From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Newsgroups: gmane.emacs.bugs Subject: bug#43764: Calc shift right broken Date: Wed, 4 Nov 2020 12:54:59 +0100 Message-ID: References: <87h7r9ozuh.fsf@gnus.org> <87wo04nnvr.fsf@gnus.org> <550C4DEF-DBAA-4175-98BC-DB484A3B89CF@acm.org> Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.17\)) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="25242"; mail-complaints-to="usenet@ciao.gmane.io" Cc: Lars Ingebrigtsen , 43764@debbugs.gnu.org To: Vincent =?UTF-8?Q?Bela=C3=AFche?= Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Wed Nov 04 13:06:41 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@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 1kaHYn-0006Sy-Hq for geb-bug-gnu-emacs@m.gmane-mx.org; Wed, 04 Nov 2020 13:06:41 +0100 Original-Received: from localhost ([::1]:37788 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kaHYm-000541-KR for geb-bug-gnu-emacs@m.gmane-mx.org; Wed, 04 Nov 2020 07:06:40 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:33052) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kaHYD-0004nT-15 for bug-gnu-emacs@gnu.org; Wed, 04 Nov 2020 07:06:05 -0500 Original-Received: from debbugs.gnu.org ([209.51.188.43]:36208) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kaHYA-0006tX-1g for bug-gnu-emacs@gnu.org; Wed, 04 Nov 2020 07:06:04 -0500 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1kaHY9-0003j7-TR for bug-gnu-emacs@gnu.org; Wed, 04 Nov 2020 07:06:01 -0500 X-Loop: help-debbugs@gnu.org Resent-From: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Wed, 04 Nov 2020 12:06:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 43764 X-GNU-PR-Package: emacs Original-Received: via spool by 43764-submit@debbugs.gnu.org id=B43764.160449152614279 (code B ref 43764); Wed, 04 Nov 2020 12:06:01 +0000 Original-Received: (at 43764) by debbugs.gnu.org; 4 Nov 2020 12:05:26 +0000 Original-Received: from localhost ([127.0.0.1]:47754 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1kaHXa-0003iF-7p for submit@debbugs.gnu.org; Wed, 04 Nov 2020 07:05:26 -0500 Original-Received: from mail228c50.megamailservers.eu ([91.136.10.238]:34908 helo=mail36c50.megamailservers.eu) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1kaHXW-0003i5-RJ for 43764@debbugs.gnu.org; Wed, 04 Nov 2020 07:05:25 -0500 X-Authenticated-User: mattiase@bredband.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=megamailservers.eu; s=maildub; t=1604490903; bh=pCEG09W3lZnRWenBtVzDcSIaizTYyN5H9Nkl2mj7bJY=; h=Subject:From:In-Reply-To:Date:Cc:References:To:From; b=EkKV8LrZ1xtCxIuVOD7qTVbO3AAuqypQv6iO9RjcHlgKFBBuWAfHPP3TDRtHUMv/z pojRxs43hWun5th/MYrUgNHQfzLMwfjS6Aah5JDIZ0gMSit40dF/GJtQq3UZCIllHG aqq2aHszpyaXOelSweEUFu2KyfxxTqwjZU8HuLzc= Feedback-ID: mattiase@acm.or Original-Received: from [192.168.0.4] (c188-150-171-71.bredband.comhem.se [188.150.171.71]) (authenticated bits=0) by mail36c50.megamailservers.eu (8.14.9/8.13.1) with ESMTP id 0A4Bt0P8008638; Wed, 4 Nov 2020 11:55:01 +0000 In-Reply-To: X-Mailer: Apple Mail (2.3445.104.17) X-CTCH-RefID: str=0001.0A782F1D.5FA29697.0058, 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-CSC: 0 X-CHA: v=2.3 cv=Q4ysHL+a c=1 sm=1 tr=0 a=SF+I6pRkHZhrawxbOkkvaA==:117 a=SF+I6pRkHZhrawxbOkkvaA==:17 a=IkcTkHD0fZMA:10 a=M51BFTxLslgA:10 a=IgnxdLyDNf8g7E7q9YIA:9 a=QEXdDO2ut3YA:10 X-Origin-Country: SE X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:192666 Archived-At: 4 nov. 2020 kl. 12.14 skrev Vincent Bela=C3=AFche = : > I can see no reason why modulo form would need some special nil case, = and I suspect that at some point of time the bit-width clipping could be = disabled by setting the width to nil. So now, don't we have two = conventions in the code : 0 and nil. =46rom my reading of math-binary-modulo-args, the word width (w) isn't = tested because calc-word-size can be nil, but because it may be passed = as an optional argument. See calcFunc-and for an example. > Also, I noticed that the Calc test suite does not have any test case = (or I missed it) for binary operations + modulo forms. The Calc test suite is minimal and mostly consists of regression tests = added when fixing bugs during the last year or so. The vast bulk of Calc = remains untested. Contributions are welcome! > Also, concerning your comment about the rotate right by n bits of = numbers with non zero least significant n bits, and with disabled bit = width clipping, Calc has the infinite mode (press 'm i'), so if you = decide some day to make this sort of implementation, then you should = emit an error w/o infinite mode, but have a +inf with infinite mode. A = bit (n-1) equal to 1 won't cause any -inf, because two complement = signing is not possible with disabled bit width clipping, as this would = result in an infinite number of FFFFFF with negative finite numbers. My remarks were probably not very well thought out, sorry. Infinities = and bitwise operations seem difficult to reconcile in general; for = example, (+inf AND 1) is undefined. Any extension to include =C2=B1inf = would need better underpinning than my feeble attempt. Note however that with disabled bit width, negative numbers do in fact = have an infinite number of leading ones, just as nonnegative numbers = have an infinite numbers of leading zeros. This is just how two's = complement works when there is no limited word size, and it doesn't = involve actual infinites. > I also notice that when two's complement signing display is on (type = 'O d 6'), and bit width is set to 0 to disable bit width clipping, then = the signing display is done as if the TwosComp mode was off. I think = that it is OK to do that, but when 'b w 0 RET' or 'O d 6' is pressed, = which ever comes last, and we have this conflict, then a warning message = should be emitted, something like =C2=AB Twos complement sign display is = ignored when bit word width is not specified =C2=BB. Yes, there are probably edge cases where usability can be improved, but = it didn't seem to involve actual errors or user deception so I didn't = bother do more work than necessary. Thank you very much for your remarks!