[FFmpeg-cvslog] vble: use LUT for vble_read_reverse_unary()
Michael Niedermayer
git at videolan.org
Sat Nov 12 03:23:42 CET 2011
ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Sat Nov 12 01:40:37 2011 +0100| [35fd7b2968834c5994bfd2a93edfbf0dea5e667e] | committer: Michael Niedermayer
vble: use LUT for vble_read_reverse_unary()
slightly faster
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=35fd7b2968834c5994bfd2a93edfbf0dea5e667e
---
libavcodec/vble.c | 12 +++++++++++-
1 files changed, 11 insertions(+), 1 deletions(-)
diff --git a/libavcodec/vble.c b/libavcodec/vble.c
index b758e23..5f78e6a 100644
--- a/libavcodec/vble.c
+++ b/libavcodec/vble.c
@@ -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 {
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