/// <summary>
/// Consumes the next byte, word, or dword.
/// </summary>
/// <returns>The next byte, word, or dword, sign-extended.</returns>
public Operand.LocationAware <int> ReadImmediate(CpuSize size)
{
int pos = this.Position;
int value;
if (size == CpuSize.Use8Bit)
{
value = (sbyte)ReadByte();
}
else if (size == CpuSize.Use16Bit)
{
value = ReadInt16();
}
else if (size == CpuSize.Use32Bit)
{
value = ReadInt32();
}
else
{
throw new ArgumentException("size must be 1, 2, or 4.");
}
return(new Operand.LocationAware <int>(
new Operand.Location((byte)pos, (byte)size),
value));
}
public virtual string FormatOperand(MemoryOperand operand)
{
CpuSize size = operand.Size;
string prefix =
(size == CpuSize.Use8Bit) ? "byte" :
(size == CpuSize.Use16Bit) ? "word" :
(size == CpuSize.Use32Bit) ? "dword" :
(size == CpuSize.Use64Bit) ? "qword" :
(size == CpuSize.Use128Bit) ? "dqword" : "";
StringBuilder sb = new StringBuilder();
if (prefix != "")
{
sb.Append(prefix);
sb.Append(" ptr ");
}
if (operand.Segment != Register.None)
{
FormatRegister(sb, operand.Segment);
sb.Append(':');
}
string strDisplacement = FormatFixableLocation(operand);
sb.Append('[');
if (operand.Base == Register.None) // only displacement
{
if (strDisplacement != null)
{
sb.Append(strDisplacement);
}
else
{
FormatNumber(sb, (UInt16)operand.Displacement.Value);
}
}
else // base+index*scale+displacement
{
FormatRegister(sb, operand.Base);
if (operand.Index != Register.None)
{
sb.Append('+');
FormatRegister(sb, operand.Index);
if (operand.Scaling != 1)
{
sb.Append('*');
sb.Append(operand.Scaling);
}
}
if (strDisplacement != null)
{
sb.Append('+');
sb.Append(strDisplacement);
}
else
{
int displacement = operand.Displacement.Value;
if (displacement > 0) // e.g. [BX+1]
{
sb.Append('+');
FormatNumber(sb, (uint)displacement);
}
else if (displacement < 0)
{
sb.Append('-');
FormatNumber(sb, (uint)-displacement);
}
}
}
sb.Append(']');
return(sb.ToString());
}
/// <summary>
/// Consumes the next byte, word, or dword.
/// </summary>
/// <returns>The next byte, word, or dword, sign-extended.</returns>
public Operand.LocationAware<int> ReadImmediate(CpuSize size)
{
int pos = this.Position;
int value;
if (size == CpuSize.Use8Bit)
value = (sbyte)ReadByte();
else if (size == CpuSize.Use16Bit)
value = ReadInt16();
else if (size == CpuSize.Use32Bit)
value = ReadInt32();
else
throw new ArgumentException("size must be 1, 2, or 4.");
return new Operand.LocationAware<int>(
new Operand.Location((byte)pos, (byte)size),
value);
}
public Register Resize(CpuSize newSize)
{
int newId = (int)id & 0xFF | ((int)newSize << 8);
return(new Register((RegisterId)newId));
}
public Register(RegisterType type, int number, CpuSize size)
{
id = (RegisterId)(number | ((int)type << 4) | ((int)size << 8));
}
public Register Resize(CpuSize newSize)
{
int newId = (int)id & 0xFF | ((int)newSize << 8);
return new Register((RegisterId)newId);
}
public Register(RegisterType type, int number, CpuSize size)
{
id = (RegisterId)(number | ((int)type << 4) | ((int)size << 8));
}
public ImmediateOperand(int value, CpuSize size)
{
this.immediate = new LocationAware <int>(value);
this.size = size;
}
public ImmediateOperand(LocationAware <int> immediate, CpuSize size)
{
this.immediate = immediate;
this.size = size;
}
static RegisterOperand CreateRegisterOperand(RegisterType type, int number, CpuSize size)
{
return new RegisterOperand(new Register(type, number, size));
}
static RelativeOperand DecodeRelativeOperand(InstructionReader reader, CpuSize size)
{
return new RelativeOperand(reader.ReadImmediate(size));
}
static ImmediateOperand DecodeImmediateOperand(InstructionReader reader, CpuSize size)
{
return new ImmediateOperand(reader.ReadImmediate(size), size);
}
// Note: we need to take into account OperandSizeOverride and
// AddressSizeOverride!!!!!!
/// <summary>
/// Decodes a memory operand encoded by the ModRM byte, SIB byte, and
/// Displacement, or a register operand if MOD=3 and registerType is
/// specified.
/// </summary>
/// <param name="reader">Instruction reader.</param>
/// <param name="registerType">Type of the register to return if the
/// Mod field of the ModR/M byte is 3. If this parameter is set to
/// RegisterType.None, an exception is thrown if Mod=3.</param>
/// <param name="operandSize">Size of the returned operand.</param>
/// <param name="context">Decoding context.</param>
/// <returns>The decoded memory or register operand.</returns>
/// <exception cref="InvalidInstructionException">If registerType is
/// set to None but the ModR/M byte encodes a register.</exception>
static Operand DecodeMemoryOperand(
InstructionReader reader,
RegisterType registerType,
CpuSize operandSize,
DecoderContext context)
{
if (context.CpuMode == CpuMode.X64Mode)
throw new NotSupportedException();
//if (operandSize == CpuSize.Default)
// throw new ArgumentException("operandSize is not specified.");
if (context.AddressSize != CpuSize.Use16Bit)
throw new NotSupportedException("32-bit addressing mode is not supported.");
ModRM modrm = reader.GetModRM();
int rm = modrm.RM;
int mod = modrm.MOD;
// Decode a register if MOD = (11).
if (mod == 3)
{
// If the instruction expects a memory operand, throw an exception.
if (registerType == RegisterType.None)
{
throw new InvalidInstructionException(
"The instruction expects a memory operand, but the ModR/M byte encodes a register.");
}
// Treat AH-DH specially.
if (registerType == RegisterType.General &&
operandSize == CpuSize.Use8Bit &&
rm >= 4)
{
return new RegisterOperand(new Register(
RegisterType.HighByte,
rm - 4,
CpuSize.Use8Bit));
}
else
{
return new RegisterOperand(new Register(registerType, rm, operandSize));
}
}
// Take into account segment override prefix if present.
Register segment = context.SegmentOverride;
// Special treatment for MOD = (00) and RM = (110).
// This encodes a 16-bit sign-extended displacement.
if (mod == 0 && rm == 6)
{
return new MemoryOperand
{
Size = operandSize,
Segment = segment,
Displacement = reader.ReadImmediate(CpuSize.Use16Bit)
};
}
/* Decode an indirect memory address XX[+YY][+disp]. */
MemoryOperand mem = new MemoryOperand();
mem.Size = operandSize;
mem.Segment = segment;
switch (rm)
{
case 0: /* [BX+SI] */
mem.Base = Register.BX;
mem.Index = Register.SI;
break;
case 1: /* [BX+DI] */
mem.Base = Register.BX;
mem.Index = Register.DI;
break;
case 2: /* [BP+SI] */
mem.Base = Register.BP;
mem.Index = Register.SI;
break;
case 3: /* [BP+DI] */
mem.Base = Register.BP;
mem.Index = Register.DI;
break;
case 4: /* [SI] */
mem.Base = Register.SI;
break;
case 5: /* [DI] */
mem.Base = Register.DI;
break;
case 6: /* [BP] */
mem.Base = Register.BP;
break;
case 7: /* [BX] */
mem.Base = Register.BX;
break;
}
if (mod == 1) /* disp8, sign-extended */
{
mem.Displacement = reader.ReadImmediate(CpuSize.Use8Bit);
}
else if (mod == 2) /* disp16, sign-extended */
{
mem.Displacement = reader.ReadImmediate(CpuSize.Use16Bit);
}
return mem;
}
/// <summary>
/// Decodes a register operand from the REG field of the ModR/M byte.
/// Since the REG field only contains the register number, additional
/// parameters are used to determine the register's type and size.
/// </summary>
/// <param name="reader">Instruction reader.</param>
/// <param name="registerType">Type of the register to return.</param>
/// <param name="operandSize">Size of the register to return.</param>
/// <param name="context">Decoding context.</param>
/// <returns>The decoded register operand.</returns>
private static RegisterOperand DecodeRegisterOperand(
InstructionReader reader,
RegisterType registerType,
CpuSize operandSize,
DecoderContext context)
{
if (context.CpuMode == CpuMode.X64Mode)
throw new NotSupportedException();
if (operandSize == CpuSize.Default)
throw new ArgumentException("operandSize is not specified.");
int reg = reader.GetModRM().REG;
if (registerType == RegisterType.General &&
operandSize == CpuSize.Use8Bit &&
reg >= 4)
{
return new RegisterOperand(new Register(
RegisterType.HighByte,
reg - 4,
CpuSize.Use8Bit));
}
return new RegisterOperand(new Register(registerType, reg, operandSize));
}