142 lines
3.0 KiB
C#
142 lines
3.0 KiB
C#
namespace BizHawk.Emulation.Consoles.Nintendo
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{
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public sealed class Mapper112 : NES.NESBoardBase
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{
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//configuration
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int prg_bank_mask_8k, chr_bank_mask_1k;
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//state
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int reg_addr;
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ByteBuffer regs = new ByteBuffer(8);
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//volatile state
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ByteBuffer chr_regs_1k = new ByteBuffer(8);
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ByteBuffer prg_regs_8k = new ByteBuffer(4);
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public override bool Configure(NES.EDetectionOrigin origin)
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{
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//analyze board type
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switch (Cart.board_type)
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{
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case "MAPPER112":
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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_8k = (Cart.prg_size / 8) - 1;
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int num_chr_banks = (Cart.chr_size);
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chr_bank_mask_1k = num_chr_banks - 1;
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SetMirrorType(EMirrorType.Vertical);
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Sync();
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return true;
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}
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public override void Dispose()
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{
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base.Dispose();
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regs.Dispose();
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chr_regs_1k.Dispose();
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prg_regs_8k.Dispose();
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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_addr", ref reg_addr);
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ser.Sync("regs", ref regs);
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Sync();
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}
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public override void WritePRG(int addr, byte value)
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{
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//Console.WriteLine("{0:X4} = {1:X2}", addr, value);
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switch (addr & 0x6001)
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{
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case 0x0000: //$8000
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reg_addr = (value & 7);
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break;
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case 0x2000: //$A000
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regs[reg_addr] = value;
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Sync();
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break;
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case 0x6000:
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if ((value & 1) == 0)
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{
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SetMirrorType(EMirrorType.Vertical);
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}
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else
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{
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SetMirrorType(EMirrorType.Horizontal);
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}
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break;
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}
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}
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void Sync()
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{
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prg_regs_8k[0] = regs[0];
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prg_regs_8k[1] = regs[1];
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prg_regs_8k[2] = 0xFE;
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prg_regs_8k[3] = 0xFF;
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byte r0_0 = (byte)(regs[2] & ~1);
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byte r0_1 = (byte)(regs[2] | 1);
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byte r1_0 = (byte)(regs[3] & ~1);
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byte r1_1 = (byte)(regs[3] | 1);
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chr_regs_1k[0] = r0_0;
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chr_regs_1k[1] = r0_1;
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chr_regs_1k[2] = r1_0;
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chr_regs_1k[3] = r1_1;
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chr_regs_1k[4] = regs[4];
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chr_regs_1k[5] = regs[5];
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chr_regs_1k[6] = regs[6];
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chr_regs_1k[7] = regs[7];
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}
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public int Get_PRGBank_8K(int addr)
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{
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int bank_8k = addr >> 13;
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bank_8k = prg_regs_8k[bank_8k];
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return bank_8k;
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}
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public int Get_CHRBank_1K(int addr)
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{
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int bank_1k = addr >> 10;
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bank_1k = chr_regs_1k[bank_1k];
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return bank_1k;
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}
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int RewireCHR(int addr)
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{
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int bank_1k = Get_CHRBank_1K(addr);
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bank_1k &= chr_bank_mask_1k;
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int ofs = addr & ((1 << 10) - 1);
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addr = (bank_1k << 10) + ofs;
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return addr;
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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) return VROM[RewireCHR(addr)];
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else return base.ReadPPU(addr);
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}
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public override void WritePPU(int addr, byte value)
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{
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if (addr < 0x2000) { }
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else base.WritePPU(addr, value);
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}
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public override byte ReadPRG(int addr)
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{
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int bank_8k = Get_PRGBank_8K(addr);
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bank_8k &= prg_bank_mask_8k;
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addr = (bank_8k << 13) | (addr & 0x1FFF);
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return ROM[addr];
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}
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}
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}
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