Statistics
| Branch: | Revision:

ffmpeg / libavutil / mem.c @ 77652a6a

History | View | Annotate | Download (3.86 KB)

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 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
/* you can redefine av_malloc and av_free in your project to use your
39
   memory allocator. You do not need to suppress this file because the
40
   linker will do it automatically */
41

    
42
void *av_malloc(unsigned int size)
43
{
44
    void *ptr = NULL;
45
#if CONFIG_MEMALIGN_HACK
46
    long diff;
47
#endif
48

    
49
    /* let's disallow possible ambiguous cases */
50
    if(size > (INT_MAX-16) )
51
        return NULL;
52

    
53
#if CONFIG_MEMALIGN_HACK
54
    ptr = malloc(size+16);
55
    if(!ptr)
56
        return ptr;
57
    diff= ((-(long)ptr - 1)&15) + 1;
58
    ptr = (char*)ptr + diff;
59
    ((char*)ptr)[-1]= diff;
60
#elif HAVE_POSIX_MEMALIGN
61
    posix_memalign(&ptr,16,size);
62
#elif HAVE_MEMALIGN
63
    ptr = memalign(16,size);
64
    /* Why 64?
65
       Indeed, we should align it:
66
         on 4 for 386
67
         on 16 for 486
68
         on 32 for 586, PPro - k6-III
69
         on 64 for K7 (maybe for P3 too).
70
       Because L1 and L2 caches are aligned on those values.
71
       But I don't want to code such logic here!
72
     */
73
     /* Why 16?
74
        Because some CPUs need alignment, for example SSE2 on P4, & most RISC CPUs
75
        it will just trigger an exception and the unaligned load will be done in the
76
        exception handler or it will just segfault (SSE2 on P4)
77
        Why not larger? Because I did not see a difference in benchmarks ...
78
     */
79
     /* benchmarks with p3
80
        memalign(64)+1          3071,3051,3032
81
        memalign(64)+2          3051,3032,3041
82
        memalign(64)+4          2911,2896,2915
83
        memalign(64)+8          2545,2554,2550
84
        memalign(64)+16         2543,2572,2563
85
        memalign(64)+32         2546,2545,2571
86
        memalign(64)+64         2570,2533,2558
87

88
        btw, malloc seems to do 8 byte alignment by default here
89
     */
90
#else
91
    ptr = malloc(size);
92
#endif
93
    return ptr;
94
}
95

    
96
void *av_realloc(void *ptr, unsigned int size)
97
{
98
#if CONFIG_MEMALIGN_HACK
99
    int diff;
100
#endif
101

    
102
    /* let's disallow possible ambiguous cases */
103
    if(size > (INT_MAX-16) )
104
        return NULL;
105

    
106
#if CONFIG_MEMALIGN_HACK
107
    //FIXME this isn't aligned correctly, though it probably isn't needed
108
    if(!ptr) return av_malloc(size);
109
    diff= ((char*)ptr)[-1];
110
    return (char*)realloc((char*)ptr - diff, size + diff) + diff;
111
#else
112
    return realloc(ptr, size);
113
#endif
114
}
115

    
116
void av_free(void *ptr)
117
{
118
    /* XXX: this test should not be needed on most libcs */
119
    if (ptr)
120
#if CONFIG_MEMALIGN_HACK
121
        free((char*)ptr - ((char*)ptr)[-1]);
122
#else
123
        free(ptr);
124
#endif
125
}
126

    
127
void av_freep(void *arg)
128
{
129
    void **ptr= (void**)arg;
130
    av_free(*ptr);
131
    *ptr = NULL;
132
}
133

    
134
void *av_mallocz(unsigned int size)
135
{
136
    void *ptr = av_malloc(size);
137
    if (ptr)
138
        memset(ptr, 0, size);
139
    return ptr;
140
}
141

    
142
char *av_strdup(const char *s)
143
{
144
    char *ptr= NULL;
145
    if(s){
146
        int len = strlen(s) + 1;
147
        ptr = av_malloc(len);
148
        if (ptr)
149
            memcpy(ptr, s, len);
150
    }
151
    return ptr;
152
}
153