Added support for LEA instruction (opcode 0x8D) with tests

X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs

@@ -3,14 +3,15 @@ using X86Disassembler.X86.Handlers.ArithmeticUnary;
 using X86Disassembler.X86.Handlers.Call;
 using X86Disassembler.X86.Handlers.FloatingPoint;
 using X86Disassembler.X86.Handlers.Jump;
+using X86Disassembler.X86.Handlers.Lea;
 using X86Disassembler.X86.Handlers.Mov;
 using X86Disassembler.X86.Handlers.Or;
 using X86Disassembler.X86.Handlers.Pop;
 using X86Disassembler.X86.Handlers.Push;
 using X86Disassembler.X86.Handlers.Ret;
 using X86Disassembler.X86.Handlers.Test;
-using X86Disassembler.X86.Handlers.Xchg;
 using X86Disassembler.X86.Handlers.Xor;
+using X86Disassembler.X86.Handlers.Xchg;
 
 namespace X86Disassembler.X86.Handlers;
 
@@ -69,6 +70,9 @@ public class InstructionHandlerFactory
         // Register Or handlers
         RegisterOrHandlers();
         
+        // Register Lea handlers
+        RegisterLeaHandlers();
+        
         // Register Data Transfer handlers
         RegisterDataTransferHandlers();
         
@@ -212,6 +216,15 @@ public class InstructionHandlerFactory
         _handlers.Add(new OrImmWithRm32SignExtendedHandler(_codeBuffer, _decoder, _length));
     }
     
+    /// <summary>
+    /// Registers all Lea instruction handlers
+    /// </summary>
+    private void RegisterLeaHandlers()
+    {
+        // Add Lea handlers
+        _handlers.Add(new LeaR32MHandler(_codeBuffer, _decoder, _length));
+    }
+    
     /// <summary>
     /// Registers all Data Transfer instruction handlers
     /// </summary>

X86Disassembler/X86/Handlers/Lea/LeaR32MHandler.cs

@@ -0,0 +1,76 @@
+namespace X86Disassembler.X86.Handlers.Lea;
+
+/// <summary>
+/// Handler for LEA r32, m instruction (0x8D)
+/// </summary>
+public class LeaR32MHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the LeaR32MHandler class
+    /// </summary>
+    /// <param name="codeBuffer">The buffer containing the code to decode</param>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    /// <param name="length">The length of the buffer</param>
+    public LeaR32MHandler(byte[] codeBuffer, InstructionDecoder decoder, int length)
+        : base(codeBuffer, decoder, length)
+    {
+    }
+
+    /// <summary>
+    /// Checks if this handler can decode the given opcode
+    /// </summary>
+    /// <param name="opcode">The opcode to check</param>
+    /// <returns>True if this handler can decode the opcode</returns>
+    public override bool CanHandle(byte opcode)
+    {
+        return opcode == 0x8D;
+    }
+
+    /// <summary>
+    /// Decodes a LEA r32, m instruction
+    /// </summary>
+    /// <param name="opcode">The opcode of the instruction</param>
+    /// <param name="instruction">The instruction object to populate</param>
+    /// <returns>True if the instruction was successfully decoded</returns>
+    public override bool Decode(byte opcode, Instruction instruction)
+    {
+        int position = Decoder.GetPosition();
+
+        if (position >= Length)
+        {
+            return false;
+        }
+
+        // Read the ModR/M byte
+        byte modRM = CodeBuffer[position++];
+        Decoder.SetPosition(position);
+
+        // Extract the fields from the ModR/M byte
+        byte mod = (byte)((modRM & 0xC0) >> 6);
+        byte reg = (byte)((modRM & 0x38) >> 3);
+        byte rm = (byte)(modRM & 0x07);
+
+        // LEA only works with memory operands, not registers
+        if (mod == 3)
+        {
+            return false;
+        }
+
+        // Set the mnemonic
+        instruction.Mnemonic = "lea";
+
+        // Get the register name
+        string regName = GetRegister32(reg);
+
+        // Get the memory operand without the size prefix
+        string operand = ModRMDecoder.DecodeModRM(mod, rm, false);
+        
+        // Remove the "dword ptr" prefix for LEA instructions
+        operand = operand.Replace("dword ptr ", "");
+
+        // Set the operands
+        instruction.Operands = $"{regName}, {operand}";
+
+        return true;
+    }
+}

X86Disassembler/X86/OpcodeMap.cs

@@ -47,6 +47,9 @@ public static class OpcodeMap
         OneByteOpcodes[0x0C] = "or"; // OR AL, imm8
         OneByteOpcodes[0x0D] = "or"; // OR EAX, imm32
         
+        // LEA instruction
+        OneByteOpcodes[0x8D] = "lea"; // LEA r32, m
+        
         // Group 1 instructions (ADD, OR, ADC, SBB, AND, SUB, XOR, CMP)
         OneByteOpcodes[0x80] = "group1b";
         OneByteOpcodes[0x81] = "group1d";

X86DisassemblerTests/LeaInstructionTests.cs

@@ -0,0 +1,87 @@
+namespace X86DisassemblerTests;
+
+using System;
+using Xunit;
+using X86Disassembler.X86;
+
+/// <summary>
+/// Tests for LEA instruction handlers
+/// </summary>
+public class LeaInstructionTests
+{
+    /// <summary>
+    /// Tests the LEA r32, m instruction (0x8D) with simple memory operand
+    /// </summary>
+    [Fact]
+    public void TestLeaR32M_Simple()
+    {
+        // Arrange
+        byte[] code = { 0x8D, 0x00 }; // LEA EAX, [EAX]
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("lea", instructions[0].Mnemonic);
+        Assert.Equal("eax, [eax]", instructions[0].Operands);
+    }
+    
+    /// <summary>
+    /// Tests the LEA r32, m instruction (0x8D) with displacement
+    /// </summary>
+    [Fact]
+    public void TestLeaR32M_WithDisplacement()
+    {
+        // Arrange
+        byte[] code = { 0x8D, 0x7E, 0xFC }; // LEA EDI, [ESI - 0x4]
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("lea", instructions[0].Mnemonic);
+        Assert.Equal("edi, [esi-0x04]", instructions[0].Operands);
+    }
+    
+    /// <summary>
+    /// Tests the LEA r32, m instruction (0x8D) with SIB byte
+    /// </summary>
+    [Fact]
+    public void TestLeaR32M_WithSIB()
+    {
+        // Arrange
+        byte[] code = { 0x8D, 0x04, 0x11 }; // LEA EAX, [ECX+EDX]
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("lea", instructions[0].Mnemonic);
+        Assert.Equal("eax, [ecx+edx]", instructions[0].Operands);
+    }
+    
+    /// <summary>
+    /// Tests the LEA r32, m instruction (0x8D) with complex addressing
+    /// </summary>
+    [Fact]
+    public void TestLeaR32M_Complex()
+    {
+        // Arrange
+        byte[] code = { 0x8D, 0x44, 0x8A, 0x10 }; // LEA EAX, [EDX + ECX*4 + 0x10]
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("lea", instructions[0].Mnemonic);
+        Assert.Equal("eax, [edx+ecx*4+0x10]", instructions[0].Operands);
+    }
+}