Created dedicated Mul namespace for MUL instruction handlers. Implemented MulRm8Handler for MUL r/m8 instruction (opcode F6 /4) and moved MulRm32Handler to the new namespace. Updated InstructionHandlerFactory to register both handlers.

X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs

@@ -10,6 +10,8 @@ using X86Disassembler.X86.Handlers.Inc;
 using X86Disassembler.X86.Handlers.Jump;
 using X86Disassembler.X86.Handlers.Lea;
 using X86Disassembler.X86.Handlers.Mov;
+using X86Disassembler.X86.Handlers.Mul;
+using X86Disassembler.X86.Handlers.Neg;
 using X86Disassembler.X86.Handlers.Nop;
 using X86Disassembler.X86.Handlers.Or;
 using X86Disassembler.X86.Handlers.Pop;
@@ -62,6 +64,8 @@ public class InstructionHandlerFactory
         RegisterAddHandlers();
         RegisterAndHandlers();
         RegisterArithmeticUnaryHandlers();
+        RegisterNegHandlers(); // Register NEG handlers
+        RegisterMulHandlers(); // Register MUL handlers
         RegisterCmpHandlers();
         RegisterXorHandlers();
         RegisterOrHandlers();
@@ -90,13 +94,6 @@ public class InstructionHandlerFactory
         // NOT handler
         _handlers.Add(new NotRm32Handler(_decoder));
 
-        // NEG handlers
-        _handlers.Add(new NegRm8Handler(_decoder));  // F6 /3 - NEG r/m8
-        _handlers.Add(new NegRm32Handler(_decoder)); // F7 /3 - NEG r/m32
-
-        // MUL handler
-        _handlers.Add(new MulRm32Handler(_decoder));
-
         // IMUL handler
         _handlers.Add(new ImulRm32Handler(_decoder));
 
@@ -441,6 +438,30 @@ public class InstructionHandlerFactory
         _handlers.Add(new MultiByteNopHandler(_decoder));
     }
 
+    /// <summary>
+    /// Registers all NEG instruction handlers
+    /// </summary>
+    private void RegisterNegHandlers()
+    {
+        // NEG r/m8 handler (F6 /3)
+        _handlers.Add(new NegRm8Handler(_decoder));
+
+        // NEG r/m32 handler (F7 /3)
+        _handlers.Add(new NegRm32Handler(_decoder));
+    }
+
+    /// <summary>
+    /// Registers all MUL instruction handlers
+    /// </summary>
+    private void RegisterMulHandlers()
+    {
+        // MUL r/m8 handler (F6 /4)
+        _handlers.Add(new MulRm8Handler(_decoder));
+
+        // MUL r/m32 handler (F7 /4)
+        _handlers.Add(new MulRm32Handler(_decoder));
+    }
+
     /// <summary>
     /// Gets the handler that can decode the given opcode
     /// </summary>

X86Disassembler/X86/Handlers/Mul/MulRm32Handler.cs

@@ -0,0 +1,75 @@
+using X86Disassembler.X86.Operands;
+
+namespace X86Disassembler.X86.Handlers.Mul;
+
+/// <summary>
+/// Handler for MUL r/m32 instruction (0xF7 /4)
+/// </summary>
+public class MulRm32Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the MulRm32Handler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public MulRm32Handler(InstructionDecoder decoder)
+        : base(decoder)
+    {
+    }
+
+    /// <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)
+    {
+        if (opcode != 0xF7)
+            return false;
+
+        // Check if the reg field of the ModR/M byte is 4 (MUL)
+        if (!Decoder.CanReadByte())
+            return false;
+
+        var reg = ModRMDecoder.PeakModRMReg();
+
+        return reg == 4; // 4 = MUL
+    }
+
+    /// <summary>
+    /// Decodes a MUL 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)
+    {
+        // Set the instruction type
+        instruction.Type = InstructionType.Mul;
+
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Read the ModR/M byte
+        // For MUL r/m32 (0xF7 /4):
+        // - The r/m field with mod specifies the operand (register or memory)
+        var (_, reg, _, operand) = ModRMDecoder.ReadModRM();
+        
+        // Verify this is a MUL instruction
+        // The reg field should be 4 (MUL), which maps to RegisterIndex.Sp in our enum
+        if (reg != RegisterIndex.Sp)
+        {
+            return false;
+        }
+
+        // Set the structured operands
+        // MUL has only one operand
+        instruction.StructuredOperands = 
+        [
+            operand
+        ];
+
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Mul/MulRm8Handler.cs

@@ -0,0 +1,75 @@
+using X86Disassembler.X86.Operands;
+
+namespace X86Disassembler.X86.Handlers.Mul;
+
+/// <summary>
+/// Handler for MUL r/m8 instruction (0xF6 /4)
+/// </summary>
+public class MulRm8Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the MulRm8Handler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public MulRm8Handler(InstructionDecoder decoder)
+        : base(decoder)
+    {
+    }
+
+    /// <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)
+    {
+        if (opcode != 0xF6)
+            return false;
+
+        // Check if the reg field of the ModR/M byte is 4 (MUL)
+        if (!Decoder.CanReadByte())
+            return false;
+
+        var reg = ModRMDecoder.PeakModRMReg();
+
+        return reg == 4; // 4 = MUL
+    }
+
+    /// <summary>
+    /// Decodes a MUL 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 instruction type
+        instruction.Type = InstructionType.Mul;
+
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Read the ModR/M byte
+        // For MUL r/m8 (0xF6 /4):
+        // - The r/m field with mod specifies the operand (register or memory)
+        var (_, reg, _, operand) = ModRMDecoder.ReadModRM8();
+        
+        // Verify this is a MUL instruction
+        // The reg field should be 4 (MUL), which maps to RegisterIndex8.AH in our enum
+        if (reg != RegisterIndex8.AH)
+        {
+            return false;
+        }
+
+        // Set the structured operands
+        // MUL has only one operand
+        instruction.StructuredOperands = 
+        [
+            operand
+        ];
+
+        return true;
+    }
+}