mirror of https://github.com/bsnes-emu/bsnes.git
31 lines
819 B
C++
31 lines
819 B
C++
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void APU::Square::run() {
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if(period && --period == 0) {
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period = 4 * (2048 - frequency);
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phase++;
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switch(duty) {
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case 0: signal = (phase == 6); break; //_____-_
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case 1: signal = (phase >= 6); break; //______--
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case 2: signal = (phase >= 4); break; //____----
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case 3: signal = (phase <= 5); break; //------__
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}
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}
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uint4 sample = volume;
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if(enable == false || signal == false) sample = 0;
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output = sample;
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}
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void APU::Square::clocklength() {
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if(enable && counter) {
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if(++length == 0) enable = false;
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}
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}
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void APU::Square::clockenvelope() {
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if(enable && envelope.frequency && --envelope.period == 0) {
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envelope.period = envelope.frequency;
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if(envelope.direction == 0 && volume > 0) volume--;
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if(envelope.direction == 1 && volume < 15) volume++;
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}
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}
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