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h264: fix invalid shifts in init_cavlc_level_tab() 

The level_code expression includes a shift which is invalid in
those cases where the value is not used.  Moving the calculation
to the branch where the result is used avoids these.

Signed-off-by: Mans Rullgard <mans@mansr.com>
This commit is contained in:
Mans Rullgard 2011-10-11 12:58:31 +01:00
parent 88d1e2b2b0
commit 8babfc033e
1 changed files with 5 additions and 4 deletions
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9
libavcodec/h264_cavlc.c
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@ -238,17 +238,18 @@ static inline int pred_non_zero_count(H264Context *h, int n){
} }
static av_cold void init_cavlc_level_tab(void){ static av_cold void init_cavlc_level_tab(void){
int suffix_length, mask; int suffix_length;
unsigned int i; unsigned int i;
for(suffix_length=0; suffix_length<7; suffix_length++){ for(suffix_length=0; suffix_length<7; suffix_length++){
for(i=0; i<(1<<LEVEL_TAB_BITS); i++){ for(i=0; i<(1<<LEVEL_TAB_BITS); i++){
int prefix= LEVEL_TAB_BITS - av_log2(2*i); int prefix= LEVEL_TAB_BITS - av_log2(2*i);
int level_code= (prefix<<suffix_length) + (i>>(LEVEL_TAB_BITS-prefix-1-suffix_length)) - (1<<suffix_length);
mask= -(level_code&1);
level_code= (((2+level_code)>>1) ^ mask) - mask;
if(prefix + 1 + suffix_length <= LEVEL_TAB_BITS){ if(prefix + 1 + suffix_length <= LEVEL_TAB_BITS){
int level_code = (prefix << suffix_length) +
(i >> (av_log2(i) - suffix_length)) - (1 << suffix_length);
int mask = -(level_code&1);
level_code = (((2 + level_code) >> 1) ^ mask) - mask;
cavlc_level_tab[suffix_length][i][0]= level_code; cavlc_level_tab[suffix_length][i][0]= level_code;
cavlc_level_tab[suffix_length][i][1]= prefix + 1 + suffix_length; cavlc_level_tab[suffix_length][i][1]= prefix + 1 + suffix_length;
}else if(prefix + 1 <= LEVEL_TAB_BITS){ }else if(prefix + 1 <= LEVEL_TAB_BITS){