A version of LWIP, provided for backwards compatibility.
Dependents: AA_DemoBoard DemoBoard HelloServerDemo DemoBoard_RangeIndicator ... more
mem.c
00001 /** 00002 * @file 00003 * Dynamic memory manager 00004 * 00005 * This is a lightweight replacement for the standard C library malloc(). 00006 * 00007 * If you want to use the standard C library malloc() instead, define 00008 * MEM_LIBC_MALLOC to 1 in your lwipopts.h 00009 * 00010 * To let mem_malloc() use pools (prevents fragmentation and is much faster than 00011 * a heap but might waste some memory), define MEM_USE_POOLS to 1, define 00012 * MEM_USE_CUSTOM_POOLS to 1 and create a file "lwippools.h" that includes a list 00013 * of pools like this (more pools can be added between _START and _END): 00014 * 00015 * Define three pools with sizes 256, 512, and 1512 bytes 00016 * LWIP_MALLOC_MEMPOOL_START 00017 * LWIP_MALLOC_MEMPOOL(20, 256) 00018 * LWIP_MALLOC_MEMPOOL(10, 512) 00019 * LWIP_MALLOC_MEMPOOL(5, 1512) 00020 * LWIP_MALLOC_MEMPOOL_END 00021 */ 00022 00023 /* 00024 * Copyright (c) 2001-2004 Swedish Institute of Computer Science. 00025 * All rights reserved. 00026 * 00027 * Redistribution and use in source and binary forms, with or without modification, 00028 * are permitted provided that the following conditions are met: 00029 * 00030 * 1. Redistributions of source code must retain the above copyright notice, 00031 * this list of conditions and the following disclaimer. 00032 * 2. Redistributions in binary form must reproduce the above copyright notice, 00033 * this list of conditions and the following disclaimer in the documentation 00034 * and/or other materials provided with the distribution. 00035 * 3. The name of the author may not be used to endorse or promote products 00036 * derived from this software without specific prior written permission. 00037 * 00038 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 00039 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 00040 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 00041 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 00042 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 00043 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 00044 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 00045 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 00046 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 00047 * OF SUCH DAMAGE. 00048 * 00049 * This file is part of the lwIP TCP/IP stack. 00050 * 00051 * Author: Adam Dunkels <adam@sics.se> 00052 * Simon Goldschmidt 00053 * 00054 */ 00055 00056 #include "lwip/opt.h" 00057 00058 #if !MEM_LIBC_MALLOC /* don't build if not configured for use in lwipopts.h */ 00059 00060 #include "lwip/def.h" 00061 #include "lwip/mem.h" 00062 #include "lwip/sys.h" 00063 #include "lwip/stats.h" 00064 00065 #include <string.h> 00066 00067 #if MEM_USE_POOLS 00068 /* lwIP head implemented with different sized pools */ 00069 00070 /** 00071 * Allocate memory: determine the smallest pool that is big enough 00072 * to contain an element of 'size' and get an element from that pool. 00073 * 00074 * @param size the size in bytes of the memory needed 00075 * @return a pointer to the allocated memory or NULL if the pool is empty 00076 */ 00077 void * 00078 mem_malloc(mem_size_t size) 00079 { 00080 struct memp_malloc_helper *element; 00081 memp_t poolnr; 00082 mem_size_t required_size = size + sizeof(struct memp_malloc_helper); 00083 00084 for (poolnr = MEMP_POOL_FIRST; poolnr <= MEMP_POOL_LAST; poolnr++) { 00085 #if MEM_USE_POOLS_TRY_BIGGER_POOL 00086 again: 00087 #endif /* MEM_USE_POOLS_TRY_BIGGER_POOL */ 00088 /* is this pool big enough to hold an element of the required size 00089 plus a struct memp_malloc_helper that saves the pool this element came from? */ 00090 if (required_size <= memp_sizes[poolnr]) { 00091 break; 00092 } 00093 } 00094 if (poolnr > MEMP_POOL_LAST) { 00095 LWIP_ASSERT("mem_malloc(): no pool is that big!", 0); 00096 return NULL; 00097 } 00098 element = (struct memp_malloc_helper*)memp_malloc(poolnr); 00099 if (element == NULL) { 00100 /* No need to DEBUGF or ASSERT: This error is already 00101 taken care of in memp.c */ 00102 #if MEM_USE_POOLS_TRY_BIGGER_POOL 00103 /** Try a bigger pool if this one is empty! */ 00104 if (poolnr < MEMP_POOL_LAST) { 00105 poolnr++; 00106 goto again; 00107 } 00108 #endif /* MEM_USE_POOLS_TRY_BIGGER_POOL */ 00109 return NULL; 00110 } 00111 00112 /* save the pool number this element came from */ 00113 element->poolnr = poolnr; 00114 /* and return a pointer to the memory directly after the struct memp_malloc_helper */ 00115 element++; 00116 00117 return element; 00118 } 00119 00120 /** 00121 * Free memory previously allocated by mem_malloc. Loads the pool number 00122 * and calls memp_free with that pool number to put the element back into 00123 * its pool 00124 * 00125 * @param rmem the memory element to free 00126 */ 00127 void 00128 mem_free(void *rmem) 00129 { 00130 struct memp_malloc_helper *hmem = (struct memp_malloc_helper*)rmem; 00131 00132 LWIP_ASSERT("rmem != NULL", (rmem != NULL)); 00133 LWIP_ASSERT("rmem == MEM_ALIGN(rmem)", (rmem == LWIP_MEM_ALIGN(rmem))); 00134 00135 /* get the original struct memp_malloc_helper */ 00136 hmem--; 00137 00138 LWIP_ASSERT("hmem != NULL", (hmem != NULL)); 00139 LWIP_ASSERT("hmem == MEM_ALIGN(hmem)", (hmem == LWIP_MEM_ALIGN(hmem))); 00140 LWIP_ASSERT("hmem->poolnr < MEMP_MAX", (hmem->poolnr < MEMP_MAX)); 00141 00142 /* and put it in the pool we saved earlier */ 00143 memp_free(hmem->poolnr, hmem); 00144 } 00145 00146 #else /* MEM_USE_POOLS */ 00147 /* lwIP replacement for your libc malloc() */ 00148 00149 /** 00150 * The heap is made up as a list of structs of this type. 00151 * This does not have to be aligned since for getting its size, 00152 * we only use the macro SIZEOF_STRUCT_MEM, which automatically alignes. 00153 */ 00154 struct mem { 00155 /** index (-> ram[next]) of the next struct */ 00156 mem_size_t next; 00157 /** index (-> ram[next]) of the next struct */ 00158 mem_size_t prev; 00159 /** 1: this area is used; 0: this area is unused */ 00160 u8_t used; 00161 }; 00162 00163 /** All allocated blocks will be MIN_SIZE bytes big, at least! 00164 * MIN_SIZE can be overridden to suit your needs. Smaller values save space, 00165 * larger values could prevent too small blocks to fragment the RAM too much. */ 00166 #ifndef MIN_SIZE 00167 #define MIN_SIZE 12 00168 #endif /* MIN_SIZE */ 00169 /* some alignment macros: we define them here for better source code layout */ 00170 #define MIN_SIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(MIN_SIZE) 00171 #define SIZEOF_STRUCT_MEM LWIP_MEM_ALIGN_SIZE(sizeof(struct mem)) 00172 #define MEM_SIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(MEM_SIZE) 00173 00174 #ifndef MEM_POSITION 00175 #define MEM_POSITION 00176 #endif 00177 00178 /** the heap. we need one struct mem at the end and some room for alignment */ 00179 static u8_t ram_heap[MEM_SIZE_ALIGNED + (2*SIZEOF_STRUCT_MEM) + MEM_ALIGNMENT] MEM_POSITION; 00180 /** pointer to the heap (ram_heap): for alignment, ram is now a pointer instead of an array */ 00181 static u8_t *ram; 00182 /** the last entry, always unused! */ 00183 static struct mem *ram_end; 00184 /** pointer to the lowest free block, this is used for faster search */ 00185 static struct mem *lfree; 00186 00187 /** concurrent access protection */ 00188 //static sys_sem_t mem_sem; 00189 00190 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00191 00192 static volatile u8_t mem_free_count; 00193 00194 /* Allow mem_free from other (e.g. interrupt) context */ 00195 #define LWIP_MEM_FREE_DECL_PROTECT() SYS_ARCH_DECL_PROTECT(lev_free) 00196 #define LWIP_MEM_FREE_PROTECT() SYS_ARCH_PROTECT(lev_free) 00197 #define LWIP_MEM_FREE_UNPROTECT() SYS_ARCH_UNPROTECT(lev_free) 00198 #define LWIP_MEM_ALLOC_DECL_PROTECT() SYS_ARCH_DECL_PROTECT(lev_alloc) 00199 #define LWIP_MEM_ALLOC_PROTECT() SYS_ARCH_PROTECT(lev_alloc) 00200 #define LWIP_MEM_ALLOC_UNPROTECT() SYS_ARCH_UNPROTECT(lev_alloc) 00201 00202 #else /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00203 00204 /* Protect the heap only by using a semaphore */ 00205 #define LWIP_MEM_FREE_DECL_PROTECT() 00206 #define LWIP_MEM_FREE_PROTECT() sys_arch_sem_wait(mem_sem, 0) 00207 #define LWIP_MEM_FREE_UNPROTECT() sys_sem_signal(mem_sem) 00208 /* mem_malloc is protected using semaphore AND LWIP_MEM_ALLOC_PROTECT */ 00209 #define LWIP_MEM_ALLOC_DECL_PROTECT() 00210 #define LWIP_MEM_ALLOC_PROTECT() 00211 #define LWIP_MEM_ALLOC_UNPROTECT() 00212 00213 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00214 00215 00216 /** 00217 * "Plug holes" by combining adjacent empty struct mems. 00218 * After this function is through, there should not exist 00219 * one empty struct mem pointing to another empty struct mem. 00220 * 00221 * @param mem this points to a struct mem which just has been freed 00222 * @internal this function is only called by mem_free() and mem_realloc() 00223 * 00224 * This assumes access to the heap is protected by the calling function 00225 * already. 00226 */ 00227 static void 00228 plug_holes(struct mem *mem) 00229 { 00230 struct mem *nmem; 00231 struct mem *pmem; 00232 00233 LWIP_ASSERT("plug_holes: mem >= ram", (u8_t *)mem >= ram); 00234 LWIP_ASSERT("plug_holes: mem < ram_end", (u8_t *)mem < (u8_t *)ram_end); 00235 LWIP_ASSERT("plug_holes: mem->used == 0", mem->used == 0); 00236 00237 /* plug hole forward */ 00238 LWIP_ASSERT("plug_holes: mem->next <= MEM_SIZE_ALIGNED", mem->next <= MEM_SIZE_ALIGNED); 00239 00240 nmem = (struct mem *)&ram[mem->next]; 00241 if (mem != nmem && nmem->used == 0 && (u8_t *)nmem != (u8_t *)ram_end) { 00242 /* if mem->next is unused and not end of ram, combine mem and mem->next */ 00243 if (lfree == nmem) { 00244 lfree = mem; 00245 } 00246 mem->next = nmem->next; 00247 ((struct mem *)&ram[nmem->next])->prev = (u8_t *)mem - ram; 00248 } 00249 00250 /* plug hole backward */ 00251 pmem = (struct mem *)&ram[mem->prev]; 00252 if (pmem != mem && pmem->used == 0) { 00253 /* if mem->prev is unused, combine mem and mem->prev */ 00254 if (lfree == mem) { 00255 lfree = pmem; 00256 } 00257 pmem->next = mem->next; 00258 ((struct mem *)&ram[mem->next])->prev = (u8_t *)pmem - ram; 00259 } 00260 } 00261 00262 /** 00263 * Zero the heap and initialize start, end and lowest-free 00264 */ 00265 void 00266 mem_init(void) 00267 { 00268 struct mem *mem; 00269 00270 LWIP_ASSERT("Sanity check alignment", 00271 (SIZEOF_STRUCT_MEM & (MEM_ALIGNMENT-1)) == 0); 00272 00273 /* align the heap */ 00274 ram = LWIP_MEM_ALIGN(ram_heap); 00275 /* initialize the start of the heap */ 00276 mem = (struct mem *)ram; 00277 mem->next = MEM_SIZE_ALIGNED; 00278 mem->prev = 0; 00279 mem->used = 0; 00280 /* initialize the end of the heap */ 00281 ram_end = (struct mem *)&ram[MEM_SIZE_ALIGNED]; 00282 ram_end->used = 1; 00283 ram_end->next = MEM_SIZE_ALIGNED; 00284 ram_end->prev = MEM_SIZE_ALIGNED; 00285 00286 //mem_sem = sys_sem_new(1); 00287 00288 /* initialize the lowest-free pointer to the start of the heap */ 00289 lfree = (struct mem *)ram; 00290 00291 MEM_STATS_AVAIL(avail, MEM_SIZE_ALIGNED); 00292 } 00293 00294 /** 00295 * Put a struct mem back on the heap 00296 * 00297 * @param rmem is the data portion of a struct mem as returned by a previous 00298 * call to mem_malloc() 00299 */ 00300 void 00301 mem_free(void *rmem) 00302 { 00303 struct mem *mem; 00304 LWIP_MEM_FREE_DECL_PROTECT(); 00305 00306 if (rmem == NULL) { 00307 LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_TRACE | 2, ("mem_free(p == NULL) was called.\n")); 00308 return; 00309 } 00310 LWIP_ASSERT("mem_free: sanity check alignment", (((mem_ptr_t)rmem) & (MEM_ALIGNMENT-1)) == 0); 00311 00312 LWIP_ASSERT("mem_free: legal memory", (u8_t *)rmem >= (u8_t *)ram && 00313 (u8_t *)rmem < (u8_t *)ram_end); 00314 00315 if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) { 00316 SYS_ARCH_DECL_PROTECT(lev); 00317 LWIP_DEBUGF(MEM_DEBUG | 3, ("mem_free: illegal memory\n")); 00318 /* protect mem stats from concurrent access */ 00319 SYS_ARCH_PROTECT(lev); 00320 MEM_STATS_INC(illegal); 00321 SYS_ARCH_UNPROTECT(lev); 00322 return; 00323 } 00324 /* protect the heap from concurrent access */ 00325 LWIP_MEM_FREE_PROTECT(); 00326 /* Get the corresponding struct mem ... */ 00327 mem = (struct mem *)((u8_t *)rmem - SIZEOF_STRUCT_MEM); 00328 /* ... which has to be in a used state ... */ 00329 LWIP_ASSERT("mem_free: mem->used", mem->used); 00330 /* ... and is now unused. */ 00331 mem->used = 0; 00332 00333 if (mem < lfree) { 00334 /* the newly freed struct is now the lowest */ 00335 lfree = mem; 00336 } 00337 00338 MEM_STATS_DEC_USED(used, mem->next - ((u8_t *)mem - ram)); 00339 00340 /* finally, see if prev or next are free also */ 00341 plug_holes(mem); 00342 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00343 mem_free_count = 1; 00344 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00345 LWIP_MEM_FREE_UNPROTECT(); 00346 } 00347 00348 /** 00349 * In contrast to its name, mem_realloc can only shrink memory, not expand it. 00350 * Since the only use (for now) is in pbuf_realloc (which also can only shrink), 00351 * this shouldn't be a problem! 00352 * 00353 * @param rmem pointer to memory allocated by mem_malloc the is to be shrinked 00354 * @param newsize required size after shrinking (needs to be smaller than or 00355 * equal to the previous size) 00356 * @return for compatibility reasons: is always == rmem, at the moment 00357 * or NULL if newsize is > old size, in which case rmem is NOT touched 00358 * or freed! 00359 */ 00360 void * 00361 mem_realloc(void *rmem, mem_size_t newsize) 00362 { 00363 mem_size_t size; 00364 mem_size_t ptr, ptr2; 00365 struct mem *mem, *mem2; 00366 /* use the FREE_PROTECT here: it protects with sem OR SYS_ARCH_PROTECT */ 00367 LWIP_MEM_FREE_DECL_PROTECT(); 00368 00369 /* Expand the size of the allocated memory region so that we can 00370 adjust for alignment. */ 00371 newsize = LWIP_MEM_ALIGN_SIZE(newsize); 00372 00373 if(newsize < MIN_SIZE_ALIGNED) { 00374 /* every data block must be at least MIN_SIZE_ALIGNED long */ 00375 newsize = MIN_SIZE_ALIGNED; 00376 } 00377 00378 if (newsize > MEM_SIZE_ALIGNED) { 00379 return NULL; 00380 } 00381 00382 LWIP_ASSERT("mem_realloc: legal memory", (u8_t *)rmem >= (u8_t *)ram && 00383 (u8_t *)rmem < (u8_t *)ram_end); 00384 00385 if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) { 00386 SYS_ARCH_DECL_PROTECT(lev); 00387 LWIP_DEBUGF(MEM_DEBUG | 3, ("mem_realloc: illegal memory\n")); 00388 /* protect mem stats from concurrent access */ 00389 SYS_ARCH_PROTECT(lev); 00390 MEM_STATS_INC(illegal); 00391 SYS_ARCH_UNPROTECT(lev); 00392 return rmem; 00393 } 00394 /* Get the corresponding struct mem ... */ 00395 mem = (struct mem *)((u8_t *)rmem - SIZEOF_STRUCT_MEM); 00396 /* ... and its offset pointer */ 00397 ptr = (u8_t *)mem - ram; 00398 00399 size = mem->next - ptr - SIZEOF_STRUCT_MEM; 00400 LWIP_ASSERT("mem_realloc can only shrink memory", newsize <= size); 00401 if (newsize > size) { 00402 /* not supported */ 00403 return NULL; 00404 } 00405 if (newsize == size) { 00406 /* No change in size, simply return */ 00407 return rmem; 00408 } 00409 00410 /* protect the heap from concurrent access */ 00411 LWIP_MEM_FREE_PROTECT(); 00412 00413 MEM_STATS_DEC_USED(used, (size - newsize)); 00414 00415 mem2 = (struct mem *)&ram[mem->next]; 00416 if(mem2->used == 0) { 00417 /* The next struct is unused, we can simply move it at little */ 00418 mem_size_t next; 00419 /* remember the old next pointer */ 00420 next = mem2->next; 00421 /* create new struct mem which is moved directly after the shrinked mem */ 00422 ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize; 00423 if (lfree == mem2) { 00424 lfree = (struct mem *)&ram[ptr2]; 00425 } 00426 mem2 = (struct mem *)&ram[ptr2]; 00427 mem2->used = 0; 00428 /* restore the next pointer */ 00429 mem2->next = next; 00430 /* link it back to mem */ 00431 mem2->prev = ptr; 00432 /* link mem to it */ 00433 mem->next = ptr2; 00434 /* last thing to restore linked list: as we have moved mem2, 00435 * let 'mem2->next->prev' point to mem2 again. but only if mem2->next is not 00436 * the end of the heap */ 00437 if (mem2->next != MEM_SIZE_ALIGNED) { 00438 ((struct mem *)&ram[mem2->next])->prev = ptr2; 00439 } 00440 /* no need to plug holes, we've already done that */ 00441 } else if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED <= size) { 00442 /* Next struct is used but there's room for another struct mem with 00443 * at least MIN_SIZE_ALIGNED of data. 00444 * Old size ('size') must be big enough to contain at least 'newsize' plus a struct mem 00445 * ('SIZEOF_STRUCT_MEM') with some data ('MIN_SIZE_ALIGNED'). 00446 * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty 00447 * region that couldn't hold data, but when mem->next gets freed, 00448 * the 2 regions would be combined, resulting in more free memory */ 00449 ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize; 00450 mem2 = (struct mem *)&ram[ptr2]; 00451 if (mem2 < lfree) { 00452 lfree = mem2; 00453 } 00454 mem2->used = 0; 00455 mem2->next = mem->next; 00456 mem2->prev = ptr; 00457 mem->next = ptr2; 00458 if (mem2->next != MEM_SIZE_ALIGNED) { 00459 ((struct mem *)&ram[mem2->next])->prev = ptr2; 00460 } 00461 /* the original mem->next is used, so no need to plug holes! */ 00462 } 00463 /* else { 00464 next struct mem is used but size between mem and mem2 is not big enough 00465 to create another struct mem 00466 -> don't do anyhting. 00467 -> the remaining space stays unused since it is too small 00468 } */ 00469 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00470 mem_free_count = 1; 00471 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00472 LWIP_MEM_FREE_UNPROTECT(); 00473 return rmem; 00474 } 00475 00476 /** 00477 * Adam's mem_malloc() plus solution for bug #17922 00478 * Allocate a block of memory with a minimum of 'size' bytes. 00479 * 00480 * @param size is the minimum size of the requested block in bytes. 00481 * @return pointer to allocated memory or NULL if no free memory was found. 00482 * 00483 * Note that the returned value will always be aligned (as defined by MEM_ALIGNMENT). 00484 */ 00485 void * 00486 mem_malloc(mem_size_t size) 00487 { 00488 mem_size_t ptr, ptr2; 00489 struct mem *mem, *mem2; 00490 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00491 u8_t local_mem_free_count = 0; 00492 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00493 LWIP_MEM_ALLOC_DECL_PROTECT(); 00494 00495 if (size == 0) { 00496 return NULL; 00497 } 00498 00499 /* Expand the size of the allocated memory region so that we can 00500 adjust for alignment. */ 00501 size = LWIP_MEM_ALIGN_SIZE(size); 00502 00503 if(size < MIN_SIZE_ALIGNED) { 00504 /* every data block must be at least MIN_SIZE_ALIGNED long */ 00505 size = MIN_SIZE_ALIGNED; 00506 } 00507 00508 if (size > MEM_SIZE_ALIGNED) { 00509 return NULL; 00510 } 00511 00512 /* protect the heap from concurrent access */ 00513 sys_arch_sem_wait(mem_sem, 0); 00514 LWIP_MEM_ALLOC_PROTECT(); 00515 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00516 /* run as long as a mem_free disturbed mem_malloc */ 00517 do { 00518 local_mem_free_count = 0; 00519 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00520 00521 /* Scan through the heap searching for a free block that is big enough, 00522 * beginning with the lowest free block. 00523 */ 00524 for (ptr = (u8_t *)lfree - ram; ptr < MEM_SIZE_ALIGNED - size; 00525 ptr = ((struct mem *)&ram[ptr])->next) { 00526 mem = (struct mem *)&ram[ptr]; 00527 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00528 mem_free_count = 0; 00529 LWIP_MEM_ALLOC_UNPROTECT(); 00530 /* allow mem_free to run */ 00531 LWIP_MEM_ALLOC_PROTECT(); 00532 if (mem_free_count != 0) { 00533 local_mem_free_count = mem_free_count; 00534 } 00535 mem_free_count = 0; 00536 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00537 00538 if ((!mem->used) && 00539 (mem->next - (ptr + SIZEOF_STRUCT_MEM)) >= size) { 00540 /* mem is not used and at least perfect fit is possible: 00541 * mem->next - (ptr + SIZEOF_STRUCT_MEM) gives us the 'user data size' of mem */ 00542 00543 if (mem->next - (ptr + SIZEOF_STRUCT_MEM) >= (size + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED)) { 00544 /* (in addition to the above, we test if another struct mem (SIZEOF_STRUCT_MEM) containing 00545 * at least MIN_SIZE_ALIGNED of data also fits in the 'user data space' of 'mem') 00546 * -> split large block, create empty remainder, 00547 * remainder must be large enough to contain MIN_SIZE_ALIGNED data: if 00548 * mem->next - (ptr + (2*SIZEOF_STRUCT_MEM)) == size, 00549 * struct mem would fit in but no data between mem2 and mem2->next 00550 * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty 00551 * region that couldn't hold data, but when mem->next gets freed, 00552 * the 2 regions would be combined, resulting in more free memory 00553 */ 00554 ptr2 = ptr + SIZEOF_STRUCT_MEM + size; 00555 /* create mem2 struct */ 00556 mem2 = (struct mem *)&ram[ptr2]; 00557 mem2->used = 0; 00558 mem2->next = mem->next; 00559 mem2->prev = ptr; 00560 /* and insert it between mem and mem->next */ 00561 mem->next = ptr2; 00562 mem->used = 1; 00563 00564 if (mem2->next != MEM_SIZE_ALIGNED) { 00565 ((struct mem *)&ram[mem2->next])->prev = ptr2; 00566 } 00567 MEM_STATS_INC_USED(used, (size + SIZEOF_STRUCT_MEM)); 00568 } else { 00569 /* (a mem2 struct does no fit into the user data space of mem and mem->next will always 00570 * be used at this point: if not we have 2 unused structs in a row, plug_holes should have 00571 * take care of this). 00572 * -> near fit or excact fit: do not split, no mem2 creation 00573 * also can't move mem->next directly behind mem, since mem->next 00574 * will always be used at this point! 00575 */ 00576 mem->used = 1; 00577 MEM_STATS_INC_USED(used, mem->next - ((u8_t *)mem - ram)); 00578 } 00579 00580 if (mem == lfree) { 00581 /* Find next free block after mem and update lowest free pointer */ 00582 while (lfree->used && lfree != ram_end) { 00583 LWIP_MEM_ALLOC_UNPROTECT(); 00584 /* prevent high interrupt latency... */ 00585 LWIP_MEM_ALLOC_PROTECT(); 00586 lfree = (struct mem *)&ram[lfree->next]; 00587 } 00588 LWIP_ASSERT("mem_malloc: !lfree->used", ((lfree == ram_end) || (!lfree->used))); 00589 } 00590 LWIP_MEM_ALLOC_UNPROTECT(); 00591 sys_sem_signal(mem_sem); 00592 LWIP_ASSERT("mem_malloc: allocated memory not above ram_end.", 00593 (mem_ptr_t)mem + SIZEOF_STRUCT_MEM + size <= (mem_ptr_t)ram_end); 00594 LWIP_ASSERT("mem_malloc: allocated memory properly aligned.", 00595 ((mem_ptr_t)mem + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT == 0); 00596 LWIP_ASSERT("mem_malloc: sanity check alignment", 00597 (((mem_ptr_t)mem) & (MEM_ALIGNMENT-1)) == 0); 00598 00599 return (u8_t *)mem + SIZEOF_STRUCT_MEM; 00600 } 00601 } 00602 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00603 /* if we got interrupted by a mem_free, try again */ 00604 } while(local_mem_free_count != 0); 00605 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00606 LWIP_DEBUGF(MEM_DEBUG | 2, ("mem_malloc: could not allocate %"S16_F" bytes\n", (s16_t)size)); 00607 MEM_STATS_INC(err); 00608 LWIP_MEM_ALLOC_UNPROTECT(); 00609 sys_sem_signal(mem_sem); 00610 return NULL; 00611 } 00612 00613 #endif /* MEM_USE_POOLS */ 00614 /** 00615 * Contiguously allocates enough space for count objects that are size bytes 00616 * of memory each and returns a pointer to the allocated memory. 00617 * 00618 * The allocated memory is filled with bytes of value zero. 00619 * 00620 * @param count number of objects to allocate 00621 * @param size size of the objects to allocate 00622 * @return pointer to allocated memory / NULL pointer if there is an error 00623 */ 00624 void *mem_calloc(mem_size_t count, mem_size_t size) 00625 { 00626 void *p; 00627 00628 /* allocate 'count' objects of size 'size' */ 00629 p = mem_malloc(count * size); 00630 if (p) { 00631 /* zero the memory */ 00632 memset(p, 0, count * size); 00633 } 00634 return p; 00635 } 00636 #endif /* !MEM_LIBC_MALLOC */
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