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