linux-kernel - Re: [PATCH net-next 2/2] reciprocal_divide: correction/update of the algorithm

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Message-ID: <20140116172406.GA17529@order.stressinduktion.org>
Date:	Thu, 16 Jan 2014 18:24:06 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Daniel Borkmann <dborkman@...hat.com>, davem@...emloft.net,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Eric Dumazet <eric.dumazet@...il.com>,
	Austin S Hemmelgarn <ahferroin7@...il.com>,
	Jesse Gross <jesse@...ira.com>,
	Jamal Hadi Salim <jhs@...atatu.com>,
	Stephen Hemminger <stephen@...workplumber.org>,
	Matt Mackall <mpm@...enic.com>,
	Pekka Enberg <penberg@...nel.org>,
	Andy Gospodarek <andy@...yhouse.net>,
	Veaceslav Falico <vfalico@...hat.com>,
	Jay Vosburgh <fubar@...ibm.com>,
	Jakub Zawadzki <darkjames-ws@...kjames.pl>
Subject: Re: [PATCH net-next 2/2] reciprocal_divide: correction/update of the algorithm

On Thu, Jan 16, 2014 at 10:37:37AM -0600, Christoph Lameter wrote:
> On Thu, 16 Jan 2014, Daniel Borkmann wrote:
> 
> > - * or else the performance is slower than a normal divide.
> > - */
> > -extern u32 reciprocal_value(u32 B);
> > +struct reciprocal_value {
> > +	u32 m;
> > +	u8 sh1, sh2;
> > +};
> >
> > +#define RECIPROCAL_VALUE_RESULT_TO_ZERO ((struct reciprocal_value){.sh1 = 32})
> >
> > -static inline u32 reciprocal_divide(u32 A, u32 R)
> > +struct reciprocal_value reciprocal_value(u32 d);
> 
> A function that returns a struct? That works? Which gcc versions support
> it?

Sure, that works and I actually like it. This is supported by the c standard,
but please don't ask me since which one. ;)

Greetings,

  Hannes

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