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Optimise the linear-interpolator a little

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Doesn't have to do two sets of shifts
This commit is contained in:
Clownacy 2020-09-03 16:01:46 +01:00
parent b68eb076ca
commit fbcb2f5f56
1 changed files with 4 additions and 4 deletions
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8
src/Backends/Audio/SoftwareMixer.cpp
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@ -202,12 +202,12 @@ ATTRIBUTE_HOT void Mixer_MixSounds(long *stream, size_t frames_total)
// Perform linear interpolation
const unsigned char interpolation_scale = sound->position_subsample >> 8;
const short output_sample = sound->samples[sound->position] * (0x100 - interpolation_scale)
+ sound->samples[sound->position + 1] * interpolation_scale;
const signed char output_sample = (sound->samples[sound->position] * (0x100 - interpolation_scale)
+ sound->samples[sound->position + 1] * interpolation_scale) >> 8;
// Mix, and apply volume
*stream_pointer++ += (output_sample * sound->volume_l) >> 8;
*stream_pointer++ += (output_sample * sound->volume_r) >> 8;
*stream_pointer++ += output_sample * sound->volume_l;
*stream_pointer++ += output_sample * sound->volume_r;
#endif
// Increment sample