sub encode_utf8 {
    my $e;
    for (map ord, split //, $_[0]) {
        if ($_ < 128) {
            $e .= chr($_);
        }
        elsif ($_ < 1024) {
            $e .= chr(0xC0 + ($_ >> 6)); 
            $e .= chr(0x80 + ($_ & 63)); 
        }
        elsif (...)
            ...
        }
    }
    return $e;
}