mirror of https://github.com/bsnes-emu/bsnes.git
43 lines
910 B
C++
43 lines
910 B
C++
auto APU::Noise::clockLength() -> void {
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if(envelope.loopMode == 0) {
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if(lengthCounter > 0) lengthCounter--;
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}
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}
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auto APU::Noise::clock() -> uint8 {
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if(lengthCounter == 0) return 0;
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uint8 result = (lfsr & 1) ? envelope.volume() : 0;
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if(--periodCounter == 0) {
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uint feedback;
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if(shortMode) {
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feedback = ((lfsr >> 0) & 1) ^ ((lfsr >> 6) & 1);
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} else {
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feedback = ((lfsr >> 0) & 1) ^ ((lfsr >> 1) & 1);
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}
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lfsr = (lfsr >> 1) | (feedback << 14);
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periodCounter = Region::PAL() ? apu.noisePeriodTablePAL[period] : apu.noisePeriodTableNTSC[period];
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}
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return result;
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}
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auto APU::Noise::power() -> void {
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lengthCounter = 0;
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envelope.speed = 0;
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envelope.useSpeedAsVolume = 0;
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envelope.loopMode = 0;
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envelope.reloadDecay = 0;
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envelope.decayCounter = 0;
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envelope.decayVolume = 0;
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period = 0;
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periodCounter = 1;
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shortMode = 0;
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lfsr = 1;
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}
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