Playing poohsticks in the Styx

#!/usr/bin/env perl
@mask = (0,192,224,240);
@limit = (1<<7,1<<5,1<<4,1<<3);
while (@ARGV) {
$c = hex shift;
die if $c > 1114111;
$str = '';
while (1) {
        if ($c < $limit[length($str)]) {
                $cur = $c | $mask[length($str)];
                $str = chr($cur) . $str;
                last;
        } else {
                $cur = $c&63|128;
                $str = chr($cur) .$str;
                $c >>= 6;
        }
}
print $str;
}
print "\n";