For some reason, Chris01234 seems resolutely committed to byte-by-byte access to the data block, but if you're going to use a block-by-block approach, why not just
    $check_sum += unpack('%16C*', $buff);
(see unpack) and then bitwise-and mask to 16 bits before returning? (I'd also use the biggest buffer I could get away with. 10MB? 100MB?)

Give a man a fish:  <%-{-{-{-<

In reply to Re^3: Accessing individual bytes of a binary file as numerical values by AnomalousMonk
in thread Accessing individual bytes of a binary file as numerical values by Chris01234

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