text: #include <pce/pce.hpp>
  
  namespace PCEngine {
  
  PSG psg;
  #include "io.cpp"
  #include "channel.cpp"
  #include "serialization.cpp"
  
  auto PSG::Enter() -> void {
    while(true) scheduler.synchronize(), psg.main();
  }
  
  auto PSG::main() -> void {
    static const uint5 volumeScale[16] = {
      0x00, 0x03, 0x05, 0x07, 0x09, 0x0b, 0x0d, 0x0f,
      0x10, 0x13, 0x15, 0x17, 0x19, 0x1b, 0x1d, 0x1f,
    };
  
    uint5 lmal = volumeScale[io.volumeLeft];
    uint5 rmal = volumeScale[io.volumeRight];
  
    double outputLeft  = 0.0;
    double outputRight = 0.0;
  
    for(auto C : range(6)) {
      uint5  al = channel[C].io.volume;
      uint5 lal = volumeScale[channel[C].io.volumeLeft];
      uint5 ral = volumeScale[channel[C].io.volumeRight];
  
      uint5 volumeLeft  = min(0x1f, (0x1f - lmal) + (0x1f - lal) + (0x1f - al));
      uint5 volumeRight = min(0x1f, (0x1f - rmal) + (0x1f - ral) + (0x1f - al));
  
      channel[C].run();
      if(C == 1 && io.lfoEnable) {
        //todo: frequency modulation of channel 0 using channel 1's output
      } else {
        outputLeft  += channel[C].io.output * volumeScalar[volumeLeft];
        outputRight += channel[C].io.output * volumeScalar[volumeRight];
      }
    }
  
    stream->sample(sclamp<16>(outputLeft) / 32768.0, sclamp<16>(outputRight) / 32768.0);
    step(1);
  }
  
  auto PSG::step(uint clocks) -> void {
    Thread::step(clocks);
    synchronize(cpu);
  }
  
  auto PSG::power() -> void {
    create(PSG::Enter, system.colorburst());
    stream = Emulator::audio.createStream(2, frequency());
    stream->addFilter(Emulator::Filter::Order::First, Emulator::Filter::Type::HighPass, 20.0);
  
    io = {};
    for(auto C : range(6)) channel[C].power(C);
  
    double level = 32767.0 / 6.0 / 32.0;  //max volume / channels / steps
    double step = 48.0 / 32.0;            //48dB volume range spread over 32 steps
    for(uint n : range(31)) {
      volumeScalar[n] = level;
      level /= pow(10.0, step / 20.0);
    }
    volumeScalar[31] = 0.0;
  }
  
  }
  