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Date: Mon, 26 Nov 2012 13:46:06 +0100
From: Antonio Quartulli <ordex@autistici.org>
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Subject: Re: [B.A.T.M.A.N.] [PATCH 1/5] batman-adv: Use common Jenkins Hash
 implementation
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To: Sven Eckelmann <sven@narfation.org>
Cc: b.a.t.m.a.n@lists.open-mesh.org


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On Mon, Nov 26, 2012 at 01:39:00PM +0100, Sven Eckelmann wrote:
> On Monday 26 November 2012 13:30:02 Antonio Quartulli wrote:
> [...]
> > > The in kernel implementation will create a different hash sum -> tt
> > > entries
> > > will end up in a different bucket -> CRC will be different (please co=
rrect
> > > me about the last step... just had this problem in the back of my hea=
d).
> > CRC computation does not rely on entries positions, because the real CR=
C16
> > is computed on the client mac address only (and this is the same
> > everywhere) then the results are XOR'd together. Since XOR is commutati=
ve
> > we do not need to keep the same order network wide.
>=20
> I've already wrote this two 2 1/2 hours ago.
>=20
> > Instead, your reasoning is correct for DAT, but for the global DAT hash
> > function only.
> > The local one can be whatever we need, so we can also use jhash for thi=
s.
>=20
> Please define global and local DAT hash function. Because you use the sam=
e=20
> function in both places.

Yes, sorry, it's my fault. At the very beginning DAT had two distinct hash
functions (before it got merged) but then I decided to use the same everywh=
ere.

At this point I would rather suggest to leave DAT as it is (so v2 it's fine=
 with
me).


Thank you.

Cheers,



--=20
Antonio Quartulli

=2E.each of us alone is worth nothing..
Ernesto "Che" Guevara

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