115 lines
2.6 KiB
C++
115 lines
2.6 KiB
C++
#pragma once
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#include "stdafx.h"
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#include "GbCart.h"
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#include "GbMemoryManager.h"
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#include "../Utilities/Serializer.h"
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class GbMbc3 : public GbCart
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{
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private:
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bool _hasRtcTimer = false;
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bool _ramRtcEnabled = false;
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uint8_t _prgBank = 1;
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uint8_t _ramBank = 0;
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uint8_t _rtcRegisters[5] = {};
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public:
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GbMbc3(bool hasRtcTimer)
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{
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_hasRtcTimer = hasRtcTimer;
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}
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void InitCart() override
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{
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_memoryManager->MapRegisters(0x0000, 0x7FFF, RegisterAccess::Write);
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}
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void RefreshMappings() override
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{
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constexpr int prgBankSize = 0x4000;
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Map(0x0000, 0x3FFF, GbMemoryType::PrgRom, 0, true);
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Map(0x4000, 0x7FFF, GbMemoryType::PrgRom, _prgBank * prgBankSize, true);
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if (_ramRtcEnabled && _ramBank <= 3)
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{
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Map(0xA000, 0xBFFF, GbMemoryType::CartRam, _ramBank, false);
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_memoryManager->MapRegisters(0xA000, 0xBFFF, RegisterAccess::None);
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}
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else if (_hasRtcTimer && _ramRtcEnabled && _ramBank >= 0x08 && _ramBank <= 0x0C)
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{
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_memoryManager->MapRegisters(0xA000, 0xBFFF, RegisterAccess::ReadWrite);
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}
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else
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{
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Unmap(0xA000, 0xBFFF);
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_memoryManager->MapRegisters(0xA000, 0xBFFF, RegisterAccess::Read);
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}
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}
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uint8_t ReadRegister(uint16_t addr) override
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{
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if (_ramRtcEnabled)
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{
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//Disabled RAM/RTC registers returns 0xFF on reads (?)
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return 0xFF;
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}
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//RTC register read (TODO)
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switch (_ramBank)
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{
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case 0x08: return _rtcRegisters[0]; //Seconds
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case 0x09: return _rtcRegisters[1]; //Minutes
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case 0x0A: return _rtcRegisters[2]; //Hours
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case 0x0B: return _rtcRegisters[3]; //Day counter
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case 0x0C: return _rtcRegisters[4]; //Day counter (upper bit) + carry/halt flags
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}
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//Not reached
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return 0xFF;
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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 <= 0x7FFF)
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{
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switch (addr & 0x6000)
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{
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case 0x0000: _ramRtcEnabled = ((value & 0x0F) == 0x0A);
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break;
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case 0x2000: _prgBank = std::max<uint8_t>(1, value);
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break;
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case 0x4000: _ramBank = value & 0x0F;
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break;
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case 0x6000:
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//RTC register read latch
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break;
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}
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RefreshMappings();
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}
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else if (addr >= 0xA000 && addr <= 0xBFFF)
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{
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//RTC register write (TODO)
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switch (_ramBank)
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{
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case 0x08: _rtcRegisters[0] = value;
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break; //Seconds
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case 0x09: _rtcRegisters[1] = value;
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break; //Minutes
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case 0x0A: _rtcRegisters[2] = value;
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break; //Hours
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case 0x0B: _rtcRegisters[3] = value;
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break; //Day counter
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case 0x0C: _rtcRegisters[4] = value;
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break; //Day counter (upper bit) + carry/halt flags
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}
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}
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}
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void Serialize(Serializer& s) override
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{
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s.Stream(_ramRtcEnabled, _prgBank, _ramBank);
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s.StreamArray(_rtcRegisters, 5);
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}
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};
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