#!/usr/local/bin/perl -w
# 
# Copyright (c) 1998 Daniel J. Gregor, Jr., 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. All advertising materials mentioning features or use of this software
#    must display the following acknowledgement:
# 	This product includes software developed by Daniel J. Gregor, Jr.
# 4. The name of Daniel J. Gregor, Jr. may not be used to endorse or promote
#    products derived from this software without specific prior written
#    permission.
# 
# THIS SOFTWARE IS PROVIDED BY DANIEL J. GREGOR, JR. ``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 DANIEL J. GREGOR, JR. 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.
#


use Getopt::Std;

$usage = <<EOF;
$0 [-h] -m <max increase> [<input files> ...]
	-h			Print detailed help message
	-m <max increase>	Maximum increase between two time values.
EOF

$help = <<EOF;
Input lines must be formatted in the form of "<timeval> <data>" (extra
whitespace is allowed).  Blank lines will be inserted in the output if
two consecutive <timeval>s are more than <max increase> apart.

This is useful for creating breaks in graphs when you are missing input
data for a certain period of time.
EOF

getopts('m:h', \%opts) || die "$0: usage:\n$usage";

die "$0: usage:\n$usage\n$help" if (defined($opts{'h'}));

die "$0: \"-m <max increase>\" option must be specified.\n\tUse \"-h\" option for help\n" unless(defined($opts{'m'}));

while (<>) {
	chomp();
	m/^\s*(\d+)\s+(\d+)\s*$/ || die "couldn't parse line $.: \"$_\"\n";

	$timeval = $1;
	$data = $2;

	if (defined($lasttimeval) && $timeval > ($lasttimeval + $opts{'m'})) {
		print "\n";	# the data is too far apart.. print blank line.
	}

	$lasttimeval = $timeval;

	print "$timeval\t$data\n";
}