lss16toppm

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