81 lines
1.5 KiB
C#
81 lines
1.5 KiB
C#
using BizHawk.Common;
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namespace BizHawk.Emulation.Cores.Nintendo.NES
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{
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// smb2j (us pirate)
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internal sealed class Mapper040 : NesBoardBase
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{
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int prg = 0;
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int irqcnt = 0;
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bool irqactive = false;
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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 "MAPPER040":
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AssertChr(8); AssertPrg(64); AssertVram(0); AssertWram(0);
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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.PadH, Cart.PadV);
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return true;
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}
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public override byte ReadWram(int addr)
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{
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// bank 6 fixed
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return Rom[addr + 0xc000];
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}
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public override byte ReadPrg(int addr)
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{
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if ((addr & 0x6000) == 0x4000)
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addr += prg;
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return Rom[addr + 0x8000];
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}
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public override void WritePrg(int addr, byte value)
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{
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switch (addr & 0x6000)
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{
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case 0x0000:
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irqcnt = 0;
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IrqSignal = false;
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irqactive = false;
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break;
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case 0x2000:
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irqactive = true;
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break;
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case 0x6000:
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prg = value & 7; // bank number
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// adjust for easy usage
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prg *= 0x2000;
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prg -= 0xc000;
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break;
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}
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}
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public override void ClockCpu()
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{
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if (irqactive)
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{
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irqcnt++;
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if (irqcnt >= 4096)
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{
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irqcnt = 4096;
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IrqSignal = true;
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}
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}
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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(nameof(prg), ref prg);
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ser.Sync(nameof(irqcnt), ref irqcnt);
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ser.Sync(nameof(irqactive), ref irqactive);
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}
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}
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}
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