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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 #include "lwip/err.h" 00065 00066 #include <string.h> 00067 00068 #if MEM_USE_POOLS 00069 /* lwIP head implemented with different sized pools */ 00070 00071 /** 00072 * Allocate memory: determine the smallest pool that is big enough 00073 * to contain an element of 'size' and get an element from that pool. 00074 * 00075 * @param size the size in bytes of the memory needed 00076 * @return a pointer to the allocated memory or NULL if the pool is empty 00077 */ 00078 void * 00079 mem_malloc(mem_size_t size) 00080 { 00081 struct memp_malloc_helper *element; 00082 memp_t poolnr; 00083 mem_size_t required_size = size + sizeof(struct memp_malloc_helper); 00084 00085 for (poolnr = MEMP_POOL_FIRST; poolnr <= MEMP_POOL_LAST; poolnr++) { 00086 #if MEM_USE_POOLS_TRY_BIGGER_POOL 00087 again: 00088 #endif /* MEM_USE_POOLS_TRY_BIGGER_POOL */ 00089 /* is this pool big enough to hold an element of the required size 00090 plus a struct memp_malloc_helper that saves the pool this element came from? */ 00091 if (required_size <= memp_sizes[poolnr]) { 00092 break; 00093 } 00094 } 00095 if (poolnr > MEMP_POOL_LAST) { 00096 LWIP_ASSERT("mem_malloc(): no pool is that big!", 0); 00097 return NULL; 00098 } 00099 element = (struct memp_malloc_helper*)memp_malloc(poolnr); 00100 if (element == NULL) { 00101 /* No need to DEBUGF or ASSERT: This error is already 00102 taken care of in memp.c */ 00103 #if MEM_USE_POOLS_TRY_BIGGER_POOL 00104 /** Try a bigger pool if this one is empty! */ 00105 if (poolnr < MEMP_POOL_LAST) { 00106 poolnr++; 00107 goto again; 00108 } 00109 #endif /* MEM_USE_POOLS_TRY_BIGGER_POOL */ 00110 return NULL; 00111 } 00112 00113 /* save the pool number this element came from */ 00114 element->poolnr = poolnr; 00115 /* and return a pointer to the memory directly after the struct memp_malloc_helper */ 00116 element++; 00117 00118 return element; 00119 } 00120 00121 /** 00122 * Free memory previously allocated by mem_malloc. Loads the pool number 00123 * and calls memp_free with that pool number to put the element back into 00124 * its pool 00125 * 00126 * @param rmem the memory element to free 00127 */ 00128 void 00129 mem_free(void *rmem) 00130 { 00131 struct memp_malloc_helper *hmem = (struct memp_malloc_helper*)rmem; 00132 00133 LWIP_ASSERT("rmem != NULL", (rmem != NULL)); 00134 LWIP_ASSERT("rmem == MEM_ALIGN(rmem)", (rmem == LWIP_MEM_ALIGN(rmem))); 00135 00136 /* get the original struct memp_malloc_helper */ 00137 hmem--; 00138 00139 LWIP_ASSERT("hmem != NULL", (hmem != NULL)); 00140 LWIP_ASSERT("hmem == MEM_ALIGN(hmem)", (hmem == LWIP_MEM_ALIGN(hmem))); 00141 LWIP_ASSERT("hmem->poolnr < MEMP_MAX", (hmem->poolnr < MEMP_MAX)); 00142 00143 /* and put it in the pool we saved earlier */ 00144 memp_free(hmem->poolnr, hmem); 00145 } 00146 00147 #else /* MEM_USE_POOLS */ 00148 /* lwIP replacement for your libc malloc() */ 00149 00150 /** 00151 * The heap is made up as a list of structs of this type. 00152 * This does not have to be aligned since for getting its size, 00153 * we only use the macro SIZEOF_STRUCT_MEM, which automatically alignes. 00154 */ 00155 struct mem { 00156 /** index (-> ram[next]) of the next struct */ 00157 mem_size_t next; 00158 /** index (-> ram[prev]) of the previous struct */ 00159 mem_size_t prev; 00160 /** 1: this area is used; 0: this area is unused */ 00161 u8_t used; 00162 }; 00163 00164 /** All allocated blocks will be MIN_SIZE bytes big, at least! 00165 * MIN_SIZE can be overridden to suit your needs. Smaller values save space, 00166 * larger values could prevent too small blocks to fragment the RAM too much. */ 00167 #ifndef MIN_SIZE 00168 #define MIN_SIZE 12 00169 #endif /* MIN_SIZE */ 00170 /* some alignment macros: we define them here for better source code layout */ 00171 #define MIN_SIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(MIN_SIZE) 00172 #define SIZEOF_STRUCT_MEM LWIP_MEM_ALIGN_SIZE(sizeof(struct mem)) 00173 #define MEM_SIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(MEM_SIZE) 00174 00175 /** If you want to relocate the heap to external memory, simply define 00176 * LWIP_RAM_HEAP_POINTER as a void-pointer to that location. 00177 * If so, make sure the memory at that location is big enough (see below on 00178 * how that space is calculated). */ 00179 #ifndef LWIP_RAM_HEAP_POINTER 00180 /** the heap. we need one struct mem at the end and some room for alignment */ 00181 u8_t ram_heap[MEM_SIZE_ALIGNED + (2*SIZEOF_STRUCT_MEM) + MEM_ALIGNMENT] MEM_POSITION; 00182 #define LWIP_RAM_HEAP_POINTER ram_heap 00183 #endif /* LWIP_RAM_HEAP_POINTER */ 00184 00185 /** pointer to the heap (ram_heap): for alignment, ram is now a pointer instead of an array */ 00186 static u8_t *ram; 00187 /** the last entry, always unused! */ 00188 static struct mem *ram_end; 00189 /** pointer to the lowest free block, this is used for faster search */ 00190 static struct mem *lfree; 00191 00192 #if (NO_SYS==0) //Pointless if monothreaded app 00193 /** concurrent access protection */ 00194 static sys_mutex_t mem_mutex; 00195 #endif 00196 00197 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00198 00199 static volatile u8_t mem_free_count; 00200 00201 /* Allow mem_free from other (e.g. interrupt) context */ 00202 #define LWIP_MEM_FREE_DECL_PROTECT() SYS_ARCH_DECL_PROTECT(lev_free) 00203 #define LWIP_MEM_FREE_PROTECT() SYS_ARCH_PROTECT(lev_free) 00204 #define LWIP_MEM_FREE_UNPROTECT() SYS_ARCH_UNPROTECT(lev_free) 00205 #define LWIP_MEM_ALLOC_DECL_PROTECT() SYS_ARCH_DECL_PROTECT(lev_alloc) 00206 #define LWIP_MEM_ALLOC_PROTECT() SYS_ARCH_PROTECT(lev_alloc) 00207 #define LWIP_MEM_ALLOC_UNPROTECT() SYS_ARCH_UNPROTECT(lev_alloc) 00208 00209 #else /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00210 00211 /* Protect the heap only by using a semaphore */ 00212 #define LWIP_MEM_FREE_DECL_PROTECT() 00213 #define LWIP_MEM_FREE_PROTECT() sys_mutex_lock(&mem_mutex) 00214 #define LWIP_MEM_FREE_UNPROTECT() sys_mutex_unlock(&mem_mutex) 00215 /* mem_malloc is protected using semaphore AND LWIP_MEM_ALLOC_PROTECT */ 00216 #define LWIP_MEM_ALLOC_DECL_PROTECT() 00217 #define LWIP_MEM_ALLOC_PROTECT() 00218 #define LWIP_MEM_ALLOC_UNPROTECT() 00219 00220 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00221 00222 00223 /** 00224 * "Plug holes" by combining adjacent empty struct mems. 00225 * After this function is through, there should not exist 00226 * one empty struct mem pointing to another empty struct mem. 00227 * 00228 * @param mem this points to a struct mem which just has been freed 00229 * @internal this function is only called by mem_free() and mem_trim() 00230 * 00231 * This assumes access to the heap is protected by the calling function 00232 * already. 00233 */ 00234 static void 00235 plug_holes(struct mem *mem) 00236 { 00237 struct mem *nmem; 00238 struct mem *pmem; 00239 00240 LWIP_ASSERT("plug_holes: mem >= ram", (u8_t *)mem >= ram); 00241 LWIP_ASSERT("plug_holes: mem < ram_end", (u8_t *)mem < (u8_t *)ram_end); 00242 LWIP_ASSERT("plug_holes: mem->used == 0", mem->used == 0); 00243 00244 /* plug hole forward */ 00245 LWIP_ASSERT("plug_holes: mem->next <= MEM_SIZE_ALIGNED", mem->next <= MEM_SIZE_ALIGNED); 00246 00247 nmem = (struct mem *)(void *)&ram[mem->next]; 00248 if (mem != nmem && nmem->used == 0 && (u8_t *)nmem != (u8_t *)ram_end) { 00249 /* if mem->next is unused and not end of ram, combine mem and mem->next */ 00250 if (lfree == nmem) { 00251 lfree = mem; 00252 } 00253 mem->next = nmem->next; 00254 ((struct mem *)(void *)&ram[nmem->next])->prev = (mem_size_t)((u8_t *)mem - ram); 00255 } 00256 00257 /* plug hole backward */ 00258 pmem = (struct mem *)(void *)&ram[mem->prev]; 00259 if (pmem != mem && pmem->used == 0) { 00260 /* if mem->prev is unused, combine mem and mem->prev */ 00261 if (lfree == mem) { 00262 lfree = pmem; 00263 } 00264 pmem->next = mem->next; 00265 ((struct mem *)(void *)&ram[mem->next])->prev = (mem_size_t)((u8_t *)pmem - ram); 00266 } 00267 } 00268 00269 /** 00270 * Zero the heap and initialize start, end and lowest-free 00271 */ 00272 void 00273 mem_init(void) 00274 { 00275 struct mem *mem; 00276 00277 LWIP_ASSERT("Sanity check alignment", 00278 (SIZEOF_STRUCT_MEM & (MEM_ALIGNMENT-1)) == 0); 00279 00280 /* align the heap */ 00281 ram = (u8_t *)LWIP_MEM_ALIGN(LWIP_RAM_HEAP_POINTER); 00282 /* initialize the start of the heap */ 00283 mem = (struct mem *)(void *)ram; 00284 mem->next = MEM_SIZE_ALIGNED; 00285 mem->prev = 0; 00286 mem->used = 0; 00287 /* initialize the end of the heap */ 00288 ram_end = (struct mem *)(void *)&ram[MEM_SIZE_ALIGNED]; 00289 ram_end->used = 1; 00290 ram_end->next = MEM_SIZE_ALIGNED; 00291 ram_end->prev = MEM_SIZE_ALIGNED; 00292 00293 /* initialize the lowest-free pointer to the start of the heap */ 00294 lfree = (struct mem *)(void *)ram; 00295 00296 MEM_STATS_AVAIL(avail, MEM_SIZE_ALIGNED); 00297 00298 if(sys_mutex_new(&mem_mutex) != ERR_OK) { 00299 LWIP_ASSERT("failed to create mem_mutex", 0); 00300 } 00301 } 00302 00303 /** 00304 * Put a struct mem back on the heap 00305 * 00306 * @param rmem is the data portion of a struct mem as returned by a previous 00307 * call to mem_malloc() 00308 */ 00309 void 00310 mem_free(void *rmem) 00311 { 00312 struct mem *mem; 00313 LWIP_MEM_FREE_DECL_PROTECT(); 00314 00315 if (rmem == NULL) { 00316 LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("mem_free(p == NULL) was called.\n")); 00317 return; 00318 } 00319 LWIP_ASSERT("mem_free: sanity check alignment", (((mem_ptr_t)rmem) & (MEM_ALIGNMENT-1)) == 0); 00320 00321 LWIP_ASSERT("mem_free: legal memory", (u8_t *)rmem >= (u8_t *)ram && 00322 (u8_t *)rmem < (u8_t *)ram_end); 00323 00324 if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) { 00325 SYS_ARCH_DECL_PROTECT(lev); 00326 LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("mem_free: illegal memory\n")); 00327 /* protect mem stats from concurrent access */ 00328 SYS_ARCH_PROTECT(lev); 00329 MEM_STATS_INC(illegal); 00330 SYS_ARCH_UNPROTECT(lev); 00331 return; 00332 } 00333 /* protect the heap from concurrent access */ 00334 LWIP_MEM_FREE_PROTECT(); 00335 /* Get the corresponding struct mem ... */ 00336 mem = (struct mem *)(void *)((u8_t *)rmem - SIZEOF_STRUCT_MEM); 00337 /* ... which has to be in a used state ... */ 00338 LWIP_ASSERT("mem_free: mem->used", mem->used); 00339 /* ... and is now unused. */ 00340 mem->used = 0; 00341 00342 if (mem < lfree) { 00343 /* the newly freed struct is now the lowest */ 00344 lfree = mem; 00345 } 00346 00347 MEM_STATS_DEC_USED(used, mem->next - (mem_size_t)(((u8_t *)mem - ram))); 00348 00349 /* finally, see if prev or next are free also */ 00350 plug_holes(mem); 00351 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00352 mem_free_count = 1; 00353 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00354 LWIP_MEM_FREE_UNPROTECT(); 00355 } 00356 00357 /** 00358 * Shrink memory returned by mem_malloc(). 00359 * 00360 * @param rmem pointer to memory allocated by mem_malloc the is to be shrinked 00361 * @param newsize required size after shrinking (needs to be smaller than or 00362 * equal to the previous size) 00363 * @return for compatibility reasons: is always == rmem, at the moment 00364 * or NULL if newsize is > old size, in which case rmem is NOT touched 00365 * or freed! 00366 */ 00367 void * 00368 mem_trim(void *rmem, mem_size_t newsize) 00369 { 00370 mem_size_t size; 00371 mem_size_t ptr, ptr2; 00372 struct mem *mem, *mem2; 00373 /* use the FREE_PROTECT here: it protects with sem OR SYS_ARCH_PROTECT */ 00374 LWIP_MEM_FREE_DECL_PROTECT(); 00375 00376 /* Expand the size of the allocated memory region so that we can 00377 adjust for alignment. */ 00378 newsize = LWIP_MEM_ALIGN_SIZE(newsize); 00379 00380 if(newsize < MIN_SIZE_ALIGNED) { 00381 /* every data block must be at least MIN_SIZE_ALIGNED long */ 00382 newsize = MIN_SIZE_ALIGNED; 00383 } 00384 00385 if (newsize > MEM_SIZE_ALIGNED) { 00386 return NULL; 00387 } 00388 00389 LWIP_ASSERT("mem_trim: legal memory", (u8_t *)rmem >= (u8_t *)ram && 00390 (u8_t *)rmem < (u8_t *)ram_end); 00391 00392 if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) { 00393 SYS_ARCH_DECL_PROTECT(lev); 00394 LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("mem_trim: illegal memory\n")); 00395 /* protect mem stats from concurrent access */ 00396 SYS_ARCH_PROTECT(lev); 00397 MEM_STATS_INC(illegal); 00398 SYS_ARCH_UNPROTECT(lev); 00399 return rmem; 00400 } 00401 /* Get the corresponding struct mem ... */ 00402 mem = (struct mem *)(void *)((u8_t *)rmem - SIZEOF_STRUCT_MEM); 00403 /* ... and its offset pointer */ 00404 ptr = (mem_size_t)((u8_t *)mem - ram); 00405 00406 size = mem->next - ptr - SIZEOF_STRUCT_MEM; 00407 LWIP_ASSERT("mem_trim can only shrink memory", newsize <= size); 00408 if (newsize > size) { 00409 /* not supported */ 00410 return NULL; 00411 } 00412 if (newsize == size) { 00413 /* No change in size, simply return */ 00414 return rmem; 00415 } 00416 00417 /* protect the heap from concurrent access */ 00418 LWIP_MEM_FREE_PROTECT(); 00419 00420 mem2 = (struct mem *)(void *)&ram[mem->next]; 00421 if(mem2->used == 0) { 00422 /* The next struct is unused, we can simply move it at little */ 00423 mem_size_t next; 00424 /* remember the old next pointer */ 00425 next = mem2->next; 00426 /* create new struct mem which is moved directly after the shrinked mem */ 00427 ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize; 00428 if (lfree == mem2) { 00429 lfree = (struct mem *)(void *)&ram[ptr2]; 00430 } 00431 mem2 = (struct mem *)(void *)&ram[ptr2]; 00432 mem2->used = 0; 00433 /* restore the next pointer */ 00434 mem2->next = next; 00435 /* link it back to mem */ 00436 mem2->prev = ptr; 00437 /* link mem to it */ 00438 mem->next = ptr2; 00439 /* last thing to restore linked list: as we have moved mem2, 00440 * let 'mem2->next->prev' point to mem2 again. but only if mem2->next is not 00441 * the end of the heap */ 00442 if (mem2->next != MEM_SIZE_ALIGNED) { 00443 ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2; 00444 } 00445 MEM_STATS_DEC_USED(used, (size - newsize)); 00446 /* no need to plug holes, we've already done that */ 00447 } else if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED <= size) { 00448 /* Next struct is used but there's room for another struct mem with 00449 * at least MIN_SIZE_ALIGNED of data. 00450 * Old size ('size') must be big enough to contain at least 'newsize' plus a struct mem 00451 * ('SIZEOF_STRUCT_MEM') with some data ('MIN_SIZE_ALIGNED'). 00452 * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty 00453 * region that couldn't hold data, but when mem->next gets freed, 00454 * the 2 regions would be combined, resulting in more free memory */ 00455 ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize; 00456 mem2 = (struct mem *)(void *)&ram[ptr2]; 00457 if (mem2 < lfree) { 00458 lfree = mem2; 00459 } 00460 mem2->used = 0; 00461 mem2->next = mem->next; 00462 mem2->prev = ptr; 00463 mem->next = ptr2; 00464 if (mem2->next != MEM_SIZE_ALIGNED) { 00465 ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2; 00466 } 00467 MEM_STATS_DEC_USED(used, (size - newsize)); 00468 /* the original mem->next is used, so no need to plug holes! */ 00469 } 00470 /* else { 00471 next struct mem is used but size between mem and mem2 is not big enough 00472 to create another struct mem 00473 -> don't do anyhting. 00474 -> the remaining space stays unused since it is too small 00475 } */ 00476 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00477 mem_free_count = 1; 00478 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00479 LWIP_MEM_FREE_UNPROTECT(); 00480 return rmem; 00481 } 00482 00483 /** 00484 * Adam's mem_malloc() plus solution for bug #17922 00485 * Allocate a block of memory with a minimum of 'size' bytes. 00486 * 00487 * @param size is the minimum size of the requested block in bytes. 00488 * @return pointer to allocated memory or NULL if no free memory was found. 00489 * 00490 * Note that the returned value will always be aligned (as defined by MEM_ALIGNMENT). 00491 */ 00492 void * 00493 mem_malloc(mem_size_t size) 00494 { 00495 mem_size_t ptr, ptr2; 00496 struct mem *mem, *mem2; 00497 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00498 u8_t local_mem_free_count = 0; 00499 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00500 LWIP_MEM_ALLOC_DECL_PROTECT(); 00501 00502 if (size == 0) { 00503 return NULL; 00504 } 00505 00506 /* Expand the size of the allocated memory region so that we can 00507 adjust for alignment. */ 00508 size = LWIP_MEM_ALIGN_SIZE(size); 00509 00510 if(size < MIN_SIZE_ALIGNED) { 00511 /* every data block must be at least MIN_SIZE_ALIGNED long */ 00512 size = MIN_SIZE_ALIGNED; 00513 } 00514 00515 if (size > MEM_SIZE_ALIGNED) { 00516 return NULL; 00517 } 00518 00519 /* protect the heap from concurrent access */ 00520 sys_mutex_lock(&mem_mutex); 00521 LWIP_MEM_ALLOC_PROTECT(); 00522 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00523 /* run as long as a mem_free disturbed mem_malloc */ 00524 do { 00525 local_mem_free_count = 0; 00526 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00527 00528 /* Scan through the heap searching for a free block that is big enough, 00529 * beginning with the lowest free block. 00530 */ 00531 for (ptr = (mem_size_t)((u8_t *)lfree - ram); ptr < MEM_SIZE_ALIGNED - size; 00532 ptr = ((struct mem *)(void *)&ram[ptr])->next) { 00533 mem = (struct mem *)(void *)&ram[ptr]; 00534 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00535 mem_free_count = 0; 00536 LWIP_MEM_ALLOC_UNPROTECT(); 00537 /* allow mem_free to run */ 00538 LWIP_MEM_ALLOC_PROTECT(); 00539 if (mem_free_count != 0) { 00540 local_mem_free_count = mem_free_count; 00541 } 00542 mem_free_count = 0; 00543 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00544 00545 if ((!mem->used) && 00546 (mem->next - (ptr + SIZEOF_STRUCT_MEM)) >= size) { 00547 /* mem is not used and at least perfect fit is possible: 00548 * mem->next - (ptr + SIZEOF_STRUCT_MEM) gives us the 'user data size' of mem */ 00549 00550 if (mem->next - (ptr + SIZEOF_STRUCT_MEM) >= (size + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED)) { 00551 /* (in addition to the above, we test if another struct mem (SIZEOF_STRUCT_MEM) containing 00552 * at least MIN_SIZE_ALIGNED of data also fits in the 'user data space' of 'mem') 00553 * -> split large block, create empty remainder, 00554 * remainder must be large enough to contain MIN_SIZE_ALIGNED data: if 00555 * mem->next - (ptr + (2*SIZEOF_STRUCT_MEM)) == size, 00556 * struct mem would fit in but no data between mem2 and mem2->next 00557 * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty 00558 * region that couldn't hold data, but when mem->next gets freed, 00559 * the 2 regions would be combined, resulting in more free memory 00560 */ 00561 ptr2 = ptr + SIZEOF_STRUCT_MEM + size; 00562 /* create mem2 struct */ 00563 mem2 = (struct mem *)(void *)&ram[ptr2]; 00564 mem2->used = 0; 00565 mem2->next = mem->next; 00566 mem2->prev = ptr; 00567 /* and insert it between mem and mem->next */ 00568 mem->next = ptr2; 00569 mem->used = 1; 00570 00571 if (mem2->next != MEM_SIZE_ALIGNED) { 00572 ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2; 00573 } 00574 MEM_STATS_INC_USED(used, (size + SIZEOF_STRUCT_MEM)); 00575 } else { 00576 /* (a mem2 struct does no fit into the user data space of mem and mem->next will always 00577 * be used at this point: if not we have 2 unused structs in a row, plug_holes should have 00578 * take care of this). 00579 * -> near fit or excact fit: do not split, no mem2 creation 00580 * also can't move mem->next directly behind mem, since mem->next 00581 * will always be used at this point! 00582 */ 00583 mem->used = 1; 00584 MEM_STATS_INC_USED(used, mem->next - (mem_size_t)((u8_t *)mem - ram)); 00585 } 00586 00587 if (mem == lfree) { 00588 /* Find next free block after mem and update lowest free pointer */ 00589 while (lfree->used && lfree != ram_end) { 00590 LWIP_MEM_ALLOC_UNPROTECT(); 00591 /* prevent high interrupt latency... */ 00592 LWIP_MEM_ALLOC_PROTECT(); 00593 lfree = (struct mem *)(void *)&ram[lfree->next]; 00594 } 00595 LWIP_ASSERT("mem_malloc: !lfree->used", ((lfree == ram_end) || (!lfree->used))); 00596 } 00597 LWIP_MEM_ALLOC_UNPROTECT(); 00598 sys_mutex_unlock(&mem_mutex); 00599 LWIP_ASSERT("mem_malloc: allocated memory not above ram_end.", 00600 (mem_ptr_t)mem + SIZEOF_STRUCT_MEM + size <= (mem_ptr_t)ram_end); 00601 LWIP_ASSERT("mem_malloc: allocated memory properly aligned.", 00602 ((mem_ptr_t)mem + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT == 0); 00603 LWIP_ASSERT("mem_malloc: sanity check alignment", 00604 (((mem_ptr_t)mem) & (MEM_ALIGNMENT-1)) == 0); 00605 00606 return (u8_t *)mem + SIZEOF_STRUCT_MEM; 00607 } 00608 } 00609 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT 00610 /* if we got interrupted by a mem_free, try again */ 00611 } while(local_mem_free_count != 0); 00612 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */ 00613 LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("mem_malloc: could not allocate %"S16_F" bytes\n", (s16_t)size)); 00614 MEM_STATS_INC(err); 00615 LWIP_MEM_ALLOC_UNPROTECT(); 00616 sys_mutex_unlock(&mem_mutex); 00617 return NULL; 00618 } 00619 00620 #endif /* MEM_USE_POOLS */ 00621 /** 00622 * Contiguously allocates enough space for count objects that are size bytes 00623 * of memory each and returns a pointer to the allocated memory. 00624 * 00625 * The allocated memory is filled with bytes of value zero. 00626 * 00627 * @param count number of objects to allocate 00628 * @param size size of the objects to allocate 00629 * @return pointer to allocated memory / NULL pointer if there is an error 00630 */ 00631 void *mem_calloc(mem_size_t count, mem_size_t size) 00632 { 00633 void *p; 00634 00635 /* allocate 'count' objects of size 'size' */ 00636 p = mem_malloc(count * size); 00637 if (p) { 00638 /* zero the memory */ 00639 memset(p, 0, count * size); 00640 } 00641 return p; 00642 } 00643 00644 #endif /* !MEM_LIBC_MALLOC */
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