nes: implement mapper249: mmc3 plus "security features"

San Shi Liu Ji,
Shui Hu Zhuan,
Myth Struggle,
Duo Bao Xiao Ying Hao - Guang Ming yu An Hei Chuan Shuo

BizHawk.Emulation/BizHawk.Emulation.csproj

@@ -315,6 +315,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\Mapper197.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\Mapper205.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\Mapper245.cs" />
+    <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\Mapper249.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\Mapper250.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\MMC3.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\NES-QJ.cs" />

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/MMC3_family/Mapper249.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BizHawk.Emulation.Consoles.Nintendo
+{
+	public class Mapper249 : MMC3Board_Base
+	{
+		bool piratecrap = false;
+
+		// mmc3 with pirate crap bolt on
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "MAPPER249":
+					break;
+				default:
+					return false;
+			}
+			AssertPrg(256, 512);
+			AssertChr(256);
+			Cart.wram_size = 8;
+			BaseSetup();
+			return true;
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			base.SyncState(ser);
+			ser.Sync("piratecrap", ref piratecrap);
+		}
+
+		public override void WriteEXP(int addr, byte value)
+		{
+			piratecrap = value.Bit(1);
+		}
+
+		protected override int Get_CHRBank_1K(int addr)
+		{
+			int v = base.Get_CHRBank_1K(addr);
+			if (piratecrap)
+				v = v & 3 | v >> 1 & 4 | v >> 4 & 8 | v >> 2 & 0x10 | v << 3 & 0x20 | v << 2 & 0xC0;
+			return v;
+		}
+
+		protected override int Get_PRGBank_8K(int addr)
+		{
+			int v = base.Get_PRGBank_8K(addr);
+			if (piratecrap)
+			{
+				if (v < 0x20)
+					v = v & 1 | v >> 3 & 2 | v >> 1 & 4 | v << 2 & 8 | v << 2 & 0x10;
+				else
+				{
+					v -= 0x20;
+					v = v & 3 | v >> 1 & 4 | v >> 4 & 8 | v >> 2 & 0x10 | v << 3 & 0x20 | v << 2 & 0xC0;
+				}
+			}
+			return v;
+		}
+	}
+}