From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#32605: [w64] (random) never returns negative Date: Sat, 14 Aug 2021 14:33:00 +0300 Message-ID: <835yw8b6s3.fsf@gnu.org> References: <855zzpf86u.fsf@gmail.com> <87zhx1ktp0.fsf@gmx.net> <87zhwwhp9i.fsf@gmail.com> <87mtpmls3p.fsf_-_@gnus.org> <83o8a2dbjo.fsf@gnu.org> <86bl62s8qm.fsf@gmail.com> <83czqhdfhm.fsf@gnu.org> <861r6xoxqa.fsf@gmail.com> <83sfzcbmfm.fsf@gnu.org> <86mtpksa0l.fsf@gmail.com> <83a6lkbe02.fsf@gnu.org> <86sfzcjnfr.fsf@gmail.com> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="6315"; mail-complaints-to="usenet@ciao.gmane.io" Cc: 32605@debbugs.gnu.org To: Andy Moreton Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Sat Aug 14 13:34:12 2021 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 1mErvW-0001Qp-Pz for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 14 Aug 2021 13:34:10 +0200 Original-Received: from localhost ([::1]:35570 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mErvV-0002Yu-FA for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 14 Aug 2021 07:34:09 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:49652) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mErvO-0002Yg-M8 for bug-gnu-emacs@gnu.org; Sat, 14 Aug 2021 07:34:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:60383) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mErvO-0008Oj-Fp for bug-gnu-emacs@gnu.org; Sat, 14 Aug 2021 07:34:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1mErvO-00009h-DV for bug-gnu-emacs@gnu.org; Sat, 14 Aug 2021 07:34:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sat, 14 Aug 2021 11:34:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 32605 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: confirmed Original-Received: via spool by 32605-submit@debbugs.gnu.org id=B32605.1628940797503 (code B ref 32605); Sat, 14 Aug 2021 11:34:02 +0000 Original-Received: (at 32605) by debbugs.gnu.org; 14 Aug 2021 11:33:17 +0000 Original-Received: from localhost ([127.0.0.1]:43690 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mEruf-000083-HB for submit@debbugs.gnu.org; Sat, 14 Aug 2021 07:33:17 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:33096) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mErue-00007d-4N for 32605@debbugs.gnu.org; Sat, 14 Aug 2021 07:33:16 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:48056) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mEruY-00089O-UJ; Sat, 14 Aug 2021 07:33:10 -0400 Original-Received: from 84.94.185.95.cable.012.net.il ([84.94.185.95]:2864 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mEruX-0001wS-QG; Sat, 14 Aug 2021 07:33:10 -0400 In-Reply-To: <86sfzcjnfr.fsf@gmail.com> (message from Andy Moreton on Sat, 14 Aug 2021 12:06:00 +0100) 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:211822 Archived-At: > From: Andy Moreton > Date: Sat, 14 Aug 2021 12:06:00 +0100 > > >> I'm not an expert on random numbers either, and your efforts are not an > >> annoyance, but I am puzzled why you so strongly prize performance over > >> correctness in this instance. > > > > Because I have no idea how important the "correctness" part is, or > > why. OTOH, this stuff, when used, tends to be in the inner loops, so > > performance matters. > > I doubt anyone expects cryptographic quality randomness or any given > statistical distribution from such a general purpose routine, but they > have a reasonable expectation that the results from 'get_random' do not > have stuck bits that are always non-random. > > In which case perhaps the solution is to change the RAND_BITS logic > in sysdep.c on Windows to override the RAND_BITS definition: > > + #ifdef WINDOWSNT > + /* Use w32.c replacement for random(). */ > + # define RAND_BITS 15 > + #endif > > #ifndef RAND_BITS > # ifdef HAVE_RANDOM > # define RAND_BITS 31 > # else /* !HAVE_RANDOM */ > ... > #endif > > ..and then in w32.c make 'random' return the 15bit value from > 'rand_as183': Why not keep the 30 bits we produce today on 32-bit builds?