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Optimization step 1: Separate the loops, save history from buffer.

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This commit is contained in:
Henrik Rydgard 2016-12-20 20:37:49 +01:00
parent 61f80edda3
commit 47df134b66
1 changed files with 20 additions and 1 deletions
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21
Core/HW/SasAudio.cpp
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@ -495,11 +495,27 @@ void SasInstance::MixVoice(SasVoice &voice) {
// Resample to the correct pitch, writing exactly "grainSize" samples.
// TODO: Special case no-resample case (and 2x and 0.5x) for speed, it's not uncommon
int16_t temp[256 * 4];
int tempPos = 0;
// Two passes: First read, then resample.
u32 sampleFrac = voice.sampleFrac;
temp[tempPos++] = voice.resampleHist[0];
temp[tempPos++] = voice.resampleHist[1];
for (int i = delay; i < grainSize; i++) {
while (sampleFrac >= PSP_SAS_PITCH_BASE) {
voice.ReadSamples(&temp[tempPos++], 1);
sampleFrac -= PSP_SAS_PITCH_BASE;
}
sampleFrac += voice.pitch;
}
sampleFrac = voice.sampleFrac;
tempPos = 2; // skip the two history samples in the read buffer for now
for (int i = delay; i < grainSize; i++) {
while (sampleFrac >= PSP_SAS_PITCH_BASE) {
voice.resampleHist[0] = voice.resampleHist[1];
voice.ReadSamples(&voice.resampleHist[1], 1);
voice.resampleHist[1] = temp[tempPos++];
sampleFrac -= PSP_SAS_PITCH_BASE;
}
@ -526,6 +542,9 @@ void SasInstance::MixVoice(SasVoice &voice) {
sendBuffer[i * 2 + 1] += sample * voice.effectRight >> 12;
}
voice.resampleHist[0] = temp[tempPos - 2];
voice.resampleHist[1] = temp[tempPos - 1];
voice.sampleFrac = sampleFrac;
if (voice.HaveSamplesEnded())