mirror of https://github.com/bsnes-emu/bsnes.git
58 lines
1.1 KiB
C++
58 lines
1.1 KiB
C++
auto APU::Noise::clock_length() -> void {
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if(envelope.loop_mode == 0) {
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if(length_counter > 0) length_counter--;
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}
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}
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auto APU::Noise::clock() -> uint8 {
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if(length_counter == 0) return 0;
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uint8 result = (lfsr & 1) ? envelope.volume() : 0;
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if(--period_counter == 0) {
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uint feedback;
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if(short_mode) {
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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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period_counter = apu.ntsc_noise_period_table[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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}
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auto APU::Noise::reset() -> void {
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length_counter = 0;
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envelope.speed = 0;
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envelope.use_speed_as_volume = 0;
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envelope.loop_mode = 0;
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envelope.reload_decay = 0;
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envelope.decay_counter = 0;
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envelope.decay_volume = 0;
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period = 0;
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period_counter = 1;
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short_mode = 0;
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lfsr = 1;
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}
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auto APU::Noise::serialize(serializer& s) -> void {
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s.integer(length_counter);
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envelope.serialize(s);
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s.integer(period);
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s.integer(period_counter);
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s.integer(short_mode);
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s.integer(lfsr);
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}
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