bsnes/higan/md/ym2612/ym2612.cpp

191 lines
4.9 KiB
C++

#include <md/md.hpp>
namespace MegaDrive {
YM2612 ym2612;
#include "io.cpp"
#include "timer.cpp"
#include "channel.cpp"
#include "constants.cpp"
#include "serialization.cpp"
auto YM2612::Enter() -> void {
while(true) scheduler.synchronize(), ym2612.main();
}
auto YM2612::main() -> void {
sample();
timerA.run();
timerB.run();
if(lfo.enable && ++lfo.divider == lfoDividers[lfo.rate]) {
lfo.divider = 0;
lfo.clock++;
for(auto& channel : channels) {
for(auto& op : channel.operators) {
op.updatePhase(); //due to vibrato
op.updateLevel(); //due to tremolo
}
}
}
if(++envelope.divider == 3) {
envelope.divider = 0;
envelope.clock++;
}
for(auto& channel : channels) {
for(auto& op : channel.operators) {
op.runPhase();
if(envelope.divider) continue;
op.runEnvelope();
}
}
step(144);
}
auto YM2612::sample() -> void {
int left = 0;
int right = 0;
for(auto& channel : channels) {
auto& op = channel.operators;
const int modMask = -(1 << 1);
const int sumMask = -(1 << 5);
const int outMask = -(1 << 5);
auto old = [&](uint n) -> int { return op[n].prior & modMask; };
auto mod = [&](uint n) -> int { return op[n].output & modMask; };
auto out = [&](uint n) -> int { return op[n].output & sumMask; };
auto wave = [&](uint n, uint modulation) -> int {
int x = (modulation >> 1) + (op[n].phase.value >> 10);
int y = sine[x & 0x3ff] + op[n].outputLevel;
return y < 0x2000 ? pow2[y & 0x1ff] << 2 >> (y >> 9) : 0;
};
int feedback = modMask & op[0].output + op[0].prior >> 9 - channel.feedback;
int accumulator = 0;
for(auto n : range(4)) op[n].prior = op[n].output;
op[0].output = wave(0, feedback * (channel.feedback > 0));
if(channel.algorithm == 0) {
//0 -> 1 -> 2 -> 3
op[1].output = wave(1, mod(0));
op[2].output = wave(2, old(1));
op[3].output = wave(3, mod(2));
accumulator += out(3);
}
if(channel.algorithm == 1) {
//(0 + 1) -> 2 -> 3
op[1].output = wave(1, 0);
op[2].output = wave(2, mod(0) + old(1));
op[3].output = wave(3, mod(2));
accumulator += out(3);
}
if(channel.algorithm == 2) {
//0 + (1 -> 2) -> 3
op[1].output = wave(1, 0);
op[2].output = wave(2, old(1));
op[3].output = wave(3, mod(0) + mod(2));
accumulator += out(3);
}
if(channel.algorithm == 3) {
//(0 -> 1) + 2 -> 3
op[1].output = wave(1, mod(0));
op[2].output = wave(2, 0);
op[3].output = wave(3, mod(1) + mod(2));
accumulator += out(3);
}
if(channel.algorithm == 4) {
//(0 -> 1) + (2 -> 3)
op[1].output = wave(1, mod(0));
op[2].output = wave(2, 0);
op[3].output = wave(3, mod(2));
accumulator += out(1) + out(3);
}
if(channel.algorithm == 5) {
//0 -> (1 + 2 + 3)
op[1].output = wave(1, mod(0));
op[2].output = wave(2, old(0));
op[3].output = wave(3, mod(0));
accumulator += out(1) + out(2) + out(3);
}
if(channel.algorithm == 6) {
//(0 -> 1) + 2 + 3
op[1].output = wave(1, mod(0));
op[2].output = wave(2, 0);
op[3].output = wave(3, 0);
accumulator += out(1) + out(2) + out(3);
}
if(channel.algorithm == 7) {
//0 + 1 + 2 + 3
op[1].output = wave(1, 0);
op[2].output = wave(2, 0);
op[3].output = wave(3, 0);
accumulator += out(0) + out(1) + out(2) + out(3);
}
int voiceData = sclamp<14>(accumulator) & outMask;
if(dac.enable && (&channel == &channels[5])) voiceData = (int)dac.sample - 0x80 << 6;
if(channel.leftEnable ) left += voiceData;
if(channel.rightEnable) right += voiceData;
}
stream->sample(sclamp<16>(left) / 32768.0, sclamp<16>(right) / 32768.0);
}
auto YM2612::step(uint clocks) -> void {
Thread::step(clocks);
synchronize(cpu);
synchronize(apu);
}
auto YM2612::power(bool reset) -> void {
create(YM2612::Enter, system.frequency() / 7.0);
stream = Emulator::audio.createStream(2, frequency() / 144.0);
stream->addFilter(Emulator::Filter::Order::First, Emulator::Filter::Type::HighPass, 20.0);
stream->addFilter(Emulator::Filter::Order::First, Emulator::Filter::Type::LowPass, 2840.0);
stream->addFilter(Emulator::Filter::Order::Second, Emulator::Filter::Type::LowPass, 20000.0, 3);
io = {};
lfo = {};
dac = {};
envelope = {};
timerA = {};
timerB = {};
for(auto& channel : channels) channel.power();
const uint positive = 0;
const uint negative = 1;
for(int x = 0; x <= 0xff; x++) {
int y = -256 * log(sin((2 * x + 1) * Math::Pi / 1024)) / log(2) + 0.5;
sine[0x000 + x] = positive + (y << 1);
sine[0x1ff - x] = positive + (y << 1);
sine[0x200 + x] = negative + (y << 1);
sine[0x3ff - x] = negative + (y << 1);
}
for(int y = 0; y <= 0xff; y++) {
int z = 1024 * pow(2, (0xff - y) / 256.0) + 0.5;
pow2[positive + (y << 1)] = +z;
pow2[negative + (y << 1)] = ~z; //not -z
}
}
}