mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-23 12:43:46 +02:00
132 lines
3.6 KiB
C
132 lines
3.6 KiB
C
/*
|
|
* default memory allocator for libavcodec
|
|
* Copyright (c) 2002 Fabrice Bellard.
|
|
*
|
|
* This library 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 of the License, or (at your option) any later version.
|
|
*
|
|
* This library 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 this library; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*/
|
|
|
|
/**
|
|
* @file mem.c
|
|
* default memory allocator for libavcodec.
|
|
*/
|
|
|
|
#include "avcodec.h"
|
|
|
|
/* here we can use OS dependant allocation functions */
|
|
#undef malloc
|
|
#undef free
|
|
#undef realloc
|
|
|
|
#ifdef HAVE_MALLOC_H
|
|
#include <malloc.h>
|
|
#endif
|
|
|
|
/* 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 */
|
|
|
|
/**
|
|
* Memory allocation of size byte with alignment suitable for all
|
|
* memory accesses (including vectors if available on the
|
|
* CPU). av_malloc(0) must return a non NULL pointer.
|
|
*/
|
|
void *av_malloc(unsigned int size)
|
|
{
|
|
void *ptr;
|
|
#ifdef MEMALIGN_HACK
|
|
int diff;
|
|
#endif
|
|
|
|
/* lets disallow possible ambiguous cases */
|
|
if(size > INT_MAX)
|
|
return NULL;
|
|
|
|
#ifdef MEMALIGN_HACK
|
|
ptr = malloc(size+16+1);
|
|
diff= ((-(int)ptr - 1)&15) + 1;
|
|
ptr += diff;
|
|
((char*)ptr)[-1]= diff;
|
|
#elif defined (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 didnt 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;
|
|
}
|
|
|
|
/**
|
|
* av_realloc semantics (same as glibc): if ptr is NULL and size > 0,
|
|
* identical to malloc(size). If size is zero, it is identical to
|
|
* free(ptr) and NULL is returned.
|
|
*/
|
|
void *av_realloc(void *ptr, unsigned int size)
|
|
{
|
|
#ifdef MEMALIGN_HACK
|
|
int diff;
|
|
#endif
|
|
|
|
/* lets disallow possible ambiguous cases */
|
|
if(size > INT_MAX)
|
|
return NULL;
|
|
|
|
#ifdef MEMALIGN_HACK
|
|
//FIXME this isnt aligned correctly though it probably isnt needed
|
|
if(!ptr) return av_malloc(size);
|
|
diff= ((char*)ptr)[-1];
|
|
return realloc(ptr - diff, size + diff) + diff;
|
|
#else
|
|
return realloc(ptr, size);
|
|
#endif
|
|
}
|
|
|
|
/* NOTE: ptr = NULL is explicetly allowed */
|
|
void av_free(void *ptr)
|
|
{
|
|
/* XXX: this test should not be needed on most libcs */
|
|
if (ptr)
|
|
#ifdef MEMALIGN_HACK
|
|
free(ptr - ((char*)ptr)[-1]);
|
|
#else
|
|
free(ptr);
|
|
#endif
|
|
}
|
|
|