67 lines
1.4 KiB
C#
67 lines
1.4 KiB
C#
using BizHawk.Common;
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using BizHawk.Common.NumberExtensions;
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namespace BizHawk.Emulation.Cores.Nintendo.NES
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{
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// 64-in-1
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// http://wiki.nesdev.com/w/index.php/INES_Mapper_204
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internal sealed class Mapper204 : NesBoardBase
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{
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private int _reg1, _reg2;
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private int prg_mask_16k, chr_mask_8k;
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public override bool Configure(EDetectionOrigin origin)
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{
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switch (Cart.BoardType)
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{
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case "MAPPER204":
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break;
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default:
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return false;
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}
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prg_mask_16k = Cart.PrgSize / 16 - 1;
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chr_mask_8k = Cart.ChrSize / 8 - 1;
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return true;
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}
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public override void SyncState(Serializer ser)
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{
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base.SyncState(ser);
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ser.Sync("reg1", ref _reg1);
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ser.Sync("reg2", ref _reg2);
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}
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public override void WritePrg(int addr, byte value)
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{
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_reg1 = addr & 0x6;
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_reg2 = _reg1 + ((_reg1 == 0x6) ? 0 : (addr & 1));
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_reg1 = _reg1 + ((_reg1 == 0x6) ? 1 : (addr & 1));
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SetMirrorType(addr.Bit(0) ? EMirrorType.Vertical : EMirrorType.Horizontal);
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}
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public override byte ReadPrg(int addr)
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{
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if (addr < 0x4000)
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{
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return Rom[((_reg2 & prg_mask_16k) * 0x4000) + (addr & 0x3FFF)];
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}
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return Rom[((_reg1 & prg_mask_16k) * 0x4000) + (addr & 0x3FFF)];
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}
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public override byte ReadPpu(int addr)
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{
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if (addr < 0x2000)
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{
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return Vrom[((_reg2 & chr_mask_8k) * 0x2000) + (addr & 0x1FFF)];
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}
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return base.ReadPpu(addr);
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}
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}
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}
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