Implemented SBB instruction handlers for the x86 disassembler

X86Disassembler/X86/Handlers/InstructionHandlerFactory.cs

@@ -100,9 +100,20 @@ public class InstructionHandlerFactory
     /// </summary>
     private void RegisterSbbHandlers()
     {
-        // SBB immediate handlers
+        // SBB immediate handlers for 8-bit operands
+        _handlers.Add(new SbbImmFromRm8Handler(_decoder));           // SBB r/m8, imm8 (opcode 80 /3)
+        _handlers.Add(new SbbAlImmHandler(_decoder));               // SBB AL, imm8 (opcode 1C)
+
+        // SBB immediate handlers for 16-bit operands (with 0x66 prefix)
+        _handlers.Add(new SbbImmFromRm16Handler(_decoder));          // SBB r/m16, imm16 (opcode 81 /3 with 0x66 prefix)
+        _handlers.Add(new SbbImmFromRm16SignExtendedHandler(_decoder)); // SBB r/m16, imm8 (opcode 83 /3 with 0x66 prefix)
+
+        // SBB immediate handlers for 32-bit operands
         _handlers.Add(new SbbImmFromRm32Handler(_decoder));         // SBB r/m32, imm32 (opcode 81 /3)
         _handlers.Add(new SbbImmFromRm32SignExtendedHandler(_decoder)); // SBB r/m32, imm8 (opcode 83 /3)
+
+        // SBB accumulator handlers
+        _handlers.Add(new SbbAccumulatorImmHandler(_decoder));     // SBB AX/EAX, imm16/32 (opcode 1D)
     }
     
     /// <summary>
@@ -140,6 +151,15 @@ public class InstructionHandlerFactory
         // Add Return handlers
         _handlers.Add(new RetHandler(_decoder));
         _handlers.Add(new RetImmHandler(_decoder));
+
+        // Add Far Return handlers
+        // 16-bit handlers with operand size prefix (must come first)
+        _handlers.Add(new Retf16Handler(_decoder));       // RETF (16-bit) (opcode 0xCB with 0x66 prefix)
+        _handlers.Add(new RetfImm16Handler(_decoder));    // RETF imm16 (16-bit) (opcode 0xCA with 0x66 prefix)
+
+        // 32-bit handlers (default)
+        _handlers.Add(new RetfHandler(_decoder));         // RETF (32-bit) (opcode 0xCB)
+        _handlers.Add(new RetfImmHandler(_decoder));      // RETF imm16 (32-bit) (opcode 0xCA)
     }
 
     /// <summary>

X86Disassembler/X86/Handlers/Sbb/SbbAccumulatorImmHandler.cs

@@ -0,0 +1,70 @@
+namespace X86Disassembler.X86.Handlers.Sbb;
+
+using Operands;
+
+/// <summary>
+/// Handler for SBB AX/EAX, imm16/32 instruction (0x1D)
+/// </summary>
+public class SbbAccumulatorImmHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the SbbAccumulatorImmHandler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public SbbAccumulatorImmHandler(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)
+    {
+        return opcode == 0x1D;
+    }
+
+    /// <summary>
+    /// Decodes a SBB AX/EAX, imm16/32 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;
+
+        // Determine operand size based on prefix
+        int operandSize = Decoder.HasOperandSizePrefix() ? 16 : 32;
+        
+        // Check if we have enough bytes for the immediate value
+        if (operandSize == 16 && !Decoder.CanReadUShort())
+        {
+            return false;
+        }
+        else if (operandSize == 32 && !Decoder.CanReadUInt())
+        {
+            return false;
+        }
+
+        // Create the accumulator register operand (AX or EAX)
+        var accumulatorOperand = OperandFactory.CreateRegisterOperand(RegisterIndex.A, operandSize);
+
+        // Read and create the immediate operand based on operand size
+        var immOperand = operandSize == 16 
+            ? OperandFactory.CreateImmediateOperand(Decoder.ReadUInt16(), operandSize)
+            : OperandFactory.CreateImmediateOperand(Decoder.ReadUInt32(), operandSize);
+
+        // Set the structured operands
+        instruction.StructuredOperands = 
+        [
+            accumulatorOperand,
+            immOperand
+        ];
+
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Sbb/SbbAlImmHandler.cs

@@ -0,0 +1,64 @@
+namespace X86Disassembler.X86.Handlers.Sbb;
+
+using Operands;
+
+/// <summary>
+/// Handler for SBB AL, imm8 instruction (0x1C)
+/// </summary>
+public class SbbAlImmHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the SbbAlImmHandler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public SbbAlImmHandler(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)
+    {
+        return opcode == 0x1C;
+    }
+
+    /// <summary>
+    /// Decodes a SBB AL, imm8 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;
+
+        // Create the AL register operand
+        var alOperand = OperandFactory.CreateRegisterOperand(RegisterIndex.A, 8);
+
+        // Check if we have enough bytes for the immediate value
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Read the immediate value
+        byte imm8 = Decoder.ReadByte();
+
+        // Create the immediate operand
+        var immOperand = OperandFactory.CreateImmediateOperand(imm8, 8);
+
+        // Set the structured operands
+        instruction.StructuredOperands = 
+        [
+            alOperand,
+            immOperand
+        ];
+
+        return true;
+    }
+}

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;
+    }
+}

X86Disassembler/X86/Handlers/Sbb/SbbImmFromRm16SignExtendedHandler.cs

@@ -0,0 +1,85 @@
+using X86Disassembler.X86.Operands;
+
+namespace X86Disassembler.X86.Handlers.Sbb;
+
+/// <summary>
+/// Handler for SBB r/m16, imm8 (sign-extended) instruction (0x83 /3 with 0x66 prefix)
+/// </summary>
+public class SbbImmFromRm16SignExtendedHandler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the SbbImmFromRm16SignExtendedHandler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public SbbImmFromRm16SignExtendedHandler(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 != 0x83)
+            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, imm8 (sign-extended) 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, imm8 (sign-extended) (0x83 /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.CanReadByte())
+        {
+            return false;
+        }
+
+        // Sign-extend to 16 bits
+        sbyte imm8 = (sbyte)Decoder.ReadByte();
+        
+        // Create the immediate operand with sign extension
+        var sourceOperand = OperandFactory.CreateImmediateOperand((ushort)imm8, 16);
+
+        // Set the structured operands
+        instruction.StructuredOperands = 
+        [
+            destinationOperand,
+            sourceOperand
+        ];
+
+        return true;
+    }
+}

X86Disassembler/X86/Handlers/Sbb/SbbImmFromRm8Handler.cs

@@ -0,0 +1,81 @@
+using X86Disassembler.X86.Operands;
+
+namespace X86Disassembler.X86.Handlers.Sbb;
+
+/// <summary>
+/// Handler for SBB r/m8, imm8 instruction (0x80 /3)
+/// </summary>
+public class SbbImmFromRm8Handler : InstructionHandler
+{
+    /// <summary>
+    /// Initializes a new instance of the SbbImmFromRm8Handler class
+    /// </summary>
+    /// <param name="decoder">The instruction decoder that owns this handler</param>
+    public SbbImmFromRm8Handler(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 != 0x80)
+            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/m8, imm8 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/m8, imm8 (0x80 /3):
+        // - The r/m field with mod specifies the destination operand (register or memory)
+        // - The immediate value is the source operand
+        var (_, _, _, destinationOperand) = ModRMDecoder.ReadModRM8();
+
+        // Check if we have enough bytes for the immediate value
+        if (!Decoder.CanReadByte())
+        {
+            return false;
+        }
+
+        // Read the immediate value
+        byte imm8 = Decoder.ReadByte();
+
+        // Create the immediate operand
+        var sourceOperand = OperandFactory.CreateImmediateOperand(imm8, 8);
+
+        // Set the structured operands
+        instruction.StructuredOperands = 
+        [
+            destinationOperand,
+            sourceOperand
+        ];
+
+        return true;
+    }
+}