#!/usr/bin/perl
use strict;
use warnings;
use FindBin qw($Bin $Script);

my ($bfn) = @ARGV;
die "Syntax: $Script <bin file to fix>" unless $bfn and -f $bfn;

open BIN, "<$bfn" or die "Unable to read $bfn: $!";
my $vectors;
read(BIN, $vectors, 8*4) == 8*4 or die "Failed to read vectors";
my @vectors = unpack("L"x8, $vectors);
print "Existing vectors: ".join(' ', map {sprintf("%08x", $_)} @vectors[0..6])."\n";
close BIN;
print "Existing checksum: ".sprintf("%08x", $vectors[7])."\n";

my $cs = 0;
for my $v (@vectors[0..6]) {
    $cs -= $v;
}

$cs &= 0xffffffff;

print "Correct  checksum: ".sprintf("%08x", $cs)."\n";

if ($cs ne $vectors[7]) {
    print "Fixing checksum\n";

    open BIN, "+<$bfn" or die "Unable to write $bfn: $!";
    seek(BIN, 7*4, 0);    
    print BIN pack("L", $cs);
    close BIN;    
}