highperfocused/ffmpeg
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

avcodec/mpeg12dec: Optimize mpeg1_decode_block_intra()

Browse Source 
sandybridge i7 274->260 cycles

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2014-01-24 17:11:39 +01:00
parent 0a59055167
commit 0c8e5fb211
1 changed files with 14 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
libavcodec/mpeg12dec.c
View File

@ -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;