use av_realloc()
[libav.git] / libavcodec / mem.c
CommitLineData
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1/*
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#include "avcodec.h"
20#ifdef HAVE_MALLOC_H
21#include <malloc.h>
22#endif
23
24/* you can redefine av_malloc and av_free in your project to use your
25 memory allocator. You do not need to suppress this file because the
26 linker will do it automatically */
27
28/* memory alloc */
18f77016 29void *av_malloc(unsigned int size)
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30{
31 void *ptr;
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32
33// if(size==0) return NULL;
34
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35#if defined (HAVE_MEMALIGN)
36 ptr = memalign(16,size);
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37 /* Why 64?
38 Indeed, we should align it:
39 on 4 for 386
40 on 16 for 486
41 on 32 for 586, PPro - k6-III
42 on 64 for K7 (maybe for P3 too).
43 Because L1 and L2 caches are aligned on those values.
44 But I don't want to code such logic here!
45 */
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46 /* Why 16?
47 because some cpus need alignment, for example SSE2 on P4, & most RISC cpus
48 it will just trigger an exception and the unaligned load will be done in the
49 exception handler or it will just segfault (SSE2 on P4)
50 Why not larger? because i didnt see a difference in benchmarks ...
51 */
52 /* benchmarks with p3
53 memalign(64)+1 3071,3051,3032
54 memalign(64)+2 3051,3032,3041
55 memalign(64)+4 2911,2896,2915
56 memalign(64)+8 2545,2554,2550
57 memalign(64)+16 2543,2572,2563
58 memalign(64)+32 2546,2545,2571
59 memalign(64)+64 2570,2533,2558
60
61 btw, malloc seems to do 8 byte alignment by default here
62 */
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63#else
64 ptr = malloc(size);
65#endif
66 if (!ptr)
67 return NULL;
8f2b21a8 68//fprintf(stderr, "%X %d\n", (int)ptr, size);
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69 /* NOTE: this memset should not be present */
70 memset(ptr, 0, size);
71 return ptr;
72}
73
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74/**
75 * realloc which does nothing if the block is large enogh
76 */
77void *av_fast_realloc(void *ptr, int *size, int min_size){
78 if(min_size < *size) return ptr;
79
80 *size= min_size + 10*1024;
81
82 return realloc(ptr, *size);
83}
84
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85/* NOTE: ptr = NULL is explicetly allowed */
86void av_free(void *ptr)
87{
88 /* XXX: this test should not be needed on most libcs */
89 if (ptr)
90 free(ptr);
91}
92