mirror of
https://github.com/SourMesen/Mesen.git
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117 lines
3.1 KiB
C++
117 lines
3.1 KiB
C++
#pragma once
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#include "BaseMapper.h"
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enum class Sachen8259Variant
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{
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Sachen8259A,
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Sachen8259B,
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Sachen8259C,
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Sachen8259D,
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};
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class Sachen8259 : public BaseMapper
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{
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private:
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Sachen8259Variant _variant;
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uint8_t _currentReg;
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uint8_t _regs[8];
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uint8_t _shift;
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uint8_t _chrOr[3];
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protected:
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uint16_t GetPRGPageSize() override { return 0x8000; }
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uint16_t GetCHRPageSize() override { return _variant == Sachen8259Variant::Sachen8259D ? 0x400 : 0x800; }
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uint16_t RegisterStartAddress() override { return 0x4100; }
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uint16_t RegisterEndAddress() override { return 0x7FFF; }
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void InitMapper() override
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{
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_currentReg = 0;
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memset(_regs, 0, sizeof(_regs));
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SelectPRGPage(0, 0);
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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(_currentReg, regs);
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}
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void UpdateState()
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{
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bool simpleMode = (_regs[7] & 0x01) == 0x01;
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switch((_regs[7] >> 1) & 0x03) {
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case 0: SetMirroringType(_variant == Sachen8259Variant::Sachen8259D ? MirroringType::Horizontal : MirroringType::Vertical); break;
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case 1: SetMirroringType(_variant == Sachen8259Variant::Sachen8259D ? MirroringType::Vertical : MirroringType::Horizontal); break;
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case 2: SetNametables(0, 1, 1, 1); break;
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case 3: SetMirroringType(MirroringType::ScreenAOnly); break;
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}
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if(_variant == Sachen8259Variant::Sachen8259D && simpleMode) {
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//"Enable "simple" mode. (mirroring is fixed to H, and banks become weird)"
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SetMirroringType(MirroringType::Horizontal);
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}
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SelectPRGPage(0, _regs[5]);
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if(_variant == Sachen8259Variant::Sachen8259D) {
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SelectCHRPage(0, _regs[0]);
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SelectCHRPage(1, ((_regs[4] & 0x01) << 4) | _regs[simpleMode ? 0 : 1]);
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SelectCHRPage(2, ((_regs[4] & 0x02) << 3) | _regs[simpleMode ? 0 : 2]);
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SelectCHRPage(3, ((_regs[4] & 0x04) << 2) | ((_regs[6] & 0x01) << 3) | _regs[simpleMode ? 0 : 3]);
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SelectChrPage4x(1, -4);
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} else {
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if(!HasChrRam()) {
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uint8_t chrHigh = _regs[4] << 3;
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SelectCHRPage(0, ((chrHigh | _regs[0]) << _shift));
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SelectCHRPage(1, ((chrHigh | (_regs[simpleMode ? 0 : 1])) << _shift) | _chrOr[0]);
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SelectCHRPage(2, ((chrHigh | (_regs[simpleMode ? 0 : 2])) << _shift) | _chrOr[1]);
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SelectCHRPage(3, ((chrHigh | (_regs[simpleMode ? 0 : 3])) << _shift) | _chrOr[2]);
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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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switch(addr & 0xC101) {
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case 0x4100: _currentReg = value & 0x07; break;
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case 0x4101: _regs[_currentReg] = value & 0x07; UpdateState(); break;
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}
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}
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public:
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Sachen8259(Sachen8259Variant variant)
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{
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_variant = variant;
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switch(variant) {
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case Sachen8259Variant::Sachen8259A:
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_shift = 1;
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_chrOr[0] = 1;
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_chrOr[1] = 0;
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_chrOr[2] = 1;
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break;
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case Sachen8259Variant::Sachen8259B:
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_shift = 0;
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_chrOr[0] = 0;
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_chrOr[1] = 0;
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_chrOr[2] = 0;
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break;
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case Sachen8259Variant::Sachen8259C:
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_shift = 2;
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_chrOr[0] = 1;
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_chrOr[1] = 2;
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_chrOr[2] = 3;
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break;
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case Sachen8259Variant::Sachen8259D:
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//Variant D does not use the _shift / _chrOr variables at all
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_shift = 0;
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_chrOr[0] = _chrOr[1] = _chrOr[2] = 0;
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break;
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}
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}
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};
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