#!/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.

# Convert a .SV file to an octal dump of a BIN format tape.

foreach $f (@ARGV) {
  #
  # First, "load" the file.
  open(INPUT, $f) || die "$f: $!";
  binmode(INPUT);
  # Read the header
  $ncs = &getword(); $ncs = 4096 - $ncs;
  $sacif = &getword();
  $sa = &getword();
  $jsw = &getword();
  # Read the segment table.
  @origins = @pages = @fields = ();
  for ($i = 0; $i < $ncs; $i++) {
    push(@origins, &getword());
    $w = &getword();
    push(@pages, ($w >> 6) & 037);
    push(@fields,($w >> 3) & 007);
  }
  # "Load" the segments.
  $blk = 1;
  @core = ();
  for ($i = 0; $i < $ncs; $i++) {
    seek(INPUT, $blk*256*3/2, 0) || die "$f: $!";
    $org = $fields[$i]*010000 + $origins[$i];
    $pages = $pages[$i];
    $words = $pages * 128;
    for ($w = 0; $w < $words; $w++) {
      $core[$org++] = &getword();
    }
    $blk += int(($pages+1)/2);
  }
  # At this point we have "loaded" the file.
  # Now to dump it back out in the correct format.
  # The checksum is simply the 12-bit sum of all bytes 
  # except field settings and leader-trailer.
  $of = $f; $of =~ y/A-Z/a-z/;
  $of =~ s/[-.](dg|sv)$/-pb.od/;
  if (-f $of) {
    warn "Skipping $of: exists\n";
    next;
  }
  open(OUTPUT, ">$of") || die "$of: $!";
  print "Writing $of\n";
  # Leader
  for ($i = 0; $i < 64; $i++) {
    print OUTPUT "0200\n";
  }
  $oaddr = -2;
  $cksum = 0;
  for ($addr = 0; $addr <= 077777; $addr++) {
    if (defined $core[$addr]) {
      # Change fields of $oadder is different field from $addr
      if (($oaddr & 070000) != ($addr & 070000)) {
        printf OUTPUT "%04o\n", 0300 + (($addr >> 9) & 070);
      }
      # Output an origin if needed.
      if ($addr != $oaddr + 1) {
        $c1 = 0100 + (($addr >> 6) & 077);
        $c2 = $addr & 077;
        printf OUTPUT "%04o\n%04o\n", $c1, $c2;
        $cksum += $c1 + $c2;
      }
      # Output the data.
      $c1 = ($core[$addr] >> 6) & 077;
      $c2 = $core[$addr] & 077;
      printf OUTPUT "%04o\n%04o\n", $c1, $c2;
      $cksum += $c1 + $c2;
      # Remember the address.
      $oaddr = $addr;
    }
  }
  # Output the 12 bit checksum.
  $c1 = ($cksum >> 6) & 077;
  $c2 = $cksum & 077;
  printf OUTPUT "%04o\n%04o\n", $c1, $c2;
  # Trailer
  for ($i = 0; $i < 64; $i++) {
    print OUTPUT "0200\n";
  }
  close(OUTPUT) || die "$of: $!";
}

#
# Get the next word.  
$gwplace = $gwstate = 0; 
sub getword {
  $gwstate = 0 unless tell(INPUT) == $gwplace;
  if ($gwstate == 0) {
    read(INPUT, $buf, 3) || die "$f: $!";
    $gwplace = tell(INPUT);
    ($b1, $b2, $b3) = unpack("CCC", $buf);
    $w1 = (($b3 & 0360) << 4) + $b1;
    $w2 = (($b3 & 0017) << 8) + $b2;
    $gwstate = 1;
    return $w1;
  } else {
    $gwstate = 0;
    return $w2;
  }
}