5 files changed, 281 insertions, 0 deletions
diff --git a/src/Noddybox.Emulation.EightBit/Binary.cs b/src/Noddybox.Emulation.EightBit/Binary.cs
new file mode 100644
index 0000000..0b1928b
--- /dev/null
+++ b/src/Noddybox.Emulation.EightBit/Binary.cs
@@ -0,0 +1,63 @@
+using System;
+using System.Net;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Documents;
+using System.Windows.Ink;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Animation;
+using System.Windows.Shapes;
+
+namespace Noddybox.Emulation.EightBit
+{
+    /// <summary>
+    /// Provides helpers for shifting smaller values around without casts all over the shop.
+    /// </summary>
+    public static class Binary
+    {
+        /// <summary>
+        /// Shift 8-bits to the left.
+        /// </summary>
+        /// <param name="b">The byte.</param>
+        /// <param name="shift">How many bits to shift.</param>
+        /// <returns>The shifted value.</returns>
+        public static byte ShiftLeft(byte b, int shift)
+        {
+            return (byte)((b << shift) & 0xff);
+        }
+
+        /// <summary>
+        /// Shift 8-bits to the right.
+        /// </summary>
+        /// <param name="b">The byte.</param>
+        /// <param name="shift">How many bits to shift.</param>
+        /// <returns>The shifted value.</returns>
+        public static byte ShiftRight(byte b, int shift)
+        {
+            return (byte)((b >> shift) & 0xff);
+        }
+
+        /// <summary>
+        /// Shift 16-bits to the left.
+        /// </summary>
+        /// <param name="w">The word.</param>
+        /// <param name="shift">How many bits to shift.</param>
+        /// <returns>The shifted value.</returns>
+        public static ushort ShiftLeft(ushort w, int shift)
+        {
+            return (ushort)((w << shift) & 0xffff);
+        }
+
+        /// <summary>
+        /// Shift 16-bits to the right.
+        /// </summary>
+        /// <param name="w">The word.</param>
+        /// <param name="shift">How many bits to shift.</param>
+        /// <returns>The shifted value.</returns>
+        public static ushort ShiftRight(ushort w, int shift)
+        {
+            return (ushort)((w >> shift) & 0xffff);
+        }
+    }
+}
diff --git a/src/Noddybox.Emulation.EightBit/ICpu.cs b/src/Noddybox.Emulation.EightBit/ICpu.cs
new file mode 100644
index 0000000..dc2f811
--- /dev/null
+++ b/src/Noddybox.Emulation.EightBit/ICpu.cs
@@ -0,0 +1,57 @@
+//
+// Copyright (c) 2012 Ian Cowburn
+//
+using System;
+using System.Net;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Documents;
+using System.Windows.Ink;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Animation;
+using System.Windows.Shapes;
+
+namespace Noddybox.Emulation.EightBit
+{
+    /// <summary>
+    /// Defines an 8-bit CPU.
+    /// </summary>
+    public interface ICpu
+    {
+        /// <summary>
+        /// Initialise the CPU to give it access to memory and devices.
+        /// </summary>
+        /// <param name="memory">The memory to access.</param>
+        /// <param name="device">The devices to access.</param>
+        /// <param name="clock">The clock to use.</param>
+        void Initialise(IMemory memory, IDevice device, Clock clock);
+
+        /// <summary>
+        /// Resets the CPU to its initial state.
+        /// </summary>
+        void Reset();
+
+        /// <summary>
+        /// Runs the next instruction.
+        /// </summary>
+        void Step();
+
+        /// <summary>
+        /// Runs the CPU until the next frame flyback.
+        /// </summary>
+        void Run();
+
+        /// <summary>
+        /// Generates a maskable interrupt to the CPU.
+        /// </summary>
+        /// <param name="value">Optional value from an interrupting device.  May be ignored depending on the CPU type.</param>
+        void MaskableInterrupt(byte value);
+
+        /// <summary>
+        /// Generates a non-maskable interrupt to the CPU.
+        /// </summary>
+        /// <param name="value">Optional value from an interrupting device.  May be ignored depending on the CPU type.</param>
+        void NonMaskableInterrupt(byte value);
+    }
+}
diff --git a/src/Noddybox.Emulation.EightBit/IDevice.cs b/src/Noddybox.Emulation.EightBit/IDevice.cs
new file mode 100644
index 0000000..b8d234a
--- /dev/null
+++ b/src/Noddybox.Emulation.EightBit/IDevice.cs
@@ -0,0 +1,37 @@
+//
+// Copyright (c) 2012 Ian Cowburn
+//
+using System;
+using System.Net;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Documents;
+using System.Windows.Ink;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Animation;
+using System.Windows.Shapes;
+
+namespace Noddybox.Emulation.EightBit
+{
+    /// <summary>
+    /// Provides an interface for devices for 8-bit processers which used special commands to access
+    /// devices rather than using memory-mapped IO, for example the Z80.
+    /// </summary>
+    public interface IDevice
+    {
+        /// <summary>
+        /// Read from a device.
+        /// </summary>
+        /// <param name="device">The address of the device.</param>
+        /// <returns>The byte returned from the device.</returns>
+        byte Read(ushort device);
+
+        /// <summary>
+        /// Write to a device.
+        /// </summary>
+        /// <param name="device">The address of the device.</param>
+        /// <param name="value">The value to write to the device.</param>
+        void Write(ushort device, byte value);
+    }
+}
diff --git a/src/Noddybox.Emulation.EightBit/IMemory.cs b/src/Noddybox.Emulation.EightBit/IMemory.cs
new file mode 100644
index 0000000..2aa63d9
--- /dev/null
+++ b/src/Noddybox.Emulation.EightBit/IMemory.cs
@@ -0,0 +1,36 @@
+//
+// Copyright (c) 2012 Ian Cowburn
+//
+using System;
+using System.Net;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Documents;
+using System.Windows.Ink;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Animation;
+using System.Windows.Shapes;
+
+namespace Noddybox.Emulation.EightBit
+{
+    /// <summary>
+    /// Defines an interface for memory.
+    /// </summary>
+    public interface IMemory
+    {
+        /// <summary>
+        /// Reads a byte at a given address.
+        /// </summary>
+        /// <param name="address">The address to read.</param>
+        /// <returns>The value at that address.</returns>
+        byte Read(ushort address); 
+
+        /// <summary>
+        /// Writes a byte at a given address.
+        /// </summary>
+        /// <param name="address">The address to write to.</param>
+        /// <param name="value">The value to write.</param>
+        void Write(ushort address, byte value);
+    }
+}
diff --git a/src/Noddybox.Emulation.EightBit/Register16.cs b/src/Noddybox.Emulation.EightBit/Register16.cs
new file mode 100644
index 0000000..06c9c01
--- /dev/null
+++ b/src/Noddybox.Emulation.EightBit/Register16.cs
@@ -0,0 +1,88 @@
+//
+// Copyright (c) 2012 Ian Cowburn
+//
+using System;
+using System.Runtime.InteropServices;
+
+namespace Noddybox.Emulation.EightBit
+{
+    /// <summary>
+    /// Provides a common 8-bit register pattern, which is two 8-bit registers rolled into one.
+    /// While this could be done at runtime using <see cref="BitConverter.IsLittleEndian"/> this
+    /// method was chosen for speed reasons; interfaces cannot define fields, which is sensible
+    /// enoough, but accessing fields directly would allow ref variables to be used with this type's
+    /// fields.
+    /// </summary>
+    [StructLayout(LayoutKind.Explicit)]
+    public struct Register16
+    {
+#if TARGET_IS_BIGENDIAN
+
+        /// <summary>
+        /// The 16-bit register.
+        /// </summary>
+        [FieldOffset(0)]
+        public ushort reg;
+
+        /// <summary>
+        /// The high 8-bits of the register.
+        /// </summary>
+        [FieldOffset(0)]
+        public byte high;
+
+        /// <summary>
+        /// The low 8-bits of the register.
+        /// </summary>
+        [FieldOffset(1)]
+        public byte low;
+
+#else
+
+        /// <summary>
+        /// The 16-bit register.
+        /// </summary>
+        [FieldOffset(0)]
+        public ushort reg;
+
+        /// <summary>
+        /// The low 8-bits of the register.
+        /// </summary>
+        [FieldOffset(0)]
+        public byte low;
+
+        /// <summary>
+        /// The high 8-bits of the register.
+        /// </summary>
+        [FieldOffset(1)]
+        public byte high;
+
+#endif
+
+        /// <summary>
+        /// Public constructor.  This is provided to stop the compiler complaining when you use the struct as it
+        /// doesn't realise that setting <see cref="reg"/> will also set <see cref="low"/> and <see cref="high"/>.
+        /// </summary>
+        /// <param name="val">The 16-bit value to assign.</param>
+        public Register16(ushort val)
+        {
+            high = 0;
+            low = 0;
+            reg = val;
+        }
+
+        /// <summary>
+        /// Used to verify the compile-time setting at runtime.
+        /// </summary>
+        public static void Verify()
+        {
+            Register16 r = new Register16(0);
+
+            r.reg = 0x1234;
+
+            if (r.low != 0x24 || r.high != 0x12)
+            {
+                throw new Exception("Compile time endian setting incorrect");
+            }
+        }
+    }
+}