#  print character table; column & row headings are compsed of hex numbers
sub hex_table
{
  my @hex = (0..9 , 'a'..'f');

  #  number of characters each table cell takes
  my $cell_width = 4;

  #  create row  separator; adjust to your liking
  my $row_sep = "\n--";

  $row_sep .= ($_ % $cell_width != 0) ? "-" : "."
                for 0 .. ( $cell_width * scalar(@hex) );

  $row_sep .= "\n";

  #  space filler heading, common to column & row headings
  print '0x|';

  #  column heading
  printf ' %s |', $_ for @hex;

  foreach my $row (@hex)
  {
    print $row_sep;

    #  row heading
    printf '%s |', $row;

    foreach my $col (@hex)
    {
      printf ' %c |', hex( $row . $col );
    }
  }
}

#  list characters 8 on each line; each character is preceded by its hex
#  & decimal number representation
sub hex_dec_list
{
  foreach (0..255)
  {
    #  print hex, decimal numbers followed by character
    printf ' %1$2x %1$3u: %1$c |' , $_;

    #  allow 8 sets per line
    print "\n" if $_ && ($_ + 1 ) % 8 == 0;
  }
}