# This function returns the 32-bit value
# of the IP address for numeric comparisons.
sub addr_value { return unpack("N", $_[0]); }

foreach my $name (sort keys %data)
{
     my $carry;

     foreach my $start (sort keys %{$data{$name}})
     {
           # Skip keys deleted after keys was calculated
           next unless defined $data{$name}{$start};

           # Add one to the end to determine the next start
           my $next_start = inet_aton(addr_value($end)+1);

           # If this block is adjacent to the next one...
           if (defined $data{$name}{$next_start})
           {
                 $carry ||= $start;

                 # ...end this block where that block ended...
                 $data{$name}{$carry} = $data{$name}{$next_start};
                 # ...and delete that block.
                 delete $data{$name}{$next_start};
           }
           else
           {
                 # No match, so reset the $carry
                 undef $carry;
           }
     }
}