Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751893AbYKKSwT (ORCPT ); Tue, 11 Nov 2008 13:52:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751096AbYKKSwK (ORCPT ); Tue, 11 Nov 2008 13:52:10 -0500 Received: from 136-022.dsl.LABridge.com ([206.117.136.22]:1741 "EHLO mail.perches.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750924AbYKKSwJ (ORCPT ); Tue, 11 Nov 2008 13:52:09 -0500 Subject: Re: [PATCH 1/2] Create a DIV_ROUND_CLOSEST macro to do division with rounding From: Joe Perches To: Andrew Morton Cc: Jean Delvare , "Darrick J. Wong" , linux-kernel , lm-sensors In-Reply-To: <20081111090702.94be2a19.akpm@linux-foundation.org> References: <20081111010132.1730.76566.stgit@elm3a70.beaverton.ibm.com> <20081111110454.073a6d94@hyperion.delvare> <20081111090702.94be2a19.akpm@linux-foundation.org> Content-Type: text/plain Date: Tue, 11 Nov 2008 10:51:50 -0800 Message-Id: <1226429510.10478.1061.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.24.0-2mdv2009.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1618 Lines: 36 On Tue, 2008-11-11 at 09:07 -0800, Andrew Morton wrote: > On Tue, 11 Nov 2008 11:04:54 +0100 Jean Delvare wrote: > > On Mon, 10 Nov 2008 17:01:32 -0800, Darrick J. Wong wrote: > > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > > > index fba141d..fb02266 100644 > > > --- a/include/linux/kernel.h > > > +++ b/include/linux/kernel.h > > > @@ -48,6 +48,12 @@ extern const char linux_proc_banner[]; > > > #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) > > > #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) > > > #define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y)) > > > +#define DIV_ROUND_CLOSEST(x, divisor)( \ > > > +{ \ > > > + typeof(divisor) __divisor = divisor; \ > > > + (((x) + ((__divisor) / 2)) / (__divisor)); \ > > > +} \ > > > +) > > I don't get why you implement this as a macro rather than an inline > > function? A function would look much better. > The idea is that DIV_ROUND_CLOSEST() can be used with arguments of any > size (char, short, ... long long) and will do all the suitable > promotion and will return a type of the appropriate width and > signedness. Perhaps the macro should be placed directly after DIV_ROUND_UP and should use the same argument naming. Perhaps HALF_UP is more descriptive and fairly common. http://java.sun.com/j2se/1.5.0/docs/api/java/math/RoundingMode.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/