use constant MAX => 50;

sub process_up_to_MAX_at_a_time {
    
    my ($port,       # comment
        @addresses,  # ...
        ) = @_;
        
    while (@addresses > MAX) {
    	my @sub_group = splice @addresses, 0, MAX;
        process_0_to_MAX($port, @sub_group);
        }
    
    process_0_to_MAX($port, @addresses);

    }

sub process_0_to_MAX { ... }