Added support for OR r8, r/m8 instruction (opcode 0x0A) with tests

X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs

@@ -4,6 +4,7 @@ using X86Disassembler.X86.Handlers.Call;
 using X86Disassembler.X86.Handlers.FloatingPoint;
 using X86Disassembler.X86.Handlers.Jump;
 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;
@@ -65,6 +66,9 @@ public class InstructionHandlerFactory
         // Register Xor handlers
         RegisterXorHandlers();
         
+        // Register Or handlers
+        RegisterOrHandlers();
+        
         // Register Data Transfer handlers
         RegisterDataTransferHandlers();
         
@@ -195,6 +199,15 @@ public class InstructionHandlerFactory
         _handlers.Add(new XorImmWithRm32SignExtendedHandler(_codeBuffer, _decoder, _length));
     }
     
+    /// <summary>
+    /// Registers all Or instruction handlers
+    /// </summary>
+    private void RegisterOrHandlers()
+    {
+        // Add Or handlers
+        _handlers.Add(new OrR8Rm8Handler(_codeBuffer, _decoder, _length));
+    }
+    
     /// <summary>
     /// Registers all Data Transfer instruction handlers
     /// </summary>

X86Disassembler/X86/Handlers/Or/OrR8Rm8Handler.cs

@@ -0,0 +1,75 @@
+namespace X86Disassembler.X86.Handlers.Or;
+
+/// <summary>
+/// Handler for OR r8, r/m8 instruction (0x0A)
+/// </summary>
+public class OrR8Rm8Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the OrR8Rm8Handler 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 OrR8Rm8Handler(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 == 0x0A;
+    }
+
+    /// <summary>
+    /// Decodes an OR r8, r/m8 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 = "or";
+
+        // Get the register name
+        string regName = GetRegister8(reg);
+
+        // For memory operands, set the operand
+        if (mod != 3) // Memory operand
+        {
+            string operand = ModRMDecoder.DecodeModRM(mod, rm, false);
+            // Replace dword ptr with byte ptr for 8-bit operations
+            operand = operand.Replace("dword ptr", "byte ptr");
+            instruction.Operands = $"{regName}, {operand}";
+        }
+        else // Register operand
+        {
+            string rmName = GetRegister8(rm);
+            instruction.Operands = $"{regName}, {rmName}";
+        }
+
+        return true;
+    }
+}

X86Disassembler/X86/OpcodeMap.cs

@@ -41,6 +41,12 @@ public static class OpcodeMap
         OneByteOpcodes[0xDE] = "fiadd";
         OneByteOpcodes[0xDF] = "fistp";
         
+        // OR instructions
+        OneByteOpcodes[0x0A] = "or"; // OR r8, r/m8
+        OneByteOpcodes[0x0B] = "or"; // OR r32, r/m32
+        OneByteOpcodes[0x0C] = "or"; // OR AL, imm8
+        OneByteOpcodes[0x0D] = "or"; // OR EAX, imm32
+        
         // Group 1 instructions (ADD, OR, ADC, SBB, AND, SUB, XOR, CMP)
         OneByteOpcodes[0x80] = "group1b";
         OneByteOpcodes[0x81] = "group1d";

X86DisassemblerTests/OrInstructionTests.cs

@@ -0,0 +1,49 @@
+namespace X86DisassemblerTests;
+
+using System;
+using Xunit;
+using X86Disassembler.X86;
+
+/// <summary>
+/// Tests for OR instruction handlers
+/// </summary>
+public class OrInstructionTests
+{
+    /// <summary>
+    /// Tests the OR r8, r/m8 instruction (0x0A)
+    /// </summary>
+    [Fact]
+    public void TestOrR8Rm8()
+    {
+        // Arrange
+        byte[] code = { 0x0A, 0xC8 }; // OR CL, AL
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("or", instructions[0].Mnemonic);
+        Assert.Equal("cl, al", instructions[0].Operands);
+    }
+    
+    /// <summary>
+    /// Tests the OR r8, m8 instruction (0x0A) with memory operand
+    /// </summary>
+    [Fact]
+    public void TestOrR8M8()
+    {
+        // Arrange
+        byte[] code = { 0x0A, 0x00 }; // OR AL, BYTE PTR [EAX]
+        
+        // Act
+        Disassembler disassembler = new Disassembler(code, 0x1000);
+        var instructions = disassembler.Disassemble();
+        
+        // Assert
+        Assert.Single(instructions);
+        Assert.Equal("or", instructions[0].Mnemonic);
+        Assert.Equal("al, byte ptr [eax]", instructions[0].Operands);
+    }
+}