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To: "Joakim Tjernlund" <Joakim.Tjernlund@lumentis.se>
Cc: "Wolfgang Denk" <wd@denx.de>,  "Marc Singer" <elf@buici.com>,
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Subject: Re: crc32() optimization
References: <20021110224142.2F39310162@denx.denx.de>
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From: ebiederman@lnxi.com (Eric W. Biederman)
Date: 10 Nov 2002 16:56:30 -0700
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"Joakim Tjernlund" <Joakim.Tjernlund@lumentis.se> writes:

> > In message <001301c28909$743f1f40$0200a8c0@telia.com> you wrote:
> > > I could not wait until tomorrow, so I did it now instead.
> > > The result was worse. The best I got was 7% improvement.
> > > I tried 16, 8, 6 and 4 as unrolling steps.
> > 
> > Makes no sense to me.  Should  be  at  least  as  efficient  as  your
> > original code (marginally better).
> 
> I don't understand this either.
> Anyone?

You might try it with 6.  But a lot depends on what gcc can do with
it and gcc may not be like all of those potential entry points.. 

Running gcc -S and checking to see the difference in the generated
assembly might be instructive.

Eric