mirror of https://github.com/bsnes-emu/bsnes.git
115 lines
2.5 KiB
C++
Executable File
115 lines
2.5 KiB
C++
Executable File
#ifdef APU_CPP
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bool APU::Square2::dac_enable() {
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return (envelope_volume || envelope_direction);
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}
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void APU::Square2::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: duty_output = (phase == 6); break; //______-_
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case 1: duty_output = (phase >= 6); break; //______--
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case 2: duty_output = (phase >= 4); break; //____----
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case 3: duty_output = (phase <= 5); break; //------__
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}
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}
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uint4 sample = (duty_output ? volume : (uint4)0);
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if(enable == false) sample = 0;
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output = sample;
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}
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void APU::Square2::clock_length() {
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//if(counter && length) {
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// if(--length == 0) enable = false;
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//}
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if(counter && enable) {
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if(++length == 0) enable = false;
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}
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}
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void APU::Square2::clock_envelope() {
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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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void APU::Square2::write(unsigned r, uint8 data) {
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if(r == 1) { //$ff16 NR21
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duty = data >> 6;
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//length = 64 - (data & 0x3f);
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length = (data & 0x3f);
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}
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if(r == 2) { //$ff17 NR22
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envelope_volume = data >> 4;
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envelope_direction = data & 0x08;
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envelope_frequency = data & 0x07;
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if(dac_enable() == false) enable = false;
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}
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if(r == 3) { //$ff18 NR23
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frequency = (frequency & 0x0700) | data;
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}
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if(r == 4) { //$ff19 NR24
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bool initialize = data & 0x80;
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counter = data & 0x40;
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frequency = ((data & 7) << 8) | (frequency & 0x00ff);
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if(initialize) {
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enable = dac_enable();
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period = 4 * (2048 - frequency);
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envelope_period = envelope_frequency;
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volume = envelope_volume;
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//if(length == 0) length = 64;
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}
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}
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}
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void APU::Square2::power() {
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enable = 0;
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duty = 0;
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length = 0;
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envelope_volume = 0;
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envelope_direction = 0;
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envelope_frequency = 0;
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frequency = 0;
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counter = 0;
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output = 0;
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duty_output = 0;
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phase = 0;
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period = 0;
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envelope_period = 0;
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volume = 0;
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}
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void APU::Square2::serialize(serializer &s) {
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s.integer(enable);
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s.integer(duty);
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s.integer(length);
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s.integer(envelope_volume);
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s.integer(envelope_direction);
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s.integer(envelope_frequency);
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s.integer(frequency);
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s.integer(counter);
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s.integer(output);
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s.integer(duty_output);
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s.integer(phase);
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s.integer(period);
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s.integer(envelope_period);
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s.integer(volume);
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}
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#endif
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