reactos/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 */