From 78c7a74a0d8f7ab47d0a4e708c6f848d9dd6a712 Mon Sep 17 00:00:00 2001
From: beirich <beirich@4bbf4f03-6f44-549e-7e59-35d4b0962838>
Date: Tue, 1 Feb 2011 05:25:28 +0000
Subject: [PATCH] PCE: improve video timing... slightly

---
 .../Consoles/PC Engine/PCEngine.cs             |  2 +-
 BizHawk.Emulation/Consoles/PC Engine/VCE.cs    |  9 +++++++++
 .../Consoles/PC Engine/VDC.Render.cs           | 18 +++++++++++++++---
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/BizHawk.Emulation/Consoles/PC Engine/PCEngine.cs b/BizHawk.Emulation/Consoles/PC Engine/PCEngine.cs
index f3d249aaef..ac91123c47 100644
--- a/BizHawk.Emulation/Consoles/PC Engine/PCEngine.cs	
+++ b/BizHawk.Emulation/Consoles/PC Engine/PCEngine.cs	
@@ -258,7 +258,7 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
 
         public byte[] SaveStateBinary()
         {
-            var buf = new byte[SuperGrafx ? 166550 : 75852];
+            var buf = new byte[SuperGrafx ? 166551 : 75853];
             var stream = new MemoryStream(buf);
             var writer = new BinaryWriter(stream);
             SaveStateBinary(writer);
diff --git a/BizHawk.Emulation/Consoles/PC Engine/VCE.cs b/BizHawk.Emulation/Consoles/PC Engine/VCE.cs
index efeac2f31c..1b45d3fd87 100644
--- a/BizHawk.Emulation/Consoles/PC Engine/VCE.cs	
+++ b/BizHawk.Emulation/Consoles/PC Engine/VCE.cs	
@@ -10,6 +10,7 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
         public ushort VceAddress;
         public ushort[] VceData = new ushort[512];
         public int[] Palette = new int[512];
+        public byte DotClock;
 
         public void WriteVCE(int port, byte value)
         {
@@ -17,6 +18,9 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
             switch (port)
             {
                 case 0: // Control Port. Doesn't control anything we care about...
+                    DotClock = (byte) (value & 3);
+                    if (DotClock == 3) 
+                        DotClock = 2;
                     break;
                 case 2: // Address LSB
                     VceAddress &= 0xFF00;
@@ -72,6 +76,7 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
         {
             writer.WriteLine("[VCE]");
             writer.WriteLine("VceAddress {0:X4}", VceAddress);
+            writer.WriteLine("DotClock {0}", DotClock);
             writer.Write("VceData ");
             VceData.SaveAsHex(writer);
             writer.WriteLine("[/VCE]\n");
@@ -86,6 +91,8 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
                 if (args[0] == "[/VCE]") break;
                 if (args[0] == "VceAddress")
                     VceAddress = ushort.Parse(args[1], NumberStyles.HexNumber);
+                else if (args[0] == "DotClock")
+                    DotClock = byte.Parse(args[1]);
                 else if (args[0] == "VceData")
                     VceData.ReadFromHex(args[1]);
                 else
@@ -99,6 +106,7 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
         public void SaveStateBinary(BinaryWriter writer)
         {
             writer.Write(VceAddress);
+            writer.Write(DotClock);
             for (int i = 0; i < VceData.Length; i++)
                 writer.Write(VceData[i]);
         }
@@ -106,6 +114,7 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
         public void LoadStateBinary(BinaryReader reader)
         {
             VceAddress = reader.ReadUInt16();
+            DotClock = reader.ReadByte();
             for (int i = 0; i < VceData.Length; i++)
             {
                 VceData[i] = reader.ReadUInt16();
diff --git a/BizHawk.Emulation/Consoles/PC Engine/VDC.Render.cs b/BizHawk.Emulation/Consoles/PC Engine/VDC.Render.cs
index 18b497b750..6eee266278 100644
--- a/BizHawk.Emulation/Consoles/PC Engine/VDC.Render.cs	
+++ b/BizHawk.Emulation/Consoles/PC Engine/VDC.Render.cs	
@@ -16,7 +16,7 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
            register at certain sync points and incremented every scanline. 
            Its values range from 0 - $1FF.
          + RCRCount is the current offset into the RCR register. It is reset to $40 
-           on the first active display line of, and incremented every line. Its effective
+           on the first active display line, and incremented every line. Its effective
            range is $40 - $146.
          
         */
@@ -40,6 +40,18 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
             ActiveLine = 0 - latchedDisplayStartLine;
             ScanLine = 0;
 
+            int HDS = (Registers[HSR] >> 8) & 0x7F;
+            int HDE = (Registers[HDR] >> 8) & 0x7F;
+            int hblankCycles = (HDS + HDE + 2) * 8;
+            //hblankCycles -= 2;
+
+            switch (vce.DotClock)
+            {
+                case 0: hblankCycles = (hblankCycles * 4) / 3; break;
+                case 1: break;
+                case 2: hblankCycles = (hblankCycles*2)/3; break;
+            }
+
             for (; ScanLine < 262;)
             {
                 //Log.Note("VDC","ScanLine {0} (ActiveLine {1}, RCR {2}, BGY {3})",ScanLine, ActiveLine, RCRCount, BackgroundY);
@@ -69,12 +81,12 @@ namespace BizHawk.Emulation.Consoles.TurboGrafx
                     StatusByte |= StatusVerticalBlanking;
                     cpu.IRQ1Assert = true;
                 }
-                cpu.Execute(82);
+                cpu.Execute(hblankCycles);
 
                 if (InActiveDisplay && render)
                     RenderScanLine();
 
-                cpu.Execute(373);
+                cpu.Execute(455-hblankCycles);
 
                 ScanLine++;
                 ActiveLine++;