Refactor the Intel hex file parser. The new parser is isolated and memory efficient.

Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
2025-07-24 06:24:06 +00:00 · 2019-06-29 11:35:08 +01:00
parent 69122eb233
commit 7b5af28f5d
3 changed files with 109 additions and 70 deletions
--- a/EightBit/IntelHexFile.cs
+++ b/EightBit/IntelHexFile.cs
@@ -0,0 +1,99 @@
+// <copyright file="IntelHexFile.cs" company="Adrian Conlon">
+// Copyright (c) Adrian Conlon. All rights reserved.
+// </copyright>
+
+namespace EightBit
+{
+    using System;
+    using System.Collections.Generic;
+    using System.IO;
+
+    public class IntelHexFile : IDisposable
+    {
+        private readonly StreamReader reader;
+        private bool disposed = false;
+
+        public IntelHexFile(string path) => this.reader = File.OpenText(path);
+
+        public void Dispose()
+        {
+            this.Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (!this.disposed)
+            {
+                if (disposing)
+                {
+                    this.reader.Dispose();
+                }
+
+                this.disposed = true;
+            }
+        }
+
+        public IEnumerable<Tuple<ushort, List<byte>>> Parse()
+        {
+            var eof = false;
+            while (!this.reader.EndOfStream && !eof)
+            {
+                var line = this.reader.ReadLine();
+                var parsed = this.Parse(line);
+                eof = parsed == null;
+                if (!eof)
+                {
+                    yield return parsed;
+                }
+            }
+        }
+
+        private Tuple<ushort, List<byte>> Parse(string line)
+        {
+            var colon = line.Substring(0, 1);
+            if (colon != ":")
+            {
+                throw new System.InvalidOperationException("Invalid hex file: line does not begin with a colon");
+            }
+
+            var countString = line.Substring(1, 2);
+            var count = Convert.ToByte(countString, 16);
+
+            var addressString = line.Substring(3, 4);
+            var address = Convert.ToUInt16(addressString, 16);
+
+            var recordTypeString = line.Substring(7, 2);
+            var recordType = Convert.ToByte(recordTypeString, 16);
+
+            switch (recordType)
+            {
+                case 0x00:
+                    {
+                        var data = new List<byte>(count);
+                        var requiredLength = 9 + 2 + (count * 2);
+                        if (line.Length != requiredLength)
+                        {
+                            throw new InvalidOperationException("Invalid hex file: line is not the required length");
+                        }
+
+                        for (var i = 0; i < count; ++i)
+                        {
+                            var position = 9 + (i * 2);
+                            var datumString = line.Substring(position, 2);
+                            var datum = Convert.ToByte(datumString, 16);
+                            data.Add(datum);
+                        }
+
+                        return new Tuple<ushort, List<byte>>(address, data);
+                    }
+
+                case 0x01:
+                    return null;
+
+                default:
+                    throw new InvalidOperationException("Unhandled hex file record.");
+            }
+        }
+    }
+}