Re: Enabling Checksums

On Fri, 2013-03-22 at 17:09 +0200, Ants Aasma wrote:
> So to conclude, the 3 approaches:

One other question: assuming that the algorithms use the full 16-bit
space, is there a good way to avoid zero without skewing the result? Can
we do something like un-finalize (after we figure out that it's zero),
compute in an extra salt value, and then re-finalize? That might work
for Fletcher; but I don't think that works for CRC or Fowler-Noll-Vo
because the final value is the same as the state.

I'm still slightly concerned about differentiating checksummed pages in
the future if we want to offer a transition path, since we no longer use
header bits. Avoiding zero might help us there. Hopefully not necessary,
but something we might find useful. Also, it would help us identify
situations where the checksum is never set.

Regards,
Jeff Davis