Swift_Encoder_QpEncoder::_standardize PHP Method

    protected function _standardize($string)
    {
        $string = str_replace(array("\t=0D=0A", ' =0D=0A', '=0D=0A'), array("=09\r\n", "=20\r\n", "\r\n"), $string);
        switch ($end = ord(substr($string, -1))) {
            case 0x9:
            case 0x20:
                $string = substr_replace($string, self::$_qpMap[$end], -1);
        }
        return $string;
    }