From 0945bae21231d3679ca2a7f5f110203b25a65b54 Mon Sep 17 00:00:00 2001
From: adelikat <adelikat@tasvideos.org>
Date: Tue, 1 Nov 2016 08:24:15 -0500
Subject: [PATCH] Attempt mapper 106, irq logic is wrong

---
 .../BizHawk.Emulation.Cores.csproj            |   1 +
 .../Consoles/Nintendo/NES/Boards/Mapper106.cs | 151 ++++++++++++++++++
 2 files changed, 152 insertions(+)
 create mode 100644 BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/Mapper106.cs

diff --git a/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj b/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
index 40161b6902..2f2a010e97 100644
--- a/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
+++ b/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
@@ -612,6 +612,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper091.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper101.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper103.cs" />
+    <Compile Include="Consoles\Nintendo\NES\Boards\Mapper106.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper107.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper108.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper116.cs" />
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/Mapper106.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/Mapper106.cs
new file mode 100644
index 0000000000..61b141c169
--- /dev/null
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/Mapper106.cs
@@ -0,0 +1,151 @@
+using BizHawk.Common;
+using BizHawk.Common.NumberExtensions;
+
+namespace BizHawk.Emulation.Cores.Nintendo.NES
+{
+	public sealed class Mapper106 : NES.NESBoardBase
+	{
+		private ByteBuffer regs = new ByteBuffer(16);
+
+		private int prg_bank_mask_8k;
+		private int chr_bank_mask_1k;
+
+		private bool IRQa;
+		private int IRQCount;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "MAPPER106":
+					break;
+				default:
+					return false;
+			}
+
+			regs[0x8] = 0xFF;
+			regs[0x9] = 0xFF;
+			regs[0xA] = 0xFF;
+			regs[0xB] = 0xFF;
+
+			prg_bank_mask_8k = Cart.prg_size / 8 - 1;
+			chr_bank_mask_1k = Cart.chr_size / 1 - 1;
+
+			return true;
+		}
+
+		public override void Dispose()
+		{
+			regs.Dispose();
+			base.Dispose();
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			ser.Sync("regs", ref regs);
+			base.SyncState(ser);
+		}
+
+		public override void WritePRG(int addr, byte value)
+		{
+			int a = addr & 0xF;
+			switch(a)
+			{
+				default:
+					regs[a] = value;
+					SetMirror();
+					break;
+
+				// TODO: IRQs
+				case 0xD:
+					IRQa = false;
+					IRQCount = 0;
+					IRQSignal = false;
+					break;
+				case 0xE:
+					IRQCount = (IRQCount & 0xFF00) | value;
+					break;
+				case 0XF:
+					IRQCount = (IRQCount & 0x00FF) | (value << 8);
+					IRQa = true;
+					break;
+			}
+		}
+
+		private void SetMirror()
+		{
+			SetMirrorType(regs[0xC].Bit(0) ? EMirrorType.Horizontal : EMirrorType.Vertical);
+		}
+
+		public override byte ReadPPU(int addr)
+		{
+			if (addr < 0x2000)
+			{
+				int bank = 0;
+				if (addr < 0x400)
+				{
+					bank = regs[0] & 0xFE;
+				}
+				else if (addr < 0x800)
+				{
+					bank = regs[1] | 1;
+				}
+				else if (addr < 0xC00)
+				{
+					bank = regs[2] & 0xFE;
+				}
+				else if (addr < 0x1000)
+				{
+					bank = regs[3] | 1;
+				}
+
+				else if (addr < 0x1400)
+				{
+					bank = regs[4];
+				}
+				else if (addr < 0x1800)
+				{
+					bank = regs[5];
+				}
+				else if (addr < 0x1C00)
+				{
+					bank = regs[6];
+				}
+				else
+				{
+					bank = regs[7];
+				}
+
+				bank &= chr_bank_mask_1k;
+				return VROM[(bank << 10) + (addr & 0x3FF)];
+			}
+
+			return base.ReadPPU(addr);
+		}
+
+		public override byte ReadPRG(int addr)
+		{
+			int index = ((addr >> 13) & 3) + 8;
+			int bank = regs[index] & prg_bank_mask_8k;
+			return ROM[(bank << 13) + (addr & 0x1FFF)];
+		}
+
+		public override void ClockPPU()
+		{
+			IrqHook(1);
+		}
+
+		private void IrqHook(int a)
+		{
+			if ((NES.ppu.ppuphase != PPU.PPUPHASE.VBL) && IRQa)
+			{
+				IRQCount += a;
+				if (IRQCount > 0x10000)
+				{
+					IRQSignal = true;
+					IRQa = false;
+				}
+			}
+		}
+	}
+}