Statistics
| Branch: | Revision:

ffmpeg / libavcodec / mem.c @ b6204677

History | View | Annotate | Download (3.69 KB)

1 d01fe86d Fabrice Bellard
/*
2
 * default memory allocator for libavcodec
3
 * Copyright (c) 2002 Fabrice Bellard.
4
 *
5
 * This library is free software; you can redistribute it and/or
6
 * modify it under the terms of the GNU Lesser General Public
7
 * License as published by the Free Software Foundation; either
8
 * version 2 of the License, or (at your option) any later version.
9
 *
10
 * This library is distributed in the hope that it will be useful,
11
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13
 * Lesser General Public License for more details.
14
 *
15
 * You should have received a copy of the GNU Lesser General Public
16
 * License along with this library; if not, write to the Free Software
17
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18
 */
19 115329f1 Diego Biurrun
20 983e3246 Michael Niedermayer
/**
21
 * @file mem.c
22
 * default memory allocator for libavcodec.
23
 */
24 115329f1 Diego Biurrun
25 d01fe86d Fabrice Bellard
#include "avcodec.h"
26 8e1e6f31 Fabrice Bellard
27
/* here we can use OS dependant allocation functions */
28
#undef malloc
29
#undef free
30
#undef realloc
31
32 d01fe86d Fabrice Bellard
#ifdef HAVE_MALLOC_H
33
#include <malloc.h>
34
#endif
35
36
/* you can redefine av_malloc and av_free in your project to use your
37
   memory allocator. You do not need to suppress this file because the
38
   linker will do it automatically */
39
40 115329f1 Diego Biurrun
/**
41 8e1e6f31 Fabrice Bellard
 * Memory allocation of size byte with alignment suitable for all
42
 * memory accesses (including vectors if available on the
43
 * CPU). av_malloc(0) must return a non NULL pointer.
44
 */
45 18f77016 Zdenek Kabelac
void *av_malloc(unsigned int size)
46 d01fe86d Fabrice Bellard
{
47
    void *ptr;
48 88730be6 Måns Rullgård
#ifdef MEMALIGN_HACK
49 d5f121e2 Michael Niedermayer
    int diff;
50 88730be6 Måns Rullgård
#endif
51 0ecca7a4 Michael Niedermayer
52
    /* lets disallow possible ambiguous cases */
53
    if(size > INT_MAX)
54
        return NULL;
55 115329f1 Diego Biurrun
56 da9b170c Michael Niedermayer
#ifdef MEMALIGN_HACK
57
    ptr = malloc(size+16+1);
58
    diff= ((-(int)ptr - 1)&15) + 1;
59
    ptr += diff;
60
    ((char*)ptr)[-1]= diff;
61 115329f1 Diego Biurrun
#elif defined (HAVE_MEMALIGN)
62 8f2b21a8 Michael Niedermayer
    ptr = memalign(16,size);
63 115329f1 Diego Biurrun
    /* Why 64?
64 d01fe86d Fabrice Bellard
       Indeed, we should align it:
65
         on 4 for 386
66
         on 16 for 486
67 bb270c08 Diego Biurrun
         on 32 for 586, PPro - k6-III
68
         on 64 for K7 (maybe for P3 too).
69 d01fe86d Fabrice Bellard
       Because L1 and L2 caches are aligned on those values.
70
       But I don't want to code such logic here!
71
     */
72 8f2b21a8 Michael Niedermayer
     /* Why 16?
73
        because some cpus need alignment, for example SSE2 on P4, & most RISC cpus
74
        it will just trigger an exception and the unaligned load will be done in the
75
        exception handler or it will just segfault (SSE2 on P4)
76
        Why not larger? because i didnt see a difference in benchmarks ...
77
     */
78
     /* benchmarks with p3
79 bb270c08 Diego Biurrun
        memalign(64)+1          3071,3051,3032
80
        memalign(64)+2          3051,3032,3041
81
        memalign(64)+4          2911,2896,2915
82
        memalign(64)+8          2545,2554,2550
83
        memalign(64)+16         2543,2572,2563
84
        memalign(64)+32         2546,2545,2571
85
        memalign(64)+64         2570,2533,2558
86 115329f1 Diego Biurrun

87 8f2b21a8 Michael Niedermayer
        btw, malloc seems to do 8 byte alignment by default here
88
     */
89 d01fe86d Fabrice Bellard
#else
90
    ptr = malloc(size);
91
#endif
92
    return ptr;
93
}
94
95 b7a22d84 Michael Niedermayer
/**
96 8e1e6f31 Fabrice Bellard
 * av_realloc semantics (same as glibc): if ptr is NULL and size > 0,
97
 * identical to malloc(size). If size is zero, it is identical to
98 115329f1 Diego Biurrun
 * free(ptr) and NULL is returned.
99 b7a22d84 Michael Niedermayer
 */
100 8e1e6f31 Fabrice Bellard
void *av_realloc(void *ptr, unsigned int size)
101
{
102 88730be6 Måns Rullgård
#ifdef MEMALIGN_HACK
103 d5f121e2 Michael Niedermayer
    int diff;
104 88730be6 Måns Rullgård
#endif
105
106 0ecca7a4 Michael Niedermayer
    /* lets disallow possible ambiguous cases */
107
    if(size > INT_MAX)
108
        return NULL;
109
110 da9b170c Michael Niedermayer
#ifdef MEMALIGN_HACK
111
    //FIXME this isnt aligned correctly though it probably isnt needed
112 c07a22fb Michael Niedermayer
    if(!ptr) return av_malloc(size);
113
    diff= ((char*)ptr)[-1];
114 da9b170c Michael Niedermayer
    return realloc(ptr - diff, size + diff) + diff;
115
#else
116 8e1e6f31 Fabrice Bellard
    return realloc(ptr, size);
117 da9b170c Michael Niedermayer
#endif
118 b7a22d84 Michael Niedermayer
}
119
120 d01fe86d Fabrice Bellard
/* NOTE: ptr = NULL is explicetly allowed */
121
void av_free(void *ptr)
122
{
123
    /* XXX: this test should not be needed on most libcs */
124
    if (ptr)
125 da9b170c Michael Niedermayer
#ifdef MEMALIGN_HACK
126
        free(ptr - ((char*)ptr)[-1]);
127
#else
128 d01fe86d Fabrice Bellard
        free(ptr);
129 da9b170c Michael Niedermayer
#endif
130 d01fe86d Fabrice Bellard
}