186 lines
3.9 KiB
C#
186 lines
3.9 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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public class Mapper253 : NES.NESBoardBase
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{
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private ByteBuffer prg = new ByteBuffer(2);
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private ByteBuffer chrlo = new ByteBuffer(8);
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private ByteBuffer chrhi = new ByteBuffer(8);
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private bool vlock;
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private int IRQLatch, IRQClock, IRQCount;
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private bool IRQa;
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private int prg_bank_mask_8k, chr_bank_mask_1k;
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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 "MAPPER253":
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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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chr_bank_mask_1k = Cart.chr_size - 1;
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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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prg.Dispose();
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chrlo.Dispose();
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chrhi.Dispose();
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base.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("preg", ref prg);
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ser.Sync("chrlo", ref chrlo);
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ser.Sync("chrhi", ref chrhi);
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}
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public override void ClockCPU()
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{
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if (IRQa)
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{
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IRQClock += 3;
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if (IRQClock >= 341)
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{
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IRQClock -= 341;
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IRQCount++;
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if (IRQCount == 0x100)
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{
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IRQSignal = true;
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IRQCount = IRQLatch;
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}
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}
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}
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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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if ((addr >= 0xB000) && (addr <= 0xE00C))
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{
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var ind = ((((addr & 8) | (addr >> 8)) >> 3) + 2) & 7;
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var sar = addr & 4;
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var clo = (chrlo[ind] & (0xF0 >> sar)) | ((value & 0x0F) << sar);
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chrlo[ind] = (byte)clo;
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if (ind == 0)
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{
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if (clo == 0xc8)
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vlock = false;
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else if (clo == 0x88)
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vlock = true;
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}
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if (sar > 0)
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chrhi[ind] = (byte)(value >> 4);
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}
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else
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{
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switch (addr)
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{
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case 0x8010: prg[0] = value; break;
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case 0xA010: prg[1] = value; break;
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case 0x9400: SetMirroring(value); break;
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case 0xF000: IRQSignal = false; IRQLatch &= 0xF0; IRQLatch |= value & 0xF; break;
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case 0xF004: IRQSignal = false; IRQLatch &= 0x0F; IRQLatch |= value << 4; break;
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case 0xF008: IRQSignal = false; IRQClock = 0; IRQCount = IRQLatch; IRQa = value.Bit(1); break;
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}
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}
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}
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private void SetMirroring(int mirr)
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{
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switch(mirr & 3)
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{
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case 0: SetMirrorType(EMirrorType.Vertical); break;
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case 1: SetMirrorType(EMirrorType.Horizontal); break;
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case 2: SetMirrorType(EMirrorType.OneScreenA); break;
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case 3: SetMirrorType(EMirrorType.OneScreenB); break;
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}
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}
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public override byte ReadPRG(int addr)
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{
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int bank;
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if (addr < 0x2000)
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{
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bank = prg[0] & prg_bank_mask_8k;
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}
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else if (addr < 0x4000)
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{
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bank = prg[1] & prg_bank_mask_8k;
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}
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else if (addr < 0x6000)
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{
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bank = prg_bank_mask_8k - 1;
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}
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else
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{
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bank = prg_bank_mask_8k;
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}
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return ROM[(bank << 13) + (addr & 0x1FFF)];
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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 x = (addr >> 10) & 7;
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var chr = chrlo[x] | (chrhi[x] << 8);
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int bank = (chr & chr_bank_mask_1k) << 10;
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if ((chrlo[x] == 4 || chrlo[x] == 5) && !vlock)
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{
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bank = chr & 1;
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return VRAM[(bank << 10) + (addr & 0x3FF)];
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}
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else
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{
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return VROM[bank + (addr & 0x3FF)];
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}
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}
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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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{
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if (VRAM != null)
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{
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int x = (addr >> 10) & 7;
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var chr = chrlo[x] | (chrhi[x] << 8);
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int bank = (chr & chr_bank_mask_1k) << 10;
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if ((chrlo[x] == 4 || chrlo[x] == 5) && !vlock)
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{
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bank = chr & 1;
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VRAM[(bank << 10) + (addr & 0x3FF)]=value;
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}
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}
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}
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else
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{
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NES.CIRAM[ApplyMirroring(addr)] = value;
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}
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}
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}
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}
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