nes-add HKROM mmc6 (startropics)

BizHawk.Emulation/BizHawk.Emulation.csproj

@@ -115,6 +115,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper242.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper078.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\DRROM.cs" />
+    <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\HKROM.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\Mapper095.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\Mapper206.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\MMC3_family.cs" />

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

@@ -0,0 +1,109 @@
+using System;
+using System.IO;
+using System.Diagnostics;
+
+namespace BizHawk.Emulation.Consoles.Nintendo
+{
+	//aka MMC6 aka StarTropics and StarTropics 2
+	//for simplicity's sake, the behaviour of mmc6 is wrapped up into this board since it isnt used anywhere else
+	public class HKROM : MMC3Board_Base
+	{
+		//configuration
+
+		//state
+		bool wram_enabled;
+		bool wram_h_enabled, wram_l_enabled;
+		bool wram_h_enabled_write, wram_l_enabled_write;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			//analyze board type
+			switch (Cart.board_type)
+			{
+				case "NES-HKROM":
+					AssertPrg(256); AssertChr(256); AssertVram(0); AssertWram(0,1);
+					Cart.wram_size = 1; //1K of wram is in the mmc6
+					Cart.wram_battery = true; //and its battery backed.
+					break;
+				default:
+					return false;
+			}
+
+			BaseSetup();
+
+			return true;
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			base.SyncState(ser);
+			ser.Sync("wram_enabled", ref wram_enabled);
+			ser.Sync("wram_h_enabled", ref wram_h_enabled);
+			ser.Sync("wram_l_enabled", ref wram_l_enabled);
+			ser.Sync("wram_h_enabled_write", ref wram_h_enabled_write);
+			ser.Sync("wram_l_enabled_write", ref wram_l_enabled_write);
+		}
+
+		public override void WritePRG(int addr, byte value)
+		{
+			switch (addr & 0x6001)
+			{
+				case 0x0000: //$8000
+					//an extra wram enabled bit is here
+					wram_enabled = value.Bit(5);
+					if (!wram_enabled)
+					{
+						wram_h_enabled = wram_l_enabled = false;
+						wram_h_enabled_write = wram_l_enabled_write = false;
+					}
+					break;
+				
+				case 0x2001: //$A001
+					//a whole host of wram configurations
+					if (wram_enabled)
+					{
+						wram_h_enabled = value.Bit(7);
+						wram_l_enabled = value.Bit(5);
+						wram_h_enabled_write = value.Bit(6);
+						wram_l_enabled_write = value.Bit(6);
+					}
+					break;
+			}
+			base.WritePRG(addr, value);
+		}
+
+		public override void WriteWRAM(int addr, byte value)
+		{
+			if (addr < 0x1000)
+				return;
+
+			addr &= (1 << 10) - 1;
+			int block = addr >> 9;
+			bool block_enabled = (block == 1) ? wram_h_enabled : wram_l_enabled;
+			bool write_enabled = (block == 1) ? wram_h_enabled_write : wram_l_enabled_write;
+
+			if (write_enabled)
+				base.WriteWRAM(addr, value);
+		}
+
+		public override byte ReadWRAM(int addr)
+		{
+			byte open_bus = 0xFF; //open bus
+			if (addr < 0x1000)
+				return open_bus;
+
+			addr &= (1 << 10) - 1;
+			int block = addr >> 9;
+			bool block_enabled = (block == 1) ? wram_h_enabled : wram_l_enabled;
+			bool write_enabled = (block == 1) ? wram_h_enabled_write : wram_l_enabled_write;
+
+			if (!wram_h_enabled && wram_l_enabled)
+				return open_bus;
+
+			if (block_enabled)
+				return base.ReadWRAM(addr);
+			else return 0;
+		}
+
+	}
+}