Is there a way to see if a character is using 1 or 2 bytes in Delphi 2009?

if ord(c) < 128 then
    // is an ascii character

function IsAnsi(const AString: string): Boolean;
var
  tempansi : AnsiString;
  temp : string;
begin
  tempansi := AnsiString(AString);
  temp := tempansi;
  Result := temp = AString;
end;