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Use MULH instead of 64x64 multiplication, around 5% overall speedup on Intel Atom. 

Patch by myself and Yuriy Kaminskiy [yumkam mail ru]

Originally committed as revision 21175 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Reimar Döffinger 2010-01-12 23:02:07 +00:00
parent 188d3c510d
commit 1460c79097
1 changed files with 2 additions and 3 deletions
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5
libavcodec/ac3dec.c
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@ -420,10 +420,9 @@ static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
int band_end = bin + s->cpl_band_sizes[band];
for (ch = 1; ch <= s->fbw_channels; ch++) {
if (s->channel_in_cpl[ch]) {
int64_t cpl_coord = s->cpl_coords[ch][band];
int cpl_coord = s->cpl_coords[ch][band] << 5;
for (bin = band_start; bin < band_end; bin++) {
s->fixed_coeffs[ch][bin] = ((int64_t)s->fixed_coeffs[CPL_CH][bin] *
cpl_coord) >> 23;
s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
}
if (ch == 2 && s->phase_flags[band]) {
for (bin = band_start; bin < band_end; bin++)