sub naechstes_paket {
    my $handle = shift;
    my @lines = ();
    while (@lines < 10) {
        my $line = <$handle>;
        last unless $line;
        push @lines, $line
    }
    return @lines;
}

while (my @next_lines = naechstes_paket($fil) {
 ... mach was
}