[libav-devel] [PATCH 3/5] svq1dec: avoid undefined get_bits(0) call

[Måns Rullgård]

Kostya Shishkov <kostya.shishkov at gmail.com> writes:

> On Sat, Nov 26, 2011 at 04:52:09PM +0000, Mans Rullgard wrote:
>> Signed-off-by: Mans Rullgard <mans at mansr.com>
>> ---
>>  libavcodec/svq1dec.c |    3 ++-
>>  1 files changed, 2 insertions(+), 1 deletions(-)
>> 
>> diff --git a/libavcodec/svq1dec.c b/libavcodec/svq1dec.c
>> index 8569615..7eb6e60 100644
>> --- a/libavcodec/svq1dec.c
>> +++ b/libavcodec/svq1dec.c
>> @@ -195,7 +195,8 @@ static const uint8_t string_table[256] = {
>>  
>>  #define SVQ1_CALC_CODEBOOK_ENTRIES(cbook)\
>>        codebook = (const uint32_t *) cbook[level];\
>> -      bit_cache = get_bits (bitbuf, 4*stages);\
>> +      if (stages > 0)\
>> +        bit_cache = get_bits (bitbuf, 4*stages);\
>>        /* calculate codebook entries for this vector */\
>>        for (j=0; j < stages; j++) {\
>>          entries[j] = (((bit_cache >> (4*(stages - j - 1))) & 0xF) + 16*j) << (level + 1);\
>> -- 
>
> maybe set it to 0 for zero bits?

That would add overhead in cases where it's impossible for it to be
zero, which should be everywhere.

-- 
Måns Rullgård
mans at mansr.com