#!/usr/bin/perl -w

######
# (In)valid UTF-8 GENerator :-)
# Generates multibyte sequences for 7-bit ASCII characters.
#
# source: http://www.devbox.be, http://pub.devbox.be
###
#
#	$DevBox: iutf8gen.pl,v 1.2 2005/11/30 15:47:21 jimmy Exp $
#
# Copyright (C) 2005 Jimmy Scott <jimmy@inet-solutions.be>. Belgium.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#   1. Redistributions of source code must retain the above copyright notice,
#      this list of conditions and the following disclaimer.
#
#   2. Redistributions in binary form must reproduce the above copyright
#      notice, this list of conditions and the following disclaimer in the
#      documentation and/or other materials provided with the distribution.
#
#   3. The names of the authors may not be used to endorse or promote products
#      derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS "AS IS" AND ANY
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
# THE POSSIBILITY OF SUCH DAMAGE.
#
######

package main;
use strict;

sub usage {
	print STDERR "usage: $0 <string> [num_bytes]\n";
	print STDERR "       num_bytes defaults to 2\n";
	exit 1;
}

sub iutf8 {
	my $num = shift;
	my $str = shift;
	my $res = "";
	my $byte;
	my $bseq;

	for ( my $i = 0; $i < length($str); ++$i ) {
		$byte = substr($str, $i, 1);
		if ( ord($byte) > 127 ) {
			print STDERR "$0: skipping byte in offset $i, " .
			             "character is not 7-bit ASCII\n";
			next;
		}
		# Split the bits according to this table:
		# 110xxxxx 10xxxxxx
		# 1110xxxx 10xxxxxx 10xxxxxx
		# 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
		# 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
		# 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
		my $bits = unpack "B*", $byte;
		my $f_bits = substr($bits, 0, 2);
		my $l_bits = substr($bits, 2, 6);
		# Concatenate the result
		if ( $num == 6 ) {
			$bseq = "11111100" . ( "10000000" x 3 );
		} elsif ( $num == 5 ) {
			$bseq = "11111000" . ( "10000000" x 2 );
		} elsif ( $num == 4 ) {
			$bseq = "11110000" . "10000000";
		} elsif ( $num == 3 ) {
			$bseq = "11100000";
		}
		if ( $num == 2 ) {
			$bseq = "110000" . $f_bits . "10" . $l_bits;
		} else {
			$bseq .= "100000" . $f_bits . "10" . $l_bits;
		}
		$res .= $bseq;
	}
	return pack "B*", $res;
}

sub main {
	# Parse arguments

	if ( scalar(@ARGV) != 1 && scalar(@ARGV) != 2 ) {
		&usage;
	}

	my $str = $ARGV[0];
	my $num = $ARGV[1] || 2;
	my $bseq;
	my $hseq;
	my $cseq = "";

	if ( ! ( $num =~ /^[2-6]$/ ) ) {
		print STDERR "$0: num_bytes must be 2 to 6\n";
		exit 1;
	}

	$bseq = &iutf8($num, $str);
	$hseq = uc(unpack("H*", $bseq));

	for ( my $i = 0; $i < length($hseq); $i += 2 ) {
		$cseq .= "\\x" . substr($hseq, $i, 2);
	}

	print "Result: " . $cseq . "\n";

	exit 0;
}

&main;