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52 lines
1.7 KiB
C++
52 lines
1.7 KiB
C++
#pragma once
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#include "stdafx.h"
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#include "BaseMapper.h"
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class CNROM : public BaseMapper
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{
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private:
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bool _enableCopyProtection;
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protected:
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virtual uint16_t GetPRGPageSize() override { return 0x8000; }
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virtual uint16_t GetCHRPageSize() override { return 0x2000; }
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void InitMapper() override
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{
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SelectPRGPage(0, 0);
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SelectCHRPage(0, GetPowerOnByte());
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}
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bool HasBusConflicts() override { return (_romInfo.MapperID == 3 && _romInfo.SubMapperID == 2) || _romInfo.MapperID == 185; }
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void WriteRegister(uint16_t addr, uint8_t value) override
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{
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if(_enableCopyProtection) {
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//Submapper 0: Use heuristics - "if C AND $0F is nonzero, and if C does not equal $13: CHR is enabled"
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//Submapper 4: Enable CHR-ROM if bits 0..1 of the latch hold the value 0, otherwise disable CHR-ROM.
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//Submapper 5: Enable CHR-ROM if bits 0..1 of the latch hold the value 1, otherwise disable CHR-ROM.
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//Submapper 6: Enable CHR-ROM if bits 0..1 of the latch hold the value 2, otherwise disable CHR-ROM.
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//Submapper 7: Enable CHR-ROM if bits 0..1 of the latch hold the value 3, otherwise disable CHR-ROM.
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bool validAccess = (
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(_romInfo.SubMapperID == 0 && (value & 0x0F) != 0 && value != 0x13) ||
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(_romInfo.SubMapperID == 4 && (value & 0x03) == 0) ||
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(_romInfo.SubMapperID == 5 && (value & 0x03) == 1) ||
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(_romInfo.SubMapperID == 6 && (value & 0x03) == 2) ||
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(_romInfo.SubMapperID == 7 && (value & 0x03) == 3)
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);
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if(validAccess) {
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SelectCHRPage(0, 0);
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} else {
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RemovePpuMemoryMapping(0x0000, 0x1FFF);
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}
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} else {
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SelectCHRPage(0, value);
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}
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}
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public:
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CNROM(bool enableCopyProtection) : _enableCopyProtection(enableCopyProtection)
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{
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}
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}; |