linux-kernel - Re: [KJ][RFC][PATCH] BIT macro cleanup

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Date:	Fri, 23 Feb 2007 09:57:52 -0500
From:	"Dmitry Torokhov" <dmitry.torokhov@...il.com>
To:	"Richard Knutsson" <ricknu-0@...dent.ltu.se>
Cc:	"Milind Choudhary" <milindchoudhary@...il.com>,
	kernel-janitors@...ts.osdl.org, linux-kernel@...r.kernel.org,
	linux-input@...ey.karlin.mff.cuni.cz,
	linux-joystick@...ey.karlin.mff.cuni.cz
Subject: Re: [KJ][RFC][PATCH] BIT macro cleanup

On 2/23/07, Richard Knutsson <ricknu-0@...dent.ltu.se> wrote:
> Milind Choudhary wrote:
> > On 2/23/07, Richard Knutsson <ricknu-0@...dent.ltu.se> wrote:
> >> > +#define BITWRAP(nr)    (1UL << ((nr) % BITS_PER_LONG))
> >> >
> >> > & make the whole input subsystem use it
> >> > The change is huge, more than 125 files using input.h
> >> > & almost all use the BIT macro.
> >> It is as a big of change, but have you dismissed the "BIT(nr %
> >> BITS_PER_LONG)" approach?
> >
> > no..
> > but just looking at the number of places it is being used,
> > it seems that adding a new  macro would be good
> > which makes it look short n sweet
> You have a point there but I still don't think it should be in bitops.h.
> Why should we favor long-wrap before byte-wrap, so what do you think
> about doing:
>
> #define BITWRAP(x)      BIT((x) % BITS_PER_LONG)
>
> in input.h? Otherwise I think it should be call LBITWRAP (or something)
> to both show what kind it is and enable us to add others later.

Why would you not want to have what you call bitwrap as a standard
behavior? Most placed to not use modulus because they know the kind of
data they are working with but should still be fine if generic
implementation did that.

-- 
Dmitry
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