Fixed floating point instruction handling. Removed redundant FNSTSW AX check from FloatingPointHandler and added dedicated test for FnstswHandler.

X86DisassemblerTests/FloatingPointInstructionTests.cs

@@ -0,0 +1,32 @@
+namespace X86DisassemblerTests;
+
+using System;
+using Xunit;
+using X86Disassembler.X86;
+using X86Disassembler.X86.Handlers;
+
+/// <summary>
+/// Tests for floating-point instruction handlers
+/// </summary>
+public class FloatingPointInstructionTests
+{
+    /// <summary>
+    /// Tests the FnstswHandler for decoding FNSTSW AX instruction
+    /// </summary>
+    [Fact]
+    public void FnstswHandler_DecodesFnstswAx_Correctly()
+    {
+        // Arrange
+        // FNSTSW AX (DF E0)
+        byte[] codeBuffer = new byte[] { 0xDF, 0xE0 };
+        var decoder = new InstructionDecoder(codeBuffer, codeBuffer.Length);
+        
+        // Act
+        var instruction = decoder.DecodeInstruction();
+        
+        // Assert
+        Assert.NotNull(instruction);
+        Assert.Equal("fnstsw", instruction.Mnemonic);
+        Assert.Equal("ax", instruction.Operands);
+    }
+}