From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: =?utf-8?Q?Mattias_Engdeg=C3=A5rd?= Newsgroups: gmane.emacs.devel Subject: Re: master ac1d15e95c 1/2: ; * src/data.c (Fash): More precise doc string Date: Tue, 19 Jul 2022 19:46:24 +0200 Message-ID: <4785DD4F-423E-498C-B18D-A5B104F38147@acm.org> References: <831quhnrf8.fsf@gnu.org> <063D21A9-801C-411B-B59C-AA7A057DFF79@acm.org> <83v8rtmb4r.fsf@gnu.org> <83r12hm733.fsf@gnu.org> Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.13\)) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="32501"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Tue Jul 19 19:48:13 2022 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oDrKO-0008K0-5Q for ged-emacs-devel@m.gmane-mx.org; Tue, 19 Jul 2022 19:48:12 +0200 Original-Received: from localhost ([::1]:37098 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oDrKN-0003jE-2q for ged-emacs-devel@m.gmane-mx.org; Tue, 19 Jul 2022 13:48:11 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:53202) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oDrIp-000228-Jw for emacs-devel@gnu.org; Tue, 19 Jul 2022 13:46:35 -0400 Original-Received: from mail205c50.megamailservers.eu ([91.136.10.215]:60570 helo=mail193c50.megamailservers.eu) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oDrIl-0000vr-MI; Tue, 19 Jul 2022 13:46:35 -0400 X-Authenticated-User: mattiase@bredband.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=megamailservers.eu; s=maildub; t=1658252787; bh=ugqy/KIQfMeK5nlUQUgKof1+s3EfMcVbR9uMSVjnh7U=; h=Subject:From:In-Reply-To:Date:Cc:References:To:From; b=UzyLReNK+Rs77AjXWsjo+tM+fxLFDx2XBRHY7UNtMDFAFcEQDmzCd+vdxMxAjker7 axkRtSGBAJyWhXu13bpQ5T+YX/9ccVkjKkOJqxU0m+zVARZXjIyV8ExbKRR1AiwIZp UvWek3/agI9h4PkoLD7GZzBqL44bNFgMeHULc3ws= Feedback-ID: mattiase@acm.or Original-Received: from smtpclient.apple (c188-150.188-179.bredband.tele2.se [188.150.188.179] (may be forged)) (authenticated bits=0) by mail193c50.megamailservers.eu (8.14.9/8.13.1) with ESMTP id 26JHkPY4025243; Tue, 19 Jul 2022 17:46:26 +0000 In-Reply-To: <83r12hm733.fsf@gnu.org> X-Mailer: Apple Mail (2.3654.120.0.1.13) X-CTCH-RefID: str=0001.0A782F29.62D6EDF3.0004, ss=1, re=0.000, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0 X-CTCH-VOD: Unknown X-CTCH-Spam: Unknown X-CTCH-Score: 0.000 X-CTCH-Flags: 0 X-CTCH-ScoreCust: 0.000 X-Origin-Country: SE Received-SPF: softfail client-ip=91.136.10.215; envelope-from=mattiase@acm.org; helo=mail193c50.megamailservers.eu X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_SOFTFAIL=0.665, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:292284 Archived-At: 19 juli 2022 kl. 17.54 skrev Eli Zaretskii : > The operation is "bit shift", so > the most natural way of describing it is in terms of shifting bits. > No? Not necessarily. The user inputs numbers and gets a number out, not bit = sequences, so it makes sense to describe the behaviour in arithmetic = terms. (We're not describing a processor instruction that manipulates = registers; `ash` is an operation on mathematical integers.) A bitwise description would require knowledge of two's complement = representation which you dismissed earlier. If it's acceptable to = complement the arithmetic description with something that refers to such = representation, then we could have: If we view VALUE as a binary two's complement number, then shifting = left introduce new 0-bits to the right and shifting right remove = rightmost bits. Since negative numbers have an infinite supply of 1-bits to the left, = a negative number remains negative no matter how far it is shifted in = either direction.