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/* |
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* default memory allocator for libavutil |
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* Copyright (c) 2002 Fabrice Bellard |
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* |
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* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* 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 |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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|
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/** |
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* @file libavutil/mem.c |
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* default memory allocator for libavutil |
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*/ |
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|
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#include "config.h" |
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|
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#include <limits.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#if HAVE_MALLOC_H |
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#include <malloc.h>
#endif
|
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#include "mem.h"
|
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/* here we can use OS-dependent allocation functions */ |
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#undef free
#undef malloc
#undef realloc
|
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/* You can redefine av_malloc and av_free in your project to use your |
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memory allocator. You do not need to suppress this file because the |
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linker will do it automatically. */ |
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|
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void *av_malloc(unsigned int size) |
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{ |
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void *ptr = NULL; |
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#if CONFIG_MEMALIGN_HACK |
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long diff; |
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#endif |
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|
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/* let's disallow possible ambiguous cases */ |
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if(size > (INT_MAX-16) ) |
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return NULL; |
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|
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#if CONFIG_MEMALIGN_HACK |
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ptr = malloc(size+16);
if(!ptr)
return ptr; |
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diff= ((-(long)ptr - 1)&15) + 1; |
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ptr = (char*)ptr + diff; |
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((char*)ptr)[-1]= diff; |
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#elif HAVE_POSIX_MEMALIGN |
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if (posix_memalign(&ptr,16,size))
ptr = NULL; |
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#elif HAVE_MEMALIGN |
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ptr = memalign(16,size); |
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/* Why 64? |
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Indeed, we should align it:
on 4 for 386
on 16 for 486 |
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on 32 for 586, PPro - K6-III |
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on 64 for K7 (maybe for P3 too). |
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Because L1 and L2 caches are aligned on those values.
But I don't want to code such logic here!
*/ |
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/* Why 16? |
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Because some CPUs need alignment, for example SSE2 on P4, & most RISC CPUs |
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it will just trigger an exception and the unaligned load will be done in the |
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exception handler or it will just segfault (SSE2 on P4). |
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Why not larger? Because I did not see a difference in benchmarks ... |
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*/ |
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/* benchmarks with P3 |
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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 |
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|
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BTW, malloc seems to do 8-byte alignment by default here. |
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*/ |
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#else
ptr = malloc(size);
#endif
return ptr;
}
|
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void *av_realloc(void *ptr, unsigned int size)
{ |
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#if CONFIG_MEMALIGN_HACK |
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int diff;
#endif |
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|
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/* let's disallow possible ambiguous cases */ |
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if(size > (INT_MAX-16) ) |
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return NULL;
|
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#if CONFIG_MEMALIGN_HACK |
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//FIXME this isn't aligned correctly, though it probably isn't needed
if(!ptr) return av_malloc(size);
diff= ((char*)ptr)[-1]; |
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ptr= realloc((char*)ptr - diff, size + diff);
if(ptr) ptr = (char*)ptr + diff;
return ptr; |
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#else
return realloc(ptr, size); |
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#endif |
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}
|
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void av_free(void *ptr)
{
/* XXX: this test should not be needed on most libcs */
if (ptr) |
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#if CONFIG_MEMALIGN_HACK |
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free((char*)ptr - ((char*)ptr)[-1]); |
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#else |
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free(ptr); |
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#endif |
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}
|
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void av_freep(void *arg)
{
void **ptr= (void**)arg;
av_free(*ptr);
*ptr = NULL;
}
void *av_mallocz(unsigned int size)
{ |
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void *ptr = av_malloc(size); |
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if (ptr)
memset(ptr, 0, size);
return ptr;
}
char *av_strdup(const char *s)
{ |
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char *ptr= NULL;
if(s){ |
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int len = strlen(s) + 1;
ptr = av_malloc(len);
if (ptr)
memcpy(ptr, s, len); |
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} |
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return ptr;
}
|