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| author | Michael Niedermayer <michaelni@gmx.at> | 2014-01-24 17:11:39 +0100 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2014-01-24 18:09:16 +0100 |
| commit | 0c8e5fb21183cba79223d3ba06d48adb90004f4d (patch) | |
| tree | ce610f285e50e2e9855903a8dcd4502147d6c4dd /libavcodec/mpeg12dec.c | |
| parent | 0a59055167eea3087a36d9091501d3bb52ed8ebe (diff) | |
| download | ffmpeg-0c8e5fb21183cba79223d3ba06d48adb90004f4d.tar.gz | |
avcodec/mpeg12dec: Optimize mpeg1_decode_block_intra()
sandybridge i7 274->260 cycles
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Diffstat (limited to 'libavcodec/mpeg12dec.c')
| -rw-r--r-- | libavcodec/mpeg12dec.c | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c index a4ff5d6925..86011d11e3 100644 --- a/libavcodec/mpeg12dec.c +++ b/libavcodec/mpeg12dec.c @@ -142,29 +142,30 @@ static inline int mpeg1_decode_block_intra(MpegEncContext *s, int16_t *block, in i = 0; { OPEN_READER(re, &s->gb); + UPDATE_CACHE(re, &s->gb); + if (((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF) + goto end; + /* now quantify & encode AC coefficients */ for (;;) { - UPDATE_CACHE(re, &s->gb); GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0); - if (level == 127) { - break; - } else if (level != 0) { + if (level != 0) { i += run; j = scantable[i]; level = (level * qscale * quant_matrix[j]) >> 4; level = (level - 1) | 1; level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1); - LAST_SKIP_BITS(re, &s->gb, 1); + SKIP_BITS(re, &s->gb, 1); } else { /* escape */ run = SHOW_UBITS(re, &s->gb, 6) + 1; LAST_SKIP_BITS(re, &s->gb, 6); UPDATE_CACHE(re, &s->gb); level = SHOW_SBITS(re, &s->gb, 8); SKIP_BITS(re, &s->gb, 8); if (level == -128) { - level = SHOW_UBITS(re, &s->gb, 8) - 256; LAST_SKIP_BITS(re, &s->gb, 8); + level = SHOW_UBITS(re, &s->gb, 8) - 256; SKIP_BITS(re, &s->gb, 8); } else if (level == 0) { - level = SHOW_UBITS(re, &s->gb, 8) ; LAST_SKIP_BITS(re, &s->gb, 8); + level = SHOW_UBITS(re, &s->gb, 8) ; SKIP_BITS(re, &s->gb, 8); } i += run; j = scantable[i]; @@ -184,7 +185,13 @@ static inline int mpeg1_decode_block_intra(MpegEncContext *s, int16_t *block, in } block[j] = level; + if (((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF) + break; + + UPDATE_CACHE(re, &s->gb); } +end: + LAST_SKIP_BITS(re, &s->gb, 2); CLOSE_READER(re, &s->gb); } s->block_last_index[n] = i; |