Added AddEaxImmHandler for decoding ADD EAX, imm32 instruction (opcode 0x05)

X86Disassembler/X86/Handlers/Add/AddEaxImmHandler.cs

@@ -0,0 +1,57 @@
+namespace X86Disassembler.X86.Handlers.Add;
+
+/// <summary>
+/// Handler for ADD EAX, imm32 instruction (0x05)
+/// </summary>
+public class AddEaxImmHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the AddEaxImmHandler 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 AddEaxImmHandler(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 == 0x05;
+    }
+    
+    /// <summary>
+    /// Decodes an ADD EAX, 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)
+    {
+        // Set the mnemonic
+        instruction.Mnemonic = "add";
+        
+        // Read the immediate value
+        int position = Decoder.GetPosition();
+        if (position + 4 > Length)
+        {
+            // Not enough bytes for the immediate value
+            instruction.Operands = "eax, ??";
+            return true; // Still return true as we've set a valid mnemonic and operands
+        }
+        
+        // Read the 32-bit immediate value
+        uint imm32 = Decoder.ReadUInt32();
+        
+        // Set the operands
+        instruction.Operands = $"eax, 0x{imm32:X8}";
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs

@@ -249,6 +249,7 @@ public class InstructionHandlerFactory
         // Add ADD handlers
         _handlers.Add(new AddR32Rm32Handler(_codeBuffer, _decoder, _length));
         _handlers.Add(new AddRm32R32Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new AddEaxImmHandler(_codeBuffer, _decoder, _length));
         
         // Add ADD immediate handlers from ArithmeticImmediate namespace
         _handlers.Add(new AddImmToRm8Handler(_codeBuffer, _decoder, _length));

X86DisassemblerTests/AddEaxImmHandlerTests.cs

@@ -0,0 +1,52 @@
+namespace X86DisassemblerTests;
+
+using System;
+using Xunit;
+using X86Disassembler.X86;
+using X86Disassembler.X86.Handlers.Add;
+
+/// <summary>
+/// Tests for ADD EAX, imm32 instruction handler
+/// </summary>
+public class AddEaxImmHandlerTests
+{
+    /// <summary>
+    /// Tests the AddEaxImmHandler for decoding ADD EAX, imm32 instruction
+    /// </summary>
+    [Fact]
+    public void AddEaxImmHandler_DecodesAddEaxImm32_Correctly()
+    {
+        // Arrange
+        // ADD EAX, 0x12345678 (05 78 56 34 12)
+        byte[] codeBuffer = new byte[] { 0x05, 0x78, 0x56, 0x34, 0x12 };
+        var decoder = new InstructionDecoder(codeBuffer, codeBuffer.Length);
+        
+        // Act
+        var instruction = decoder.DecodeInstruction();
+        
+        // Assert
+        Assert.NotNull(instruction);
+        Assert.Equal("add", instruction.Mnemonic);
+        Assert.Equal("eax, 0x12345678", instruction.Operands);
+    }
+    
+    /// <summary>
+    /// Tests the AddEaxImmHandler for handling insufficient bytes
+    /// </summary>
+    [Fact]
+    public void AddEaxImmHandler_HandlesInsufficientBytes_Gracefully()
+    {
+        // Arrange
+        // ADD EAX, ?? (05) - missing immediate value
+        byte[] codeBuffer = new byte[] { 0x05 };
+        var decoder = new InstructionDecoder(codeBuffer, codeBuffer.Length);
+        
+        // Act
+        var instruction = decoder.DecodeInstruction();
+        
+        // Assert
+        Assert.NotNull(instruction);
+        Assert.Equal("add", instruction.Mnemonic);
+        Assert.Equal("eax, ??", instruction.Operands);
+    }
+}