commodore64: add cartridge mapper 0012 (Zaxxon, Super Zaxxon), fix mapper 0000 to support 4k roms

BizHawk.Emulation/BizHawk.Emulation.csproj

@@ -84,6 +84,7 @@
     <Compile Include="Computers\Commodore64\Cartridges\Mapper0000.cs" />
     <Compile Include="Computers\Commodore64\C64.Input.cs" />
     <Compile Include="Computers\Commodore64\Cartridges\Mapper0005.cs" />
+    <Compile Include="Computers\Commodore64\Cartridges\Mapper0012.cs" />
     <Compile Include="Computers\Commodore64\Media\PRG.cs" />
     <Compile Include="Computers\Commodore64\Memory.cs" />
     <Compile Include="Computers\Commodore64\Cartridges\Cartridge.cs" />

BizHawk.Emulation/Computers/Commodore64/Cartridges/Cartridge.cs

@@ -70,6 +70,9 @@ namespace BizHawk.Emulation.Computers.Commodore64.Cartridges
 						case 0x0005:
 							result = new Mapper0005(chipAddress, chipBank, chipData);
 							break;
+						case 0x0012:
+							result = new Mapper0012(chipAddress, chipBank, chipData);
+							break;
 						default:
 							break;
 					}

BizHawk.Emulation/Computers/Commodore64/Cartridges/Mapper0000.cs

@@ -10,6 +10,8 @@ namespace BizHawk.Emulation.Computers.Commodore64.Cartridges
 		private byte[] romA;
 		private byte[] romB;
 
+		// standard cartridge mapper (Commodore)
+
 		public Mapper0000(byte[] data, bool exrom, bool game)
 		{
 			pinGame = game;
@@ -17,17 +19,32 @@ namespace BizHawk.Emulation.Computers.Commodore64.Cartridges
 
 			romA = new byte[0x2000];
 			romB = new byte[0x2000];
+			validCartridge = true;
 
-			Array.Copy(data, 0x0000, romA, 0x0000, 0x2000);
+			// we can expect three different configurations:
+			// bank of 4k, bank of 8k, or two banks of 8k
 
-			if (data.Length == 0x2000)
+			if (data.Length == 0x1000)
 			{
+				Array.Copy(data, 0x0000, romA, 0x0000, 0x1000);
+				Array.Copy(data, 0x0000, romA, 0x1000, 0x1000);
 				for (int i = 0; i < 0x2000; i++)
 					romB[i] = 0xFF;
 			}
+			else if (data.Length == 0x2000)
+			{
+				Array.Copy(data, 0x0000, romA, 0x0000, 0x2000);
+				for (int i = 0; i < 0x2000; i++)
+					romB[i] = 0xFF;
+			}
+			else if (data.Length == 0x4000)
+			{
+				Array.Copy(data, 0x0000, romA, 0x0000, 0x2000);
+				Array.Copy(data, 0x2000, romB, 0x0000, 0x2000);
+			}
 			else
 			{
-				Array.Copy(data, 0x2000, romB, 0x0000, 0x2000);
+				validCartridge = false;
 			}
 
 			HardReset();

BizHawk.Emulation/Computers/Commodore64/Cartridges/Mapper0012.cs

@@ -0,0 +1,72 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BizHawk.Emulation.Computers.Commodore64.Cartridges
+{
+	public class Mapper0012 : Cartridge
+	{
+		private byte[] bankMain;
+		private byte[][] bankHigh;
+		private byte[] bankHighSelected;
+		private byte[] dummyBank;
+
+		// Zaxxon and Super Zaxxon cartridges
+		// - read to 8xxx selects bank 0 in A000-BFFF
+		// - read to 9xxx selects bank 1 in A000-BFFF
+
+		public Mapper0012(List<uint> newAddresses, List<uint> newBanks, List<byte[]> newData)
+		{
+			bankMain = new byte[0x2000];
+			bankHigh = new byte[2][];
+			dummyBank = new byte[0x2000];
+
+			// create dummy bank just in case
+			for (uint i = 0; i < 0x2000; i++)
+				dummyBank[i] = 0xFF;
+
+			bankHigh[0] = dummyBank;
+			bankHigh[1] = dummyBank;
+
+			// load in the banks
+			for (int i = 0; i < newAddresses.Count; i++)
+			{
+				if (newAddresses[i] == 0x8000)
+					Array.Copy(newData[i], bankMain, 0x1000);
+				else if (newAddresses[i] == 0xA000 && newBanks[i] < 2)
+					bankHigh[newBanks[i]] = newData[i];
+			}
+
+			// mirror the main rom from 8000 to 9000
+			Array.Copy(bankMain, 0x0000, bankMain, 0x1000, 0x1000);
+
+			// set both pins low for 16k rom config
+			pinExRom = false;
+			pinGame = false;
+
+		}
+
+		public override byte Peek8000(int addr)
+		{
+			return bankMain[addr];
+		}
+
+		public override byte PeekA000(int addr)
+		{
+			return bankHighSelected[addr];
+		}
+
+		public override byte Read8000(ushort addr)
+		{
+			uint bank = (addr & (uint)0x1000) >> 12;
+			bankHighSelected = bankHigh[bank];
+			return bankMain[addr];
+		}
+
+		public override byte ReadA000(ushort addr)
+		{
+			return bankHighSelected[addr];
+		}
+	}
+}

BizHawk.Emulation/Computers/Commodore64/MOS/MOS6569.cs

@@ -168,20 +168,20 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 				},
 				new uint[] // BA
 				{
-					0x0834, 0x0834,
+					0x0843, 0x0843,
-					0x0345, 0x0345,
+					0x0543, 0x0543,
-					0x0845,	0x0845,
+					0x0548,	0x0548,
-					0x0456, 0x0456,
+					0x0546, 0x0546,
-					0x0856, 0x0856,
+					0x0586, 0x0586,
 					
-					0x0567, 0x0567,
+					0x0576, 0x0576,
-					0x0867, 0x0867,
+					0x0876, 0x0876,
-					0x0887,	0x0887,
+					0x0876,	0x0876,
-					0x0887, 0x0887,
+					0x0878, 0x0878,
-					0x0000, 0x0000,
+					0x0878, 0x0878,
 					
 					0x0000, 0x0000,
-					0x1000, 0x1000,
+					0x1000, 0x1000, // 12: badline
 					0x1000,	0x1000,
 					0x1000, 0x1000,
 					0x1000, 0x1000,
@@ -232,17 +232,17 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 					0x1000, 0x1000,
 					0x1000,	0x1000,
 					0x1000, 0x1000,
-					0x1000, 0x1000,
+					0x0880, 0x0880, // 55: sprites
 					
 					0x0880, 0x0880,
-					0x0880, 0x0880,
+					0x0810, 0x0810,
-					0x0801,	0x0801,
+					0x0810,	0x0810,
-					0x0012, 0x0012,
+					0x0210, 0x0210,
-					0x0812, 0x0812,
+					0x0218, 0x0218,
 					
-					0x0123, 0x0123,
+					0x0213, 0x0213,
-					0x0823, 0x0823,
+					0x0283, 0x0283,
-					0x0234,	0x0234
+					0x0243,	0x0243
 				},
 				new uint[] // actions
 				{

BizHawk.Emulation/Computers/Commodore64/MOS/Vic.cs

@@ -171,7 +171,7 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 			backgroundColor1 = 0;
 			backgroundColor2 = 0;
 			backgroundColor3 = 0;
-			baCount = 4;
+			baCount = baResetCounter;
 			badline = false;
 			badlineEnable = false;
 			bitmapMode = false;
@@ -243,9 +243,10 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 		private void UpdateBA()
 		{
 			if (pinBA)
-				baCount = 4;
+				baCount = baResetCounter;
 			else if (baCount > 0)
 				baCount--;
+			pinAEC = (baCount > 0);
 		}
 
 		private void UpdateBorder()
@@ -279,12 +280,17 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 		protected const uint pipelineChkSprDisp = 512;
 		protected const uint pipelineUpdateRc = 1024;
 
+		protected const uint rasterIrqLine0Cycle = 1;
+		protected const uint rasterIrqLineXCycle = 0;
+
+		protected const uint baResetCounter = 4;
+
 		// ------------------------------------
 
 		public void ExecutePhase1()
 		{
 			// raster IRQ compare
-			if ((cycle == 0 && rasterLine > 0) || (cycle == 1 && rasterLine == 0))
+			if ((cycle == rasterIrqLineXCycle && rasterLine > 0) || (cycle == rasterIrqLine0Cycle && rasterLine == 0))
 			{
 				if (rasterLine != lastRasterLine)
 					if (rasterLine == rasterInterruptLine)
@@ -327,6 +333,9 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 			xOffset = 0;
 			Render();
 
+			// if the BA counter is nonzero, allow CPU bus access
+			UpdateBA();
+
 			// must always come last
 			UpdatePins();
 		}
@@ -355,10 +364,6 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 				}
 			}
 
-			// if the BA counter is nonzero, allow CPU bus access
-			UpdateBA();
-			pinAEC = (baCount > 0);
-
 			Render();
 
 			// must always come last
@@ -367,7 +372,6 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 
 		private void ParseCycle()
 		{
-			bool baPinThisCycle = true;
 			ushort addr = 0x3FFF;
 			uint cycleBAsprite0;
 			uint cycleBAsprite1;
@@ -477,10 +481,10 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 			switch (ba)
 			{
 				case 0x0000:
-					baPinThisCycle = true;
+					pinBA = true;
 					break;
 				case 0x1000:
-					baPinThisCycle = !badline;
+					pinBA = !badline;
 					break;
 				default:
 					cycleBAsprite0 = ba & 0x000F;
@@ -489,10 +493,11 @@ namespace BizHawk.Emulation.Computers.Commodore64.MOS
 					if ((cycleBAsprite0 < 8 && sprites[cycleBAsprite0].dma) ||
 						(cycleBAsprite1 < 8 && sprites[cycleBAsprite1].dma) ||
 						(cycleBAsprite2 < 8 && sprites[cycleBAsprite2].dma))
-						baPinThisCycle = false;
+						pinBA = false;
+					else
+						pinBA = true;
 					break;
 			}
-			pinBA = baPinThisCycle;
 
 			// perform actions
 			borderCheckLEnable = true;