voku / portable-utf8

  public static function iconv_substr($s, $start, $length = 2147483647, $encoding = INF)

  {

    INF === $encoding && $encoding = self::$internal_encoding;

    if (0 === strncasecmp($encoding, 'utf-8', 5)) {

      $encoding = INF;

    } elseif (false === $s = self::iconv($encoding, 'utf-8', $s)) {

      return false;

    }

    $s .= '';

    $slen = self::iconv_strlen($s, 'utf-8');

  {

    INF === $encoding && $encoding = self::$internal_encoding;

    if (0 !== strncasecmp($encoding, 'utf-8', 5) && false === $s = self::iconv($encoding, 'utf-8', $s)) {

      return false;

    }

    return strlen(utf8_decode($s));

  }

  {

    INF === $encoding && $encoding = self::$internal_encoding;

    if (0 !== strncasecmp($encoding, 'utf-8', 5) && false === $s = self::iconv($encoding, 'utf-8', $s)) {

      return false;

    }

    $ulen_mask = self::$ulen_mask;