Date: Sun, 8 May 2005 12:56:08 +0200 From: Jose M Rodriguez <josemi@freebsd.jazztel.es> To: Marcel Moolenaar <marcel@xcllnt.net> Cc: freebsd-current@freebsd.org Subject: Re: rigth crc32 implementation Message-ID: <200505081256.09115.josemi@freebsd.jazztel.es> In-Reply-To: <05b71132f579685de0459a3b762b26b5@xcllnt.net> References: <200504261143.55195.josemi@redesjm.local> <426EF6BD.6030207@errno.com> <05b71132f579685de0459a3b762b26b5@xcllnt.net>
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El Mi=E9rcoles, 27 de Abril de 2005 04:57, Marcel Moolenaar escribi=F3:
> On Apr 26, 2005, at 7:19 PM, Sam Leffler wrote:
> > Marcel Moolenaar wrote:
> >> On Tue, Apr 26, 2005 at 01:01:32PM -0700, Sam Leffler wrote:
> >>> Note also there is CRC32 code of this sort in WEP and TKIP crypto
> >>> modules in the net80211 support.
> >>
> >> Sam,
> >> Given the seperation of crc32() into crc32_raw() and crc32(), with
> >> either crc32() only or otherwise both functions inlined, are there
> >> any obstacles preventing the 802.11 code from using the ones in
> >> src/sys/libkern?
> >
> > The wep+tkip usage is integral to the cipher so splitting it out
> > would likely slow them and, more importantly, would also require
> > revalidation (there are test vectors but they're pretty limited).
> > These modules are self-contained for various reasons so I'm leary
> > of switching.
>
> Understood. Seems like a good reason to leave it as-is.
>
> > I'll think about adding it under an #ifdef for those that want to
> > save 2Kbytes (the size of the crc tables).
>
> In my book, 2K isn't worth the trouble.
> Thanks for the info,
After some digging, seems that libkern crc32 is really a ether-II crc=20
implementation, using the reflected tabbed alg.
The only difference I found is that the not reflected alg. is more usual=20
and used, at last, in ueagle.
Only a latest thing about this rest. Can be crc32_tab and his consumers=20
alter to use a const definition?
uint32_t const crc32_tab[] =3D {
=2E..
This will stop an ill defined module can alter the shared crc table.
Thanks in advance,
=2D-
josemi
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