From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <0d43ff0b0f3fc5742f94b963c508be10@quanstro.net>
From: erik quanstrom <quanstro@quanstro.net>
Date: Fri, 11 Jan 2008 14:39:08 -0500
To: 9fans@cse.psu.edu
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Subject: [9fans] snap checksum
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does anyone know if the function /sys/src/cmd/snap/take.c:/^sumr
can return 0 for a buffer that is not all zeros?

i think it can not, since for sum&1, the next sum at least
has 0x8000 set and otherwise if (sum&1) == 0, then either
sum == 0 or sum>>1 != 0.

fletcher-16 seems similar except for the extra sum.  does anyone
know of any writeups on this algorithm?  or at least an example
that shows that sum can return 0 for a non-zeroed buffer?

- erik