Add ZX-81 symbols and a skeletal Z80 symbol parser

Z80/Disassembler.cs

@@ -6,9 +6,12 @@ namespace Z80
 {
     using EightBit;
     using System.Globalization;
+    using System.Diagnostics;
 
-    public class Disassembler(Bus bus)
+    public class Disassembler(Bus bus, Labels labels)
     {
+        private readonly Labels _labels = labels;
+
         private bool _prefixCB;
         private bool _prefixDD;
         private bool _prefixED;
@@ -69,6 +72,11 @@ namespace Z80
                 + $"{(cpu.INT.Lowered() ? "I" : "-")}";
         }
 
+        public Disassembler(Bus bus)
+        : this(bus, new Labels())
+        {
+        }
+
         public string Disassemble(Z80 cpu)
         {
             ArgumentNullException.ThrowIfNull(cpu);
@@ -158,6 +166,13 @@ namespace Z80
             if (outputFormatSpecification)
             {
                 output += '\t';
+
+                if (this._labels.Lookup(pc, out var label))
+                {
+                    Debug.Assert(label is not null);
+                    output += $"{label}: ";
+                }
+
                 output += string.Format(CultureInfo.InvariantCulture, specification, (int)immediate, (int)absolute, relative, (int)displacement, indexedImmediate);
             }
 

Z80/Labels.cs

@@ -0,0 +1,60 @@
+namespace Z80
+{
+    using System.Diagnostics;
+    using System.Globalization;
+    using System.Collections.Generic;
+
+    public class Labels(EightBit.ILogger logger)
+    {
+        private readonly EightBit.ILogger _logger = logger;
+        private readonly Dictionary<ushort, string> _symbols = [];   // Address to symbol lookup
+
+        public Dictionary<ushort, string> Symbols => this._symbols;
+
+        public Labels()
+        : this(new EightBit.ConsoleLogger())
+        {}
+
+        public bool Lookup(ushort address, out string? label) => this.Symbols.TryGetValue(address, out label);
+
+        public void Parse(string path)
+        {
+            this._logger.Inform($"Labels: reading {path}");
+            using var reader = new StreamReader(path);
+            while (!reader.EndOfStream)
+            {
+                var line = reader.ReadLine();
+                this.ParseLine(line);
+            }
+        }
+
+        private void ParseLine(string? line)
+        {
+            if (string.IsNullOrEmpty(line))
+            {
+                this._logger.Debug($"Ignoring empty line");
+                return;
+            }
+            this._logger.Debug($"Parsing: {line}");
+            var elements = line.Split(' ', '\t');
+            Debug.Assert(elements is not null);
+            if (elements.Length != 2)
+            {
+                this._logger.Debug("Ignoring invalid line");
+                return;
+            }
+
+            if (!ushort.TryParse(elements[0], NumberStyles.HexNumber, CultureInfo.InvariantCulture, out var address))
+            {
+                this._logger.Debug($"First element ({elements[0]}), cannot be parsed as a hexadecimal number");
+                return;
+            }
+
+            var label = elements[1];
+            if (!this.Symbols.TryAdd(address, label))
+            {
+                this._logger.Debug($"Label {label}, has already been used");
+            }
+        }
+    }
+}