sub comb_sort (&\@) {
    my $code_ref = shift;
    my $v_ref = shift;
    my $max = scalar (@$v_ref);
    my $gap = $max;
    while (1) {
        my $swapped = 0;
        $gap = int ($gap / 1.3);
        $gap = 1 if $gap < 1;
        my $lmax = $max - $gap - 1;
        foreach my $i (0..$lmax) {
            local ($a, $b) = ($$v_ref[$i], $$v_ref[$i+$gap]);
            ($$v_ref[$i], $$v_ref[$i+$gap], $swapped) = ($$v_ref[$i+$gap], $$v_ref[$i], 1)
                if $code_ref->($a, $b) > 0;
        }
        last if $gap == 1 and $swapped == 0;
    }
}