public Instruction(IWordStream stream, ulong address)
{
var bits = new BitStream(stream.ReadWord(address++));
this.Length = 1;
this.Code = bits.ReadU8(8);
this.Definition = InstructionDefinition.Find(this.Code);
if (this.Definition.ParameterCount > 0)
{
this.Parameter1 = this.DecodeParameter(stream, ref address, bits);
}
if (this.Definition.ParameterCount > 1)
{
this.Parameter2 = this.DecodeParameter(stream, ref address, bits);
}
if (this.Definition.ParameterCount > 2)
{
this.Parameter3 = this.DecodeParameter(stream, ref address, bits);
}
bits.Advance((3 - this.Definition.ParameterCount) * 8);
if (bits.ReadU1())
{
this.ConditionalZero = bits.ReadU1();
this.ConditionalParameter = this.DecodeParameter(stream, ref address, bits);
}
}
private Parameter DecodeParameter(IWordStream stream, ref ulong address, BitStream bits)
{
var para = new Parameter()
{
IsRIPRelative = bits.ReadU1(),
IsIndirect = bits.ReadU1(),
Type = (ParameterType)bits.ReadU8(2),
Register = (Register)bits.ReadU8(5)
};
if (para.Type == ParameterType.Calculated)
{
this.DecodeCalculatedParameter(stream, ref address, para);
this.Length++;
}
else if (para.Type == ParameterType.Literal)
{
para.Literal = stream.ReadWord(address++);
this.Length++;
}
return(para);
}
private void DecodeCalculatedParameter(IWordStream stream, ref ulong address, Parameter parameter)
{
var bits = new BitStream(stream.ReadWord(address++));
parameter.Base = this.DecodeCalculatedOperand(stream, ref address, bits);
parameter.Index = this.DecodeCalculatedOperand(stream, ref address, bits);
parameter.Scale = this.DecodeCalculatedOperand(stream, ref address, bits);
parameter.Offset = this.DecodeCalculatedOperand(stream, ref address, bits);
}
private Parameter.Calculated DecodeCalculatedOperand(IWordStream stream, ref ulong address, BitStream bits) => new Parameter.Calculated(bits.ReadU1(), this.DecodeParameter(stream, ref address, bits));
