#!/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.

@rem = '
@echo off
c:\perl5\bin\perl %0 %1 %2 %3 %4 %5 %6 %7 %8 %9
goto endofperl
@rem ' if @rem;

$max = 0;

#open(STDERR, ">log") || die "log: $!";
#
# Open the first file in binary mode and read it in.
# Issue: Many of the DEC tapes have the location bit set in
# their checksums, so we must allow that.
open(INPUT, $ARGV[0]) || die "$ARGV[0]: $!";
binmode(INPUT);
@core1 = (); $loc = $store = undef;
$sum = $add = $field = 0;
while (read(INPUT, $top, 1)) {
  $top = unpack("C", $top);
  next if $top == 0200;	# Leader or Trailer
  last if $top == 0232; # End of file
  # It isn't trailer.  That implies time to store the previous word
  # if any.
  if (defined($store)) {
    $core1[$field*4096+$loc] = $store;
    $max = $field*4096+$loc unless $max > $field*4096+$loc;
    $store = undef;
    $loc = ($loc + 1) & 07777;
    $sum += $add;
    $fortran = 0;
  }
  if ($top & 0200) { # Better be field setting!
    die "$ARGV[0]: Invalid field setting" unless $top >= 0300;
    die "$ARGV[0]: Invalid field setting" if $top & 0007;
    $fortran = 1 if $top == 0340;
    $field = ($top & 070) >> 3;
    next;
  }
  # Read and verify the format of the bottom half.
  read(INPUT, $bot, 1) || die "$ARGV[0] read: $!";
  $bot = unpack("c", $bot);
  die "$ARGV[0]: ".$bot." not in bin format ". tell(INPUT) unless $bot <= 077;
  # Assemble the word, and figure out the checksum update.
  $word = ($top << 6) + $bot;
  $add = $top + $bot; # Update checksum
  # If the word has the 010000 bit set, it's a location setting.
  if ($word > 07777) {
    #
    # Change location counter
    $loc = $word & 07777;
#printf "Loc == %04o\n", $loc;
    $sum += $add;
  } else {
    die "$ARGV[0]: no location counter" unless defined($loc);
    $store = $word;
  }
}
close(INPUT);
if ($fortran) {
  warn "$ARGV[0]: 4K Fortran Binary\n" if $fortran;
  $sum += 0640; # 4K Fortran loader counts 0300 and 0340
}
if (!defined($store)) {
  # This is that weird case where the checksum has location bit set!
  $store = $loc;
  $sum -= $add;
}
$sum &= 07777;
printf "$ARGV[0]: Checksum is %04o, not %04o\n", $sum, $store if $sum != $store;
#printf STDERR "$ARGV[0]: Checksum is %04o, not %04o\n", $sum, $store if $sum != $store;

#
# Open the second file in binary mode and compare it.
open(INPUT, $ARGV[1]) || die "$ARGV[1]: $!";
binmode(INPUT);
@core2 = (); $loc = $store = undef;
$sum = $add = $field = 0;
while (read(INPUT, $top, 1)) {
  $top = unpack("C", $top);
  next if $top == 0200;	# Leader or Trailer
  last if $top == 0232; # End of file
  if (defined($store)) {
    $core2[$field*4096+$loc] = $store;
    $max = $field*4096+$loc unless $max > $field*4096+$loc;
    $store = undef;
    $loc = ($loc + 1) & 07777;
    $sum += $add;
    $fortran = 0;
  }
  if ($top & 0200) { # Better be field setting!
    die "$ARGV[1]: Invalid field setting" unless $top >= 0300;
    die "$ARGV[1]: Invalid field setting" if $top & 0007;
    $fortran = 1 if $top == 0340;
    $field = ($top & 070) >> 3;
    next;
  }
  read(INPUT, $bot, 1) || die "$ARGV[1] read: $!";
  $bot = unpack("c", $bot);
  die "$ARGV[1]: ".$bot." not in bin format ". tell(INPUT) unless $bot <= 077;
  $word = ($top << 6) + $bot;
  $add = $top + $bot; # Update checksum
  if ($word > 07777) {
    #
    # Change location counter
    $loc = $word & 07777;
    $sum += $add;
  } else {
    die "$ARGV[1]: no location counter" unless defined($loc);
    $store = $word;
  }
}
close(INPUT);
if ($fortran) {
  warn "$ARGV[0]: 4K Fortran Binary\n" if $fortran;
  $sum += 0640; # 4K Fortran loader counts 0300 and 0340
}
if (!defined($store)) {
  # This is that weird case where the checksum has location bit set!
  $store = $loc;
  $sum -= $add;
}
$sum &= 07777;
printf "$ARGV[1]: Checksum is %04o, not %04o\n", $sum, $store if $sum != $store;
#printf STDERR "$ARGV[1]: Checksum is %04o, not %04o\n", $sum, $store if $sum != $store;

$status = 0;
for ($loc = 0; $loc <= $max; $loc++) {
  next unless defined($core1[$loc]) || defined($core2[$loc]);
  $c1 = defined $core1[$loc]? sprintf("%04o", $core1[$loc]): "XXXX";
  $c2 = defined $core2[$loc]? sprintf("%04o", $core2[$loc]): "XXXX";
  if ($c1 ne $c2) {
    printf "%04o: $c1 != $c2\n", $loc;
    $status = 1;
  }
}
exit $status;

__END__
:endofperl