Mesen/Core/FrontFareast.h
2016-12-17 23:14:47 -05:00

122 lines
2.8 KiB
C++

#pragma once
#include "BaseMapper.h"
#include "CPU.h"
class FrontFareast : public BaseMapper
{
private:
uint16_t _irqCounter;
bool _irqEnabled;
bool _ffeAltMode;
protected:
uint16_t GetPRGPageSize() override { return 0x2000; }
uint16_t GetCHRPageSize() override { return 0x400; }
uint32_t GetChrRamSize() override { return 0x8000; }
uint16_t RegisterStartAddress() override { return 0x42FE; }
uint16_t RegisterEndAddress() override { return 0x4517; }
void InitMapper() override
{
_irqCounter = 0;
_irqEnabled = false;
_ffeAltMode = true;
switch(_mapperID) {
case 6:
AddRegisterRange(0x8000, 0xFFFF, MemoryOperation::Write);
SelectPrgPage2x(0, 0);
SelectPrgPage2x(1, 14);
break;
case 8:
AddRegisterRange(0x8000, 0xFFFF, MemoryOperation::Write);
SelectPrgPage4x(0, 0);
break;
case 17:
SelectPrgPage4x(0, -4);
break;
}
}
void StreamState(bool saving) override
{
BaseMapper::StreamState(saving);
Stream(_irqCounter, _irqEnabled, _ffeAltMode);
}
void ProcessCpuClock() override
{
if(_irqEnabled) {
_irqCounter++;
if(_irqCounter == 0) {
CPU::SetIRQSource(IRQSource::External);
_irqEnabled = false;
}
}
}
void WriteRegister(uint16_t addr, uint8_t value) override
{
switch(addr) {
case 0x42FE:
_ffeAltMode = (value & 0x80) == 0x00;
switch((value >> 4) & 0x01) {
case 0: SetMirroringType(MirroringType::ScreenAOnly); break;
case 1: SetMirroringType(MirroringType::ScreenBOnly); break;
}
break;
case 0x42FF:
switch((value >> 4) & 0x01) {
case 0: SetMirroringType(MirroringType::Vertical); break;
case 1: SetMirroringType(MirroringType::Horizontal); break;
}
break;
case 0x4501:
_irqEnabled = false;
CPU::ClearIRQSource(IRQSource::External);
break;
case 0x4502:
_irqCounter = (_irqCounter & 0xFF00) | value;
CPU::ClearIRQSource(IRQSource::External);
break;
case 0x4503:
_irqCounter = (_irqCounter & 0x00FF) | (value << 8);
_irqEnabled = true;
CPU::ClearIRQSource(IRQSource::External);
break;
default:
if(_mapperID == 6) {
if(addr >= 0x8000) {
if(HasChrRam() || _ffeAltMode) {
SelectPrgPage2x(0, (value & 0xFC) >> 1);
value &= 0x03;
}
SelectChrPage8x(0, value << 3);
}
} else if(_mapperID == 8) {
if(addr >= 0x8000) {
SelectPrgPage2x(0, (value & 0xF8) >> 2);
SelectChrPage8x(0, (value & 0x07) << 3);
}
} else {
switch(addr) {
case 0x4504: case 0x4505: case 0x4506: case 0x4507:
SelectPRGPage(addr - 0x4504, value);
break;
case 0x4510: case 0x4511: case 0x4512: case 0x4513: case 0x4514: case 0x4515: case 0x4516: case 0x4517:
SelectCHRPage(addr - 0x4510, value);
break;
}
}
}
}
};