Checksum BIOS

function GetBiosCheckSum: string;
var
s: int64;
i: longword;
p: PChar;
begin
i := 0;
s := 0;
p := PChar($F0000);
repeat
inc(s, Int64(Ord(p^)) shl i);
if i < 64 then inc(i) else i := 0;
inc(p);
until p > PChar($FFFFF);
Result := IntToHex(s,16);
end;