On Mon, Jan 04, 2016 at 04:04:02AM +0100, Michael Niedermayer wrote: > On Wed, Dec 30, 2015 at 08:34:55PM -0800, Ganesh Ajjanagadde wrote: > > This gets rid of some branches to speed up table generation slightly > > (impact higher on mulaw than alaw). Tables are identical to before, > > tested with FATE. > > > > Sample benchmark (Haswell, GNU/Linux+gcc): > > old: > > 313494 decicycles in build_alaw_table, 4094 runs, 2 skips > > 315959 decicycles in build_alaw_table, 8190 runs, 2 skips > > > > 323599 decicycles in build_ulaw_table, 4095 runs, 1 skips > > 318849 decicycles in build_ulaw_table, 8188 runs, 4 skips > > > > new: > > 261902 decicycles in build_alaw_table, 4096 runs, 0 skips > > 266519 decicycles in build_alaw_table, 8192 runs, 0 skips > > > > 209657 decicycles in build_ulaw_table, 4096 runs, 0 skips > > 232656 decicycles in build_ulaw_table, 8192 runs, 0 skips > > > > Signed-off-by: Ganesh Ajjanagadde <[email protected]> > > --- > > libavcodec/pcm_tablegen.h | 24 ++++++++++++------------ > > 1 file changed, 12 insertions(+), 12 deletions(-) > > > > diff --git a/libavcodec/pcm_tablegen.h b/libavcodec/pcm_tablegen.h > > index 1387210..7269977 100644 > > --- a/libavcodec/pcm_tablegen.h > > +++ b/libavcodec/pcm_tablegen.h > > @@ -87,21 +87,21 @@ static av_cold void build_xlaw_table(uint8_t > > *linear_to_xlaw, > > { > > int i, j, v, v1, v2; > > > > - j = 0; > > - for(i=0;i<128;i++) { > > - if (i != 127) { > > - v1 = xlaw2linear(i ^ mask); > > - v2 = xlaw2linear((i + 1) ^ mask); > > - v = (v1 + v2 + 4) >> 3; > > - } else { > > - v = 8192; > > - } > > - for(;j<v;j++) { > > + j = 1; > > + linear_to_xlaw[8192] = mask; > > + for(i=0;i<127;i++) { > > + v1 = xlaw2linear(i ^ mask); > > + v2 = xlaw2linear((i + 1) ^ mask); > > + v = (v1 + v2 + 4) >> 3; > > + for(;j<v;j+=1) { > > + linear_to_xlaw[8192 - j] = (i ^ (mask ^ 0x80)); > > linear_to_xlaw[8192 + j] = (i ^ mask); > > - if (j > 0) > > - linear_to_xlaw[8192 - j] = (i ^ (mask ^ 0x80)); > > } > > } > > + for(;j<8192;j++) { > > + linear_to_xlaw[8192 - j] = (127 ^ (mask ^ 0x80)); > > + linear_to_xlaw[8192 + j] = (127 ^ mask); > > + } > > linear_to_xlaw[0] = linear_to_xlaw[1]; > > i think you can make the tables 8 times smaller
forget this, i should have checked the whole table or looked when i am awake ... [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I do not agree with what you have to say, but I'll defend to the death your right to say it. -- Voltaire
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