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66 lines
1.7 KiB
C++
66 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 VRC1 : public BaseMapper
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{
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private:
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uint8_t _chrBanks[2];
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void UpdateChrBanks()
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{
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SelectCHRPage(0, _chrBanks[0]);
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SelectCHRPage(1, _chrBanks[1]);
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}
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protected:
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virtual uint16_t GetPRGPageSize() override { return 0x2000; }
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virtual uint16_t GetCHRPageSize() override { return 0x1000; }
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void InitMapper() override
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{
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SelectPRGPage(3, -1);
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}
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virtual void StreamState(bool saving) override
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{
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BaseMapper::StreamState(saving);
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ArrayInfo<uint8_t> chrBanks = { _chrBanks, 2 };
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Stream(chrBanks);
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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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//TODO: Create a setting to enable/disable oversized PRG
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bool allowOversizedPrg = true;
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uint8_t prgMask = allowOversizedPrg ? 0xFF : 0x0F;
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switch(addr & 0xF000) {
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case 0x8000: SelectPRGPage(0, value & prgMask); break;
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case 0x9000:
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if(GetMirroringType() != MirroringType::FourScreens) {
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//"The mirroring bit is ignored if the cartridge is wired for 4-screen VRAM, as is typical for Vs. System games using the VRC1."
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SetMirroringType((value & 0x01) == 0x01 ? MirroringType::Horizontal : MirroringType::Vertical);
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}
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_chrBanks[0] = (_chrBanks[0] & 0x0F) | ((value & 0x02) << 3);
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_chrBanks[1] = (_chrBanks[1] & 0x0F) | ((value & 0x04) << 2);
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UpdateChrBanks();
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break;
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case 0xA000: SelectPRGPage(1, value & prgMask); break;
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case 0xC000: SelectPRGPage(2, value & prgMask); break;
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case 0xE000:
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_chrBanks[0] = (_chrBanks[0] & 0x10) | (value & 0x0F);
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UpdateChrBanks();
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break;
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case 0xF000:
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_chrBanks[1] = (_chrBanks[1] & 0x10) | (value & 0x0F);
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UpdateChrBanks();
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break;
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}
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}
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}; |