libavutil's av_malloc

gistfile1.c

void *av_malloc(size_t size)
{
    void *ptr = NULL;
#if CONFIG_MEMALIGN_HACK
    long diff;
#endif

    /* let's disallow possible ambiguous cases */
    if (size > (max_alloc_size-32))
        return NULL;

#if CONFIG_MEMALIGN_HACK
    ptr = malloc(size+ALIGN);
    if(!ptr)
        return ptr;
    diff= ((-(long)ptr - 1)&(ALIGN-1)) + 1;
    ptr = (char*)ptr + diff;
    ((char*)ptr)[-1]= diff;
#elif HAVE_POSIX_MEMALIGN
    if (size) //OS X on SDK 10.6 has a broken posix_memalign implementation
    if (posix_memalign(&ptr,ALIGN,size))
        ptr = NULL;
#elif HAVE_MEMALIGN
    ptr = memalign(ALIGN,size);
#else
    ptr = malloc(size);
#endif
    if(!ptr && !size)
        ptr= av_malloc(1);
    return ptr;
}