always @(intreg or selector)
  begin
    if (selector == 2’b00)
      result_int = intreg[0];
    else if (selector == 2’b01)
      result_int = intreg[1];
    else if (selector == 2’b10)
      result_int = intreg[2];
    else if (selector == 2’b11)
      result_int = intreg[3];
  end