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    # Get rid of all line endings, regardless of which flavor they are
    (my $line = shift) =~ s/[\r\n]//g;

    # does this look like a S1, S2, or S3 record? These are the only o
+nes that
    # carry an actual data payload. Other record types do not, so just
+ ignore
...
    # Make sure the COUNT field makes sense. It should represent the s
+um of
    # address, data, and checksum fields, in bytes
    return unless hex($count) == (length($address) + length($data) + l
+ength($cs)) / 2;

    my $compCs = hex($count);
    foreach my $nibble ($address =~ m/../g, $data =~ m/../g) {
        $compCs += hex($nibble);
    }

    my $compCs = hex($count);
    $compCs += hex($_) foreach($address =~ m/../g, $data =~ m/../g);

    my $compCs = reduce { $a + $b }
                 map    { hex $_  }
                 ($count, $address =~ m/../g, $data =~ m/../g);

    my $status = $compCs == hex($cs);

use List::Util;

...

    return ($status, $address, $data);
}

    # ...

    # if the checksum actually matches, then call it a good S-record
    return ($compCs == hex($cs), $address, $data);