Mesen/Core/MMC3_249.h

#pragma once
#include "stdafx.h"
#include "MMC3.h"

class MMC3_249 : public MMC3
{
private:
	uint8_t _exReg;

protected:
	virtual void InitMapper() override
	{
		MMC3::InitMapper();

		AddRegisterRange(0x5000, 0x5000, MemoryOperation::Write);
	}

	void StreamState(bool saving) override
	{
		MMC3::StreamState(saving);
		Stream(_exReg);
	}

	virtual void SelectCHRPage(uint16_t slot, uint16_t page, ChrMemoryType memoryType = ChrMemoryType::Default) override
	{
		if(_exReg & 0x02) {
			page = (page & 0x03) | ((page >> 1) & 0x04) | ((page >> 4) & 0x08) | ((page >> 2) & 0x10) | ((page << 3) & 0x20) | ((page << 2) & 0xC0);
		}

		BaseMapper::SelectCHRPage(slot, page, memoryType);
	}

	virtual void SelectPRGPage(uint16_t slot, uint16_t page, PrgMemoryType memoryType = PrgMemoryType::PrgRom) override
	{
		if(_exReg & 0x02) {
			if(page < 0x20) {
				page = (page & 0x01) | ((page >> 3) & 0x02) | ((page >> 1) & 0x04) | ((page << 2) & 0x18);
			} else {
				page -= 0x20;
				page = (page & 0x03) | ((page >> 1) & 0x04) | ((page >> 4) & 0x08) | ((page >> 2) & 0x10) | ((page << 3) & 0x20) | ((page << 2) & 0xC0);
			}
		}

		BaseMapper::SelectPRGPage(slot, page, memoryType);
	}

	virtual void WriteRegister(uint16_t addr, uint8_t value) override
	{
		if(addr == 0x5000) {
			_exReg = value;
			UpdatePrgMapping();
			UpdateChrMapping();
		} else {
			MMC3::WriteRegister(addr, value);
		}
	}
};