From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Removing assumption of unsigned long pixel values for colours Date: Mon, 06 May 2019 12:51:24 -0400 Message-ID: References: <87v9yqjdnh.fsf@gmail.com> <83a7g2kqsi.fsf@gnu.org> <87lfzlkeic.fsf@gmail.com> <83zho0khdu.fsf@gnu.org> <87h8a8k84a.fsf@gmail.com> <83pnowjo63.fsf@gnu.org> <878svjk1g0.fsf@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="96568"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon May 06 18:51:49 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hNgqC-000Ozv-UA for ged-emacs-devel@m.gmane.org; Mon, 06 May 2019 18:51:49 +0200 Original-Received: from localhost ([127.0.0.1]:59373 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hNgqB-0004GG-Sy for ged-emacs-devel@m.gmane.org; Mon, 06 May 2019 12:51:47 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:54976) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hNgq3-0004Ez-8g for emacs-devel@gnu.org; Mon, 06 May 2019 12:51:40 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hNgq2-0003p0-Cb for emacs-devel@gnu.org; Mon, 06 May 2019 12:51:39 -0400 Original-Received: from [195.159.176.226] (port=39396 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hNgq0-0003ne-Uu for emacs-devel@gnu.org; Mon, 06 May 2019 12:51:38 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.89) (envelope-from ) id 1hNgpx-000OjR-9t for emacs-devel@gnu.org; Mon, 06 May 2019 18:51:33 +0200 X-Injected-Via-Gmane: http://gmane.org/ Cancel-Lock: sha1:DrGd0D3CxazQgHbD8Rzq+S0ahJo= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:236200 Archived-At: > The original plan was to avoid any conversion at all (no conversion > necessary on the Emacs side to create the struct of doubles); would you > still consider the difference between no conversion and 4 conversions to > be negligible? That which costs is when we can't use a pre-existing struct and need to allocate a new struct and copy the values to it (with or without conversion). If we need to do the copy anyway, the added cost of a conversion along the way is very likely to be negligible. The rule of thumb is that arithmetic operations are free (contrary to data movement). [ Which also means that "the conversion" can be costly in the case where the need for the conversion in turn requires allocation of a new struct. ] Stefan