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

X86Disassembler/X86/Handlers/Test/TestEaxImmHandler.cs

@@ -0,0 +1,63 @@
+namespace X86Disassembler.X86.Handlers.Test;
+
+/// <summary>
+/// Handler for TEST EAX, imm32 instruction (0xA9)
+/// </summary>
+public class TestEaxImmHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the TestEaxImmHandler 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 TestEaxImmHandler(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 == 0xA9;
+    }
+    
+    /// <summary>
+    /// Decodes a TEST EAX, imm32 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)
+    {
+        // Set the mnemonic
+        instruction.Mnemonic = "test";
+        
+        int position = Decoder.GetPosition();
+        
+        if (position + 3 >= Length)
+        {
+            return false;
+        }
+        
+        // Read the immediate value - x86 is little-endian, so we need to read the bytes in the correct order
+        byte b0 = CodeBuffer[position];
+        byte b1 = CodeBuffer[position + 1];
+        byte b2 = CodeBuffer[position + 2];
+        byte b3 = CodeBuffer[position + 3];
+        
+        // Combine the bytes to form a 32-bit immediate value
+        uint imm32 = (uint)(b0 | (b1 << 8) | (b2 << 16) | (b3 << 24));
+        
+        Decoder.SetPosition(position + 4);
+        
+        // Set the operands
+        instruction.Operands = $"eax, 0x{imm32:X8}";
+        
+        return true;
+    }
+}