mirror of
https://github.com/libretro/Mesen.git
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99 lines
2.5 KiB
C++
99 lines
2.5 KiB
C++
#pragma once
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#include "stdafx.h"
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#include "BaseMapper.h"
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#include "CPU.h"
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class Mapper183 : public BaseMapper
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{
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private:
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uint8_t _chrRegs[8];
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uint8_t _prgReg;
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uint8_t _irqCounter;
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uint8_t _irqScaler;
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bool _irqEnabled;
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bool _needIrq;
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protected:
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virtual uint16_t RegisterStartAddress() override { return 0x6000; }
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virtual uint16_t RegisterEndAddress() override { return 0xFFFF; }
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virtual uint16_t GetPRGPageSize() override { return 0x2000; }
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virtual uint16_t GetCHRPageSize() override { return 0x400; }
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void InitMapper() override
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{
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memset(_chrRegs, 0, sizeof(_chrRegs));
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_prgReg = 0;
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_irqCounter = 0;
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_irqScaler = 0;
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_irqEnabled = false;
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_needIrq = false;
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UpdatePrg();
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}
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void StreamState(bool saving) override
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{
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BaseMapper::StreamState(saving);
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ArrayInfo<uint8_t> chrRegs{ _chrRegs, 8 };
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Stream(_prgReg, _irqCounter, _irqEnabled, _irqScaler, _needIrq, chrRegs);
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}
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void UpdatePrg()
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{
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SetCpuMemoryMapping(0x6000, 0x7FFF, _prgReg, PrgMemoryType::PrgRom);
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SelectPRGPage(3, -1);
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}
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void WriteRegister(uint16_t addr, uint8_t value) override
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{
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if((addr & 0xF800) == 0x6800) {
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_prgReg = addr & 0x3F;
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UpdatePrg();
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} else if(((addr & 0xF80C) >= 0xB000) && ((addr & 0xF80C) <= 0xE00C)) {
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int slot = (((addr >> 11) - 6) | (addr >> 3)) & 0x07;
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_chrRegs[slot] = (_chrRegs[slot] & (0xF0 >> (addr & 0x04))) | ((value & 0x0F) << (addr & 0x04));
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SelectCHRPage(slot, _chrRegs[slot]);
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} else switch(addr & 0xF80C) {
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case 0x8800: SelectPRGPage(0, value); break;
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case 0xA800: SelectPRGPage(1, value); break;
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case 0xA000: SelectPRGPage(2, value); break;
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case 0x9800:
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switch(value & 0x03) {
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case 0: SetMirroringType(MirroringType::Vertical); break;
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case 1: SetMirroringType(MirroringType::Horizontal); break;
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case 2: SetMirroringType(MirroringType::ScreenAOnly); break;
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case 3: SetMirroringType(MirroringType::ScreenBOnly); break;
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}
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break;
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case 0xF000: _irqCounter = (_irqCounter & 0xF0) | (value & 0x0F); break;
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case 0xF004: _irqCounter = (_irqCounter & 0x0F) | ((value & 0x0F) << 4); break;
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case 0xF008:
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_irqEnabled = value > 0;
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if(!_irqEnabled) {
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_irqScaler = 0;
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}
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CPU::ClearIRQSource(IRQSource::External);
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break;
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}
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}
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virtual void ProcessCpuClock() override
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{
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if(_needIrq) {
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CPU::SetIRQSource(IRQSource::External);
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_needIrq = false;
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}
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_irqScaler++;
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if(_irqScaler == 114) {
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_irqScaler = 0;
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if(_irqEnabled) {
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_irqCounter++;
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if(_irqCounter == 0) {
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_needIrq = true;
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}
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}
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}
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}
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}; |