56 lines
1.2 KiB
C#
56 lines
1.2 KiB
C#
using BizHawk.Common;
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// https://wiki.nesdev.com/w/index.php/INES_Mapper_203
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namespace BizHawk.Emulation.Cores.Nintendo.NES
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{
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internal sealed class Mapper203 : NesBoardBase
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{
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int prg_reg_16k, chr_reg_8k;
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int prg_bank_mask_16k;
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int chr_bank_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 "MAPPER203":
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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_bank_mask_16k = Cart.PrgSize / 16 - 1;
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chr_bank_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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ser.Sync(nameof(prg_reg_16k), ref prg_reg_16k);
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ser.Sync(nameof(chr_reg_8k), ref chr_reg_8k);
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base.SyncState(ser);
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}
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public override void WritePrg(int addr, byte value)
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{
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prg_reg_16k = (value >> 2) & prg_bank_mask_16k;
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chr_reg_8k = (value & 0x03) & chr_bank_mask_8k;
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}
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public override byte ReadPrg(int addr)
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{
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return Rom[(prg_reg_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[(chr_reg_8k * 0x2000) + addr];
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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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