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/FistpInt64Handler.cs

@@ -0,0 +1,94 @@
+namespace X86Disassembler.X86.Handlers.FloatingPoint.LoadStore;
+
+using X86Disassembler.X86.Operands;
+
+/// <summary>
+/// Handler for FISTP int64 instruction (DF /7)
+/// </summary>
+public class FistpInt64Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the FistpInt64Handler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public FistpInt64Handler(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)
+    {
+        // FISTP int64 is DF /7
+        if (opcode != 0xDF) return false;
+
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Check if the ModR/M byte has reg field = 7
+        byte modRm = Decoder.PeakByte();
+        byte reg = (byte)((modRm >> 3) & 0x7);
+        byte mod = (byte)((modRm >> 6) & 0x3);
+        
+        // Only handle memory operands (mod != 3) with reg = 7
+        return reg == 7 && mod != 3;
+    }
+    
+    /// <summary>
+    /// Decodes a FISTP int64 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)
+    {
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Read the ModR/M byte
+        var (mod, reg, rm, rawMemoryOperand) = ModRMDecoder.ReadModRM();
+        
+        // Set the instruction type
+        instruction.Type = InstructionType.Fistp;
+
+        // Create a 64-bit memory operand
+        Operand memoryOperand;
+        
+        if (rawMemoryOperand is DirectMemoryOperand directMemory)
+        {
+            memoryOperand = OperandFactory.CreateDirectMemoryOperand(directMemory.Address, 64);
+        }
+        else if (rawMemoryOperand is BaseRegisterMemoryOperand baseMemory)
+        {
+            memoryOperand = OperandFactory.CreateBaseRegisterMemoryOperand(baseMemory.BaseRegister, 64);
+        }
+        else if (rawMemoryOperand is DisplacementMemoryOperand dispMemory)
+        {
+            memoryOperand = OperandFactory.CreateDisplacementMemoryOperand(dispMemory.BaseRegister, dispMemory.Displacement, 64);
+        }
+        else if (rawMemoryOperand is ScaledIndexMemoryOperand scaledMemory)
+        {
+            memoryOperand = OperandFactory.CreateScaledIndexMemoryOperand(scaledMemory.IndexRegister, scaledMemory.Scale, scaledMemory.BaseRegister, scaledMemory.Displacement, 64);
+        }
+        else
+        {
+            memoryOperand = rawMemoryOperand;
+        }
+
+        // Set the structured operands
+        instruction.StructuredOperands = 
+        [
+            memoryOperand
+        ];
+
+        return true;
+    }
+}