Core_Email::_prep_quoted_printable

protected function _prep_quoted_printable($str, $charlim = '')
{
    // Set the character limit
    // Don't allow over 76, as that will make servers and MUAs barf
    // all over quoted-printable data
    if ($charlim === '' || $charlim > 76)
    {
        $charlim = 76;
    }

    // Reduce multiple spaces & remove nulls
    $str = preg_replace(array('| +|', '/\x00+/'), array(' ', ''), $str);

    // Standardize newlines
    if (strpos($str, "\r") !== false)
    {
        $str = str_replace(array("\r\n", "\r"), "\n", $str);
    }

    // We are intentionally wrapping so mail servers will encode characters
    // properly and MUAs will behave, so {unwrap} must go!
    $str = str_replace(array('{unwrap}', '{/unwrap}'), '', $str);

    $escape = '=';
    $output = '';

    foreach (explode("\n", $str) as $line)
    {
        $length = strlen($line);
        $temp = '';

        // Loop through each character in the line to add soft-wrap
        // characters at the end of a line " =\r\n" and add the newly
        // processed line(s) to the output (see comment on $crlf class property)
        for ($i = 0; $i < $length; $i++)
        {
            // Grab the next character
            $char = $line[$i];
            $ascii = ord($char);

            // Convert spaces and tabs but only if it's the end of the line
            if ($i === ($length - 1) && ($ascii === 32 || $ascii === 9))
            {
                $char = $escape.sprintf('%02s', dechex($ascii));
            }
            elseif ($ascii === 61) // encode = signs
            {
                $char = $escape.strtoupper(sprintf('%02s', dechex($ascii)));  // =3D
            }

            // If we're at the character limit, add the line to the output,
            // reset our temp variable, and keep on chuggin'
            if ((strlen($temp) + strlen($char)) >= $charlim)
            {
                $output .= $temp.$escape.$this->crlf;
                $temp = '';
            }

            // Add the character to our temporary line
            $temp .= $char;
        }

        // Add our completed line to the output
        $output .= $temp.$this->crlf;
    }

    // get rid of extra CRLF tacked onto the end
    return substr($output, 0, strlen($this->crlf) * -1);
}