From b3d755ec8b516ff45a9cfff9066922ff8196694f Mon Sep 17 00:00:00 2001 From: David Conrad <lessen42@gmail.com> Date: Fri, 23 Jul 2010 21:46:08 +0000 Subject: [PATCH] Split renorm of vp56 arith decoder to its own function Originally committed as revision 24466 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/vp56.h | 36 ++++++++++++++++++++---------------- 1 file changed, 20 insertions(+), 16 deletions(-) diff --git a/libavcodec/vp56.h b/libavcodec/vp56.h index 298aba3d2d..a1904d56d5 100644 --- a/libavcodec/vp56.h +++ b/libavcodec/vp56.h @@ -191,25 +191,11 @@ static inline void vp56_init_range_decoder(VP56RangeCoder *c, c->code_word = bytestream_get_be16(&c->buffer); } -static inline int vp56_rac_get_prob(VP56RangeCoder *c, uint8_t prob) +static av_always_inline void vp56_rac_renorm(VP56RangeCoder *c, unsigned int code_word) { - /* Don't put c->high in a local variable; if we do that, gcc gets - * the stupids and turns the code below into a branch again. */ + int shift = ff_h264_norm_shift[c->high] - 1; int bits = c->bits; - unsigned int code_word = c->code_word; - unsigned int low = 1 + (((c->high - 1) * prob) >> 8); - unsigned int low_shift = low << 8; - int bit = code_word >= low_shift; - int shift; - /* Incantation to convince GCC to turn these into conditional moves - * instead of branches -- faster, as this branch is basically - * unpredictable. */ - c->high = bit ? c->high - low : low; - code_word = bit ? code_word - low_shift : code_word; - - /* normalize */ - shift = ff_h264_norm_shift[c->high] - 1; c->high <<= shift; code_word <<= shift; bits += shift; @@ -219,6 +205,24 @@ static inline int vp56_rac_get_prob(VP56RangeCoder *c, uint8_t prob) } c->bits = bits; c->code_word = code_word; +} + +static inline int vp56_rac_get_prob(VP56RangeCoder *c, uint8_t prob) +{ + /* Don't put c->high in a local variable; if we do that, gcc gets + * the stupids and turns the code below into a branch again. */ + unsigned int code_word = c->code_word; + unsigned int low = 1 + (((c->high - 1) * prob) >> 8); + unsigned int low_shift = low << 8; + int bit = code_word >= low_shift; + + /* Incantation to convince GCC to turn these into conditional moves + * instead of branches -- faster, as this branch is basically + * unpredictable. */ + c->high = bit ? c->high - low : low; + code_word = bit ? code_word - low_shift : code_word; + + vp56_rac_renorm(c, code_word); return bit; }