[FFmpeg-devel] [PATCH] Simplify codebook allocation for Escape 124

[Benoit Fouet]

Hi,

Eli Friedman wrote:
> Index: libavcodec/escape124.c
> ===================================================================
> --- libavcodec/escape124.c	(revision 12665)
> +++ libavcodec/escape124.c	(working copy)
> @@ -83,23 +83,27 @@
>      return 0;
>  }
>  
> -static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
> -                                 unsigned size)
> +static void unpack_codebook(GetBitContext* gb, unsigned depth,
> +                            unsigned size, CodeBook* cb)
>  {
>      unsigned i, j;
> -    CodeBook cb = { 0 };
>  
> +    cb->depth = depth;
> +    cb->size = 0;
> +    av_free(cb->blocks);
> +    cb->blocks = NULL;
> +
>      if (!can_safely_read(gb, size * 34))
> -        return cb;
> +        return;
>  
>      if (size >= INT_MAX / sizeof(MacroBlock))
> -        return cb;
> -    cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
> -    if (!cb.blocks)
> -        return cb;
> +        return;
> +    cb->blocks = av_malloc(size * sizeof(MacroBlock));
> +    if (!cb->blocks)
> +        return;
>  
> -    cb.depth = depth;
> -    cb.size = size;
> +    cb->size = size;
> +
>      for (i = 0; i < size; i++) {
>          unsigned mask_bits = get_bits(gb, 4);
>          unsigned color0 = get_bits(gb, 15);
> @@ -107,12 +111,12 @@
>  
>          for (j = 0; j < 4; j++) {
>              if (mask_bits & (1 << j))
> -                cb.blocks[i].pixels[j] = color1;
> +                cb->blocks[i].pixels[j] = color1;
>              else
> -                cb.blocks[i].pixels[j] = color0;
> +                cb->blocks[i].pixels[j] = color0;
>          }
>      }
> -    return cb;
> +    return;
>  }
>  
>  static unsigned decode_skip_count(GetBitContext* gb)
> @@ -265,10 +269,7 @@
>                      cb_size = s->num_superblocks << cb_depth;
>                  }
>              }
> -            av_free(s->codebooks[i].blocks);
> -            s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
> -            if (!s->codebooks[i].blocks)
> -                return -1;
>   

why does this check is removed ?

> +            unpack_codebook(&gb, cb_depth, cb_size, &s->codebooks[i]);
>          }
>      }
>   

-- 
Benoit Fouet
Purple Labs S.A.
www.purplelabs.com