From ea080c2c398ab3e30bafb5baaf073443737fb408 Mon Sep 17 00:00:00 2001
From: alyosha-tas <alexei.f.k@gmail.com>
Date: Sun, 2 Oct 2016 11:56:49 -0400
Subject: [PATCH] pocahontas mapper

---
 .../NES/Boards/MMC3_family/Pocahontas.cs      | 141 ++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/Pocahontas.cs

diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/Pocahontas.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/Pocahontas.cs
new file mode 100644
index 0000000000..22c028b0d4
--- /dev/null
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/Pocahontas.cs
@@ -0,0 +1,141 @@
+using BizHawk.Common;
+using System;
+
+namespace BizHawk.Emulation.Cores.Nintendo.NES
+{
+	public class MapperPocahontas : MMC3Board_Base
+	{
+		private ByteBuffer exRegs = new ByteBuffer(3);
+
+		public ByteBuffer prg_regs_8k = new ByteBuffer(4);
+
+		private int prg_mask_8k, chr_mask_1k;
+
+		private byte[] regs_sec = { 0, 2, 6, 1, 7, 3, 4, 5 }; 
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "Pocahontas":
+					break;
+				default:
+					return false;
+			}
+
+			BaseSetup();
+			exRegs[0] = 0;
+			exRegs[1] = 0;
+			exRegs[2] = 0;
+
+			prg_mask_8k = Cart.prg_size / 8 - 1;
+			chr_mask_1k = Cart.chr_size - 1;
+
+			prg_regs_8k[0] = 0;
+			prg_regs_8k[1] = 1;
+			prg_regs_8k[2] = (byte)(0xFE & prg_mask_8k);
+			prg_regs_8k[3] = (byte)(0xFF & prg_mask_8k);
+
+			
+			return true;
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			base.SyncState(ser);
+			ser.Sync("exRegs", ref exRegs);
+			ser.Sync("ptg_regs_8k", ref prg_regs_8k);
+			ser.Sync("prg_mask", ref prg_mask_8k);
+			ser.Sync("chr_mask", ref chr_mask_1k);
+		}
+
+		public override void WriteEXP(int addr, byte value)
+		{
+			if (addr == 0x1000) { exRegs[0] = value; }
+			if (addr == 0x1001) { exRegs[1] = value; }
+
+			base.WriteEXP(addr, value);
+		}
+
+		public override void WritePRG(int addr, byte value)
+		{
+			addr += 0x8000;
+
+			if (addr < 0xA000)
+			{
+				if (((value >> 7) | value)==0)
+				{
+					SetMirrorType(EMirrorType.Vertical);
+				}
+				else
+				{
+					SetMirrorType(EMirrorType.Horizontal);
+				}
+			}
+			else if (addr < 0xC000)
+			{
+				value = (byte)((value & 0xC0) | regs_sec[value & 0x07]);
+				exRegs[2] = 1;
+
+				base.WritePRG(0x0000, value);
+			}
+			else if (addr < 0xE000)
+			{
+				if (exRegs[2] >0)
+				{
+					exRegs[2] = 0;
+					base.WritePRG(0x0001, value);
+				}
+			}
+			else if (addr < 0xF000)
+			{
+				// nothing
+				base.WritePRG(0x6000, value);
+			}
+			else
+			{
+				base.WritePRG(0x6001, value);
+				base.WritePRG(0x4000, value);
+				base.WritePRG(0x4001, value);
+			}
+		}
+
+		public override byte ReadPPU(int addr)
+		{
+			if (addr < 0x2000)
+			{
+				int bank_1k = base.Get_CHRBank_1K(addr);
+
+				bank_1k |= (exRegs[1] << 6 & 0x100);
+				bank_1k &= chr_mask_1k;
+				addr = (bank_1k << 10) | (addr & 0x3FF);
+				return VROM[addr];
+			}
+			else return base.ReadPPU(addr);
+		}
+
+		public override byte ReadPRG(int addr)
+		{
+			int bank = exRegs[0] & 0xF;
+			if ((exRegs[0] & 0x80)>0)
+			{
+				if ((exRegs[0] & 0x20)>0)
+				{
+					return ROM[((bank >> 1) << 15) + (addr & 0x7FFF)];
+				}
+				else
+				{
+					return ROM[((bank) << 14) + (addr & 0x3FFF)];
+				}
+			}
+
+			else
+			{
+				bank = mmc3.Get_PRGBank_8K(addr);
+				bank &= prg_mask_8k;
+				return ROM[(bank << 13) + (addr & 0x1FFF)];
+			}
+			
+		}
+	}
+}