Fix a bunch of analysis issues

LR35902/AbstractColourPalette.cs

@@ -3,13 +3,18 @@
 // </copyright>
 namespace LR35902
 {
+    using System.Collections.ObjectModel;
+
     public class AbstractColourPalette<T>
     {
         protected AbstractColourPalette()
         {
+            this.Colours = [.. _colours];
         }
 
-        protected T[] Colours { get; } = new T[4];
+        private readonly List<T> _colours = new(4);
+
+        protected Collection<T> Colours { get; }
 
         public T Colour(int index) => this.Colours[index];
     }

LR35902/ColourShades.cs

@@ -1,13 +0,0 @@
-// <copyright file="ColourShades.cs" company="Adrian Conlon">
-// Copyright (c) Adrian Conlon. All rights reserved.
-// </copyright>
-namespace LR35902
-{
-    public enum ColourShades
-    {
-        Off,
-        Light,
-        Medium,
-        Dark,
-    }
-}

LR35902/Disassembler.cs

@@ -25,6 +25,8 @@ namespace LR35902
 
         public static string AsFlag(byte value, StatusBits flag, string represents) => AsFlag(value, (byte)flag, represents);
 
+        public static string AsFlag(byte value, Interrupts flag, string represents) => AsFlag(value, (byte)flag, represents);
+
         public static string AsFlag(byte value, Bits flag, string represents) => AsFlag(value, (byte)flag, represents);
 
         public static string AsFlags(byte value) =>
@@ -37,6 +39,13 @@ namespace LR35902
                     + $"{AsFlag(value, Bits.Bit1, "+")}"
                     + $"{AsFlag(value, Bits.Bit0, "+")}";
 
+        public static string AsInterrupt(byte value) =>
+                      $"{AsFlag(value, Interrupts.KeypadPressed, "K")}"
+                    + $"{AsFlag(value, Interrupts.SerialTransfer, "S")}"
+                    + $"{AsFlag(value, Interrupts.TimerOverflow, "T")}"
+                    + $"{AsFlag(value, Interrupts.DisplayControlStatus, "D")}"
+                    + $"{AsFlag(value, Interrupts.VerticalBlank, "V")}";
+
         public static string State(LR35902 cpu)
         {
             ArgumentNullException.ThrowIfNull(cpu);
@@ -56,12 +65,18 @@ namespace LR35902
             var h = cpu.H;
             var l = cpu.L;
 
+            var ime = cpu.IME?1:0;
+            var ie = cpu.IE;
+            var i_f = cpu.IF;
+            var masked = cpu.MaskedInterrupts;
+
             return
-                    $"PC={pc.Word:x4} SP={sp.Word:x4} "
+                  $"PC={pc.Word:x4} SP={sp.Word:x4} "
                 + $"A={a:x2} F={AsFlags(f)} "
                 + $"B={b:x2} C={c:x2} "
                 + $"D={d:x2} E={e:x2} "
-                + $"H={h:x2} L={l:x2}";
+                + $"H={h:x2} L={l:x2} "
+                + $"IME={ime} IE={AsInterrupt(ie)} IF={AsInterrupt(i_f)} Masked={AsInterrupt(masked)}";
         }
 
         public string Disassemble(LR35902 cpu)

LR35902/LR35902.cs

@@ -59,6 +59,8 @@ namespace LR35902
             set => this.bus.IO.Poke(IoRegisters.IF, value);
         }
 
+        public byte MaskedInterrupts => (byte)(this.IE & this.IF);
+
         private bool Stopped { get; set; }
 
         #region MWR pin
@@ -199,14 +201,13 @@ namespace LR35902
         {
             this.prefixCB = false;
 
-            var masked = (byte)(this.IE & this.IF);
-            if (masked != 0)
+            if (this.MaskedInterrupts != 0)
             {
                 if (this.IME)
                 {
                     this.IF = 0;
                     this.LowerINT();
-                    var index = FindFirstSet(masked);
+                    var index = FindFirstSet(this.MaskedInterrupts);
                     this.Bus.Data = (byte)(0x38 + (index << 3));
                 }
                 else
@@ -225,7 +226,7 @@ namespace LR35902
             }
             else if (this.HALT.Lowered())
             {
-                this.Execute(0);  // NOP
+                //this.Execute(0);  // NOP
             }
             else
             {