1 files changed, 106 insertions, 0 deletions
diff --git a/Assembler/Assembler.cs b/Assembler/Assembler.cs
new file mode 100644
index 0000000..14a33fd
--- /dev/null
+++ b/Assembler/Assembler.cs
@@ -0,0 +1,106 @@
+namespace Q1Emu.Assembler;
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+
+public class Assembler
+{
+    public readonly BinaryWriter Writer;
+    public readonly StringReader Reader;
+
+    public Assembler(StringReader reader, BinaryWriter writer)
+    {
+        this.Reader = reader;
+        this.Writer = writer;
+    }
+
+    public void Assemble()
+    {
+        while (this.Reader.ReadLine() is { } line)
+        {
+            string trimmedLine = line.Trim();
+            if (string.IsNullOrEmpty(trimmedLine) || trimmedLine.StartsWith(';'))
+                continue;
+
+            this.ParseInstruction(trimmedLine);
+        }
+    }
+
+    private void ParseInstruction(string instruction)
+    {
+        string[] parts = instruction.Split(' ', 2);
+        string opcode = parts[0].ToUpperInvariant();
+
+        parts = parts.Length > 1 ? parts[1].Split(',') : [];
+        if (parts.Length > 2)
+            throw new ArgumentException($"Invalid instruction format: {instruction}");
+
+        u8 m1 = 0, m2 = 0;
+        if (parts.Length > 0)
+        {
+            m1 = this.ParseOperand(parts[0]);
+            if (parts.Length > 1)
+                m2 = this.ParseOperand(parts[1]);
+        }
+
+        switch (opcode)
+        {
+            case "NOP":
+                this.Writer.Write((u8) 0x00);
+                break;
+
+            default:
+                throw new NotSupportedException($"Unsupported opcode: {opcode}");
+        }
+    }
+
+    private u8 ParseOperand(string operand)
+    {
+        operand = operand.Trim();
+
+        bool IsRegister(string text)
+        {
+            if (text.Length > 1 && text[0] == 'V')
+                return true;
+
+            string[] hardcodedRegisters =
+            [
+                "AX",
+                "AH",
+                "AL",
+                "DX",
+                "DH",
+                "DL",
+                "LX",
+                "PC",
+                "SP",
+            ];
+
+            return hardcodedRegisters.Contains(text);
+        }
+
+        if (operand.StartsWith("@"))
+        {
+            return 0x03; // Indirect
+        }
+
+        if (operand.StartsWith("[") && operand.EndsWith("]"))
+        {
+            string inner = operand[1..^1].Trim();
+            if (inner.Contains("+"))
+                return 0x07; // Register indirect with offset
+            
+            if (IsRegister(inner))
+                return 0x06; // Register indirect
+
+            return 0x02; // Direct
+        }
+
+        if (IsRegister(operand))
+            return 0x05; // Register
+
+        return 0x01; // Immediate
+    }
+}
+\ No newline at end of file