From bfe328caf087d05cdd07d69b1858d0fe39b99b97 Mon Sep 17 00:00:00 2001 From: Loren Merritt Date: Sun, 27 Aug 2006 09:19:02 +0000 Subject: [PATCH] tweak cabac. 0.5% faster h264. Originally committed as revision 6106 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/cabac.h | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/libavcodec/cabac.h b/libavcodec/cabac.h index e797741577..038d4a2067 100644 --- a/libavcodec/cabac.h +++ b/libavcodec/cabac.h @@ -295,28 +295,30 @@ static inline void renorm_cabac_decoder(CABACContext *c){ } static inline void renorm_cabac_decoder_once(CABACContext *c){ - int mask= (c->range - (0x200 << CABAC_BITS))>>31; - c->range+= c->range&mask; - c->low += c->low &mask; + int shift= (uint32_t)(c->range - (0x200 << CABAC_BITS))>>31; + c->range<<= shift; + c->low <<= shift; if(!(c->low & CABAC_MASK)) refill(c); } static inline int get_cabac(CABACContext *c, uint8_t * const state){ - int RangeLPS= c->lps_range[*state][c->range>>(CABAC_BITS+7)]<<(CABAC_BITS+1); + //FIXME gcc generates duplicate load/stores for c->low and c->range + int s = *state; + int RangeLPS= c->lps_range[s][c->range>>(CABAC_BITS+7)]<<(CABAC_BITS+1); int bit, lps_mask attribute_unused; c->range -= RangeLPS; #if 1 if(c->low < c->range){ - bit= (*state)&1; - *state= c->mps_state[*state]; + bit= s&1; + *state= c->mps_state[s]; renorm_cabac_decoder_once(c); }else{ // int shift= ff_h264_norm_shift[RangeLPS>>17]; - bit= ((*state)&1)^1; + bit= (s&1)^1; c->low -= c->range; - *state= c->lps_state[*state]; + *state= c->lps_state[s]; c->range = RangeLPS; renorm_cabac_decoder(c); /* c->range = RangeLPS<low -= c->range & lps_mask; c->range += (RangeLPS - c->range) & lps_mask; - bit= ((*state)^lps_mask)&1; - *state= c->mps_state[(*state) - (128&lps_mask)]; + bit= (s^lps_mask)&1; + *state= c->mps_state[s - (128&lps_mask)]; lps_mask= ff_h264_norm_shift[c->range>>(CABAC_BITS+2)]; c->range<<= lps_mask; -- 2.11.0