From b6a786d5a2fa7961e81786b32d470bc46af0ce98 Mon Sep 17 00:00:00 2001
From: alyosha-tas <alexei.f.k@gmail.com>
Date: Sun, 30 Oct 2016 19:31:41 -0400
Subject: [PATCH] Update for VS Castlevania

---
 .../Consoles/Nintendo/NES/Boards/UxROM.cs     | 48 +++++++++++++++++--
 1 file changed, 45 insertions(+), 3 deletions(-)

diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/UxROM.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/UxROM.cs
index b30bead6c4..ddb8cd51cb 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/UxROM.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/UxROM.cs
@@ -26,6 +26,10 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 		//state
 		int prg;
 
+		//the VS actually does have 2 KB of nametable address space
+		//let's make the extra space here, instead of in the main NES to avoid confusion
+		byte[] CIRAM_VS = new byte[0x800];
+
 		public override bool Configure(NES.EDetectionOrigin origin)
 		{
 			adjust_prg = (x) => x;
@@ -58,7 +62,9 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 				case "JALECO-JF-18":
 					AssertPrg(256); AssertChr(0); AssertVram(8); AssertWram(0);
 					break;
-
+				case "NES-UNROM_VS":
+					NES._isVS = true;
+					break;
 				default:
 					return false;
 			}
@@ -88,7 +94,23 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			{
 				return VRAM[addr & vram_byte_mask];
 			}
-			else return base.ReadPPU(addr);
+			else
+			{
+				if (NES._isVS)
+				{
+					addr = addr - 0x2000;
+					if (addr < 0x800)
+					{
+						return NES.CIRAM[addr];
+					}
+					else
+					{
+						return CIRAM_VS[addr - 0x800];
+					}
+				}
+				else
+					return base.ReadPPU(addr);
+			}
 		}
 
 		public override void WritePPU(int addr, byte value)
@@ -97,13 +119,33 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			{
 				VRAM[addr & vram_byte_mask] = value;
 			}
-			else base.WritePPU(addr,value);
+			else if (NES._isVS)
+			{
+				// The game VS Castlevania apparently scans for more CIRAM then actually exists, so we have to mask out nonsensical values 
+				addr &= 0x2FFF;
+
+
+				addr = addr - 0x2000;
+				if (addr < 0x800)
+				{
+					NES.CIRAM[addr] = value;
+				}
+				else
+				{
+					CIRAM_VS[addr - 0x800] = value;
+				}
+			}
+			else
+				base.WritePPU(addr,value);
 		}
 
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
 			ser.Sync("prg", ref prg);
+
+			if (NES.IsVS)
+				ser.Sync("VS_CIRAM", ref CIRAM_VS, false);
 		}
 	}
 }
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