use strict;
use warnings;

my @labels = ({label=>'compressed',start=>3}, {label=>'deleted',start=>6},
              {label=>'this',start=>7}, {label=>'that',start=>12},
              {label=>'other',start=>18}, {label=>'something else',start=>20},
              {label=>'and another',start=>30}, {label=>'foo',start=>45},
              {label=>'bar',start=>47}, {label=>'up',start=>63},
              {label=>'down',start=>64}, {label=>'sideways',start=>65});
print "0b0x00xx0000x00000x0x000000000x00000000000000x0x000000000000000xxx\n";

my (@lines);
# for each label
LOOP: foreach my $lab (@labels) {
  # look thru the available lines
  foreach my $line (@lines) {
    my $delta = $lab->{start} - length($line);
    # for a line shorter than start
    if ($delta >= 0) {
      # and tack the label on there
      $line .= ' ' x $delta . '|' . $lab->{label};
      next LOOP;
    }
    # or fit into empty space on existing line
    my $len = length($lab->{label}) + 1;
    if (substr($line, $lab->{start}, $len) eq ' ' x $len) {
      substr($line, $lab->{start}, $len,'|' . $lab->{label});
      next LOOP;
    }
  }
  # or create a new line if needed
  push @lines, ' ' x $lab->{start} . '|' . $lab->{label};
}

print "$_\n" for @lines;