[FFmpeg-devel] [Read EXIF metadata 1/3] Refactor TIFF tag related functions to share the code.

[Michael Niedermayer]

On Fri, Aug 02, 2013 at 10:15:05PM +0200, Thilo Borgmann wrote:
> Updated Patch according to latest comments.
> 
> -Thilo

[...]
> @@ -702,10 +546,7 @@ static int tiff_decode_tag(TiffContext *s, AVFrame *frame)
>      uint32_t *pal;
>      double *dp;
>  
> -    tag   = tget_short(&s->gb, s->le);
> -    type  = tget_short(&s->gb, s->le);
> -    count = tget_long(&s->gb, s->le);
> -    off   = tget_long(&s->gb, s->le);
> +    ff_tread_tag_data(&s->gb, s->le, &tag, &type, &count, &off);
>      start = bytestream2_tell(&s->gb);
>  
>      if (type == 0 || type >= FF_ARRAY_ELEMS(type_sizes)) {
> @@ -714,30 +555,20 @@ static int tiff_decode_tag(TiffContext *s, AVFrame *frame)
>          return 0;
>      }
>  
> +    ff_tseek_tag_value(&s->gb, type, count, off);
>      if (count == 1) {
>          switch (type) {
>          case TIFF_BYTE:
>          case TIFF_SHORT:
> -            bytestream2_seek(&s->gb, -4, SEEK_CUR);
> -            value = tget(&s->gb, type, s->le);
> +            value = ff_tget(&s->gb, type, s->le);
>              break;
>          case TIFF_LONG:
>              value = off;
>              break;
> -        case TIFF_STRING:
> -            if (count <= 4) {
> -                bytestream2_seek(&s->gb, -4, SEEK_CUR);
> -                break;
> -            }
>          default:
>              value = UINT_MAX;
>              bytestream2_seek(&s->gb, off, SEEK_SET);
>          }
> -    } else {
> -        if (count <= 4 && type_sizes[type] * count <= 4)
> -            bytestream2_seek(&s->gb, -4, SEEK_CUR);
> -        else
> -            bytestream2_seek(&s->gb, off, SEEK_SET);
>      }
>  
>      switch (tag) {

this should be factored differently.
what the change does is having a function read some values and
then having a 2nd function (ff_tseek_tag_value) check if it was
wrong, seek back and then have code outside the functions read the
correct values.
I think there should be no seek back needed and all the reading and
skiping/seeking should be in the same function if possible


[...]

-- 
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