netdev - Re: [RFC] div64

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Message-ID: <45E38762.5040407@zytor.com>
Date:	Mon, 26 Feb 2007 17:20:34 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Stephen Hemminger <shemminger@...ux-foundation.org>
CC:	Jan Engelhardt <jengelh@...ux01.gwdg.de>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RFC] div64_64 support

Stephen Hemminger wrote:
> 
> Hmm. Those are the GCC internal versions, that are picked up but
> doing divide in place. Do we want to allow general 64 bit in kernel to
> be easily used? It could cause sloppy slow code, but it would look
> cleaner.
> 

... and it would handle datatypes which may be architecture-dependent a 
lot cleaner.

I thought the motivation for div64() was that a 64:32->32 divide could 
be done a lot faster on a number of platforms (including the important 
x86) than a generic 64:64->64 divide, but gcc doesn't handle the 
devolution automatically -- there is no such libgcc function.

	-hpa
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