steamid converter

    public function Steam64ToID($Steam64, $NewID = false) {
        if(!$NewID) {
            $Server = bcsub($Steam64, '76561197960265728') & 1;
            $Auth = (string)bcdiv(bcsub(bcsub($Steam64, '76561197960265728'), $Server), '2');
            if(strpos($Auth, '.') !== false)
                $Auth = substr($Auth, 0, strpos($Auth, '.'));
            $SteamID = 'STEAM_0:'.$Server.':'.$Auth;
            if($this->ValidID($SteamID, 1))
                return $SteamID;
        } else {
            $Server = bcsub($Steam64, '76561197960265728') & 1;
            $Auth = bcsub(bcsub($Steam64, '76561197960265728'), $Server);
            $ID = (int)bcadd($Auth, $Server);
            $SteamID = '[U:1:'.$ID.']';
            if($this->ValidID($SteamID, 2))
                return $SteamID;
        }
    }