split float handlers

X86Disassembler/X86/Handlers/FloatingPoint/Float64OperationHandler.cs

@@ -0,0 +1,83 @@
+namespace X86Disassembler.X86.Handlers.FloatingPoint;
+
+/// <summary>
+/// Handler for floating-point operations on float64 (DC opcode)
+/// </summary>
+public class Float64OperationHandler : FloatingPointBaseHandler
+{
+    // DC opcode - operations on float64
+    private static readonly string[] Mnemonics =
+    [
+        "fadd",
+        "fmul",
+        "fcom",
+        "fcomp",
+        "fsub",
+        "fsubr",
+        "fdiv",
+        "fdivr"
+    ];
+
+    /// <summary>
+    /// Initializes a new instance of the Float64OperationHandler 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 Float64OperationHandler(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 == 0xDC;
+    }
+    
+    /// <summary>
+    /// Decodes a floating-point instruction for float64 operations
+    /// </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)
+    {
+        int position = Decoder.GetPosition();
+        
+        if (position >= Length)
+        {
+            return false;
+        }
+
+        // Read the ModR/M byte
+        byte modRM = CodeBuffer[position++];
+        Decoder.SetPosition(position);
+        
+        // Extract the fields from the ModR/M byte
+        byte mod = (byte)((modRM & 0xC0) >> 6);
+        byte reg = (byte)((modRM & 0x38) >> 3);
+        byte rm = (byte)(modRM & 0x07);
+        
+        // Set the mnemonic based on the opcode and reg field
+        instruction.Mnemonic = Mnemonics[reg];
+        
+        // For memory operands, set the operand
+        if (mod != 3) // Memory operand
+        {
+            string operand = ModRMDecoder.DecodeModRM(mod, rm, false);
+            instruction.Operands = $"qword ptr {operand}";
+        }
+        else // Register operand (ST(i))
+        {
+            // For DC C0-DC FF, the operands are reversed: ST(i), ST(0)
+            instruction.Operands = $"st({rm}), st(0)";
+        }
+        
+        return true;
+    }
+}