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/*
* default memory allocator for libavutil
* Copyright (c) 2002 Fabrice Bellard
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file mem.c
* default memory allocator for libavutil.
*/
#include "config.h"
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#if HAVE_MALLOC_H
#include <malloc.h>
#endif
#include "mem.h"
/* you can redefine av_malloc and av_free in your project to use your
memory allocator. You do not need to suppress this file because the
linker will do it automatically */
void *av_malloc(unsigned int size)
{
void *ptr = NULL;
#if CONFIG_MEMALIGN_HACK
long diff;
#endif
/* let's disallow possible ambiguous cases */
if(size > (INT_MAX-16) )
return NULL;
#if CONFIG_MEMALIGN_HACK
ptr = malloc(size+16);
if(!ptr)
return ptr;
diff= ((-(long)ptr - 1)&15) + 1;
ptr = (char*)ptr + diff;
((char*)ptr)[-1]= diff;
#elif HAVE_POSIX_MEMALIGN
posix_memalign(&ptr,16,size);
#elif HAVE_MEMALIGN
ptr = memalign(16,size);
/* Why 64?
Indeed, we should align it:
on 4 for 386
on 16 for 486
on 32 for 586, PPro - k6-III
on 64 for K7 (maybe for P3 too).
Because L1 and L2 caches are aligned on those values.
But I don't want to code such logic here!
*/
/* Why 16?
Because some CPUs need alignment, for example SSE2 on P4, & most RISC CPUs
it will just trigger an exception and the unaligned load will be done in the
exception handler or it will just segfault (SSE2 on P4)
Why not larger? Because I did not see a difference in benchmarks ...
*/
/* benchmarks with p3
memalign(64)+1 3071,3051,3032
memalign(64)+2 3051,3032,3041
memalign(64)+4 2911,2896,2915
memalign(64)+8 2545,2554,2550
memalign(64)+16 2543,2572,2563
memalign(64)+32 2546,2545,2571
memalign(64)+64 2570,2533,2558
btw, malloc seems to do 8 byte alignment by default here
*/
#else
ptr = malloc(size);
#endif
return ptr;
}
void *av_realloc(void *ptr, unsigned int size)
{
#if CONFIG_MEMALIGN_HACK
int diff;
#endif
/* let's disallow possible ambiguous cases */
if(size > (INT_MAX-16) )
return NULL;
#if CONFIG_MEMALIGN_HACK
//FIXME this isn't aligned correctly, though it probably isn't needed
if(!ptr) return av_malloc(size);
diff= ((char*)ptr)[-1];
return (char*)realloc((char*)ptr - diff, size + diff) + diff;
#else
return realloc(ptr, size);
#endif
}
void av_free(void *ptr)
{
/* XXX: this test should not be needed on most libcs */
if (ptr)
#if CONFIG_MEMALIGN_HACK
free((char*)ptr - ((char*)ptr)[-1]);
#else
free(ptr);
#endif
}
void av_freep(void *arg)
{
void **ptr= (void**)arg;
av_free(*ptr);
*ptr = NULL;
}
void *av_mallocz(unsigned int size)
{
void *ptr = av_malloc(size);
if (ptr)
memset(ptr, 0, size);
return ptr;
}
char *av_strdup(const char *s)
{
char *ptr= NULL;
if(s){
int len = strlen(s) + 1;
ptr = av_malloc(len);
if (ptr)
memcpy(ptr, s, len);
}
return ptr;
}
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