Refactored floating point handlers into specialized classes for better organization and maintainability

X86Disassembler/X86/Handlers/FloatingPoint/Arithmetic/FisubInt32Handler.cs

@@ -0,0 +1,70 @@
+namespace X86Disassembler.X86.Handlers.FloatingPoint.Arithmetic;
+
+using X86Disassembler.X86.Operands;
+
+/// <summary>
+/// Handler for FISUB int32 instruction (DA /4)
+/// </summary>
+public class FisubInt32Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the FisubInt32Handler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public FisubInt32Handler(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)
+    {
+        // FISUB is DA /4
+        if (opcode != 0xDA) return false;
+
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Check if the ModR/M byte has reg field = 4
+        byte modRm = Decoder.PeakByte();
+        byte reg = (byte)((modRm >> 3) & 0x7);
+        byte mod = (byte)((modRm >> 6) & 0x3);
+        
+        // Only handle memory operands (mod != 3)
+        return reg == 4 && mod != 3;
+    }
+    
+    /// <summary>
+    /// Decodes a FISUB int32 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, rawOperand) = ModRMDecoder.ReadModRM();
+        
+        // Set the instruction type
+        instruction.Type = InstructionType.Fisub;
+
+        // Set the structured operands - the operand already has the correct size from ReadModRM
+        instruction.StructuredOperands = 
+        [
+            rawOperand
+        ];
+
+        return true;
+    }
+}