Refactored floating point instruction handlers for better organization and maintainability. Split generic handlers into specialized classes for DD and DF opcodes.

X86Disassembler/X86/Handlers/FloatingPoint/LoadStore/FstpDfHandler.cs

@@ -0,0 +1,70 @@
+namespace X86Disassembler.X86.Handlers.FloatingPoint.LoadStore;
+
+using X86Disassembler.X86.Operands;
+
+/// <summary>
+/// Handler for FSTP instruction with DF opcode (DF D0-D8)
+/// </summary>
+public class FstpDfHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the FstpDfHandler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public FstpDfHandler(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)
+    {
+        // FSTP with DF opcode is DF D0 or DF D8
+        if (opcode != 0xDF) return false;
+
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Check if the ModR/M byte is D0 (reg = 2, rm = 0, mod = 3) or D8 (reg = 3, rm = 0, mod = 3)
+        byte modRm = Decoder.PeakByte();
+        return modRm == 0xD0 || modRm == 0xD8;
+    }
+    
+    /// <summary>
+    /// Decodes a FSTP instruction with DF opcode
+    /// </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)
+    {
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Read the ModR/M byte
+        var (mod, reg, rm, _) = ModRMDecoder.ReadModRM();
+        
+        // Set the instruction type
+        instruction.Type = InstructionType.Fstp;
+
+        // Create the FPU register operand
+        // For both D0 and D8, the operand is ST1
+        var fpuRegisterOperand = OperandFactory.CreateFPURegisterOperand(FpuRegisterIndex.ST1);
+        
+        // Set the structured operands
+        instruction.StructuredOperands = 
+        [
+            fpuRegisterOperand
+        ];
+
+        return true;
+    }
+}