mirror of
https://github.com/SourMesen/Mesen2.git
synced 2025-04-02 10:21:44 -04:00
133 lines
No EOL
3.1 KiB
C++
133 lines
No EOL
3.1 KiB
C++
#pragma once
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#include "pch.h"
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#include "NES/BaseMapper.h"
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class Mapper253 : public BaseMapper
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{
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private:
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uint8_t _chrLow[8] = {};
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uint8_t _chrHigh[8] = {};
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bool _forceChrRom = false;
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uint8_t _irqReloadValue = 0;
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uint8_t _irqCounter = 0;
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bool _irqEnabled = false;
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uint16_t _irqScaler = 0;
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protected:
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uint16_t GetPrgPageSize() override { return 0x2000; }
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uint16_t GetChrPageSize() override { return 0x400; }
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uint32_t GetChrRamSize() override { return 0x800; }
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uint16_t GetChrRamPageSize() override { return 0x400; }
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bool EnableCpuClockHook() override { return true; }
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void InitMapper() override
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{
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memset(_chrLow, 0, sizeof(_chrLow));
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memset(_chrHigh, 0, sizeof(_chrHigh));
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_forceChrRom = false;
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_irqReloadValue = 0;
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_irqScaler = 0;
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_irqCounter = 0;
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_irqEnabled = false;
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SelectPrgPage(2, -2);
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SelectPrgPage(3, -1);
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}
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void Serialize(Serializer& s) override
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{
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BaseMapper::Serialize(s);
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SVArray(_chrLow, 8);
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SVArray(_chrHigh, 8);
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SV(_forceChrRom);
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SV(_irqReloadValue);
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SV(_irqCounter);
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SV(_irqEnabled);
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SV(_irqScaler);
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if(!s.IsSaving()) {
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UpdateChr();
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}
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}
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void UpdateChr()
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{
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for(uint16_t i = 0; i < 8; i++) {
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uint16_t page = _chrLow[i] | (_chrHigh[i] << 8);
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if((_chrLow[i] == 4 || _chrLow[i] == 5) && !_forceChrRom) {
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SelectChrPage(i, page & 0x01, ChrMemoryType::ChrRam);
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} else {
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SelectChrPage(i, page);
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}
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}
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}
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void ProcessCpuClock() override
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{
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BaseProcessCpuClock();
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if(_irqEnabled) {
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_irqScaler++;
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if(_irqScaler >= 114) {
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_irqScaler = 0;
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_irqCounter++;
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if(_irqCounter == 0) {
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_irqCounter = _irqReloadValue;
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_console->GetCpu()->SetIrqSource(IRQSource::External);
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}
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}
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}
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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 >= 0xB000 && addr <= 0xE00C) {
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uint8_t slot = ((((addr & 0x08) | (addr >> 8)) >> 3) + 2) & 0x07;
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uint8_t shift = addr & 0x04;
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uint8_t chrLow = (_chrLow[slot] & (0xF0 >> shift)) | (value << shift);
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_chrLow[slot] = chrLow;
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if(slot == 0) {
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if(chrLow == 0xc8) {
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_forceChrRom = false;
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} else if(chrLow == 0x88) {
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_forceChrRom = true;
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}
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}
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if(shift) {
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_chrHigh[slot] = value >> 4;
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}
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UpdateChr();
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} else {
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switch(addr) {
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case 0x8010: SelectPrgPage(0, value); break;
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case 0xA010: SelectPrgPage(1, value); break;
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case 0x9400:
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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:
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_irqReloadValue = (_irqReloadValue & 0xF0) | (value & 0x0F);
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_console->GetCpu()->ClearIrqSource(IRQSource::External);
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break;
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case 0xF004:
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_irqReloadValue = (_irqReloadValue & 0x0F) | (value << 4);
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_console->GetCpu()->ClearIrqSource(IRQSource::External);
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break;
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case 0xF008:
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_irqCounter = _irqReloadValue;
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_irqEnabled = (value & 0x02) == 0x02;
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_irqScaler = 0;
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_console->GetCpu()->ClearIrqSource(IRQSource::External);
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break;
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}
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}
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}
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}; |