89 lines
1.7 KiB
C#
89 lines
1.7 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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// 1997-in-1
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// 999999-in-1
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// 1000000-in-1
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// http://wiki.nesdev.com/w/index.php/INES_Mapper_212
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public class Mapper212 : NES.NESBoardBase
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{
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private int _reg;
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private int prg_bank_mask_32k, prg_bank_mask_16k, chr_bank_mask_8k;
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public override bool Configure(NES.EDetectionOrigin origin)
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{
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switch (Cart.board_type)
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{
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case "MAPPER212":
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break;
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default:
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return false;
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}
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SetMirrorType(Cart.pad_h, Cart.pad_v);
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chr_bank_mask_8k = Cart.chr_size / 8 - 1;
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prg_bank_mask_16k = Cart.prg_size / 16 - 1;
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prg_bank_mask_32k = Cart.prg_size / 32 - 1;
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_reg = 65535;
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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("_reg", ref _reg);
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}
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public override void WritePRG(int addr, byte value)
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{
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addr += 0x8000;
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_reg = addr;
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SetMirrorType(addr.Bit(3) ? EMirrorType.Horizontal : EMirrorType.Vertical);
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}
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public override byte ReadPRG(int addr)
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{
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addr += 0x8000;
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byte ret;
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if ((_reg & 0x4000) > 0)
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{
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int bank = (_reg >> 1) & 3;
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bank &= prg_bank_mask_32k;
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ret = ROM[(bank * 0x8000) + (addr & 0x7FFF)];
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}
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else
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{
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int bank = _reg & 7;
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bank &= prg_bank_mask_16k;
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ret = ROM[(bank * 0x4000) + (addr & 0x3FFF)];
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}
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if ((addr & 0xE010) == 0x6000)
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{
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ret |= 0x80;
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}
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return ret;
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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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int bank = _reg & 7;
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bank &= chr_bank_mask_8k;
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return VROM[(bank * 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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