Added support for CMP r32, r/m32 (0x3B) and MOV r/m32, imm32 (0xC7) instructions with tests

X86Disassembler/X86/Handlers/Cmp/CmpR32Rm32Handler.cs

@@ -0,0 +1,73 @@
+namespace X86Disassembler.X86.Handlers.Cmp;
+
+/// <summary>
+/// Handler for CMP r32, r/m32 instruction (0x3B)
+/// </summary>
+public class CmpR32Rm32Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the CmpR32Rm32Handler 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 CmpR32Rm32Handler(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 == 0x3B;
+    }
+
+    /// <summary>
+    /// Decodes a CMP r32, r/m32 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);
+
+        // Set the mnemonic
+        instruction.Mnemonic = "cmp";
+
+        // Get the register name
+        string regName = GetRegister32(reg);
+
+        // For memory operands, set the operand
+        if (mod != 3) // Memory operand
+        {
+            string operand = ModRMDecoder.DecodeModRM(mod, rm, false);
+            instruction.Operands = $"{regName}, {operand}";
+        }
+        else // Register operand
+        {
+            string rmName = GetRegister32(rm);
+            instruction.Operands = $"{regName}, {rmName}";
+        }
+
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs

@@ -1,6 +1,7 @@
 using X86Disassembler.X86.Handlers.ArithmeticImmediate;
 using X86Disassembler.X86.Handlers.ArithmeticUnary;
 using X86Disassembler.X86.Handlers.Call;
+using X86Disassembler.X86.Handlers.Cmp;
 using X86Disassembler.X86.Handlers.FloatingPoint;
 using X86Disassembler.X86.Handlers.Jump;
 using X86Disassembler.X86.Handlers.Lea;
@@ -10,8 +11,8 @@ using X86Disassembler.X86.Handlers.Pop;
 using X86Disassembler.X86.Handlers.Push;
 using X86Disassembler.X86.Handlers.Ret;
 using X86Disassembler.X86.Handlers.Test;
-using X86Disassembler.X86.Handlers.Xor;
 using X86Disassembler.X86.Handlers.Xchg;
+using X86Disassembler.X86.Handlers.Xor;
 
 namespace X86Disassembler.X86.Handlers;
 
@@ -73,6 +74,9 @@ public class InstructionHandlerFactory
         // Register Lea handlers
         RegisterLeaHandlers();
         
+        // Register Cmp handlers
+        RegisterCmpHandlers();
+        
         // Register Data Transfer handlers
         RegisterDataTransferHandlers();
         
@@ -225,6 +229,15 @@ public class InstructionHandlerFactory
         _handlers.Add(new LeaR32MHandler(_codeBuffer, _decoder, _length));
     }
     
+    /// <summary>
+    /// Registers all Cmp instruction handlers
+    /// </summary>
+    private void RegisterCmpHandlers()
+    {
+        // Add Cmp handlers
+        _handlers.Add(new CmpR32Rm32Handler(_codeBuffer, _decoder, _length));
+    }
+    
     /// <summary>
     /// Registers all Data Transfer instruction handlers
     /// </summary>
@@ -237,6 +250,7 @@ public class InstructionHandlerFactory
         _handlers.Add(new MovRegImm8Handler(_codeBuffer, _decoder, _length));
         _handlers.Add(new MovEaxMoffsHandler(_codeBuffer, _decoder, _length));
         _handlers.Add(new MovMoffsEaxHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new MovRm32Imm32Handler(_codeBuffer, _decoder, _length));
         
         // Add PUSH handlers
         _handlers.Add(new PushRegHandler(_codeBuffer, _decoder, _length));

X86Disassembler/X86/Handlers/Mov/MovRm32Imm32Handler.cs

@@ -0,0 +1,115 @@
+namespace X86Disassembler.X86.Handlers.Mov;
+
+/// <summary>
+/// Handler for MOV r/m32, imm32 instruction (0xC7)
+/// </summary>
+public class MovRm32Imm32Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the MovRm32Imm32Handler 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 MovRm32Imm32Handler(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 == 0xC7;
+    }
+
+    /// <summary>
+    /// Decodes a MOV r/m32, imm32 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++];
+        
+        // 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);
+        
+        // MOV r/m32, imm32 only uses reg=0
+        if (reg != 0)
+        {
+            return false;
+        }
+        
+        // Process SIB and displacement bytes if needed
+        if (mod != 3 && rm == 4) // SIB byte present
+        {
+            if (position >= Length)
+            {
+                return false;
+            }
+            position++; // Skip SIB byte
+        }
+        
+        // Handle displacement
+        if ((mod == 1 && position >= Length) || (mod == 2 && position + 3 >= Length))
+        {
+            return false;
+        }
+        
+        if (mod == 1) // 8-bit displacement
+        {
+            position++;
+        }
+        else if (mod == 2) // 32-bit displacement
+        {
+            position += 4;
+        }
+        
+        // Read the immediate dword
+        if (position + 3 >= Length)
+        {
+            return false;
+        }
+        
+        byte b0 = CodeBuffer[position++];
+        byte b1 = CodeBuffer[position++];
+        byte b2 = CodeBuffer[position++];
+        byte b3 = CodeBuffer[position++];
+        uint imm32 = (uint)(b0 | (b1 << 8) | (b2 << 16) | (b3 << 24));
+        Decoder.SetPosition(position);
+
+        // Set the mnemonic
+        instruction.Mnemonic = "mov";
+
+        // Get the operand string
+        string operand;
+        if (mod != 3) // Memory operand
+        {
+            operand = ModRMDecoder.DecodeModRM(mod, rm, false);
+        }
+        else // Register operand
+        {
+            operand = GetRegister32(rm);
+        }
+
+        // Set the operands
+        instruction.Operands = $"{operand}, 0x{imm32:X8}";
+
+        return true;
+    }
+}

X86Disassembler/X86/OpcodeMap.cs

@@ -50,6 +50,18 @@ public static class OpcodeMap
         // LEA instruction
         OneByteOpcodes[0x8D] = "lea"; // LEA r32, m
         
+        // CMP instructions
+        OneByteOpcodes[0x38] = "cmp"; // CMP r/m8, r8
+        OneByteOpcodes[0x39] = "cmp"; // CMP r/m32, r32
+        OneByteOpcodes[0x3A] = "cmp"; // CMP r8, r/m8
+        OneByteOpcodes[0x3B] = "cmp"; // CMP r32, r/m32
+        OneByteOpcodes[0x3C] = "cmp"; // CMP AL, imm8
+        OneByteOpcodes[0x3D] = "cmp"; // CMP EAX, imm32
+        
+        // MOV instructions
+        OneByteOpcodes[0xC6] = "mov"; // MOV r/m8, imm8
+        OneByteOpcodes[0xC7] = "mov"; // MOV r/m32, imm32
+        
         // Group 1 instructions (ADD, OR, ADC, SBB, AND, SUB, XOR, CMP)
         OneByteOpcodes[0x80] = "group1b";
         OneByteOpcodes[0x81] = "group1d";

X86DisassemblerTests/CmpInstructionTests.cs

@@ -0,0 +1,49 @@
+namespace X86DisassemblerTests;
+
+using System;
+using Xunit;
+using X86Disassembler.X86;
+
+/// <summary>
+/// Tests for CMP instruction handlers
+/// </summary>
+public class CmpInstructionTests
+{
+    /// <summary>
+    /// Tests the CMP r32, r/m32 instruction (0x3B) with register operand
+    /// </summary>
+    [Fact]
+    public void TestCmpR32Rm32_Register()
+    {
+        // Arrange
+        byte[] code = { 0x3B, 0xC7 }; // CMP EAX, EDI
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("cmp", instructions[0].Mnemonic);
+        Assert.Equal("eax, edi", instructions[0].Operands);
+    }
+    
+    /// <summary>
+    /// Tests the CMP r32, m32 instruction (0x3B) with memory operand
+    /// </summary>
+    [Fact]
+    public void TestCmpR32M32()
+    {
+        // Arrange
+        byte[] code = { 0x3B, 0x00 }; // CMP EAX, DWORD PTR [EAX]
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("cmp", instructions[0].Mnemonic);
+        Assert.Equal("eax, dword ptr [eax]", instructions[0].Operands);
+    }
+}

X86DisassemblerTests/MovRm32Imm32Tests.cs

@@ -0,0 +1,49 @@
+namespace X86DisassemblerTests;
+
+using System;
+using Xunit;
+using X86Disassembler.X86;
+
+/// <summary>
+/// Tests for MOV r/m32, imm32 instruction (0xC7)
+/// </summary>
+public class MovRm32Imm32Tests
+{
+    /// <summary>
+    /// Tests the MOV r32, imm32 instruction (0xC7) with register operand
+    /// </summary>
+    [Fact]
+    public void TestMovR32Imm32()
+    {
+        // Arrange
+        byte[] code = { 0xC7, 0xC0, 0x78, 0x56, 0x34, 0x12 }; // MOV EAX, 0x12345678
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("mov", instructions[0].Mnemonic);
+        Assert.Equal("eax, 0x12345678", instructions[0].Operands);
+    }
+    
+    /// <summary>
+    /// Tests the MOV m32, imm32 instruction (0xC7) with memory operand
+    /// </summary>
+    [Fact]
+    public void TestMovM32Imm32()
+    {
+        // Arrange
+        byte[] code = { 0xC7, 0x00, 0x78, 0x56, 0x34, 0x12 }; // MOV DWORD PTR [EAX], 0x12345678
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("mov", instructions[0].Mnemonic);
+        Assert.Equal("dword ptr [eax], 0x12345678", instructions[0].Operands);
+    }
+}