/// <summary>
/// Checks whether the specified object is valid to be assigned to
/// the <see cref="OperandType"/>.
/// </summary>
/// <param name="operandType">A bitwise combination of <see cref="OperandType"/> members
/// for which the operand must be valid.</param>
/// <param name="registerType">A bitwise combination of <see cref="RegisterType"/> members
/// for which the operand must be valid. The lower 8 bits are ignored.</param>
/// <param name="operand">The <see cref="Operand"/> to check.</param>
/// <returns><see langword="true"/> when an <paramref name="operand"/> may be assigned
/// to an operand with the specified operand type and register type; otherwise, <see langword="false"/>.</returns>
/// <remarks>
/// When <paramref name="operand"/> is <see langword="null"/>, this method always returns <see langword="true"/>
/// because there is no flag in <see cref="OperandType"/> to indicate that <see langword="null"/> operands are
/// (dis)allowed.
/// </remarks>
public static bool IsValidArgument(OperandType operandType, RegisterType registerType, Operand operand)
{
// Null operands are implicitly allowed.
if (operand == null)
{
return(true);
}
// Ignore the lower 8 bits.
registerType = (RegisterType)((int)registerType & ~0xFF);
// TODO: Implement.
if (operandType.HasFlag(OperandType.MemoryOffset))
{
throw new NotImplementedException();
}
// Check the type of operand.
if (operand is Immediate)
{
return(operandType.HasFlag(OperandType.Immediate));
}
if (operand is EffectiveAddress)
{
return(operandType.HasFlag(OperandType.MemoryOperand) ||
operandType.HasFlag(OperandType.RegisterOrMemoryOperand));
}
if (operand is RelativeOffset)
{
return(operandType.HasFlag(OperandType.RelativeOffset));
}
if (operand is FarPointer)
{
return(operandType.HasFlag(OperandType.FarPointer));
}
if (operand is RegisterOperand)
{
if (!operandType.HasFlag(OperandType.RegisterOperand) &&
!operandType.HasFlag(OperandType.FixedRegister) &&
!operandType.HasFlag(OperandType.RegisterOrMemoryOperand))
{
return(false);
}
if (operandType.HasFlag(OperandType.FixedRegister))
{
return(true);
}
// Check the type of register.
return(registerType.HasFlag((RegisterType)((int)(operand as RegisterOperand).Register.GetRegisterType() & ~0xFF)));
}
return(false);
}
