Dica Delphi - Convertendo valor Hexadecimal para Inteiro

function HexToInt(const HexStr: string): longint;
var
x: integer;
cTmp: Char;
begin
Result := 0;
for x := 1 to Length(HexStr) do
begin
cTmp := HexStr[x];
case cTmp of
'0'..'9': Result := 16 * Result + (Ord(cTmp) - $30);
'A'..'F': Result := 16 * Result + (Ord(cTmp) - $37);
'a'..'f': Result := 16 * Result + (Ord(cTmp) - $57);
else
raise EConvertError.Create('Illegal character in hex string');
end;
end;
end;