Implemented SBB instruction handlers for the x86 disassembler

X86Disassembler/X86/Handlers/Sbb/SbbImmFromRm16Handler.cs

@@ -0,0 +1,85 @@
+using X86Disassembler.X86.Operands;
+
+namespace X86Disassembler.X86.Handlers.Sbb;
+
+/// <summary>
+/// Handler for SBB r/m16, imm16 instruction (0x81 /3 with 0x66 prefix)
+/// </summary>
+public class SbbImmFromRm16Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the SbbImmFromRm16Handler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public SbbImmFromRm16Handler(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)
+    {
+        if (opcode != 0x81)
+            return false;
+
+        // Must have operand size prefix for 16-bit operation
+        if (!Decoder.HasOperandSizePrefix())
+            return false;
+
+        // Check if the reg field of the ModR/M byte is 3 (SBB)
+        if (!Decoder.CanReadByte())
+            return false;
+
+        var reg = ModRMDecoder.PeakModRMReg();
+
+        return reg == 3; // 3 = SBB
+    }
+
+    /// <summary>
+    /// Decodes a SBB r/m16, imm16 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 instruction type
+        instruction.Type = InstructionType.Sbb;
+
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Read the ModR/M byte
+        // For SBB r/m16, imm16 (0x81 /3 with 0x66 prefix):
+        // - The r/m field with mod specifies the destination operand (register or memory)
+        // - The immediate value is the source operand
+        var (_, _, _, destinationOperand) = ModRMDecoder.ReadModRM16();
+
+        // Check if we have enough bytes for the immediate value
+        if (!Decoder.CanReadUShort())
+        {
+            return false;
+        }
+
+        // Read the immediate value
+        ushort imm16 = Decoder.ReadUInt16();
+
+        // Create the immediate operand
+        var sourceOperand = OperandFactory.CreateImmediateOperand(imm16, 16);
+
+        // Set the structured operands
+        instruction.StructuredOperands = 
+        [
+            destinationOperand,
+            sourceOperand
+        ];
+
+        return true;
+    }
+}