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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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