netdev - Re: [PATCH] - trivial - Improve appletalk checksum calculation

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Date:	Mon, 22 Oct 2007 20:39:59 -0700
From:	Joe Perches <joe@...ches.com>
To:	Stephen Hemminger <shemminger@...ux-foundation.org>
Cc:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH] - trivial - Improve appletalk checksum calculation

On Mon, 2007-10-22 at 20:30 -0700, Stephen Hemminger wrote:
> > Corrected fast code is:
> > 
> >         while (len--) {
> >                 sum += *data++;
> >                 sum <<= 1;
> >                 sum = (((sum & 0x10000) >> 16) + sum) & 0xffff;
> >         }
> > 
> > At least it is correct on the standalone random data test, and the
> > new code is 30% faster for the cached memory case (13.7 clks/byte vs 18 
> > clks/byte).
> Your code looks different...

Both are 16 bit rotate lefts.
Which looks clearer?

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