private static byte ComputeRegOrMemToken(X86Operand operand)
{
// Mechanism:
// http://ref.x86asm.net/coder32.html#modrm_byte_32
// ModR/M byte:
// mod | reg/mem | (reg2)
// -----+---------+-------
// 7 6 | 5 4 3 | (2 1 0)
var modifier = DetermineRegOrMemModifier(operand);
var token = (byte)((byte)modifier << 6);
if (operand.ScaledIndex != null)
{
token |= ComputeRegisterToken(X86Register.Esp);
}
else if (operand.Value is X86Register)
{
token |= ComputeRegisterToken((X86Register)operand.Value);
}
else
{
return(ComputeRegisterToken(X86Register.Ebp));
}
return(token);
}
private static X86RegOrMemModifier DetermineRegOrMemModifier(X86Operand operand)
{
if (operand.Value is X86Register)
{
switch (operand.OffsetType)
{
case X86OffsetType.None:
return(operand.OperandUsage == X86OperandUsage.Normal
? X86RegOrMemModifier.RegisterOnly
: X86RegOrMemModifier.RegisterPointer);
case X86OffsetType.Short:
return(X86RegOrMemModifier.RegisterDispShortPointer);
case X86OffsetType.Long:
return(X86RegOrMemModifier.RegisterDispLongPointer);
}
throw new NotSupportedException("Unsupported or unrecognized operand offset type.");
}
if (operand.Value is uint)
{
return(X86RegOrMemModifier.RegisterPointer);
}
throw new ArgumentException("Operand is not a valid RegOrMem operand.", "operand");
}
private void WriteOperandValue(X86OperandType method, X86OperandSize size, X86Operand operand)
{
switch (method)
{
case X86OperandType.MemoryAddress:
case X86OperandType.DirectAddress:
case X86OperandType.ImmediateData:
{
WriteNumber(operand.Value, size);
break;
}
case X86OperandType.RegisterOrMemoryAddress:
{
if ((operand.ScaledIndex != null) ||
(operand.OperandUsage != X86OperandUsage.Normal && operand.Value is X86Register &&
(X86Register)operand.Value == X86Register.Esp))
{
_writer.WriteByte(ComputeRegOrMemSibToken(operand));
}
else if (!(operand.Value is X86Register))
{
WriteNumber(operand.Value, X86OperandSize.Dword);
}
break;
}
case X86OperandType.RelativeOffset:
{
WriteNumber(Convert.ToUInt32(operand.Value) - (_writer.Position + sizeof(sbyte)), size);
break;
}
}
}
private X86Operand GetRegOrMemOperand32(byte registerToken, X86OperandSize size)
{
// Mechanism:
// http://ref.x86asm.net/coder32.html#modrm_byte_32
// ModR/M byte:
// mod | reg/mem | (reg2)
// -----+---------+-------
// 7 6 | 5 4 3 | (2 1 0)
var modifier = (X86RegOrMemModifier)(registerToken >> 6);
var operand = new X86Operand();
// Register-only operands:
if (modifier == X86RegOrMemModifier.RegisterOnly)
{
operand.Value = GetRegisterFromToken((byte)(registerToken & 0x7), GetRegisterSize(size));
operand.OperandUsage = X86OperandUsage.Normal;
return(operand);
}
// Register-pointer operands are always 32-bit registers.
var register = GetRegisterFromToken((byte)(registerToken & 0x7), X86RegisterSize.Dword);
operand.OperandUsage = GetOperandType(size);
operand.Value = register;
// EBP register is replaced by a direct address.
if (modifier == X86RegOrMemModifier.RegisterPointer && register == X86Register.Ebp)
{
operand.Value = _reader.ReadUInt32();
return(operand);
}
// ESP register are replaced by a scaled index operand.
if (register == X86Register.Esp)
{
MakeScaledIndexOperandFromToken(operand, _reader.ReadByte());
}
// Read correction based on modifier.
switch (modifier)
{
case X86RegOrMemModifier.RegisterDispShortPointer:
operand.Offset = _reader.ReadSByte();
operand.OffsetType = X86OffsetType.Short;
break;
case X86RegOrMemModifier.RegisterDispLongPointer:
operand.Offset = _reader.ReadInt32();
operand.OffsetType = X86OffsetType.Long;
break;
}
return(operand);
}
private static byte ComputeRegisterTokenPart(X86OperandType method, X86OperandSize size, X86Operand operand)
{
switch (method)
{
case X86OperandType.Register:
{
return (byte)(ComputeRegisterToken((X86Register)operand.Value) << 3);
}
case X86OperandType.RegisterOrMemoryAddress:
{
return ComputeRegOrMemToken(operand);
}
}
return 0;
}
public virtual string FormatOperand(X86Operand operand)
{
if (operand == null)
{
return(string.Empty);
}
string prefix = FormatOperandUsagePrefix(operand.OperandUsage);
var formattedValue = FormatValue(operand.Value);
var formattedOffset = FormatOffset(operand.Offset);
var formattedScaledIndex = operand.ScaledIndex != null ? '+' + operand.ScaledIndex.ToString() : string.Empty;
return(prefix == null
? formattedValue
: string.Format("{0} [{1}{2}{3}]", prefix, formattedValue, formattedScaledIndex, formattedOffset));
}
private static byte ComputeRegOrMemSibToken(X86Operand operand)
{
// Mechanism:
// http://ref.x86asm.net/coder32.html#sib_byte_32
// SIB-byte:
// mul | scaled_reg | reg
// -----+------------+-------
// 7 6 | 5 4 3 | 2 1 0
var token = ComputeRegisterToken((X86Register)operand.Value);
if (operand.ScaledIndex == null)
{
token |= 0x20;
}
else
{
token |= (byte)(ComputeRegisterToken(operand.ScaledIndex.Register) << 3);
switch (operand.ScaledIndex.Multiplier)
{
case 1:
break;
case 2:
token |= 0x40;
break;
case 4:
token |= 0x80;
break;
case 8:
token |= 0xC0;
break;
default:
throw new ArgumentException("Operand has an invalid scaled index multiplier.", "operand");
}
}
return(token);
}
private static IEnumerable<X86Instruction> CreateRegOrMemSibTestInstructions(X86OpCode opcode, X86Mnemonic mnemonic)
{
for (int operandType = 0; operandType < 3; operandType++)
{
for (int multiplier = 1; multiplier < 16; multiplier*=2)
{
for (int scaledRegIndex = 0; scaledRegIndex < 8; scaledRegIndex++)
{
if (scaledRegIndex == 4)
continue;
var operand1 = new X86Operand(X86OperandUsage.BytePointer, X86Register.Eax,
new X86ScaledIndex((X86Register)scaledRegIndex | X86Register.Eax, multiplier));
var operand2 = new X86Operand(X86OperandUsage.Normal, X86Register.Al);
var instruction = new X86Instruction()
{
OpCode = opcode,
Mnemonic = mnemonic,
Operand1 = operand1,
Operand2 = operand2,
};
switch (operandType)
{
case 1:
operand1.Offset = 1;
operand1.OffsetType = X86OffsetType.Short;
break;
case 2:
operand1.Offset = 0x1337;
operand1.OffsetType = X86OffsetType.Long;
break;
}
yield return instruction;
}
}
}
}
private static void MakeScaledIndexOperandFromToken(X86Operand operand, byte token)
{
// Mechanism:
// http://ref.x86asm.net/coder32.html#sib_byte_32
// SIB-byte:
// mul | scaled_reg | reg
// -----+------------+-------
// 7 6 | 5 4 3 | 2 1 0
var scaledIndex = new X86ScaledIndex
{
Register = GetRegisterFromToken((byte)((token >> 3) & 7), X86RegisterSize.Dword),
Multiplier = 1 << ((token >> 6) & 3),
};
// ESP scales are ignored.
if (scaledIndex.Register != X86Register.Esp)
{
operand.ScaledIndex = scaledIndex;
}
operand.Value = GetRegisterFromToken((byte)(token & 0x7), X86RegisterSize.Dword);
}
private void WriteOperand(X86OperandType method, X86OperandSize size, X86Operand operand)
{
WriteOperandValue(method, size, operand);
WriteOperandOffset(operand.OffsetType, operand.Offset);
}
private static byte ComputeRegOrMemSibToken(X86Operand operand)
{
// Mechanism:
// http://ref.x86asm.net/coder32.html#sib_byte_32
// SIB-byte:
// mul | scaled_reg | reg
// -----+------------+-------
// 7 6 | 5 4 3 | 2 1 0
var token = ComputeRegisterToken((X86Register)operand.Value);
if (operand.ScaledIndex == null)
token |= 0x20;
else
{
token |= (byte)(ComputeRegisterToken(operand.ScaledIndex.Register) << 3);
switch (operand.ScaledIndex.Multiplier)
{
case 1:
break;
case 2:
token |= 0x40;
break;
case 4:
token |= 0x80;
break;
case 8:
token |= 0xC0;
break;
default:
throw new ArgumentException("Operand has an invalid scaled index multiplier.", "operand");
}
}
return token;
}
private static int GetTotalOperandSize(X86OperandType operandType, X86OperandSize operandSize, X86Operand operand)
{
int size = (int)operand.OffsetType;
switch (operandType)
{
case X86OperandType.None:
case X86OperandType.ControlRegister:
case X86OperandType.DebugRegister:
case X86OperandType.StackRegister:
case X86OperandType.Register:
case X86OperandType.RegisterCl:
case X86OperandType.RegisterDx:
case X86OperandType.RegisterEax:
case X86OperandType.RegisterAl:
case X86OperandType.ImmediateOne:
case X86OperandType.SegmentRegister:
case X86OperandType.OpCodeRegister:
break;
case X86OperandType.DirectAddress:
case X86OperandType.MemoryAddress:
size += 4;
break;
case X86OperandType.RelativeOffset:
case X86OperandType.ImmediateData:
size += GetSize(operandSize);
break;
case X86OperandType.RegisterOrMemoryAddress:
case X86OperandType.StackRegisterOrMemoryAddress:
if ((operand.ScaledIndex != null) ||
(operand.OperandUsage != X86OperandUsage.Normal && operand.Value is X86Register &&
(X86Register)operand.Value == X86Register.Esp))
size += 1;
if (!(operand.Value is X86Register))
size += 4;
break;
}
return size;
}
private static int GetTotalOperandSize(X86OperandType operandType, X86OperandSize operandSize, X86Operand operand)
{
int size = (int)operand.OffsetType;
switch (operandType)
{
case X86OperandType.None:
case X86OperandType.ControlRegister:
case X86OperandType.DebugRegister:
case X86OperandType.StackRegister:
case X86OperandType.Register:
case X86OperandType.RegisterCl:
case X86OperandType.RegisterDx:
case X86OperandType.RegisterEax:
case X86OperandType.RegisterAl:
case X86OperandType.ImmediateOne:
case X86OperandType.SegmentRegister:
case X86OperandType.OpCodeRegister:
break;
case X86OperandType.DirectAddress:
case X86OperandType.MemoryAddress:
size += 4;
break;
case X86OperandType.RelativeOffset:
case X86OperandType.ImmediateData:
size += GetSize(operandSize);
break;
case X86OperandType.RegisterOrMemoryAddress:
case X86OperandType.StackRegisterOrMemoryAddress:
if ((operand.ScaledIndex != null) ||
(operand.OperandUsage != X86OperandUsage.Normal && operand.Value is X86Register &&
(X86Register)operand.Value == X86Register.Esp))
{
size += 1;
}
if (!(operand.Value is X86Register))
{
size += 4;
}
break;
}
return(size);
}
private static byte ComputeRegisterTokenPart(X86OperandType method, X86OperandSize size, X86Operand operand)
{
switch (method)
{
case X86OperandType.Register:
{
return((byte)(ComputeRegisterToken((X86Register)operand.Value) << 3));
}
case X86OperandType.RegisterOrMemoryAddress:
{
return(ComputeRegOrMemToken(operand));
}
}
return(0);
}
private static byte ComputeRegOrMemToken(X86Operand operand)
{
// Mechanism:
// http://ref.x86asm.net/coder32.html#modrm_byte_32
// ModR/M byte:
// mod | reg/mem | (reg2)
// -----+---------+-------
// 7 6 | 5 4 3 | (2 1 0)
var modifier = DetermineRegOrMemModifier(operand);
var token = (byte)((byte)modifier << 6);
if (operand.ScaledIndex != null)
token |= ComputeRegisterToken(X86Register.Esp);
else if (operand.Value is X86Register)
token |= ComputeRegisterToken((X86Register)operand.Value);
else
return ComputeRegisterToken(X86Register.Ebp);
return token;
}
private static X86RegOrMemModifier DetermineRegOrMemModifier(X86Operand operand)
{
if (operand.Value is X86Register)
{
switch (operand.OffsetType)
{
case X86OffsetType.None:
return operand.OperandUsage == X86OperandUsage.Normal
? X86RegOrMemModifier.RegisterOnly
: X86RegOrMemModifier.RegisterPointer;
case X86OffsetType.Short:
return X86RegOrMemModifier.RegisterDispShortPointer;
case X86OffsetType.Long:
return X86RegOrMemModifier.RegisterDispLongPointer;
}
throw new NotSupportedException("Unsupported or unrecognized operand offset type.");
}
if (operand.Value is uint)
return X86RegOrMemModifier.RegisterPointer;
throw new ArgumentException("Operand is not a valid RegOrMem operand.", "operand");
}
private X86Operand GetRegOrMemOperand32(byte registerToken, X86OperandSize size)
{
// Mechanism:
// http://ref.x86asm.net/coder32.html#modrm_byte_32
// ModR/M byte:
// mod | reg/mem | (reg2)
// -----+---------+-------
// 7 6 | 5 4 3 | (2 1 0)
var modifier = (X86RegOrMemModifier)(registerToken >> 6);
var operand = new X86Operand();
// Register-only operands:
if (modifier == X86RegOrMemModifier.RegisterOnly)
{
operand.Value = GetRegisterFromToken((byte)(registerToken & 0x7), GetRegisterSize(size));
operand.OperandUsage = X86OperandUsage.Normal;
return operand;
}
// Register-pointer operands are always 32-bit registers.
var register = GetRegisterFromToken((byte)(registerToken & 0x7), X86RegisterSize.Dword);
operand.OperandUsage = GetOperandType(size);
operand.Value = register;
// EBP register is replaced by a direct address.
if (modifier == X86RegOrMemModifier.RegisterPointer && register == X86Register.Ebp)
{
operand.Value = _reader.ReadUInt32();
return operand;
}
// ESP register are replaced by a scaled index operand.
if (register == X86Register.Esp)
MakeScaledIndexOperandFromToken(operand, _reader.ReadByte());
// Read correction based on modifier.
switch (modifier)
{
case X86RegOrMemModifier.RegisterDispShortPointer:
operand.Offset = _reader.ReadSByte();
operand.OffsetType = X86OffsetType.Short;
break;
case X86RegOrMemModifier.RegisterDispLongPointer:
operand.Offset = _reader.ReadInt32();
operand.OffsetType = X86OffsetType.Long;
break;
}
return operand;
}
private static IEnumerable<X86Instruction> CreateRegOrMemTestInstructions(X86OpCode opcode, X86Mnemonic mnemonic, bool flippedOperands)
{
for (int operandType = 0; operandType < 3; operandType++)
{
for (int register2Index = 0; register2Index < 8; register2Index++)
{
for (int register1Index = 0; register1Index < 8; register1Index++)
{
var operand1 = new X86Operand(X86OperandUsage.BytePointer,
(X86Register)register1Index | X86Register.Eax);
var operand2 = new X86Operand(X86OperandUsage.Normal, (X86Register)register2Index);
var instruction = new X86Instruction()
{
OpCode = opcode,
Mnemonic = mnemonic,
};
if (flippedOperands)
{
instruction.Operand2 = operand1;
instruction.Operand1 = operand2;
}
else
{
instruction.Operand1 = operand1;
instruction.Operand2 = operand2;
}
switch (register1Index)
{
case 4: // esp
continue;
case 5: // ebp
if (operandType != 0)
continue;
operand1.Value = 0x1337u;
break;
}
switch (operandType)
{
case 1:
operand1.Offset = 1;
operand1.OffsetType = X86OffsetType.Short;
break;
case 2:
operand1.Offset = 0x1337;
operand1.OffsetType = X86OffsetType.Long;
break;
}
yield return instruction;
}
}
}
}
private void WriteOperand(X86OperandType method, X86OperandSize size, X86Operand operand)
{
WriteOperandValue(method, size, operand);
WriteOperandOffset(operand.OffsetType, operand.Offset);
}
private void WriteOperandValue(X86OperandType method, X86OperandSize size, X86Operand operand)
{
switch (method)
{
case X86OperandType.MemoryAddress:
case X86OperandType.DirectAddress:
case X86OperandType.ImmediateData:
{
WriteNumber(operand.Value, size);
break;
}
case X86OperandType.RegisterOrMemoryAddress:
{
if ((operand.ScaledIndex != null) ||
(operand.OperandUsage != X86OperandUsage.Normal && operand.Value is X86Register &&
(X86Register)operand.Value == X86Register.Esp))
_writer.WriteByte(ComputeRegOrMemSibToken(operand));
else if (!(operand.Value is X86Register))
WriteNumber(operand.Value, X86OperandSize.Dword);
break;
}
case X86OperandType.RelativeOffset:
{
WriteNumber(Convert.ToUInt32(operand.Value) - (_writer.Position + sizeof (sbyte)), size);
break;
}
}
}
private static void MakeScaledIndexOperandFromToken(X86Operand operand, byte token)
{
// Mechanism:
// http://ref.x86asm.net/coder32.html#sib_byte_32
// SIB-byte:
// mul | scaled_reg | reg
// -----+------------+-------
// 7 6 | 5 4 3 | 2 1 0
var scaledIndex = new X86ScaledIndex
{
Register = GetRegisterFromToken((byte)((token >> 3) & 7), X86RegisterSize.Dword),
Multiplier = 1 << ((token >> 6) & 3),
};
// ESP scales are ignored.
if (scaledIndex.Register != X86Register.Esp)
operand.ScaledIndex = scaledIndex;
operand.Value = GetRegisterFromToken((byte)(token & 0x7), X86RegisterSize.Dword);
}
public virtual string FormatOperand(X86Operand operand)
{
if (operand == null)
return string.Empty;
string prefix = FormatOperandUsagePrefix(operand.OperandUsage);
var formattedValue = FormatValue(operand.Value);
var formattedOffset = FormatOffset(operand.Offset);
var formattedScaledIndex = operand.ScaledIndex != null ? '+' + operand.ScaledIndex.ToString() : string.Empty;
return prefix == null
? formattedValue
: string.Format("{0} [{1}{2}{3}]", prefix, formattedValue, formattedScaledIndex, formattedOffset);
}
