Mesen/Core/Mapper106.h

#pragma once
#include "stdafx.h"
#include "BaseMapper.h"

class Mapper106 : public BaseMapper
{
private:
	uint16_t _irqCounter;
	bool _irqEnabled;

protected:
	virtual uint16_t GetPRGPageSize() override { return 0x2000; }
	virtual uint16_t GetCHRPageSize() override { return 0x400; }

	void InitMapper() override
	{
		_irqEnabled = false;
		_irqCounter = 0;

		SelectPRGPage(0, -1);
		SelectPRGPage(1, -1);
		SelectPRGPage(2, -1);
		SelectPRGPage(3, -1);
	}

	void StreamState(bool saving) override
	{
		BaseMapper::StreamState(saving);
		Stream(_irqCounter, _irqEnabled);
	}

	void ProcessCpuClock() override
	{
		if(_irqEnabled) {
			_irqCounter++;
			if(_irqCounter == 0) {
				_console->GetCpu()->SetIrqSource(IRQSource::External);
				_irqEnabled = false;
			}
		}
	}

	void WriteRegister(uint16_t addr, uint8_t value) override
	{
		switch(addr & 0x0F) {
			case 0: case 2: SelectCHRPage(addr & 0x0F, value & 0xFE); break;
			case 1: case 3: SelectCHRPage(addr & 0x0F, value | 0x01); break;
			case 4: case 5: case 6: case 7: SelectCHRPage(addr & 0x0F, value); break;

			case 8: case 0x0B: SelectPRGPage((addr & 0x0F) - 8, (value & 0x0F) | 0x10); break;
			case 9: case 0x0A: SelectPRGPage((addr & 0x0F) - 8, value & 0x1F); break;

			case 0x0D: 
				_irqEnabled = false; 
				_irqCounter = 0; 
				_console->GetCpu()->ClearIrqSource(IRQSource::External);
				break;

			case 0x0E:
				_irqCounter = (_irqCounter & 0xFF00) | value;
				break;

			case 0x0F:
				_irqCounter = (_irqCounter & 0xFF) | (value << 8);
				_irqEnabled = true;
				break;
		}
	}
};