#!/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.

#
# Look for -pb, .bin, or .bn files with similar content.
# For now, "similar content" means the same result from &hash.
#

$max = 0;

#open(STDERR, ">log") || die "log: $!";
#
# Open a file in binary mode and read it in.
sub readbin {
  local($f) = @_;
  open(INPUT, $f) || die "$f: $!";
  binmode(INPUT);
  @core1 = (); $loc = $store = undef;
  $sum = $add = $field = 0;
  $fortran = $fpp = 0;
  while (read(INPUT, $top, 1)) {
    $top = unpack("C", $top);
    next if $top == 0200;	# Leader or Trailer
    if (defined($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!
      last if $top == 0232; # End of file
      warn "$f: Invalid field setting $top" unless $top >= 0300;
      return 0 unless $top >= 0300;
      warn "$f: Invalid field setting $top" if $top & 0007;
      return 0 if $top & 0007;
      $fortran = 1 if $top == 0340;
      $field = ($top & 070) >> 3;
      next;
    }
    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;
    }
    read(INPUT, $bot, 1) || do { warn "$f read: $!"; return 0; };
    $bot = unpack("c", $bot);
    warn "$f: ".$bot." not in bin format ". tell(INPUT) unless $bot <= 077;
    return 0 unless $bot <= 077;
    $word = ($top << 6) + $bot;
    $add = $top + $bot; # Update checksum
    if ($word > 07777) {
      #
      # Change location counter
      $loc = $word & 07777;
#printf "Loc == %04o\n", $loc;
      $sum += $add;
    } else {
      warn "$f: no location counter" unless defined($loc);
      return 0 unless defined($loc);
      $store = $word;
    }
  }
  close(INPUT);
  if ($fortran) {
    warn "$f: 4K Fortran Binary\n" if $fortran;
    $sum += 0640; # 4K Fortran loader counts 0300 and 0340
  }
  $sum &= 07777;
# printf "$f: Checksum is %04o, not %04o\n", $sum, $store if $sum != $store;
  #printf STDERR "$f: Checksum is %04o, not %04o\n", $sum, $store if $sum != $store;
  return 1;
}

#
# Read in the file and compute the hash function on it's contents.
# Initially, the lowest four words loaded seemed like a good hash,
# but unfortunately it hashes nearly all the maindec files into the 
# same hash bucket.  For now, just sum the words loaded.
sub hash {
  local($f) = @_;
  return undef unless &readbin($f);
  @hash = ();
  $sum = 0;
  # BUGBUG: Better load at least 4 locations!
  for ($loc = 0; $loc < 0100000; $loc++) {
    $sum += $core1[$loc] if defined $core1[$loc];
  }
  return sprintf("%0o", $sum);
}

#
# Walk the directories and files given, building a hash table.
$status = 0;
@todo = @ARGV;
%hash = (); # Nothing hashed yet
while  (@todo) {
  $f = shift @todo;
#warn "processing $f\n";
  if (-d $f) {
    $d = $f;
    # It is really a directory; enumerate it,
    # taking note of *-pb, *.bin, and *.bn.
    opendir(DIR, $d) || die "$d: $!";
    while (($f = readdir(DIR))) {
      if (-d "$d/$f") {
        # Examine it later
#warn "unshift $d/$f\n" unless $f =~ /^[.]/;
        unshift(@todo, "$d/$f") unless $f =~ /^[.]/;
        next;
      }
      $isbin = $f =~ /-pb[0-9]*$/;
      $isbin |= $f =~ /[.]bin$/;
      $isbin |= $f =~ /[.]bn$/;
      next unless $isbin;
#warn "unshift $d/$f\n";
      unshift(@todo, "$d/$f"); # Examine it later
    }
    next;
  }
  # It is a file.
  $h = &hash($f);
#warn "hash of $d/$f is $h\n";
  next unless defined $h;
  if (defined $hash{$h}) {
    print "Hash collsion of $f with $hash{$h}\n";
    $hash{$h} .= ":$f";
  } else {
    $hash{$h} = $f;
  }
}
exit $status;