tool/mbed/mbed-sdk/libraries/net/lwip/lwip/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
 181 #if defined(TARGET_LPC4088) || defined(TARGET_LPC4088_DM)
 182 #  if defined (__ICCARM__)
 183 #     define ETHMEM_SECTION
 184 #  elif defined(TOOLCHAIN_GCC_CR)
 185 #     define ETHMEM_SECTION __attribute__((section(".data.$RamPeriph32")))
 186 #  else
 187 #     define ETHMEM_SECTION __attribute__((section("AHBSRAM1"),aligned))
 188 #  endif
 189 #elif defined(TARGET_LPC1768)
 190 #   define ETHMEM_SECTION __attribute((section("AHBSRAM0")))
 191 #else
 192 #               define ETHMEM_SECTION
 193 #endif
 194
 195 /** the heap. we need one struct mem at the end and some room for alignment */
 196 u8_t ram_heap[MEM_SIZE_ALIGNED + (2*SIZEOF_STRUCT_MEM) + MEM_ALIGNMENT] ETHMEM_SECTION;
 197 #define LWIP_RAM_HEAP_POINTER ram_heap
 198 #endif /* LWIP_RAM_HEAP_POINTER */
 199
 200 /** pointer to the heap (ram_heap): for alignment, ram is now a pointer instead of an array */
 201 static u8_t *ram;
 202 /** the last entry, always unused! */
 203 static struct mem *ram_end;
 204 /** pointer to the lowest free block, this is used for faster search */
 205 static struct mem *lfree;
 206
 207 /** concurrent access protection */
 208 static sys_mutex_t mem_mutex;
 209
 210 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
 211
 212 static volatile u8_t mem_free_count;
 213
 214 /* Allow mem_free from other (e.g. interrupt) context */
 215 #define LWIP_MEM_FREE_DECL_PROTECT()  SYS_ARCH_DECL_PROTECT(lev_free)
 216 #define LWIP_MEM_FREE_PROTECT()       SYS_ARCH_PROTECT(lev_free)
 217 #define LWIP_MEM_FREE_UNPROTECT()     SYS_ARCH_UNPROTECT(lev_free)
 218 #define LWIP_MEM_ALLOC_DECL_PROTECT() SYS_ARCH_DECL_PROTECT(lev_alloc)
 219 #define LWIP_MEM_ALLOC_PROTECT()      SYS_ARCH_PROTECT(lev_alloc)
 220 #define LWIP_MEM_ALLOC_UNPROTECT()    SYS_ARCH_UNPROTECT(lev_alloc)
 221
 222 #else /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
 223
 224 /* Protect the heap only by using a semaphore */
 225 #define LWIP_MEM_FREE_DECL_PROTECT()
 226 #define LWIP_MEM_FREE_PROTECT()    sys_mutex_lock(&mem_mutex)
 227 #define LWIP_MEM_FREE_UNPROTECT()  sys_mutex_unlock(&mem_mutex)
 228 /* mem_malloc is protected using semaphore AND LWIP_MEM_ALLOC_PROTECT */
 229 #define LWIP_MEM_ALLOC_DECL_PROTECT()
 230 #define LWIP_MEM_ALLOC_PROTECT()
 231 #define LWIP_MEM_ALLOC_UNPROTECT()
 232
 233 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
 234
 235
 236 /**
 237  * "Plug holes" by combining adjacent empty struct mems.
 238  * After this function is through, there should not exist
 239  * one empty struct mem pointing to another empty struct mem.
 240  *
 241  * @param mem this points to a struct mem which just has been freed
 242  * @internal this function is only called by mem_free() and mem_trim()
 243  *
 244  * This assumes access to the heap is protected by the calling function
 245  * already.
 246  */
 247 static void
 248 plug_holes(struct mem *mem)
 249 {
 250   struct mem *nmem;
 251   struct mem *pmem;
 252
 253   LWIP_ASSERT("plug_holes: mem >= ram", (u8_t *)mem >= ram);
 254   LWIP_ASSERT("plug_holes: mem < ram_end", (u8_t *)mem < (u8_t *)ram_end);
 255   LWIP_ASSERT("plug_holes: mem->used == 0", mem->used == 0);
 256
 257   /* plug hole forward */
 258   LWIP_ASSERT("plug_holes: mem->next <= MEM_SIZE_ALIGNED", mem->next <= MEM_SIZE_ALIGNED);
 259
 260   nmem = (struct mem *)(void *)&ram[mem->next];
 261   if (mem != nmem && nmem->used == 0 && (u8_t *)nmem != (u8_t *)ram_end) {
 262     /* if mem->next is unused and not end of ram, combine mem and mem->next */
 263     if (lfree == nmem) {
 264       lfree = mem;
 265     }
 266     mem->next = nmem->next;
 267     ((struct mem *)(void *)&ram[nmem->next])->prev = (mem_size_t)((u8_t *)mem - ram);
 268   }
 269
 270   /* plug hole backward */
 271   pmem = (struct mem *)(void *)&ram[mem->prev];
 272   if (pmem != mem && pmem->used == 0) {
 273     /* if mem->prev is unused, combine mem and mem->prev */
 274     if (lfree == mem) {
 275       lfree = pmem;
 276     }
 277     pmem->next = mem->next;
 278     ((struct mem *)(void *)&ram[mem->next])->prev = (mem_size_t)((u8_t *)pmem - ram);
 279   }
 280 }
 281
 282 /**
 283  * Zero the heap and initialize start, end and lowest-free
 284  */
 285 void
 286 mem_init(void)
 287 {
 288   struct mem *mem;
 289
 290   LWIP_ASSERT("Sanity check alignment",
 291     (SIZEOF_STRUCT_MEM & (MEM_ALIGNMENT-1)) == 0);
 292
 293   /* align the heap */
 294   ram = (u8_t *)LWIP_MEM_ALIGN(LWIP_RAM_HEAP_POINTER);
 295   /* initialize the start of the heap */
 296   mem = (struct mem *)(void *)ram;
 297   mem->next = MEM_SIZE_ALIGNED;
 298   mem->prev = 0;
 299   mem->used = 0;
 300   /* initialize the end of the heap */
 301   ram_end = (struct mem *)(void *)&ram[MEM_SIZE_ALIGNED];
 302   ram_end->used = 1;
 303   ram_end->next = MEM_SIZE_ALIGNED;
 304   ram_end->prev = MEM_SIZE_ALIGNED;
 305
 306   /* initialize the lowest-free pointer to the start of the heap */
 307   lfree = (struct mem *)(void *)ram;
 308
 309   MEM_STATS_AVAIL(avail, MEM_SIZE_ALIGNED);
 310
 311   if(sys_mutex_new(&mem_mutex) != ERR_OK) {
 312     LWIP_ASSERT("failed to create mem_mutex", 0);
 313   }
 314 }
 315
 316 /**
 317  * Put a struct mem back on the heap
 318  *
 319  * @param rmem is the data portion of a struct mem as returned by a previous
 320  *             call to mem_malloc()
 321  */
 322 void
 323 mem_free(void *rmem)
 324 {
 325   struct mem *mem;
 326   LWIP_MEM_FREE_DECL_PROTECT();
 327
 328   if (rmem == NULL) {
 329     LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("mem_free(p == NULL) was called.\n"));
 330     return;
 331   }
 332   LWIP_ASSERT("mem_free: sanity check alignment", (((mem_ptr_t)rmem) & (MEM_ALIGNMENT-1)) == 0);
 333
 334   LWIP_ASSERT("mem_free: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
 335     (u8_t *)rmem < (u8_t *)ram_end);
 336
 337   if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
 338     SYS_ARCH_DECL_PROTECT(lev);
 339     LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("mem_free: illegal memory\n"));
 340     /* protect mem stats from concurrent access */
 341     SYS_ARCH_PROTECT(lev);
 342     MEM_STATS_INC(illegal);
 343     SYS_ARCH_UNPROTECT(lev);
 344     return;
 345   }
 346   /* protect the heap from concurrent access */
 347   LWIP_MEM_FREE_PROTECT();
 348   /* Get the corresponding struct mem ... */
 349   mem = (struct mem *)(void *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);
 350   /* ... which has to be in a used state ... */
 351   LWIP_ASSERT("mem_free: mem->used", mem->used);
 352   /* ... and is now unused. */
 353   mem->used = 0;
 354
 355   if (mem < lfree) {
 356     /* the newly freed struct is now the lowest */
 357     lfree = mem;
 358   }
 359
 360   MEM_STATS_DEC_USED(used, mem->next - (mem_size_t)(((u8_t *)mem - ram)));
 361
 362   /* finally, see if prev or next are free also */
 363   plug_holes(mem);
 364 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
 365   mem_free_count = 1;
 366 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
 367   LWIP_MEM_FREE_UNPROTECT();
 368 }
 369
 370 /**
 371  * Shrink memory returned by mem_malloc().
 372  *
 373  * @param rmem pointer to memory allocated by mem_malloc the is to be shrinked
 374  * @param newsize required size after shrinking (needs to be smaller than or
 375  *                equal to the previous size)
 376  * @return for compatibility reasons: is always == rmem, at the moment
 377  *         or NULL if newsize is > old size, in which case rmem is NOT touched
 378  *         or freed!
 379  */
 380 void *
 381 mem_trim(void *rmem, mem_size_t newsize)
 382 {
 383   mem_size_t size;
 384   mem_size_t ptr, ptr2;
 385   struct mem *mem, *mem2;
 386   /* use the FREE_PROTECT here: it protects with sem OR SYS_ARCH_PROTECT */
 387   LWIP_MEM_FREE_DECL_PROTECT();
 388
 389   /* Expand the size of the allocated memory region so that we can
 390      adjust for alignment. */
 391   newsize = LWIP_MEM_ALIGN_SIZE(newsize);
 392
 393   if(newsize < MIN_SIZE_ALIGNED) {
 394     /* every data block must be at least MIN_SIZE_ALIGNED long */
 395     newsize = MIN_SIZE_ALIGNED;
 396   }
 397
 398   if (newsize > MEM_SIZE_ALIGNED) {
 399     return NULL;
 400   }
 401
 402   LWIP_ASSERT("mem_trim: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
 403    (u8_t *)rmem < (u8_t *)ram_end);
 404
 405   if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
 406     SYS_ARCH_DECL_PROTECT(lev);
 407     LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("mem_trim: illegal memory\n"));
 408     /* protect mem stats from concurrent access */
 409     SYS_ARCH_PROTECT(lev);
 410     MEM_STATS_INC(illegal);
 411     SYS_ARCH_UNPROTECT(lev);
 412     return rmem;
 413   }
 414   /* Get the corresponding struct mem ... */
 415   mem = (struct mem *)(void *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);
 416   /* ... and its offset pointer */
 417   ptr = (mem_size_t)((u8_t *)mem - ram);
 418
 419   size = mem->next - ptr - SIZEOF_STRUCT_MEM;
 420   LWIP_ASSERT("mem_trim can only shrink memory", newsize <= size);
 421   if (newsize > size) {
 422     /* not supported */
 423     return NULL;
 424   }
 425   if (newsize == size) {
 426     /* No change in size, simply return */
 427     return rmem;
 428   }
 429
 430   /* protect the heap from concurrent access */
 431   LWIP_MEM_FREE_PROTECT();
 432
 433   mem2 = (struct mem *)(void *)&ram[mem->next];
 434   if(mem2->used == 0) {
 435     /* The next struct is unused, we can simply move it at little */
 436     mem_size_t next;
 437     /* remember the old next pointer */
 438     next = mem2->next;
 439     /* create new struct mem which is moved directly after the shrinked mem */
 440     ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
 441     if (lfree == mem2) {
 442       lfree = (struct mem *)(void *)&ram[ptr2];
 443     }
 444     mem2 = (struct mem *)(void *)&ram[ptr2];
 445     mem2->used = 0;
 446     /* restore the next pointer */
 447     mem2->next = next;
 448     /* link it back to mem */
 449     mem2->prev = ptr;
 450     /* link mem to it */
 451     mem->next = ptr2;
 452     /* last thing to restore linked list: as we have moved mem2,
 453      * let 'mem2->next->prev' point to mem2 again. but only if mem2->next is not
 454      * the end of the heap */
 455     if (mem2->next != MEM_SIZE_ALIGNED) {
 456       ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
 457     }
 458     MEM_STATS_DEC_USED(used, (size - newsize));
 459     /* no need to plug holes, we've already done that */
 460   } else if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED <= size) {
 461     /* Next struct is used but there's room for another struct mem with
 462      * at least MIN_SIZE_ALIGNED of data.
 463      * Old size ('size') must be big enough to contain at least 'newsize' plus a struct mem
 464      * ('SIZEOF_STRUCT_MEM') with some data ('MIN_SIZE_ALIGNED').
 465      * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty
 466      *       region that couldn't hold data, but when mem->next gets freed,
 467      *       the 2 regions would be combined, resulting in more free memory */
 468     ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
 469     mem2 = (struct mem *)(void *)&ram[ptr2];
 470     if (mem2 < lfree) {
 471       lfree = mem2;
 472     }
 473     mem2->used = 0;
 474     mem2->next = mem->next;
 475     mem2->prev = ptr;
 476     mem->next = ptr2;
 477     if (mem2->next != MEM_SIZE_ALIGNED) {
 478       ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
 479     }
 480     MEM_STATS_DEC_USED(used, (size - newsize));
 481     /* the original mem->next is used, so no need to plug holes! */
 482   }
 483   /* else {
 484     next struct mem is used but size between mem and mem2 is not big enough
 485     to create another struct mem
 486     -> don't do anyhting.
 487     -> the remaining space stays unused since it is too small
 488   } */
 489 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
 490   mem_free_count = 1;
 491 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
 492   LWIP_MEM_FREE_UNPROTECT();
 493   return rmem;
 494 }
 495
 496 /**
 497  * Adam's mem_malloc() plus solution for bug #17922
 498  * Allocate a block of memory with a minimum of 'size' bytes.
 499  *
 500  * @param size is the minimum size of the requested block in bytes.
 501  * @return pointer to allocated memory or NULL if no free memory was found.
 502  *
 503  * Note that the returned value will always be aligned (as defined by MEM_ALIGNMENT).
 504  */
 505 void *
 506 mem_malloc(mem_size_t size)
 507 {
 508   mem_size_t ptr, ptr2;
 509   struct mem *mem, *mem2;
 510 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
 511   u8_t local_mem_free_count = 0;
 512 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
 513   LWIP_MEM_ALLOC_DECL_PROTECT();
 514
 515   if (size == 0) {
 516     return NULL;
 517   }
 518
 519   /* Expand the size of the allocated memory region so that we can
 520      adjust for alignment. */
 521   size = LWIP_MEM_ALIGN_SIZE(size);
 522
 523   if(size < MIN_SIZE_ALIGNED) {
 524     /* every data block must be at least MIN_SIZE_ALIGNED long */
 525     size = MIN_SIZE_ALIGNED;
 526   }
 527
 528   if (size > MEM_SIZE_ALIGNED) {
 529     return NULL;
 530   }
 531
 532   /* protect the heap from concurrent access */
 533   sys_mutex_lock(&mem_mutex);
 534   LWIP_MEM_ALLOC_PROTECT();
 535 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
 536   /* run as long as a mem_free disturbed mem_malloc */
 537   do {
 538     local_mem_free_count = 0;
 539 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
 540
 541     /* Scan through the heap searching for a free block that is big enough,
 542      * beginning with the lowest free block.
 543      */
 544     for (ptr = (mem_size_t)((u8_t *)lfree - ram); ptr < MEM_SIZE_ALIGNED - size;
 545          ptr = ((struct mem *)(void *)&ram[ptr])->next) {
 546       mem = (struct mem *)(void *)&ram[ptr];
 547 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
 548       mem_free_count = 0;
 549       LWIP_MEM_ALLOC_UNPROTECT();
 550       /* allow mem_free to run */
 551       LWIP_MEM_ALLOC_PROTECT();
 552       if (mem_free_count != 0) {
 553         local_mem_free_count = mem_free_count;
 554       }
 555       mem_free_count = 0;
 556 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
 557
 558       if ((!mem->used) &&
 559           (mem->next - (ptr + SIZEOF_STRUCT_MEM)) >= size) {
 560         /* mem is not used and at least perfect fit is possible:
 561          * mem->next - (ptr + SIZEOF_STRUCT_MEM) gives us the 'user data size' of mem */
 562
 563         if (mem->next - (ptr + SIZEOF_STRUCT_MEM) >= (size + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED)) {
 564           /* (in addition to the above, we test if another struct mem (SIZEOF_STRUCT_MEM) containing
 565            * at least MIN_SIZE_ALIGNED of data also fits in the 'user data space' of 'mem')
 566            * -> split large block, create empty remainder,
 567            * remainder must be large enough to contain MIN_SIZE_ALIGNED data: if
 568            * mem->next - (ptr + (2*SIZEOF_STRUCT_MEM)) == size,
 569            * struct mem would fit in but no data between mem2 and mem2->next
 570            * @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty
 571            *       region that couldn't hold data, but when mem->next gets freed,
 572            *       the 2 regions would be combined, resulting in more free memory
 573            */
 574           ptr2 = ptr + SIZEOF_STRUCT_MEM + size;
 575           /* create mem2 struct */
 576           mem2 = (struct mem *)(void *)&ram[ptr2];
 577           mem2->used = 0;
 578           mem2->next = mem->next;
 579           mem2->prev = ptr;
 580           /* and insert it between mem and mem->next */
 581           mem->next = ptr2;
 582           mem->used = 1;
 583
 584           if (mem2->next != MEM_SIZE_ALIGNED) {
 585             ((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
 586           }
 587           MEM_STATS_INC_USED(used, (size + SIZEOF_STRUCT_MEM));
 588         } else {
 589           /* (a mem2 struct does no fit into the user data space of mem and mem->next will always
 590            * be used at this point: if not we have 2 unused structs in a row, plug_holes should have
 591            * take care of this).
 592            * -> near fit or excact fit: do not split, no mem2 creation
 593            * also can't move mem->next directly behind mem, since mem->next
 594            * will always be used at this point!
 595            */
 596           mem->used = 1;
 597           MEM_STATS_INC_USED(used, mem->next - (mem_size_t)((u8_t *)mem - ram));
 598         }
 599
 600         if (mem == lfree) {
 601           /* Find next free block after mem and update lowest free pointer */
 602           while (lfree->used && lfree != ram_end) {
 603             LWIP_MEM_ALLOC_UNPROTECT();
 604             /* prevent high interrupt latency... */
 605             LWIP_MEM_ALLOC_PROTECT();
 606             lfree = (struct mem *)(void *)&ram[lfree->next];
 607           }
 608           LWIP_ASSERT("mem_malloc: !lfree->used", ((lfree == ram_end) || (!lfree->used)));
 609         }
 610         LWIP_MEM_ALLOC_UNPROTECT();
 611         sys_mutex_unlock(&mem_mutex);
 612         LWIP_ASSERT("mem_malloc: allocated memory not above ram_end.",
 613          (mem_ptr_t)mem + SIZEOF_STRUCT_MEM + size <= (mem_ptr_t)ram_end);
 614                                 LWIP_ASSERT("mem_malloc: allocated memory properly aligned.",
 615                                                 ((mem_ptr_t)mem + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT == 0);
 616         LWIP_ASSERT("mem_malloc: sanity check alignment",
 617                                                 (((mem_ptr_t)mem) & (MEM_ALIGNMENT-1)) == 0);
 618
 619         return (u8_t *)mem + SIZEOF_STRUCT_MEM;
 620       }
 621     }
 622 #if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
 623     /* if we got interrupted by a mem_free, try again */
 624   } while(local_mem_free_count != 0);
 625 #endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
 626   LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("mem_malloc: could not allocate %"S16_F" bytes\n", (s16_t)size));
 627   MEM_STATS_INC(err);
 628   LWIP_MEM_ALLOC_UNPROTECT();
 629   sys_mutex_unlock(&mem_mutex);
 630   return NULL;
 631 }
 632
 633 #endif /* MEM_USE_POOLS */
 634 /**
 635  * Contiguously allocates enough space for count objects that are size bytes
 636  * of memory each and returns a pointer to the allocated memory.
 637  *
 638  * The allocated memory is filled with bytes of value zero.
 639  *
 640  * @param count number of objects to allocate
 641  * @param size size of the objects to allocate
 642  * @return pointer to allocated memory / NULL pointer if there is an error
 643  */
 644 void *mem_calloc(mem_size_t count, mem_size_t size)
 645 {
 646   void *p;
 647
 648   /* allocate 'count' objects of size 'size' */
 649   p = mem_malloc(count * size);
 650   if (p) {
 651     /* zero the memory */
 652     memset(p, 0, count * size);
 653   }
 654   return p;
 655 }
 656
 657 #endif /* !MEM_LIBC_MALLOC */