mirror of https://github.com/bsnes-emu/bsnes.git
96 lines
2.0 KiB
C++
96 lines
2.0 KiB
C++
auto APU::Wave::run() -> void {
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if(period && --period == 0) {
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period = 1 * (2048 - frequency);
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patternsample = pattern[patternbank * 16 + patternaddr++];
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if(patternaddr == 0) patternbank ^= mode;
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}
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output = patternsample;
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static uint multiplier[] = {0, 4, 2, 1, 3, 3, 3, 3};
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output = (output * multiplier[volume]) / 4;
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if(enable == false) output = 0;
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}
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auto APU::Wave::clocklength() -> void {
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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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auto APU::Wave::read(uint addr) const -> uint8 {
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switch(addr) {
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case 0: return (mode << 5) | (bank << 6) | (dacenable << 7);
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case 1: return 0;
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case 2: return (volume << 5);
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case 3: return 0;
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case 4: return (counter << 6);
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}
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}
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auto APU::Wave::write(uint addr, uint8 byte) -> void {
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switch(addr) {
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case 0: //NR30
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mode = byte >> 5;
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bank = byte >> 6;
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dacenable = byte >> 7;
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if(dacenable == false) enable = false;
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break;
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case 1: //NR31
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length = byte >> 0;
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break;
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case 2: //NR32
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volume = byte >> 5;
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break;
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case 3: //NR33
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frequency = (frequency & 0xff00) | (byte << 0);
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break;
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case 4: //NR34
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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 = dacenable;
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period = 1 * (2048 - frequency);
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patternaddr = 0;
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patternbank = mode ? (uint1)0 : bank;
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}
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break;
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}
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}
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auto APU::Wave::readram(uint addr) const -> uint8 {
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uint8 byte = 0;
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byte |= pattern[addr * 2 + 0] << 0;
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byte |= pattern[addr * 2 + 1] << 4;
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return byte;
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}
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auto APU::Wave::writeram(uint addr, uint8 byte) -> void {
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pattern[addr * 2 + 0] = byte >> 0;
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pattern[addr * 2 + 1] = byte >> 4;
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}
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auto APU::Wave::power() -> void {
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mode = 0;
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bank = 0;
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dacenable = 0;
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length = 0;
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volume = 0;
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frequency = 0;
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counter = 0;
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initialize = 0;
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for(auto& sample : pattern) sample = 0;
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enable = 0;
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output = 0;
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patternaddr = 0;
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patternbank = 0;
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patternsample = 0;
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period = 0;
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}
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