From 50bff99fdd758ead34489814b8e40695e712b0dd Mon Sep 17 00:00:00 2001
From: Ian C <ianc@noddybox.co.uk>
Date: Tue, 3 Jan 2012 22:45:48 +0000
Subject: First pass of single byte opcodes done.

---
 src/Noddybox.Emulation.EightBit.Z80/Z80Cpu.cs | 80 ++++++++++++++++++++++++---
 1 file changed, 72 insertions(+), 8 deletions(-)

(limited to 'src/Noddybox.Emulation.EightBit.Z80/Z80Cpu.cs')

diff --git a/src/Noddybox.Emulation.EightBit.Z80/Z80Cpu.cs b/src/Noddybox.Emulation.EightBit.Z80/Z80Cpu.cs
index 0717ef5..13e8582 100644
--- a/src/Noddybox.Emulation.EightBit.Z80/Z80Cpu.cs
+++ b/src/Noddybox.Emulation.EightBit.Z80/Z80Cpu.cs
@@ -67,16 +67,75 @@ namespace Noddybox.Emulation.EightBit.Z80
 
         // Auxilliary registers and flags
         //
-        private byte        I;
+        private ushort      I;
         private byte        R;
         private bool        IFF1;
         private bool        IFF2;
+        private bool        raise;
+        private bool        nmi;
+        private byte        devbyte;
         private int         IM;
         private bool        HALT;
         private int         shift;
 
         #endregion
 
+        #region Private members
+
+        private void CheckInterrupts()
+        {
+            if (raise)
+            {
+                if (nmi)
+                {
+                    if (HALT)
+                    {
+                        HALT = false;
+                        PC++;
+                    }
+
+                    clock.Add(2);
+                    IFF1 = false;
+                    nmi = false;
+                    PUSH(PC);
+                    PC = 0x66;
+                }
+                else if (IFF1)
+                {
+                    if (HALT)
+                    {
+                        HALT = false;
+                        PC++;
+                    }
+
+                    clock.Add(2);
+                    IFF1 = false;
+                    IFF2 = false;
+
+                    switch(IM)
+                    {
+                        case 1:
+                            PUSH(PC);
+                            PC = 0x38;
+                            break;
+
+                        case 2:
+                            PUSH(PC);
+                            PC = (ushort)((I << 8) + devbyte);
+                            break;
+
+                        default:
+                            DecodeByte(devbyte);
+                            break;
+                    }
+                }
+
+                raise = false;
+            }
+        }
+
+        #endregion
+
         #region ICpu Members
 
         public void Initialise(IMemory memory, IDevice device, Clock clock)
@@ -114,11 +173,17 @@ namespace Noddybox.Emulation.EightBit.Z80
             R = 0;
             HALT = false;
             shift = 0;
+            raise = false;
+            nmi = false;
+            devbyte = 0;
         }
 
         public void Step()
         {
-            // TODO: Single step.
+            CheckInterrupts();
+            AddR(1);
+            shift = 0;
+            DecodeByte(memory.Read(PC++));
         }
 
         public void Run()
@@ -131,16 +196,15 @@ namespace Noddybox.Emulation.EightBit.Z80
 
         public void MaskableInterrupt(byte value)
         {
-            clock.Add(2);
-
-            // TODO: INT
+            raise = true;
+            devbyte = value;
+            nmi = false;
         }
 
         public void NonMaskableInterrupt(byte value)
         {
-            clock.Add(2);
-
-            // TODO: NMI
+            raise = true;
+            nmi = true;
         }
 
         #endregion
-- 
cgit v1.2.3