PeerStreamer

/*

 * 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 libavutil/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"

/* here we can use OS-dependent allocation functions */

#undef free

#undef malloc

#undef realloc

/* 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

    if (posix_memalign(&ptr,16,size))

        ptr = NULL;

#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;

}