#!/usr/bin/perl

use strict;
use warnings;

$|++;

die "Usage: $0 file1 file2\n" unless @ARGV==2;

my ($f1, $f2) = map { open my $fh, '<:raw', $_ or 
      die "Can't open `$_': $!\n"; $fh } @ARGV;

$/ = \0x100_000;

while (my $s1=<$f1>) {
    defined +(my $s2=<$f2>) or last;
    printf "Block %04d: no differences\r", $.
      and next if $s1 eq $s2;
    my @l = map length, ($s1 ^ $s2) =~ /^(\0*)(.+?)(\0*)\z/;
    printf "\nBlock %04d: A=[0 x %d], B=[* x %d], C=[0 x %d]\n", $., @l;
    print "\tB=[@{[ unpack '(H2)*' => substr $_, $l[0], $l[1] ]}]\n"
      for $s1, $s2;
}

__END__