mirror of https://github.com/bsnes-emu/bsnes.git
28 lines
688 B
C++
28 lines
688 B
C++
auto APU::Channel4::noiseSample() -> uint4 {
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return s.noiseOutput ? 0xf : 0x0;
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}
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auto APU::Channel4::run() -> void {
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if(--s.period == r.pitch) {
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s.period = 0;
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auto output = r.noise ? noiseSample() : apu.sample(4, s.sampleOffset++);
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o.left = output * r.volumeLeft;
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o.right = output * r.volumeRight;
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if(r.noiseReset) {
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r.noiseReset = 0;
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s.noiseLFSR = 0;
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s.noiseOutput = 0;
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}
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if(r.noiseUpdate) {
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static const int taps[8] = {14, 10, 13, 4, 8, 6, 9, 11};
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auto tap = taps[r.noiseMode];
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s.noiseOutput = (1 ^ (s.noiseLFSR >> 7) ^ (s.noiseLFSR >> tap)) & 1;
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s.noiseLFSR = s.noiseLFSR << 1 | s.noiseOutput;
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}
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}
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}
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