Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751618AbXBAVzv (ORCPT ); Thu, 1 Feb 2007 16:55:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751602AbXBAVzv (ORCPT ); Thu, 1 Feb 2007 16:55:51 -0500 Received: from gockel.physik3.uni-rostock.de ([139.30.44.16]:1180 "EHLO gockel.physik3.uni-rostock.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751438AbXBAVzu (ORCPT ); Thu, 1 Feb 2007 16:55:50 -0500 Date: Thu, 1 Feb 2007 22:55:49 +0100 (CET) From: Tim Schmielau To: Valdis.Kletnieks@vt.edu cc: David Howells , "Robert P. J. Day" , Linux kernel mailing list , Andrew Morton , Paul Mackerras , galak@kernel.crashing.org Subject: Re: [PATCH] Add "is_power_of_2" checking to log2.h. In-Reply-To: <200702012017.l11KHBG7026805@turing-police.cc.vt.edu> Message-ID: References: <3565.1170326639@redhat.com> <200702012017.l11KHBG7026805@turing-police.cc.vt.edu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 776 Lines: 23 On Thu, 1 Feb 2007, Valdis.Kletnieks@vt.edu wrote: > On Thu, 01 Feb 2007 13:39:15 +0100, Tim Schmielau said: > > #define is_power_of_4(x) (is_power_of_2_or_zero(x) \ > > && (x & ((typeof(x))0x55555555))) > > Those 5's are going to need more magic if x is a 64-bit typeof? Yeah, I can't count. Make that #define is_power_of_2_or_zero(x) ((x & (x-1))==0) #define is_power_of_4(x) (is_power_of_2_or_zero(x) \ && (x & ((typeof(x))0x5555555555555555ull))) of course. Thanks, Tim - 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/