Fixed FnstswHandler test by registering the handler in InstructionHandlerFactory

X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs

@@ -1,23 +1,26 @@
 using X86Disassembler.X86.Handlers.Call;
+using X86Disassembler.X86.Handlers.Group1;
+using X86Disassembler.X86.Handlers.Group3;
 using X86Disassembler.X86.Handlers.Jump;
+using X86Disassembler.X86.Handlers.Mov;
+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;
 
 namespace X86Disassembler.X86.Handlers;
 
-using X86Disassembler.X86.Handlers.Group1;
-using X86Disassembler.X86.Handlers.Group3;
-
 /// <summary>
 /// Factory for creating instruction handlers
 /// </summary>
 public class InstructionHandlerFactory
 {
+    private readonly List<IInstructionHandler> _handlers = new();
     private readonly byte[] _codeBuffer;
     private readonly InstructionDecoder _decoder;
     private readonly int _length;
-    private readonly List<IInstructionHandler> _handlers = [];
     
     /// <summary>
     /// Initializes a new instance of the InstructionHandlerFactory class
@@ -31,7 +34,6 @@ public class InstructionHandlerFactory
         _decoder = decoder;
         _length = length;
         
-        // Register all instruction handlers
         RegisterHandlers();
     }
     
@@ -40,49 +42,38 @@ public class InstructionHandlerFactory
     /// </summary>
     private void RegisterHandlers()
     {
-        // Register Group3 handlers first to ensure they take precedence
+        // Register group handlers
-        // over generic handlers for the same opcodes
         RegisterGroup3Handlers();
-        
-        // Register Group1 handlers
         RegisterGroup1Handlers();
         
         // Register specific instruction handlers
         _handlers.Add(new Int3Handler(_codeBuffer, _decoder, _length));
 
-        _handlers.Add(new RetHandler(_codeBuffer, _decoder, _length));
+        // Register Return handlers
-        _handlers.Add(new RetImmHandler(_codeBuffer, _decoder, _length));
+        RegisterReturnHandlers();
-        _handlers.Add(new CallRel32Handler(_codeBuffer, _decoder, _length));
         
-        // XOR handlers
+        // Register Call handlers
-        _handlers.Add(new XorRegMemHandler(_codeBuffer, _decoder, _length));
+        RegisterCallHandlers();
-        _handlers.Add(new XorMemRegHandler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new XorAlImmHandler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new XorEaxImmHandler(_codeBuffer, _decoder, _length));
         
+        // Register Jump handlers
+        RegisterJumpHandlers();
+        
+        // Register Test handlers
+        RegisterTestHandlers();
+        
+        // Register Xor handlers
+        RegisterXorHandlers();
+        
+        // Register Data Transfer handlers
+        RegisterDataTransferHandlers();
+        
+        // Register floating point handlers
         _handlers.Add(new FnstswHandler(_codeBuffer, _decoder, _length));
-
-        // TEST handlers
-        _handlers.Add(new TestImmWithRm32Handler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new TestImmWithRm8Handler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new TestRegMem8Handler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new TestRegMemHandler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new TestAlImmHandler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new TestEaxImmHandler(_codeBuffer, _decoder, _length));
-        
-        // JMP handlers
-        _handlers.Add(new JmpRel32Handler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new JmpRel8Handler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new ConditionalJumpHandler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new TwoByteConditionalJumpHandler(_codeBuffer, _decoder, _length));
-        
-        // Register group handlers for instructions that share similar decoding logic
         _handlers.Add(new FloatingPointHandler(_codeBuffer, _decoder, _length));
-        _handlers.Add(new DataTransferHandler(_codeBuffer, _decoder, _length));
     }
     
     /// <summary>
-    /// Registers the Group1 handlers
+    /// Registers all Group1 instruction handlers
     /// </summary>
     private void RegisterGroup1Handlers()
     {
@@ -122,7 +113,7 @@ public class InstructionHandlerFactory
     }
     
     /// <summary>
-    /// Registers the Group3 handlers
+    /// Registers all Group3 instruction handlers
     /// </summary>
     private void RegisterGroup3Handlers()
     {
@@ -146,20 +137,96 @@ public class InstructionHandlerFactory
     }
     
     /// <summary>
-    /// Gets a handler that can decode the given opcode
+    /// Registers all Return instruction handlers
+    /// </summary>
+    private void RegisterReturnHandlers()
+    {
+        // Add Return handlers
+        _handlers.Add(new RetHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new RetImmHandler(_codeBuffer, _decoder, _length));
+    }
+    
+    /// <summary>
+    /// Registers all Call instruction handlers
+    /// </summary>
+    private void RegisterCallHandlers()
+    {
+        // Add Call handlers
+        _handlers.Add(new CallRel32Handler(_codeBuffer, _decoder, _length));
+    }
+    
+    /// <summary>
+    /// Registers all Jump instruction handlers
+    /// </summary>
+    private void RegisterJumpHandlers()
+    {
+        // JMP handlers
+        _handlers.Add(new JmpRel32Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new JmpRel8Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new ConditionalJumpHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new TwoByteConditionalJumpHandler(_codeBuffer, _decoder, _length));
+    }
+    
+    /// <summary>
+    /// Registers all Test instruction handlers
+    /// </summary>
+    private void RegisterTestHandlers()
+    {
+        // TEST handlers
+        _handlers.Add(new TestImmWithRm32Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new TestImmWithRm8Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new TestRegMem8Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new TestRegMemHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new TestAlImmHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new TestEaxImmHandler(_codeBuffer, _decoder, _length));
+    }
+    
+    /// <summary>
+    /// Registers all Xor instruction handlers
+    /// </summary>
+    private void RegisterXorHandlers()
+    {
+        // Add Xor handlers
+        _handlers.Add(new XorAlImmHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new XorEaxImmHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new XorMemRegHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new XorRegMemHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new XorImmWithRm32Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new XorImmWithRm32SignExtendedHandler(_codeBuffer, _decoder, _length));
+    }
+    
+    /// <summary>
+    /// Registers all Data Transfer instruction handlers
+    /// </summary>
+    private void RegisterDataTransferHandlers()
+    {
+        // Add MOV handlers
+        _handlers.Add(new MovRegMemHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new MovMemRegHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new MovRegImm32Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new MovRegImm8Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new MovEaxMoffsHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new MovMoffsEaxHandler(_codeBuffer, _decoder, _length));
+        
+        // Add PUSH handlers
+        _handlers.Add(new PushRegHandler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new PushImm32Handler(_codeBuffer, _decoder, _length));
+        _handlers.Add(new PushImm8Handler(_codeBuffer, _decoder, _length));
+        
+        // Add POP handlers
+        _handlers.Add(new PopRegHandler(_codeBuffer, _decoder, _length));
+        
+        // Add XCHG handlers
+        _handlers.Add(new XchgEaxRegHandler(_codeBuffer, _decoder, _length));
+    }
+    
+    /// <summary>
+    /// Gets the handler that can decode the given opcode
     /// </summary>
     /// <param name="opcode">The opcode to decode</param>
-    /// <returns>A handler that can decode the opcode, or null if no handler is found</returns>
+    /// <returns>The handler that can decode the opcode, or null if no handler can decode it</returns>
     public IInstructionHandler? GetHandler(byte opcode)
     {
-        foreach (var handler in _handlers)
+        return _handlers.FirstOrDefault(h => h.CanHandle(opcode));
-        {
-            if (handler.CanHandle(opcode))
-            {
-                return handler;
-            }
-        }
-        
-        return null;
     }
 }

X86Disassembler/X86/Handlers/Mov/MovEaxMoffsHandler.cs

@@ -0,0 +1,56 @@
+namespace X86Disassembler.X86.Handlers.Mov;
+
+/// <summary>
+/// Handler for MOV EAX, moffs32 instruction (0xA1) and MOV AL, moffs8 instruction (0xA0)
+/// </summary>
+public class MovEaxMoffsHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the MovEaxMoffsHandler 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 MovEaxMoffsHandler(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 == 0xA0 || opcode == 0xA1;
+    }
+    
+    /// <summary>
+    /// Decodes a MOV EAX, moffs32 or MOV AL, moffs8 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 = "mov";
+        
+        // Get the operand size and register name
+        int operandSize = (opcode == 0xA0) ? 8 : 32;
+        string regName = (opcode == 0xA0) ? "al" : "eax";
+        
+        // Read the memory offset
+        uint offset = Decoder.ReadUInt32();
+        if (Decoder.GetPosition() > Length)
+        {
+            return false;
+        }
+        
+        // Set the operands
+        instruction.Operands = $"{regName}, [0x{offset:X}]";
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Mov/MovMemRegHandler.cs

@@ -0,0 +1,70 @@
+namespace X86Disassembler.X86.Handlers.Mov;
+
+/// <summary>
+/// Handler for MOV r/m32, r32 instruction (0x89) and MOV r/m8, r8 instruction (0x88)
+/// </summary>
+public class MovMemRegHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the MovMemRegHandler 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 MovMemRegHandler(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 == 0x88 || opcode == 0x89;
+    }
+    
+    /// <summary>
+    /// Decodes a MOV r/m32, r32 or MOV r/m8, r8 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 = "mov";
+        
+        int position = Decoder.GetPosition();
+        
+        if (position >= Length)
+        {
+            return false;
+        }
+        
+        // Determine operand size (0 = 8-bit, 1 = 32-bit)
+        bool operandSize32 = (opcode & 0x01) != 0;
+        int operandSize = operandSize32 ? 32 : 8;
+        
+        // Read the ModR/M byte
+        var (mod, reg, rm, memOperand) = ModRMDecoder.ReadModRM();
+        
+        // Get register name based on size
+        string regName = ModRMDecoder.GetRegisterName(reg, operandSize);
+        
+        // For mod == 3, both operands are registers
+        if (mod == 3)
+        {
+            string rmRegName = ModRMDecoder.GetRegisterName(rm, operandSize);
+            instruction.Operands = $"{regName}, {rmRegName}";
+        }
+        else // Memory operand
+        {
+            instruction.Operands = $"{regName}, {memOperand}";
+        }
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Mov/MovMoffsEaxHandler.cs

@@ -0,0 +1,56 @@
+namespace X86Disassembler.X86.Handlers.Mov;
+
+/// <summary>
+/// Handler for MOV moffs32, EAX instruction (0xA3) and MOV moffs8, AL instruction (0xA2)
+/// </summary>
+public class MovMoffsEaxHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the MovMoffsEaxHandler 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 MovMoffsEaxHandler(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 == 0xA2 || opcode == 0xA3;
+    }
+    
+    /// <summary>
+    /// Decodes a MOV moffs32, EAX or MOV moffs8, AL 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 = "mov";
+        
+        // Get the operand size and register name
+        int operandSize = (opcode == 0xA2) ? 8 : 32;
+        string regName = (opcode == 0xA2) ? "al" : "eax";
+        
+        // Read the memory offset
+        uint offset = Decoder.ReadUInt32();
+        if (Decoder.GetPosition() > Length)
+        {
+            return false;
+        }
+        
+        // Set the operands
+        instruction.Operands = $"[0x{offset:X}], {regName}";
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Mov/MovRegImm32Handler.cs

@@ -0,0 +1,56 @@
+namespace X86Disassembler.X86.Handlers.Mov;
+
+/// <summary>
+/// Handler for MOV r32, imm32 instruction (0xB8-0xBF)
+/// </summary>
+public class MovRegImm32Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the MovRegImm32Handler 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 MovRegImm32Handler(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 >= 0xB8 && opcode <= 0xBF;
+    }
+    
+    /// <summary>
+    /// Decodes a MOV r32, 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 = "mov";
+        
+        // Register is encoded in the low 3 bits of the opcode
+        int reg = opcode & 0x07;
+        string regName = ModRMDecoder.GetRegisterName(reg, 32);
+        
+        // Read the immediate value
+        uint imm32 = Decoder.ReadUInt32();
+        if (Decoder.GetPosition() > Length)
+        {
+            return false;
+        }
+        
+        // Set the operands
+        instruction.Operands = $"{regName}, 0x{imm32:X}";
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Mov/MovRegImm8Handler.cs

@@ -0,0 +1,56 @@
+namespace X86Disassembler.X86.Handlers.Mov;
+
+/// <summary>
+/// Handler for MOV r8, imm8 instruction (0xB0-0xB7)
+/// </summary>
+public class MovRegImm8Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the MovRegImm8Handler 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 MovRegImm8Handler(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 >= 0xB0 && opcode <= 0xB7;
+    }
+    
+    /// <summary>
+    /// Decodes a MOV r8, imm8 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 = "mov";
+        
+        // Register is encoded in the low 3 bits of the opcode
+        int reg = opcode & 0x07;
+        string regName = ModRMDecoder.GetRegisterName(reg, 8);
+        
+        // Read the immediate value
+        byte imm8 = Decoder.ReadByte();
+        if (Decoder.GetPosition() > Length)
+        {
+            return false;
+        }
+        
+        // Set the operands
+        instruction.Operands = $"{regName}, 0x{imm8:X2}";
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Mov/MovRegMemHandler.cs

@@ -0,0 +1,70 @@
+namespace X86Disassembler.X86.Handlers.Mov;
+
+/// <summary>
+/// Handler for MOV r32, r/m32 instruction (0x8B) and MOV r8, r/m8 instruction (0x8A)
+/// </summary>
+public class MovRegMemHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the MovRegMemHandler 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 MovRegMemHandler(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 == 0x8A || opcode == 0x8B;
+    }
+    
+    /// <summary>
+    /// Decodes a MOV r32, r/m32 or MOV 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)
+    {
+        // Set the mnemonic
+        instruction.Mnemonic = "mov";
+        
+        int position = Decoder.GetPosition();
+        
+        if (position >= Length)
+        {
+            return false;
+        }
+        
+        // Determine operand size (0 = 8-bit, 1 = 32-bit)
+        bool operandSize32 = (opcode & 0x01) != 0;
+        int operandSize = operandSize32 ? 32 : 8;
+        
+        // Read the ModR/M byte
+        var (mod, reg, rm, memOperand) = ModRMDecoder.ReadModRM();
+        
+        // Get register name based on size
+        string regName = ModRMDecoder.GetRegisterName(reg, operandSize);
+        
+        // For mod == 3, both operands are registers
+        if (mod == 3)
+        {
+            string rmRegName = ModRMDecoder.GetRegisterName(rm, operandSize);
+            instruction.Operands = $"{rmRegName}, {regName}";
+        }
+        else // Memory operand
+        {
+            instruction.Operands = $"{memOperand}, {regName}";
+        }
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Pop/PopRegHandler.cs

@@ -0,0 +1,49 @@
+namespace X86Disassembler.X86.Handlers.Pop;
+
+/// <summary>
+/// Handler for POP r32 instruction (0x58-0x5F)
+/// </summary>
+public class PopRegHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the PopRegHandler 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 PopRegHandler(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 >= 0x58 && opcode <= 0x5F;
+    }
+    
+    /// <summary>
+    /// Decodes a POP r32 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 = "pop";
+        
+        // Register is encoded in the low 3 bits of the opcode
+        int reg = opcode & 0x07;
+        string regName = ModRMDecoder.GetRegisterName(reg, 32);
+        
+        // Set the operands
+        instruction.Operands = regName;
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Push/PushImm32Handler.cs

@@ -0,0 +1,52 @@
+namespace X86Disassembler.X86.Handlers.Push;
+
+/// <summary>
+/// Handler for PUSH imm32 instruction (0x68)
+/// </summary>
+public class PushImm32Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the PushImm32Handler 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 PushImm32Handler(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 == 0x68;
+    }
+    
+    /// <summary>
+    /// Decodes a PUSH 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 = "push";
+        
+        // Read the immediate value
+        uint imm32 = Decoder.ReadUInt32();
+        if (Decoder.GetPosition() > Length)
+        {
+            return false;
+        }
+        
+        // Set the operands
+        instruction.Operands = $"0x{imm32:X}";
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Push/PushImm8Handler.cs

@@ -0,0 +1,52 @@
+namespace X86Disassembler.X86.Handlers.Push;
+
+/// <summary>
+/// Handler for PUSH imm8 instruction (0x6A)
+/// </summary>
+public class PushImm8Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the PushImm8Handler 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 PushImm8Handler(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 == 0x6A;
+    }
+    
+    /// <summary>
+    /// Decodes a PUSH imm8 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 = "push";
+        
+        // Read the immediate value
+        byte imm8 = Decoder.ReadByte();
+        if (Decoder.GetPosition() > Length)
+        {
+            return false;
+        }
+        
+        // Set the operands
+        instruction.Operands = $"0x{imm8:X2}";
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Push/PushRegHandler.cs

@@ -0,0 +1,49 @@
+namespace X86Disassembler.X86.Handlers.Push;
+
+/// <summary>
+/// Handler for PUSH r32 instruction (0x50-0x57)
+/// </summary>
+public class PushRegHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the PushRegHandler 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 PushRegHandler(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 >= 0x50 && opcode <= 0x57;
+    }
+    
+    /// <summary>
+    /// Decodes a PUSH r32 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 = "push";
+        
+        // Register is encoded in the low 3 bits of the opcode
+        int reg = opcode & 0x07;
+        string regName = ModRMDecoder.GetRegisterName(reg, 32);
+        
+        // Set the operands
+        instruction.Operands = regName;
+        
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Xchg/XchgEaxRegHandler.cs

@@ -0,0 +1,57 @@
+namespace X86Disassembler.X86.Handlers.Xchg;
+
+/// <summary>
+/// Handler for XCHG EAX, r32 instruction (0x90-0x97)
+/// </summary>
+public class XchgEaxRegHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the XchgEaxRegHandler 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 XchgEaxRegHandler(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 >= 0x90 && opcode <= 0x97;
+    }
+    
+    /// <summary>
+    /// Decodes an XCHG EAX, r32 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)
+    {
+        // Special case for NOP (XCHG EAX, EAX)
+        if (opcode == 0x90)
+        {
+            instruction.Mnemonic = "nop";
+            instruction.Operands = "";
+            return true;
+        }
+        
+        // Set the mnemonic
+        instruction.Mnemonic = "xchg";
+        
+        // Register is encoded in the low 3 bits of the opcode
+        int reg = opcode & 0x07;
+        string regName = ModRMDecoder.GetRegisterName(reg, 32);
+        
+        // Set the operands
+        instruction.Operands = $"eax, {regName}";
+        
+        return true;
+    }
+}