[FFmpeg-devel] [PATCH 01/25] avcodec/photocd: Simplify parsing Huffman tables a bit

[Andreas Rheinhardt]

Paul B Mahol:
> On Sat, Sep 26, 2020 at 12:27:40PM +0200, Andreas Rheinhardt wrote:
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>>  libavcodec/photocd.c | 13 ++++++-------
>>  1 file changed, 6 insertions(+), 7 deletions(-)
>>
> 
> should be ok if tested.
> 

Tested with the (NSFW) files from
http://cd.textfiles.com/prettywomen/IMAGES/

>> diff --git a/libavcodec/photocd.c b/libavcodec/photocd.c
>> index 057c9d33d4..8fd4536a65 100644
>> --- a/libavcodec/photocd.c
>> +++ b/libavcodec/photocd.c
>> @@ -245,21 +245,20 @@ static av_noinline int decode_huff(AVCodecContext *avctx, AVFrame *frame,
>>          int x2, idx;
>>  
>>          for (; get_bits_left(&g) > 0;) {
>> -            if ((show_bits(&g, 24) & 0xfff000) == 0xfff000)
>> +            if (show_bits(&g, 12) == 0xfff)
>>                  break;
>>              skip_bits(&g, 8);
>>          }
>>  
>> -        shiftreg = show_bits_long(&g, 32) & 0xffffff00;
>> -        while (shiftreg != 0xfffffe00) {
>> +        shiftreg = show_bits(&g, 24);
>> +        while (shiftreg != 0xfffffe) {
>>              if (get_bits_left(&g) <= 0)
>>                  return AVERROR_INVALIDDATA;
>>              skip_bits(&g, 1);
>> -            shiftreg = show_bits_long(&g, 32) & 0xffffff00;
>> +            shiftreg = show_bits(&g, 24);
>>          }
>> -        skip_bits(&g, 16);
>> -        y = show_bits_long(&g, 23) & 0x1fff;
>> -        skip_bits(&g, 8);
>> +        skip_bits(&g, 24);
>> +        y = show_bits(&g, 15) & 0x1fff;
>>          if (y >= height)
>>              break;
>>          type = get_bits(&g, 2);
>> -- 
>> 2.25.1
>>