From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758746Ab2HUWTO (ORCPT ); Tue, 21 Aug 2012 18:19:14 -0400 Received: from fieldses.org ([174.143.236.118]:44726 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758711Ab2HUWTL (ORCPT ); Tue, 21 Aug 2012 18:19:11 -0400 Date: Tue, 21 Aug 2012 18:19:08 -0400 From: "J. Bruce Fields" To: Al Viro Cc: Jim Rees , linux-kernel@vger.kernel.org Subject: Re: [PATCH] strings: helper for maximum decimal encoding of an unsigned integer Message-ID: <20120821221908.GD19185@fieldses.org> References: <20120821212910.GD18637@fieldses.org> <20120821212227.GA14194@umich.edu> <20120821220613.GK23464@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120821220613.GK23464@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 21, 2012 at 11:06:13PM +0100, Al Viro wrote: > On Tue, Aug 21, 2012 at 05:22:27PM -0400, Jim Rees wrote: > > J. Bruce Fields wrote: > > > > From: "J. Bruce Fields" > > > > I've seen a couple examples recently where we've gotten this wrong. > > Maybe something like this would help? Is there some better way? > > > > (Approximation due to Jim Rees). > > > > Please add Suggested-by: Jim Rees . I'm thinking of > > patenting the algorithm. > > Is that a joke? Patenting the fact that log10(256) is 2.408..., which > is about 2.4, which is 24/10? I really hope we are Poe'd... BTW, NAK > the comment - s/36/26/ in there; check it yourself - > $ echo '2^(8*27)' | bc > 105312291668557186697918027683670432318895095400549111254310977536 > which is 66-digit, not 65 as the estimate would be. Erp, you're right. Anyway, does something like base10len(type) seem reasonable? Or define macros that enumerate the sizes? (ULONG_STR_MAX or something?) --b.