voku / portable-utf8

            $buf .= $cc1 . $cc2;

          }

        } elseif ($c1 >= "\xe0" & $c1 <= "\xef") { // looks like 3 bytes UTF8

          if ($c2 >= "\x80" && $c2 <= "\xbf" && $c3 >= "\x80" && $c3 <= "\xbf") { // yeah, almost sure it's UTF8 already

            $buf .= $c1 . $c2 . $c3;

            $i += 2;

          } else { // not valid UTF8 - convert it

            $cc1 = (chr(ord($c1) / 64) | "\xc0");

            $cc2 = ($c1 & "\x3f") | "\x80";

            $buf .= $cc1 . $cc2;

          }

        } elseif ($c1 >= "\xf0" & $c1 <= "\xf7") { // looks like 4 bytes UTF8

          if ($c2 >= "\x80" && $c2 <= "\xbf" && $c3 >= "\x80" && $c3 <= "\xbf" && $c4 >= "\x80" && $c4 <= "\xbf") { // yeah, almost sure it's UTF8 already

            $buf .= $c1 . $c2 . $c3 . $c4;

        } elseif ($c1 >= "\xf0" & $c1 <= "\xf7") { // looks like 4 bytes UTF8

          if ($c2 >= "\x80" && $c2 <= "\xbf" && $c3 >= "\x80" && $c3 <= "\xbf" && $c4 >= "\x80" && $c4 <= "\xbf") { // yeah, almost sure it's UTF8 already

            $buf .= $c1 . $c2 . $c3 . $c4;

            $i += 3;

          } else { // not valid UTF8 - convert it

            $cc1 = (chr(ord($c1) / 64) | "\xc0");

            $cc2 = ($c1 & "\x3f") | "\x80";

            $buf .= $cc1 . $cc2;

          }

        } else { // doesn't look like UTF8, but should be converted

          $cc1 = (chr(ord($c1) / 64) | "\xc0");