454 mem2 = (struct mem *)(void *)&ram[ptr2];
455 if (mem2 < lfree) {
456 lfree = mem2;
457 }
458 mem2->used = 0;
459 mem2->next = mem->next;
460 mem2->prev = ptr;
461 mem->next = ptr2;
462 if (mem2->next != MEM_SIZE_ALIGNED) {
463 ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
464 }
465 MEM_STATS_DEC_USED(used, (size - newsize));
466 /* the original mem->next is used, so no need to plug holes! */
467 }
468 /* else {
469 next struct mem is used but size between mem and mem2 is not big enough
470 to create another struct mem
471 -> don't do anyhting.
472 -> the remaining space stays unused since it is too small
473 } */
474 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
475 mem_free_count = 1;
476 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
477 LWIP_MEM_FREE_UNPROTECT();
478 return rmem;
479 }
480
481 /**
482 * Adam's mem_malloc() plus solution for bug #17922
483 * Allocate a block of memory with a minimum of 'size' bytes.
484 *
485 * @param size is the minimum size of the requested block in bytes.
486 * @return pointer to allocated memory or NULL if no free memory was found.
487 *
488 * Note that the returned value will always be aligned (as defined by MEM_ALIGNMENT).
489 */
490 void *
491 mem_malloc(mem_size_t size)
492 {
493 mem_size_t ptr, ptr2;
494 struct mem *mem, *mem2;
495 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
496 u8_t local_mem_free_count = 0;
497 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
498 LWIP_MEM_ALLOC_DECL_PROTECT();
499
500 if (size == 0) {
501 return NULL;
502 }
503
504 /* Expand the size of the allocated memory region so that we can
505 adjust for alignment. */
506 size = LWIP_MEM_ALIGN_SIZE(size);
507
508 if(size < MIN_SIZE_ALIGNED) {
509 /* every data block must be at least MIN_SIZE_ALIGNED long */
510 size = MIN_SIZE_ALIGNED;
511 }
512
513 if (size > MEM_SIZE_ALIGNED) {
514 return NULL;
515 }
516
517 /* protect the heap from concurrent access */
518 sys_mutex_lock(&mem_mutex);
519 LWIP_MEM_ALLOC_PROTECT();
520 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
521 /* run as long as a mem_free disturbed mem_malloc */
522 do {
523 local_mem_free_count = 0;
524 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
525
526 /* Scan through the heap searching for a free block that is big enough,
527 * beginning with the lowest free block.
528 */
529 for (ptr = (mem_size_t)((u8_t *)lfree - ram); ptr < MEM_SIZE_ALIGNED - size;
530 ptr = ((struct mem *)(void *)&ram[ptr])->next) {
531 mem = (struct mem *)(void *)&ram[ptr];
532 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
533 mem_free_count = 0;
534 LWIP_MEM_ALLOC_UNPROTECT();
535 /* allow mem_free to run */
536 LWIP_MEM_ALLOC_PROTECT();
537 if (mem_free_count != 0) {
538 local_mem_free_count = mem_free_count;
539 }
540 mem_free_count = 0;
541 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
542
543 if ((!mem->used) &&
544 (mem->next - (ptr + SIZEOF_STRUCT_MEM)) >= size) {
545 /* mem is not used and at least perfect fit is possible:
546 * mem->next - (ptr + SIZEOF_STRUCT_MEM) gives us the 'user data size' of mem */
547
548 if (mem->next - (ptr + SIZEOF_STRUCT_MEM) >= (size + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED)) {
549 /* (in addition to the above, we test if another struct mem (SIZEOF_STRUCT_MEM) containing
550 * at least MIN_SIZE_ALIGNED of data also fits in the 'user data space' of 'mem')
551 * -> split large block, create empty remainder,
552 * remainder must be large enough to contain MIN_SIZE_ALIGNED data: if
553 * mem->next - (ptr + (2*SIZEOF_STRUCT_MEM)) == size,
554 * struct mem would fit in but no data between mem2 and mem2->next
555 * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty
556 * region that couldn't hold data, but when mem->next gets freed,
557 * the 2 regions would be combined, resulting in more free memory
558 */
559 ptr2 = ptr + SIZEOF_STRUCT_MEM + size;
560 /* create mem2 struct */
561 mem2 = (struct mem *)(void *)&ram[ptr2];
562 mem2->used = 0;
563 mem2->next = mem->next;
564 mem2->prev = ptr;
565 /* and insert it between mem and mem->next */
566 mem->next = ptr2;
567 mem->used = 1;
568
569 if (mem2->next != MEM_SIZE_ALIGNED) {
570 ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
571 }
572 MEM_STATS_INC_USED(used, (size + SIZEOF_STRUCT_MEM));
573 } else {
574 /* (a mem2 struct does no fit into the user data space of mem and mem->next will always
575 * be used at this point: if not we have 2 unused structs in a row, plug_holes should have
576 * take care of this).
577 * -> near fit or excact fit: do not split, no mem2 creation
578 * also can't move mem->next directly behind mem, since mem->next
579 * will always be used at this point!
580 */
581 mem->used = 1;
582 MEM_STATS_INC_USED(used, mem->next - (mem_size_t)((u8_t *)mem - ram));
583 }
584
585 if (mem == lfree) {
586 /* Find next free block after mem and update lowest free pointer */
587 while (lfree->used && lfree != ram_end) {
588 LWIP_MEM_ALLOC_UNPROTECT();
589 /* prevent high interrupt latency... */
590 LWIP_MEM_ALLOC_PROTECT();
591 lfree = (struct mem *)(void *)&ram[lfree->next];
592 }
593 LWIP_ASSERT("mem_malloc: !lfree->used", ((lfree == ram_end) || (!lfree->used)));
594 }
595 LWIP_MEM_ALLOC_UNPROTECT();
596 sys_mutex_unlock(&mem_mutex);
597 LWIP_ASSERT("mem_malloc: allocated memory not above ram_end.",
598 (mem_ptr_t)mem + SIZEOF_STRUCT_MEM + size <= (mem_ptr_t)ram_end);
599 LWIP_ASSERT("mem_malloc: allocated memory properly aligned.",
600 ((mem_ptr_t)mem + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT == 0);
601 LWIP_ASSERT("mem_malloc: sanity check alignment",
602 (((mem_ptr_t)mem) & (MEM_ALIGNMENT-1)) == 0);
603
604 return (u8_t *)mem + SIZEOF_STRUCT_MEM;
605 }
606 }
607 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
608 /* if we got interrupted by a mem_free, try again */
609 } while(local_mem_free_count != 0);
610 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
611 LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("mem_malloc: could not allocate %"S16_F" bytes\n", (s16_t)size));
612 MEM_STATS_INC(err);
613 LWIP_MEM_ALLOC_UNPROTECT();
614 sys_mutex_unlock(&mem_mutex);
615 return NULL;
616 }
617
618 #endif /* MEM_USE_POOLS */
619 /**
620 * Contiguously allocates enough space for count objects that are size bytes
621 * of memory each and returns a pointer to the allocated memory.
622 *
623 * The allocated memory is filled with bytes of value zero.
624 *
625 * @param count number of objects to allocate
626 * @param size size of the objects to allocate
627 * @return pointer to allocated memory / NULL pointer if there is an error
628 */
629 void *mem_calloc(mem_size_t count, mem_size_t size)
630 {
631 void *p;
632
633 /* allocate 'count' objects of size 'size' */
634 p = mem_malloc(count * size);
635 if (p) {
636 /* zero the memory */
637 memset(p, 0, count * size);
638 }
639 return p;
640 }
641
642 #endif /* !MEM_LIBC_MALLOC */