hoffmandirt

I'm looking for more information about this statement:

I have never used sumchecks before, but I need to include one in a request via RS232. Does anyone have any code examples or links to relative information?

Thanks

DaWei

Generally speaking, you will sum or sum-without-carry (xor) the bytes then negate or invert the sum and tack it on the end. The reason for the negation or inversion is that when you re-sum the whole thing, including the sum, the result will be zero if there are no errors.

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hoffmandirt

That sounds pretty straight forward. Thank you for the information. An error would typically mean that a byte is missing or has been tampered with correct? Also if there was seeding in this sumcheck, what would that do to the overall sum?

DaWei

The seed would vary the checksum, so you'd need to know the seed to recover. There's a lot of literature on this for beyond-simple implementations.

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Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code.
Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers