#!/usr/bin/perl -w
#
# gif-gct - find Global Color Table in a GIF
#
#    gif-gct
#
#
# Copyright(C) 1999 Yoshimasa Watanabe <naney@j.dendai.ac.jp>
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc., 59
# Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
#
# The Graphics Interchange Format(c) is the Copyright property of CompuServe
# Incorporated. GIF(sm) is a Service Mark property of CompuServe
# Incorporated.
#
#
# $Id: gif-gct,v 1.1 1999/01/02 12:50:20 naney Exp $
#
#


use strict;

my $buff;

#----- [read Header] -----
die if read(STDIN, $buff, 3) != 3;
die if unpack('a3', $buff) ne 'GIF';

die if read(STDIN, $buff, 3) != 3;
die if read(STDIN, $buff, 4) != 4;

die if read(STDIN, $buff, 1) != 1;

my $bits = unpack('C', $buff);
my $globalColorTableFlag = ($bits & 0x80) >> 7;
my $globalColorTableSize = 2 ** (($bits & 0x07) + 1);

die if read(STDIN, $buff, 2) != 2;

#----- [read Global Color Table] -----
if ($globalColorTableFlag) {
  my $i;
  my ($r, $g, $b);

  for ($i = 0; $i < $globalColorTableSize; $i++) {
    die if read(STDIN, $buff, 3) != 3;
    ($r, $g, $b) = unpack('CCC', $buff);
    print "$r $g $b\n";
  }
}


exit 0;


__END__


=head1 NAME

gif-gct - find Global Color Table in a GIF

=head1 SYNOPSIS

  gif-gct

=head1 DESCRIPTION

C<gif-gct> displays the Global Color Table in the GIF in the standard input.

=head1 AUTHOR

Yoshimasa Watanabe <naney@j.dendai.ac.jp>

=cut