mirror of https://github.com/bsnes-emu/bsnes.git
62 lines
1.4 KiB
C++
62 lines
1.4 KiB
C++
uint8 APU::Square2::read(unsigned addr) const {
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switch(addr) {
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case 1: return (length << 0) | (duty << 6);
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case 2: return (envelope.frequency << 0) | (envelope.direction << 3) | (envelope.volume << 4);
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case 3: return (frequency >> 0);
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case 4: return (frequency >> 8) | (counter << 6) | (initialize << 7);
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}
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}
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void APU::Square2::write(unsigned addr, uint8 byte) {
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switch(addr) {
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case 1: //NR21
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length = byte >> 0;
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duty = byte >> 6;
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break;
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case 2: //NR22
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envelope.frequency = byte >> 0;
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envelope.direction = byte >> 3;
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envelope.volume = byte >> 4;
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if(envelope.dacenable() == false) enable = false;
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break;
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case 3: //NR23
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frequency = (frequency & 0xff00) | (byte << 0);
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break;
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case 4: //NR24
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frequency = (frequency & 0x00ff) | (byte << 8);
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counter = byte >> 6;
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initialize = byte >> 7;
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if(initialize) {
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enable = envelope.dacenable();
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period = 2 * (2048 - frequency);
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envelope.period = envelope.frequency;
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volume = envelope.volume;
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}
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break;
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}
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}
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void APU::Square2::power() {
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envelope.frequency = 0;
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envelope.direction = 0;
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envelope.direction = 0;
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envelope.period = 0;
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enable = 0;
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length = 0;
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duty = 0;
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frequency = 0;
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counter = 0;
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initialize = 0;
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shadowfrequency = 0;
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signal = 0;
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output = 0;
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period = 0;
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phase = 0;
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volume = 0;
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}
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