#!/usr/bin/perl
# 
# Copyright © 2015-2020 by Vincent Slyngstad
# 
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS LISTED ABOVE BE LIABLE
# FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
# CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
# 
# Except as contained in this notice, the names of the authors above
# shall not be used in advertising or otherwise to promote the sale, use
# or other dealings in this Software without prior written authorization
# from those authors.

# Unpack every 3 TSS8 bytes into 2 words.  Output the words as a
# rudimentary file in .bin format.  Each input file is presumed to
# be a program in .sav format, designed to load starting at location 0.

$bsize = 2*0400;

# Output leader/trailer.
sub leader {
  for ($i = 0; $i < 120; $i++) {
    print OUTPUT pack("C", 0200);
  }
}

# Ouput a word and update the checksum.
sub dframe {
  local($word) = @_;
  print OUTPUT pack("CC", $word >> 6, 077 & $word);
  $checksum += $word >> 6;
  $checksum += 077 & $word;
}

# Read and remember the memory map from the header block.
sub header {
  die "header read $f: $!\n" unless read(INPUT, $map, $bsize) == $bsize;
  @map = unpack("S*", $map);
  printf "SA=0%o%04o, %s mode\n",
         ($map[1]& 070)>>3,
         $map[3],
         $map[0] == 2? "pdp8": "linc";
  # Should output a suitable SAVE command to STDOUT.
  for ($i = 0; $i < 0340; $i++) {
    shift @map;
  }
}

foreach $f (@ARGV) {
  open(INPUT, $f) || die "$f: $!";
  binmode(INPUT);
  &header;
  $of = $f; $of =~ s/[.]bd$/.bin/;
  die "$f: Expected .bd" if $f eq $of;
  open(OUTPUT, ">$of") || die "$of: $!";
  binmode(OUTPUT);
  &leader;
  $origin = 0;
  $field = 0;
  $checksum = 0;
  for ($bno = 0; $bno < 040; $bno++) {
    # Skip unallocated blocks!
    if (!$map[$bno]) {
      $origin += 0400;
      next;
    }
    die "block read $f: $!\n" unless read(INPUT, $bdata, $bsize) == $bsize;
    @bdata = unpack("S*", $bdata);
    &dframe(010000 + ($origin&07777));
    while (@bdata) {
      $b1 = shift @bdata;
      if (($origin % 010000) == 0) {
        # Start a new field
        print OUTPUT pack("C", 0300+$field);
        $field += 010;
        # New field requires location setting for *0.
      }
      &dframe($b1);
      $origin++;
      last unless $origin % 0400;
    }
  }
  &dframe(07777 & $checksum);
  &leader;
}