1/* 2 * default memory allocator for libavutil 3 * Copyright (c) 2002 Fabrice Bellard 4 * 5 * This file is part of FFmpeg. 6 * 7 * FFmpeg 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 * FFmpeg 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 FFmpeg; 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 <stdlib.h> 31#include <string.h> 32#if HAVE_MALLOC_H 33#include <malloc.h> 34#endif 35 36#include "avutil.h" 37#include "mem.h" 38 39/* here we can use OS-dependent allocation functions */ 40#undef free 41#undef malloc 42#undef realloc 43 44#ifdef MALLOC_PREFIX 45 46#define malloc AV_JOIN(MALLOC_PREFIX, malloc) 47#define memalign AV_JOIN(MALLOC_PREFIX, memalign) 48#define posix_memalign AV_JOIN(MALLOC_PREFIX, posix_memalign) 49#define realloc AV_JOIN(MALLOC_PREFIX, realloc) 50#define free AV_JOIN(MALLOC_PREFIX, free) 51 52void *malloc(size_t size); 53void *memalign(size_t align, size_t size); 54int posix_memalign(void **ptr, size_t align, size_t size); 55void *realloc(void *ptr, size_t size); 56void free(void *ptr); 57 58#endif /* MALLOC_PREFIX */ 59 60/* You can redefine av_malloc and av_free in your project to use your 61 memory allocator. You do not need to suppress this file because the 62 linker will do it automatically. */ 63 64void *av_malloc(unsigned int size) 65{ 66 void *ptr = NULL; 67#if CONFIG_MEMALIGN_HACK 68 long diff; 69#endif 70 71 /* let's disallow possible ambiguous cases */ 72 if(size > (INT_MAX-16) ) 73 return NULL; 74 75#if CONFIG_MEMALIGN_HACK 76 ptr = malloc(size+16); 77 if(!ptr) 78 return ptr; 79 diff= ((-(long)ptr - 1)&15) + 1; 80 ptr = (char*)ptr + diff; 81 ((char*)ptr)[-1]= diff; 82#elif HAVE_POSIX_MEMALIGN 83 if (posix_memalign(&ptr,16,size)) 84 ptr = NULL; 85#elif HAVE_MEMALIGN 86 ptr = memalign(16,size); 87 /* Why 64? 88 Indeed, we should align it: 89 on 4 for 386 90 on 16 for 486 91 on 32 for 586, PPro - K6-III 92 on 64 for K7 (maybe for P3 too). 93 Because L1 and L2 caches are aligned on those values. 94 But I don't want to code such logic here! 95 */ 96 /* Why 16? 97 Because some CPUs need alignment, for example SSE2 on P4, & most RISC CPUs 98 it will just trigger an exception and the unaligned load will be done in the 99 exception handler or it will just segfault (SSE2 on P4). 100 Why not larger? Because I did not see a difference in benchmarks ... 101 */ 102 /* benchmarks with P3 103 memalign(64)+1 3071,3051,3032 104 memalign(64)+2 3051,3032,3041 105 memalign(64)+4 2911,2896,2915 106 memalign(64)+8 2545,2554,2550 107 memalign(64)+16 2543,2572,2563 108 memalign(64)+32 2546,2545,2571 109 memalign(64)+64 2570,2533,2558 110 111 BTW, malloc seems to do 8-byte alignment by default here. 112 */ 113#else 114 ptr = malloc(size); 115#endif 116 return ptr; 117} 118 119void *av_realloc(void *ptr, unsigned int size) 120{ 121#if CONFIG_MEMALIGN_HACK 122 int diff; 123#endif 124 125 /* let's disallow possible ambiguous cases */ 126 if(size > (INT_MAX-16) ) 127 return NULL; 128 129#if CONFIG_MEMALIGN_HACK 130 //FIXME this isn't aligned correctly, though it probably isn't needed 131 if(!ptr) return av_malloc(size); 132 diff= ((char*)ptr)[-1]; 133 return (char*)realloc((char*)ptr - diff, size + diff) + diff; 134#else 135 return realloc(ptr, size); 136#endif 137} 138 139void av_free(void *ptr) 140{ 141 /* XXX: this test should not be needed on most libcs */ 142 if (ptr) 143#if CONFIG_MEMALIGN_HACK 144 free((char*)ptr - ((char*)ptr)[-1]); 145#else 146 free(ptr); 147#endif 148} 149 150void av_freep(void *arg) 151{ 152 void **ptr= (void**)arg; 153 av_free(*ptr); 154 *ptr = NULL; 155} 156 157void *av_mallocz(unsigned int size) 158{ 159 void *ptr = av_malloc(size); 160 if (ptr) 161 memset(ptr, 0, size); 162 return ptr; 163} 164 165char *av_strdup(const char *s) 166{ 167 char *ptr= NULL; 168 if(s){ 169 int len = strlen(s) + 1; 170 ptr = av_malloc(len); 171 if (ptr) 172 memcpy(ptr, s, len); 173 } 174 return ptr; 175} 176 177