From 6ea208d8bfa13653a94aec2439e96407cff0109d Mon Sep 17 00:00:00 2001
From: bird_egop <sampletext32@bk.ru>
Date: Fri, 18 Apr 2025 13:08:18 +0300
Subject: [PATCH] Fix FCLEX/FNCLEX instruction types and rename handler for
 consistency

---
 .../FloatingPoint/Control/FclexHandler.cs     |  2 +-
 .../FloatingPoint/Control/FclexWaitHandler.cs | 71 +++++++++++++++++++
 .../X86/Handlers/InstructionHandlerFactory.cs |  3 +-
 3 files changed, 74 insertions(+), 2 deletions(-)
 create mode 100644 X86Disassembler/X86/Handlers/FloatingPoint/Control/FclexWaitHandler.cs

diff --git a/X86Disassembler/X86/Handlers/FloatingPoint/Control/FclexHandler.cs b/X86Disassembler/X86/Handlers/FloatingPoint/Control/FclexHandler.cs
index bf04f46..89802d3 100644
--- a/X86Disassembler/X86/Handlers/FloatingPoint/Control/FclexHandler.cs
+++ b/X86Disassembler/X86/Handlers/FloatingPoint/Control/FclexHandler.cs
@@ -53,7 +53,7 @@ public class FclexHandler : InstructionHandler
         byte secondByte = Decoder.ReadByte();
         
         // Set the instruction type
-        instruction.Type = InstructionType.Fclex;
+        instruction.Type = InstructionType.Fnclex;
 
         // FCLEX has no operands
         instruction.StructuredOperands = [];
diff --git a/X86Disassembler/X86/Handlers/FloatingPoint/Control/FclexWaitHandler.cs b/X86Disassembler/X86/Handlers/FloatingPoint/Control/FclexWaitHandler.cs
new file mode 100644
index 0000000..ce8b076
--- /dev/null
+++ b/X86Disassembler/X86/Handlers/FloatingPoint/Control/FclexWaitHandler.cs
@@ -0,0 +1,71 @@
+namespace X86Disassembler.X86.Handlers.FloatingPoint.Control;
+
+/// <summary>
+/// Handler for FCLEX instruction with WAIT prefix (0x9B 0xDB 0xE2)
+/// </summary>
+public class FclexWaitHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the FclexWaitHandler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public FclexWaitHandler(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)
+    {
+        // FCLEX with WAIT prefix starts with 0x9B
+        if (opcode != 0x9B) return false;
+
+        // Check if we can read the next two bytes
+        if (!Decoder.CanReadByte())
+            return false;
+
+        // Check if the next bytes are 0xDB 0xE2 (for FCLEX with WAIT)
+        var (nextByte, thirdByte) = Decoder.PeakTwoBytes();
+
+        // The sequence must be 9B DB E2 for FCLEX with WAIT
+        return nextByte == 0xDB && thirdByte == 0xE2;
+    }
+    
+    /// <summary>
+    /// Decodes a FCLEX instruction with WAIT prefix
+    /// </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)
+    {
+        // Skip the WAIT prefix (0x9B) - we already read it in CanHandle
+        if (!Decoder.CanReadByte())
+            return false;
+
+        // Read the second byte (0xDB)
+        byte secondByte = Decoder.ReadByte();
+        if (secondByte != 0xDB)
+            return false;
+            
+        // Read the third byte (0xE2)
+        if (!Decoder.CanReadByte())
+            return false;
+
+        byte thirdByte = Decoder.ReadByte();
+        if (thirdByte != 0xE2)
+            return false;
+        
+        // Set the instruction type
+        instruction.Type = InstructionType.Fclex;
+        
+        // FCLEX has no operands
+        instruction.StructuredOperands = [];
+        
+        return true;
+    }
+}
diff --git a/X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs b/X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs
index 57ad0b6..37c6aed 100644
--- a/X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs
+++ b/X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs
@@ -435,7 +435,8 @@ public class InstructionHandlerFactory
         _handlers.Add(new FloatingPoint.Conditional.FcmovnuHandler(_decoder));     // FCMOVNU (DB D8-DF)
         
         // DB opcode handlers (control instructions)
-        _handlers.Add(new FloatingPoint.Control.FclexHandler(_decoder));           // FCLEX (DB E2)
+        _handlers.Add(new FloatingPoint.Control.FclexHandler(_decoder));           // FNCLEX (DB E2)
+        _handlers.Add(new FloatingPoint.Control.FclexWaitHandler(_decoder));       // FCLEX (9B DB E2)
         _handlers.Add(new FloatingPoint.Control.FinitHandler(_decoder));           // FINIT (DB E3)
         
         // DB opcode handlers (comparison instructions)