support mapper218: Magic Floor (Homebrew)

BizHawk.Emulation/BizHawk.Emulation.csproj

@@ -171,6 +171,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper201.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper203.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper207.cs" />
+    <Compile Include="Consoles\Nintendo\NES\Boards\Mapper218.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper225.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper226.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper227.cs" />

BizHawk.Emulation/Consoles/Nintendo/NES/BoardSystem.cs

@@ -306,6 +306,8 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			public byte pad_h, pad_v, mapper;
 			public bool wram_battery;
 			public bool bad;
+			/// <summary>in [0,3]; combination of bits 0 and 3 of flags6.  try not to use; will be null for bootgod-identified roms always</summary>
+			public int? inesmirroring;
 
 			public string board_type;
 			public string pcb;

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/Mapper218.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BizHawk.Emulation.Consoles.Nintendo
+{
+	// rewires pins to use internal CIRAM as both nametable and pattern data, so
+	// the entire cart is just a single PRGROM chip (plus CIC)
+	public class Mapper218 : NES.NESBoardBase
+	{
+		//configuration
+		int prg_byte_mask;
+		int chr_addr_mask;
+				
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "MAPPER218":
+					// the cart actually has 0k vram, but due to massive abuse of the ines format, is labeled as 8k
+					// supposed vram is (correctly) not used in our implementation
+					AssertPrg(8, 16, 32); AssertChr(0); /*AssertVram(0);*/ AssertWram(0);
+					break;
+				default:
+					return false;
+			}
+
+			// due to massive abuse of the ines format, the mirroring and 4 screen bits have slightly different meanings
+			switch (Cart.inesmirroring)
+			{
+				case 1: // VA10 to PA10
+					chr_addr_mask = 1 << 10;
+					break;
+				case 0: // VA10 to PA11
+					chr_addr_mask = 1 << 11;
+					break;
+				case 2: // VA10 to PA12
+					chr_addr_mask = 1 << 12;
+					break;
+				case 3: // VA10 to PA13
+					chr_addr_mask = 1 << 13;
+					break;
+				default:
+					// we need an ines identification for correct mirroring
+					return false;
+			}
+			prg_byte_mask = (Cart.prg_size*1024) - 1;
+			return true;
+		}
+
+		int TransformPPU(int addr)
+		{
+			if ((addr & chr_addr_mask) != 0)
+				addr = addr & 0x3ff | 0x400;
+			else
+				addr = addr & 0x3ff;
+			return addr;
+		}
+
+		public override byte ReadPPU(int addr)
+		{
+			if (addr < 0x3f00)
+				return NES.CIRAM[TransformPPU(addr)];
+			else
+				// palettes only
+				return base.ReadPPU(addr);
+		}
+
+		public override void WritePPU(int addr, byte value)
+		{
+			if (addr < 0x3f00)
+				NES.CIRAM[TransformPPU(addr)] = value;
+			else
+				// palettes only
+				base.WritePPU(addr, value);
+		}
+
+		public override byte ReadPRG(int addr)
+		{
+			addr &= prg_byte_mask;
+			return ROM[addr];
+		}
+	}
+}

BizHawk.Emulation/Consoles/Nintendo/NES/iNES.cs

@@ -79,9 +79,10 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				mapper |= (ROM_type2 & 0xF0);
 				ret.mapper = (byte)mapper;
 				int mirroring = (ROM_type & 1);
-				if ((ROM_type & 8) != 0) mirroring = 2;
+				if ((ROM_type & 8) != 0) mirroring += 2;
 				if (mirroring == 0) ret.pad_v = 1;
 				else if (mirroring == 1) ret.pad_h = 1;
+				ret.inesmirroring = mirroring;
 				ret.prg_size = (short)(ROM_size * 16);
 				if (ret.prg_size == 0)
 					ret.prg_size = 256 * 16;