#!/usr/bin/perl

# author: bliako
# date: 16/11/2018
# https://perlmonks.org/?node_id=1225889

# for given width, it counts from 0 to 2**W
# and prints the count in binary.
# It misses logic to discard some nibbles

use strict;
use warnings;

my $W = 4; # width in nibbles

my $count = 0;
my $stop = 2**$W;
# format an integer as binary
my $format = "%0.${W}b";
while( $count < $stop ){
        my $x = sprintf($format, $count);
        # x now contains a binary number of the count
        # between 0 and the stop 2^width_in_nibbles
        # now make each digit a nibble, e.g 0 -> 0000
        $x =~ s/0/a/g;
        $x =~ s/1/b/g;
        $x =~ s/a/0000 /g;
        $x =~ s/b/1111 /g;
        print "x=$x ($count)\n";
        $count++;
}