Reorganized OR instruction handlers into a dedicated folder

X86Disassembler/X86/Handlers/Or/OrImmToRm8Handler.cs

@@ -0,0 +1,95 @@
+namespace X86Disassembler.X86.Handlers.Or;
+
+/// <summary>
+/// Handler for OR r/m8, imm8 instruction (0x80 /1)
+/// </summary>
+public class OrImmToRm8Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the OrImmToRm8Handler 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 OrImmToRm8Handler(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)
+    {
+        if (opcode != 0x80)
+            return false;
+            
+        // Check if the reg field of the ModR/M byte is 1 (OR)
+        int position = Decoder.GetPosition();
+        if (position >= Length)
+            return false;
+            
+        byte modRM = CodeBuffer[position];
+        byte reg = (byte)((modRM & 0x38) >> 3);
+        
+        return reg == 1; // 1 = OR
+    }
+    
+    /// <summary>
+    /// Decodes an OR r/m8, 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 = "or";
+        
+        int position = Decoder.GetPosition();
+        
+        if (position >= Length)
+        {
+            return false;
+        }
+        
+        // Read the ModR/M byte
+        byte modRM = CodeBuffer[position++];
+        
+        // Extract the fields from the ModR/M byte
+        byte mod = (byte)((modRM & 0xC0) >> 6);
+        byte reg = (byte)((modRM & 0x38) >> 3); // Should be 1 for OR
+        byte rm = (byte)(modRM & 0x07);
+        
+        // For direct register addressing (mod == 3), use 8-bit register names
+        string destOperand;
+        if (mod == 3)
+        {
+            // Use 8-bit register names for direct register addressing
+            destOperand = GetRegister8(rm);
+        }
+        else
+        {
+            // Use ModR/M decoder for memory addressing
+            destOperand = ModRMDecoder.DecodeModRM(mod, rm, false);
+        }
+        
+        Decoder.SetPosition(position);
+        
+        // Read the immediate value
+        if (position >= Length)
+        {
+            return false;
+        }
+        
+        byte imm8 = CodeBuffer[position++];
+        Decoder.SetPosition(position);
+        
+        // Set the operands
+        instruction.Operands = $"{destOperand}, 0x{imm8:X2}";
+        
+        return true;
+    }
+}