manchester

#!/usr/bin/perl
#
# add/remove manchester encoding
# -samy kamkar
# https://samy.pl

#$_=pop;while(length($_)>2){s/^(..?.?)//;$x=$1;if($x eq"110"){print"0"}elsif($x eq"100"){print"1"}else{print"_"}}print$/.$_.$/

use strict;
die "usage: $0 <data>\n" unless @ARGV;

foreach my $in (@ARGV)
{
	my $bin;
	my $man;
	if ($in =~ /^[01]+$/)
	{
		$bin = $in;
	}
	elsif ($in =~ /^[a-f\d]+$/i)
	{
		$bin = unpack("B*", pack("H*", $in));
	}
	else
	{
		die "unknown format: $in\n";
	}
	my $orig = $bin;
	$orig =~ s/(.)/$1 ? "01" : "10"/eg;
	$orig =~ s/(.{8}+)(.*)/"$1$2" . ("0" x 8 - length($2))/eg;

	# check if we're off a bit in manchester
	if ($bin =~ /^(..){0,}(11|00)/)
	{
		$bin =~ s/^(.)//;
		print STDERR "Removing first bit: $1\n\n";
	}

	while (my $two = substr($bin, 0, 2, ""))
	{
		if ($two !~ /^01$|^10$/)
		{
			print STDERR "error: $two\n";
		}
		else
		{
			$man .= substr($two, 0, 1);
		}
	}

	print STDERR "$man\n";
	my $hex = unpack("H*", pack("B*", $man));
	$man =~ s/(.)/$1 ? 0 : 1/eg;
	print STDERR "$man\n\n";
	print "$hex\n";
	print unpack("H*", pack("B*", $man)) . "\n";
#	print unpack("H*", pack("B*", $man . ("0" x (8 - length($man)) ) )) . "\n";

	print "TO manchester: ";
	print unpack("H*", pack("B*", $orig)) . "\n";
}