lss16toppm

   1 #!/usr/bin/perl
   2 ## $Id$
   3 ## -----------------------------------------------------------------------
   4 ##
   5 ##   Copyright 2001-2004 H. Peter Anvin - All Rights Reserved
   6 ##
   7 ##   This program is free software; you can redistribute it and/or modify
   8 ##   it under the terms of the GNU General Public License as published by
   9 ##   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
  10 ##   Boston MA 02111-1307, USA; either version 2 of the License, or
  11 ##   (at your option) any later version; incorporated herein by reference.
  12 ##
  13 ## -----------------------------------------------------------------------
  14
  15 ##
  16 ## lss16toppm:
  17 ## Convert an LSS-16 image to PPM
  18 ##
  19 ## Usage:
  20 ##
  21 ##      lss16toppm [-map] < file.lss > file.ppm
  22 ##
  23 ## The -map causes the color map to be output on stderr.
  24 ##
  25
  26 eval { use bytes; };
  27 eval { binmode STDIN; };
  28 eval { binmode STDOUT; };
  29
  30 $map = 0;
  31 foreach $arg ( @ARGV ) {
  32     if ( $arg eq '-map' ) {
  33         $map = 1;
  34     } else {
  35         print STDERR "$0: Unknown option: $arg\n";
  36         exit 127;
  37     }
  38 }
  39
  40 if ( read(STDIN, $header, 56) != 56 ) {
  41     print STDERR "$0: Short file\n";
  42     exit 1;
  43 }
  44
  45 ($magic, $xsize, $ysize, @colorset) = unpack("Vvvc48", $header);
  46
  47 if ( $magic != 0x1413f33d ) {
  48     print STDERR "$0: Invalid file format\n";
  49     exit 1;
  50 }
  51
  52 %color = ();
  53 for ( $i = 0 ; $i < 16 ; $i++ ) {
  54     $r = int((shift @colorset) * 255 / 63 + 0.5);
  55     $g = int((shift @colorset) * 255 / 63 + 0.5);
  56     $b = int((shift @colorset) * 255 / 63 + 0.5);
  57
  58     $color{$i} = pack("ccc", $r, $g, $b);
  59
  60     if ( $map ) {
  61         printf STDERR "#%02x%02x%02x=%d\n", $r, $g, $b, $i;
  62     }
  63 }
  64
  65 sub get_nybble() {
  66     my($ch,$n);
  67     if ( defined($nybble_buf) ) {
  68         $n = $nybble_buf;
  69         undef $nybble_buf;
  70     } else {
  71         if ( read(STDIN, $ch, 1) != 1 ) {
  72             print STDERR "$0: Short read on input (file corrupt)\n";
  73             exit 1;
  74         }
  75         $ch = ord($ch);
  76         $nybble_buf = $ch >> 4;
  77         $n = $ch & 0xF;
  78     }
  79     return $n;
  80 }
  81
  82 print "P6\n";
  83 print "$xsize $ysize\n";
  84 print "255\n";
  85
  86 for ( $y = 0 ; $y < $ysize ; $y++ ) {
  87     $x = 0;
  88     $last = 0;
  89     undef $nybble_buf;          # Nybble buffer starts clear on each line
  90     while ( $x < $xsize ) {
  91         $n = get_nybble();
  92
  93         if ( $n != $last ) {
  94             print $color{$n};
  95             $last = $n;
  96             $x++;
  97         } else {
  98             $c = get_nybble();
  99             if ( $c == 0 ) {
 100                 # Double-nybble run
 101                 $c = get_nybble();
 102                 $c += get_nybble() << 4;
 103                 $c += 16;
 104             }
 105             # Truncate overlong runs
 106             $c = $xsize-$x if ( $c > $xsize-$x );
 107             # Output run
 108             print $color{$n} x $c;
 109             $x += $c;
 110         }
 111     }
 112 }