From 6d1c25245c7d10df82548055bbec2f2612cdb619 Mon Sep 17 00:00:00 2001
From: Ian C <ianc@noddybox.co.uk>
Date: Tue, 3 Apr 2012 22:50:43 +0000
Subject: Some more emulation fixes.

---
 .../Z80CpuBaseOpcodes.cs                           | 62 ++++++++++++++++++----
 .../Z80CpuDecodeED.cs                              |  2 +
 2 files changed, 54 insertions(+), 10 deletions(-)

diff --git a/src/Noddybox.Emulation.EightBit.Z80/Z80CpuBaseOpcodes.cs b/src/Noddybox.Emulation.EightBit.Z80/Z80CpuBaseOpcodes.cs
index cc02e94..eed7258 100644
--- a/src/Noddybox.Emulation.EightBit.Z80/Z80CpuBaseOpcodes.cs
+++ b/src/Noddybox.Emulation.EightBit.Z80/Z80CpuBaseOpcodes.cs
@@ -789,17 +789,21 @@ namespace Noddybox.Emulation.EightBit.Z80
             HL.reg++;
             BC.reg--;
 
+            ClearFlag(Z80Flags.HalfCarry | Z80Flags.Neg | Z80Flags.Hidden | Z80Flags.PV);
+
             if (BC.reg != 0)
             {
-                ClearFlag(Z80Flags.HalfCarry | Z80Flags.Neg);
                 SetFlag(Z80Flags.PV);
             }
-            else
+
+            b += A;
+
+            if ((b & 2) == 2)
             {
-                ClearFlag(Z80Flags.HalfCarry | Z80Flags.Neg | Z80Flags.PV);
+                F |= Z80Flags.Hidden5;
             }
 
-            F |= H35table[A + b];
+            F |= (Z80Flags)(b & 8);
         }
 
         /// <summary>
@@ -831,11 +835,18 @@ namespace Noddybox.Emulation.EightBit.Z80
         /// </summary>
         private void CPI()
         {
-            Z80Flags c = F & Z80Flags.Carry;
             byte b = memory.Read(HL.reg);
+            byte tmp = (byte)(A - b);
+            int w = A - b;
+
+            if (w < 0)
+            {
+                w += 0x200;
+            }
+
+            int lookup = ((A & 0x08) >> 3) | ((b & 0x08) >> 2) | ((tmp & 0x08) >> 1);
 
-            CP(b);
-            F |= c;
+            F = (F & Z80Flags.Carry) | SZtable[w] | Z80Flags.Neg | halfcarry_sub_table[lookup];
 
             HL.reg++;
             BC.reg--;
@@ -848,6 +859,18 @@ namespace Noddybox.Emulation.EightBit.Z80
             {
                 ClearFlag(Z80Flags.PV);
             }
+
+            if ((F & Z80Flags.HalfCarry) == Z80Flags.HalfCarry)
+            {
+                tmp--;
+            }
+
+            if ((tmp & 2) == 2)
+            {
+                F |= Z80Flags.Hidden5;
+            }
+
+            F |= (Z80Flags)(tmp & 8);
         }
 
         /// <summary>
@@ -855,11 +878,18 @@ namespace Noddybox.Emulation.EightBit.Z80
         /// </summary>
         private void CPD()
         {
-            Z80Flags c = F & Z80Flags.Carry;
             byte b = memory.Read(HL.reg);
+            byte tmp = (byte)(A - b);
+            int w = A - b;
+
+            if (w < 0)
+            {
+                w += 0x200;
+            }
 
-            CP(b);
-            F |= c;
+            int lookup = ((A & 0x08) >> 3) | ((b & 0x08) >> 2) | ((tmp & 0x08) >> 1);
+
+            F = (F & Z80Flags.Carry) | SZtable[w] | Z80Flags.Neg | halfcarry_sub_table[lookup];
 
             HL.reg--;
             BC.reg--;
@@ -872,6 +902,18 @@ namespace Noddybox.Emulation.EightBit.Z80
             {
                 ClearFlag(Z80Flags.PV);
             }
+
+            if ((F & Z80Flags.HalfCarry) == Z80Flags.HalfCarry)
+            {
+                tmp--;
+            }
+
+            if ((tmp & 2) == 2)
+            {
+                F |= Z80Flags.Hidden5;
+            }
+
+            F |= (Z80Flags)(tmp & 8);
         }
 
         /// <summary>
diff --git a/src/Noddybox.Emulation.EightBit.Z80/Z80CpuDecodeED.cs b/src/Noddybox.Emulation.EightBit.Z80/Z80CpuDecodeED.cs
index f9cc84e..7ad170c 100644
--- a/src/Noddybox.Emulation.EightBit.Z80/Z80CpuDecodeED.cs
+++ b/src/Noddybox.Emulation.EightBit.Z80/Z80CpuDecodeED.cs
@@ -376,6 +376,8 @@ namespace Noddybox.Emulation.EightBit.Z80
                 case 0x78:  // IN A,(C)
                     clock.Add(12);
                     A = device.Read(BC.reg);
+                    F &= Z80Flags.Carry;
+                    F |= PSZtable[A] | H35table[A];
                     break;
 
                 case 0x79:  // OUT (C),A
-- 
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