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80 lines
2.2 KiB
C++
80 lines
2.2 KiB
C++
#pragma once
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#include "stdafx.h"
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#include "BaseMapper.h"
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class Sachen74LS374N : public BaseMapper
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{
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private:
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uint8_t _currentRegister;
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uint8_t _regs[8];
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protected:
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uint32_t GetDipSwitchCount() override { return _romInfo.MapperID == 150 ? 1 : 0; }
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uint16_t RegisterStartAddress() override { return 0x4100; }
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uint16_t RegisterEndAddress() override { return 0x7FFF; }
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uint16_t GetPRGPageSize() override { return 0x8000; }
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uint16_t GetCHRPageSize() override { return 0x2000; }
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bool AllowRegisterRead() override { return true; }
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void InitMapper() override
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{
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_currentRegister = 0;
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memset(_regs, 0, sizeof(_regs));
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UpdateState();
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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> regs{ _regs, 8 };
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Stream(_currentRegister, regs);
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}
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void UpdateState()
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{
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uint8_t chrPage;
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if(_romInfo.MapperID == 150) {
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chrPage = ((_regs[4] & 0x01) << 2) | (_regs[6] & 0x03);
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} else {
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chrPage = (_regs[2] & 0x01) | ((_regs[4] & 0x01) << 1) | ((_regs[6] & 0x03) << 2);
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}
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SelectCHRPage(0, chrPage);
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SelectPRGPage(0, _regs[5] & 0x03);
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switch((_regs[7] >> 1) & 0x03) {
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case 0: SetNametables(0, 0, 0, 1); break;
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case 1: SetMirroringType(MirroringType::Horizontal); break;
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case 2: SetMirroringType(MirroringType::Vertical); break;
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case 3: SetMirroringType(MirroringType::ScreenAOnly); break;
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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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uint8_t openBus = _console->GetMemoryManager()->GetOpenBus();
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if((addr & 0xC101) == 0x4101) {
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if(GetDipSwitches() & 0x01) {
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//"In the latter setting, the ASIC sees all writes as being OR'd with $04, while on reads, D2 is open bus."
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return (openBus & 0xFC) | (_regs[_currentRegister] & 0x03);
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} else {
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return (openBus & 0xF8) | (_regs[_currentRegister] & 0x07);
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}
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}
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return openBus;
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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(GetDipSwitches() & 0x01) {
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//"In the latter setting, the ASIC sees all writes as being OR'd with $04, while on reads, D2 is open bus."
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value |= 0x04;
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}
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switch(addr & 0xC101) {
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case 0x4100: _currentRegister = value & 0x07; break;
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case 0x4101: _regs[_currentRegister] = (value & 0x07); UpdateState(); break;
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}
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}
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};
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