crowbar

1 files changed, 87 insertions, 0 deletions

diff --git a/Assembler/Disassembler.cs b/Assembler/Disassembler.cs
new file mode 100644
index 0000000..9b1c44d
--- /dev/null
+++ b/Assembler/Disassembler.cs
@@ -0,0 +1,87 @@
+namespace Q1Emu.Assembler;
+
+using System;
+using System.Collections.Generic;
+
+public class Disassembler
+{
+    public static Dictionary<u8, string[]> InstructionLookup = new()
+    {
+        { 0x00, ["NOP", "JMP", "HALT", "MOV"] },
+        { 0x01, ["RET", "CALL", "SUS", "CMP"] },
+        { 0x02, ["BR", "BZ", "BZ_LX", "LT"] },
+        { 0x03, ["NOP", "NOP", "NOP", "GT"] },
+
+        { 0x04, ["NOT_LX", "NOT", "NOP", "AND"] },
+        { 0x05, ["INV_DX", "INV", "NOP", "OR"] },
+        { 0x06, ["SHL_DX", "SHL", "NOP", "XOR"] },
+        { 0x07, ["SHR_DX", "SHR", "NOP", "NOP"] },
+
+        { 0x08, ["INC_AX", "INC", "NOP", "ADD"] },
+        { 0x09, ["DEC_AX", "DEC", "NOP", "SUB"] },
+        { 0x0A, ["NOP", "NOP", "NOP", "DIV"] },
+        { 0x0B, ["NOP", "NOP", "NOP", "MUL"] },
+        { 0x0C, ["NOP", "NOP", "NOP", "MOD"] },
+    };
+    
+    public static Dictionary<u8, string> ModeLookup = new()
+    {
+        { 0x00, "" },
+        { 0x01, "c" },
+        { 0x02, "[a]" },
+        { 0x03, "@[a]" },
+        { 0x04, "pc + c" },
+        { 0x05, "r" },
+        { 0x06, "[r]" },
+        { 0x07, "[r + c]" },
+    };
+    
+    public static string ParseInstruction(u16 instruction)
+    {
+        u8 op = (u8) ((instruction >> 8) & 0xFF); // 256 opcodes
+        u8 m1 = (u8) ((instruction >> 4) & 0x0F); // 16 modes
+        u8 m2 = (u8) (instruction        & 0x0F); // 16 modes
+
+        u8 i = (m1, m2) switch
+        {
+            (0x00, 0x00) => 0, // Implicit
+            (0x00, _)    => 2, // Extended implicit
+            (_, 0x00)    => 1, // Simple addressing mode
+            _            => 3  // Extended addressing mode
+        };
+        
+        string opcodeName = GetOpcodeName(op, i);
+        string mode1 = GetModeName(m1);
+        string mode2 = GetModeName(m2);
+
+        if (i == 0)
+            return opcodeName;
+        
+        if (i == 2)
+            return $"{opcodeName}";
+        
+        if (i == 1)
+            return $"{opcodeName} {mode1}";
+        
+        if (i == 3)
+            return $"{opcodeName} {mode1}, {mode2}";
+        
+        throw new InvalidOperationException($"Unknown instruction format for opcode {op:X2} with modes {m1:X2}, {m2:X2}");
+    }
+    
+    private static string GetOpcodeName(u8 opcode, u8 i)
+    {
+        if (!InstructionLookup.ContainsKey(opcode) || i >= InstructionLookup[opcode].Length)
+            return $"{opcode:X2}";
+        
+        return InstructionLookup[opcode][i];
+    }
+    
+    private static string GetModeName(u8 mode)
+    {
+        if (ModeLookup.TryGetValue(mode, out string modeName))
+            return modeName;
+        
+        return $"[{mode:X2}]"; // Fallback for unknown modes
+    }
+}
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