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vble: use LUT for vble_read_reverse_unary() 

slightly faster

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2011-11-12 01:40:37 +01:00
parent c5e55e214c
commit 35fd7b2968
1 changed files with 11 additions and 1 deletions
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12
libavcodec/vble.c
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@ -40,11 +40,21 @@ typedef struct {
static uint8_t vble_read_reverse_unary(GetBitContext *gb)
{
static const uint8_t LUT[256] = {
8,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
6,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
7,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
6,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,
};
/* At most we need to read 9 bits total to get indices up to 8 */
int val = show_bits(gb, 8);
if (val) {
val = 7 - av_log2_16bit(av_reverse[val]);
val = LUT[val];
skip_bits(gb, val + 1);
return val;
} else {