Added support for DEC r32 instructions (0x48-0x4F) with tests

X86Disassembler/X86/Handlers/Dec/DecRegHandler.cs

@@ -0,0 +1,49 @@
+namespace X86Disassembler.X86.Handlers.Dec;
+
+/// <summary>
+/// Handler for DEC r32 instructions (0x48-0x4F)
+/// </summary>
+public class DecRegHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the DecRegHandler 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 DecRegHandler(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)
+    {
+        // DEC EAX = 0x48, DEC ECX = 0x49, ..., DEC EDI = 0x4F
+        return opcode >= 0x48 && opcode <= 0x4F;
+    }
+
+    /// <summary>
+    /// Decodes a DEC 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)
+    {
+        // Calculate the register index (0 for EAX, 1 for ECX, etc.)
+        byte reg = (byte)(opcode - 0x48);
+        
+        // Set the mnemonic
+        instruction.Mnemonic = "dec";
+        
+        // Set the operand (register name)
+        instruction.Operands = GetRegister32(reg);
+        
+        return true;
+    }
+}