libavutil/mem.c

   1 /*
   2  * default memory allocator for libavutil
   3  * Copyright (c) 2002 Fabrice Bellard
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * Libav is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * default memory allocator for libavutil
  25  */
  26
  27 #include "config.h"
  28
  29 #include <limits.h>
  30 #include <stdint.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #if HAVE_MALLOC_H
  34 #include <malloc.h>
  35 #endif
  36
  37 #include "avutil.h"
  38 #include "common.h"
  39 #include "intreadwrite.h"
  40 #include "mem.h"
  41
  42 #ifdef MALLOC_PREFIX
  43
  44 #define malloc         AV_JOIN(MALLOC_PREFIX, malloc)
  45 #define memalign       AV_JOIN(MALLOC_PREFIX, memalign)
  46 #define posix_memalign AV_JOIN(MALLOC_PREFIX, posix_memalign)
  47 #define realloc        AV_JOIN(MALLOC_PREFIX, realloc)
  48 #define free           AV_JOIN(MALLOC_PREFIX, free)
  49
  50 void *malloc(size_t size);
  51 void *memalign(size_t align, size_t size);
  52 int   posix_memalign(void **ptr, size_t align, size_t size);
  53 void *realloc(void *ptr, size_t size);
  54 void  free(void *ptr);
  55
  56 #endif /* MALLOC_PREFIX */
  57
  58 /* You can redefine av_malloc and av_free in your project to use your
  59  * memory allocator. You do not need to suppress this file because the
  60  * linker will do it automatically. */
  61
  62 void *av_malloc(size_t size)
  63 {
  64     void *ptr = NULL;
  65
  66     /* let's disallow possibly ambiguous cases */
  67     if (size > (INT_MAX - 32) || !size)
  68         return NULL;
  69
  70 #if HAVE_POSIX_MEMALIGN
  71     if (posix_memalign(&ptr, 32, size))
  72         ptr = NULL;
  73 #elif HAVE_ALIGNED_MALLOC
  74     ptr = _aligned_malloc(size, 32);
  75 #elif HAVE_MEMALIGN
  76     ptr = memalign(32, size);
  77     /* Why 64?
  78      * Indeed, we should align it:
  79      *   on  4 for 386
  80      *   on 16 for 486
  81      *   on 32 for 586, PPro - K6-III
  82      *   on 64 for K7 (maybe for P3 too).
  83      * Because L1 and L2 caches are aligned on those values.
  84      * But I don't want to code such logic here!
  85      */
  86     /* Why 32?
  87      * For AVX ASM. SSE / NEON needs only 16.
  88      * Why not larger? Because I did not see a difference in benchmarks ...
  89      */
  90     /* benchmarks with P3
  91      * memalign(64) + 1          3071, 3051, 3032
  92      * memalign(64) + 2          3051, 3032, 3041
  93      * memalign(64) + 4          2911, 2896, 2915
  94      * memalign(64) + 8          2545, 2554, 2550
  95      * memalign(64) + 16         2543, 2572, 2563
  96      * memalign(64) + 32         2546, 2545, 2571
  97      * memalign(64) + 64         2570, 2533, 2558
  98      *
  99      * BTW, malloc seems to do 8-byte alignment by default here.
 100      */
 101 #else
 102     ptr = malloc(size);
 103 #endif
 104     return ptr;
 105 }
 106
 107 void *av_realloc(void *ptr, size_t size)
 108 {
 109     /* let's disallow possibly ambiguous cases */
 110     if (size > (INT_MAX - 16))
 111         return NULL;
 112
 113 #if HAVE_ALIGNED_MALLOC
 114     return _aligned_realloc(ptr, size, 32);
 115 #else
 116     return realloc(ptr, size);
 117 #endif
 118 }
 119
 120 int av_reallocp(void *ptr, size_t size)
 121 {
 122     void *val;
 123
 124     if (!size) {
 125         av_freep(ptr);
 126         return 0;
 127     }
 128
 129     memcpy(&val, ptr, sizeof(val));
 130     val = av_realloc(val, size);
 131
 132     if (!val) {
 133         av_freep(ptr);
 134         return AVERROR(ENOMEM);
 135     }
 136
 137     memcpy(ptr, &val, sizeof(val));
 138     return 0;
 139 }
 140
 141 void *av_malloc_array(size_t nmemb, size_t size)
 142 {
 143     if (!size || nmemb >= INT_MAX / size)
 144         return NULL;
 145     return av_malloc(nmemb * size);
 146 }
 147
 148 void *av_mallocz_array(size_t nmemb, size_t size)
 149 {
 150     if (!size || nmemb >= INT_MAX / size)
 151         return NULL;
 152     return av_mallocz(nmemb * size);
 153 }
 154
 155 void *av_realloc_array(void *ptr, size_t nmemb, size_t size)
 156 {
 157     if (!size || nmemb >= INT_MAX / size)
 158         return NULL;
 159     return av_realloc(ptr, nmemb * size);
 160 }
 161
 162 int av_reallocp_array(void *ptr, size_t nmemb, size_t size)
 163 {
 164     void *val;
 165
 166     if (!size || nmemb >= INT_MAX / size)
 167         return AVERROR(ENOMEM);
 168     if (!nmemb) {
 169         av_freep(ptr);
 170         return 0;
 171     }
 172
 173     memcpy(&val, ptr, sizeof(val));
 174     val = av_realloc(val, nmemb * size);
 175     if (!val) {
 176         av_freep(ptr);
 177         return AVERROR(ENOMEM);
 178     }
 179
 180     memcpy(ptr, &val, sizeof(val));
 181     return 0;
 182 }
 183
 184 void av_free(void *ptr)
 185 {
 186 #if HAVE_ALIGNED_MALLOC
 187     _aligned_free(ptr);
 188 #else
 189     free(ptr);
 190 #endif
 191 }
 192
 193 void av_freep(void *arg)
 194 {
 195     void *val;
 196
 197     memcpy(&val, arg, sizeof(val));
 198     memcpy(arg, &(void *){ NULL }, sizeof(val));
 199     av_free(val);
 200 }
 201
 202 void *av_mallocz(size_t size)
 203 {
 204     void *ptr = av_malloc(size);
 205     if (ptr)
 206         memset(ptr, 0, size);
 207     return ptr;
 208 }
 209
 210 char *av_strdup(const char *s)
 211 {
 212     char *ptr = NULL;
 213     if (s) {
 214         int len = strlen(s) + 1;
 215         ptr = av_realloc(NULL, len);
 216         if (ptr)
 217             memcpy(ptr, s, len);
 218     }
 219     return ptr;
 220 }
 221
 222 char *av_strndup(const char *s, size_t len)
 223 {
 224     char *ret = NULL, *end;
 225
 226     if (!s)
 227         return NULL;
 228
 229     end = memchr(s, 0, len);
 230     if (end)
 231         len = end - s;
 232
 233     ret = av_realloc(NULL, len + 1);
 234     if (!ret)
 235         return NULL;
 236
 237     memcpy(ret, s, len);
 238     ret[len] = 0;
 239     return ret;
 240 }
 241
 242 static void fill16(uint8_t *dst, int len)
 243 {
 244     uint32_t v = AV_RN16(dst - 2);
 245
 246     v |= v << 16;
 247
 248     while (len >= 4) {
 249         AV_WN32(dst, v);
 250         dst += 4;
 251         len -= 4;
 252     }
 253
 254     while (len--) {
 255         *dst = dst[-2];
 256         dst++;
 257     }
 258 }
 259
 260 static void fill24(uint8_t *dst, int len)
 261 {
 262 #if HAVE_BIGENDIAN
 263     uint32_t v = AV_RB24(dst - 3);
 264     uint32_t a = v << 8  | v >> 16;
 265     uint32_t b = v << 16 | v >> 8;
 266     uint32_t c = v << 24 | v;
 267 #else
 268     uint32_t v = AV_RL24(dst - 3);
 269     uint32_t a = v       | v << 24;
 270     uint32_t b = v >> 8  | v << 16;
 271     uint32_t c = v >> 16 | v << 8;
 272 #endif
 273
 274     while (len >= 12) {
 275         AV_WN32(dst,     a);
 276         AV_WN32(dst + 4, b);
 277         AV_WN32(dst + 8, c);
 278         dst += 12;
 279         len -= 12;
 280     }
 281
 282     if (len >= 4) {
 283         AV_WN32(dst, a);
 284         dst += 4;
 285         len -= 4;
 286     }
 287
 288     if (len >= 4) {
 289         AV_WN32(dst, b);
 290         dst += 4;
 291         len -= 4;
 292     }
 293
 294     while (len--) {
 295         *dst = dst[-3];
 296         dst++;
 297     }
 298 }
 299
 300 static void fill32(uint8_t *dst, int len)
 301 {
 302     uint32_t v = AV_RN32(dst - 4);
 303
 304     while (len >= 4) {
 305         AV_WN32(dst, v);
 306         dst += 4;
 307         len -= 4;
 308     }
 309
 310     while (len--) {
 311         *dst = dst[-4];
 312         dst++;
 313     }
 314 }
 315
 316 void av_memcpy_backptr(uint8_t *dst, int back, int cnt)
 317 {
 318     const uint8_t *src = &dst[-back];
 319     if (!back)
 320         return;
 321
 322     if (back == 1) {
 323         memset(dst, *src, cnt);
 324     } else if (back == 2) {
 325         fill16(dst, cnt);
 326     } else if (back == 3) {
 327         fill24(dst, cnt);
 328     } else if (back == 4) {
 329         fill32(dst, cnt);
 330     } else {
 331         if (cnt >= 16) {
 332             int blocklen = back;
 333             while (cnt > blocklen) {
 334                 memcpy(dst, src, blocklen);
 335                 dst       += blocklen;
 336                 cnt       -= blocklen;
 337                 blocklen <<= 1;
 338             }
 339             memcpy(dst, src, cnt);
 340             return;
 341         }
 342         if (cnt >= 8) {
 343             AV_COPY32U(dst,     src);
 344             AV_COPY32U(dst + 4, src + 4);
 345             src += 8;
 346             dst += 8;
 347             cnt -= 8;
 348         }
 349         if (cnt >= 4) {
 350             AV_COPY32U(dst, src);
 351             src += 4;
 352             dst += 4;
 353             cnt -= 4;
 354         }
 355         if (cnt >= 2) {
 356             AV_COPY16U(dst, src);
 357             src += 2;
 358             dst += 2;
 359             cnt -= 2;
 360         }
 361         if (cnt)
 362             *dst = *src;
 363     }
 364 }
 365
 366 void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
 367 {
 368     if (min_size < *size)
 369         return ptr;
 370
 371     min_size = FFMAX(17 * min_size / 16 + 32, min_size);
 372
 373     ptr = av_realloc(ptr, min_size);
 374     /* we could set this to the unmodified min_size but this is safer
 375      * if the user lost the ptr and uses NULL now
 376      */
 377     if (!ptr)
 378         min_size = 0;
 379
 380     *size = min_size;
 381
 382     return ptr;
 383 }
 384
 385 void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size)
 386 {
 387     void **p = ptr;
 388     if (min_size < *size)
 389         return;
 390     min_size = FFMAX(17 * min_size / 16 + 32, min_size);
 391     av_free(*p);
 392     *p = av_malloc(min_size);
 393     if (!*p)
 394         min_size = 0;
 395     *size = min_size;
 396 }