$lf += s/(?<!\x0d)\x0a(?!\x0d)/x/g;
$ctlf += s/\x0a\x0d/xx/g + s/\x0d\x0a/xx/g;

##</code><code>##

$lf += @match = /(?<!\x0d)\x0a(?!\x0d)/g;
$ctlf += @match = ( /\x0a\x0d/g, /\x0d\x0a/g ] );