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