Mesen-X/Core/APU.cpp

#include "stdafx.h"
#include "APU.h"
#include "CPU.h"
#include "SquareChannel.h"
#include "TriangleChannel.h"
#include "NoiseChannel.h"
#include "DeltaModulationChannel.h"
#include "ApuFrameCounter.h"
#include "EmulationSettings.h"
#include "SoundMixer.h"
#include "MemoryManager.h"

APU::APU(shared_ptr<Console> console)
{
	_nesModel = NesModel::Auto;
	_apuEnabled = true;

	_console = console;
	_mixer = _console->GetSoundMixer();
	_settings = _console->GetSettings();

	_squareChannel[0].reset(new SquareChannel(AudioChannel::Square1, _console, _mixer.get(), true));
	_squareChannel[1].reset(new SquareChannel(AudioChannel::Square2, _console, _mixer.get(), false));
	_triangleChannel.reset(new TriangleChannel(AudioChannel::Triangle, _console, _mixer.get()));
	_noiseChannel.reset(new NoiseChannel(AudioChannel::Noise, _console, _mixer.get()));
	_deltaModulationChannel.reset(new DeltaModulationChannel(AudioChannel::DMC, _console, _mixer.get()));
	_frameCounter.reset(new ApuFrameCounter(_console));

	_console->GetMemoryManager()->RegisterIODevice(_squareChannel[0].get());
	_console->GetMemoryManager()->RegisterIODevice(_squareChannel[1].get());
	_console->GetMemoryManager()->RegisterIODevice(_frameCounter.get());
	_console->GetMemoryManager()->RegisterIODevice(_triangleChannel.get());
	_console->GetMemoryManager()->RegisterIODevice(_noiseChannel.get());
	_console->GetMemoryManager()->RegisterIODevice(_deltaModulationChannel.get());

	Reset(false);
}

APU::~APU()
{
}

void APU::SetNesModel(NesModel model, bool forceInit)
{
	if(_nesModel != model || forceInit) {
		//Finish the current apu frame before switching model
		Run();

		_nesModel = model;
		_squareChannel[0]->SetNesModel(model);
		_squareChannel[1]->SetNesModel(model);
		_triangleChannel->SetNesModel(model);
		_noiseChannel->SetNesModel(model);
		_deltaModulationChannel->SetNesModel(model);
		_frameCounter->SetNesModel(model);

		_mixer->SetNesModel(model);
	}
}

void APU::FrameCounterTick(FrameType type)
{
	//Quarter & half frame clock envelope & linear counter
	_squareChannel[0]->TickEnvelope();
	_squareChannel[1]->TickEnvelope();
	_triangleChannel->TickLinearCounter();
	_noiseChannel->TickEnvelope();

	if(type == FrameType::HalfFrame) {
		//Half frames clock length counter & sweep
		_squareChannel[0]->TickLengthCounter();
		_squareChannel[1]->TickLengthCounter();
		_triangleChannel->TickLengthCounter();
		_noiseChannel->TickLengthCounter();

		_squareChannel[0]->TickSweep();
		_squareChannel[1]->TickSweep();
	}
}

uint8_t APU::GetStatus()
{
	uint8_t status = 0;
	status |= _squareChannel[0]->GetStatus() ? 0x01 : 0x00;
	status |= _squareChannel[1]->GetStatus() ? 0x02 : 0x00;
	status |= _triangleChannel->GetStatus() ? 0x04 : 0x00;
	status |= _noiseChannel->GetStatus() ? 0x08 : 0x00;
	status |= _deltaModulationChannel->GetStatus() ? 0x10 : 0x00;
	status |= _console->GetCpu()->HasIrqSource(IRQSource::FrameCounter) ? 0x40 : 0x00;
	status |= _console->GetCpu()->HasIrqSource(IRQSource::DMC) ? 0x80 : 0x00;

	return status;
}

uint8_t APU::ReadRAM(uint16_t addr)
{
	//$4015 read
	Run();

	uint8_t status = GetStatus();

	//Reading $4015 clears the Frame Counter interrupt flag.
	_console->GetCpu()->ClearIrqSource(IRQSource::FrameCounter);

	return status;
}

uint8_t APU::PeekRAM(uint16_t addr)
{
	if(_console->GetEmulationThreadId() == std::this_thread::get_id()) {
		//Only run the APU (to catch up) if we're running this in the emulation thread (not 100% accurate, but we can't run the APU from any other thread without locking)
		Run();
	}
	return GetStatus();
}

void APU::WriteRAM(uint16_t addr, uint8_t value)
{
	//$4015 write
	Run();

	//Writing to $4015 clears the DMC interrupt flag.
	//This needs to be done before setting the enabled flag for the DMC (because doing so can trigger an IRQ)
	_console->GetCpu()->ClearIrqSource(IRQSource::DMC);

	_squareChannel[0]->SetEnabled((value & 0x01) == 0x01);
	_squareChannel[1]->SetEnabled((value & 0x02) == 0x02);
	_triangleChannel->SetEnabled((value & 0x04) == 0x04);
	_noiseChannel->SetEnabled((value & 0x08) == 0x08);
	_deltaModulationChannel->SetEnabled((value & 0x10) == 0x10);
}

void APU::GetMemoryRanges(MemoryRanges &ranges)
{
	ranges.AddHandler(MemoryOperation::Read, 0x4015);
	ranges.AddHandler(MemoryOperation::Write, 0x4015);
}

void APU::Run()
{
	//Update framecounter and all channels
	//This is called:
	//-At the end of a frame
	//-Before APU registers are read/written to
	//-When a DMC or FrameCounter interrupt needs to be fired
	int32_t cyclesToRun = _currentCycle - _previousCycle;

	while(cyclesToRun > 0) {
		_previousCycle += _frameCounter->Run(cyclesToRun);

		//Reload counters set by writes to 4003/4008/400B/400F after running the frame counter to allow the length counter to be clocked first
		//This fixes the test "len_reload_timing" (tests 4 & 5)
		_squareChannel[0]->ReloadCounter();
		_squareChannel[1]->ReloadCounter();
		_noiseChannel->ReloadCounter();
		_triangleChannel->ReloadCounter();

		_squareChannel[0]->Run(_previousCycle);
		_squareChannel[1]->Run(_previousCycle);
		_noiseChannel->Run(_previousCycle);
		_triangleChannel->Run(_previousCycle);
		_deltaModulationChannel->Run(_previousCycle);
	}
}

void APU::SetNeedToRun()
{
	_needToRun = true;
}

bool APU::NeedToRun(uint32_t currentCycle)
{
	if(_needToRun || _deltaModulationChannel->NeedToRun()) {
		//Need to run whenever we alter the length counters
		//Need to run every cycle when DMC is running to get accurate emulation (CPU stalling, interaction with sprite DMA, etc.)
		_needToRun = false;
		return true;
	}

	uint32_t cyclesToRun = currentCycle - _previousCycle;
	return _frameCounter->NeedToRun(cyclesToRun) || _deltaModulationChannel->IrqPending(cyclesToRun);
}

void APU::Exec()
{
	_currentCycle++;
	if(_currentCycle == SoundMixer::CycleLength - 1) {
		EndFrame();
	} else if(NeedToRun(_currentCycle)) {
		Run();
	}
}

void APU::EndFrame()
{
	Run();
	_squareChannel[0]->EndFrame();
	_squareChannel[1]->EndFrame();
	_triangleChannel->EndFrame();
	_noiseChannel->EndFrame();
	_deltaModulationChannel->EndFrame();

	_mixer->PlayAudioBuffer(_currentCycle);

	_currentCycle = 0;
	_previousCycle = 0;
}

void APU::ProcessCpuClock()
{
	if(_apuEnabled) {
		if(_settings->GetOverclockRate() == 100 || !_settings->GetOverclockAdjustApu()) {
			Exec();
		} else {
			_cyclesNeeded += 1.0 / ((double)_settings->GetOverclockRate() / 100.0);
			while(_cyclesNeeded >= 1.0) {
				Exec();
				_cyclesNeeded--;
			}
		}
	}
}

void APU::Reset(bool softReset)
{
	_apuEnabled = true;
	_cyclesNeeded = 0;
	_currentCycle = 0;
	_previousCycle = 0;
	_squareChannel[0]->Reset(softReset);
	_squareChannel[1]->Reset(softReset);
	_triangleChannel->Reset(softReset);
	_noiseChannel->Reset(softReset);
	_deltaModulationChannel->Reset(softReset);
	_frameCounter->Reset(softReset);
}

void APU::StreamState(bool saving)
{
	if(saving) {
		//End the APU frame - makes it simpler to restore sound after a state reload
		EndFrame();
	} else {
		_previousCycle = 0;
		_currentCycle = 0;
	}

	SnapshotInfo squareChannel0{ _squareChannel[0].get() };
	SnapshotInfo squareChannel1{ _squareChannel[1].get() };
	SnapshotInfo triangleChannel{ _triangleChannel.get() };
	SnapshotInfo noiseChannel{ _noiseChannel.get() };
	SnapshotInfo deltaModulationChannel{ _deltaModulationChannel.get() };
	SnapshotInfo frameCounter{ _frameCounter.get() };
	SnapshotInfo mixer{ _mixer.get() };
	Stream(_nesModel, squareChannel0, squareChannel1, triangleChannel, noiseChannel, deltaModulationChannel, frameCounter, mixer, _cyclesNeeded);
}

void APU::AddExpansionAudioDelta(AudioChannel channel, int16_t delta)
{
	_mixer->AddDelta(channel, _currentCycle, delta);
}

void APU::SetApuStatus(bool enabled)
{
	_apuEnabled = enabled;
}

bool APU::IsApuEnabled()
{
	//Adding extra lines before/after NMI temporarely turns off the APU
	//This appears to result in less side-effects than spreading out the APU's
	//load over the entire PPU frame, like what was done before.
	//This is most likely due to the timing of the Frame Counter & DMC IRQs.
	return _apuEnabled;
}

void APU::FillDmcReadBuffer()
{
	_deltaModulationChannel->FillReadBuffer();
}

ApuState APU::GetState()
{
	ApuState state;
	state.Dmc = _deltaModulationChannel->GetState();
	state.FrameCounter = _frameCounter->GetState();
	state.Noise = _noiseChannel->GetState();
	state.Square1 = _squareChannel[0]->GetState();
	state.Square2 = _squareChannel[1]->GetState();
	state.Triangle = _triangleChannel->GetState();
	return state;
}