16 bytes aligned memory malloc and free

见

ffmpeg .\libavcodec\mem.c

 

    void *av_malloc(size_t size)
    {
        char *ptr;
        ptr = malloc(size+16+1);
        diff= ((-(long)ptr - 1)&15) + 1;
        ptr += diff;
        ptr[-1]= diff;
        return ptr;
    }
   
    void av_free(void *ptr)
    {
        if (ptr)
        {
            char *_ptr=ptr;
            free(_ptr - _ptr[-1]);
        }
    }