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: Thu, 12 Aug 2021 16:42:35 +0300 Message-ID: <83o8a2dbjo.fsf@gnu.org> References: <855zzpf86u.fsf@gmail.com> <87zhx1ktp0.fsf@gmx.net> <87zhwwhp9i.fsf@gmail.com> <87mtpmls3p.fsf_-_@gnus.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="14071"; mail-complaints-to="usenet@ciao.gmane.io" Cc: andrewjmoreton@gmail.com, 32605@debbugs.gnu.org To: Lars Ingebrigtsen Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Thu Aug 12 15:44:12 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 1mEB0G-0003RI-9i for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 12 Aug 2021 15:44:12 +0200 Original-Received: from localhost ([::1]:40334 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mEB0E-0000YH-Aw for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 12 Aug 2021 09:44:10 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:42608) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mEB07-0000Tr-VL for bug-gnu-emacs@gnu.org; Thu, 12 Aug 2021 09:44:03 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:54542) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mEB06-0000cB-KG for bug-gnu-emacs@gnu.org; Thu, 12 Aug 2021 09:44:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1mEB06-0005va-HS for bug-gnu-emacs@gnu.org; Thu, 12 Aug 2021 09:44:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Thu, 12 Aug 2021 13:44:02 +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=B32605.162877578722715 (code B ref 32605); Thu, 12 Aug 2021 13:44:02 +0000 Original-Received: (at 32605) by debbugs.gnu.org; 12 Aug 2021 13:43:07 +0000 Original-Received: from localhost ([127.0.0.1]:37855 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mEAz9-0005uF-9e for submit@debbugs.gnu.org; Thu, 12 Aug 2021 09:43:07 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:33476) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mEAz3-0005tg-HJ for 32605@debbugs.gnu.org; Thu, 12 Aug 2021 09:43:01 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:38006) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mEAyy-0008UW-A0; Thu, 12 Aug 2021 09:42:52 -0400 Original-Received: from 84.94.185.95.cable.012.net.il ([84.94.185.95]:4923 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 1mEAyx-0002kz-TB; Thu, 12 Aug 2021 09:42:52 -0400 In-Reply-To: <87mtpmls3p.fsf_-_@gnus.org> (message from Lars Ingebrigtsen on Thu, 12 Aug 2021 15:17:46 +0200) 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:211676 Archived-At: > From: Lars Ingebrigtsen > Cc: 32605@debbugs.gnu.org, Eli Zaretskii > Date: Thu, 12 Aug 2021 15:17:46 +0200 > > Andy Moreton writes: > > >> This bug seems specific to 64 bit Windows builds. > > > > ON 64bit Windows, sysdep.c sets RAND_BITS to 31, but random (in w32.c) > > only provides 30 bits. It looks like the mixing in get_random does not > > result in the top fixnum bit being set. > > So it's this: > > int > random (void) > { > /* rand_as183 () gives us 15 random bits...hack together 30 bits. */ > return ((rand_as183 () << 15) | rand_as183 ()); > } > > So running rand_as183 and taking another bit from that might do the > trick? Eli, do you have any comments here? The 'random' emulation in w32.c was never adapted to w64. Instead of calling rand_as183 one more time, perhaps it's better to trivially transform the value we have? Something like int val = ((rand_as183 () << 15) | rand_as183 ()); #ifdef __x86_64__ return 2 * val - 0x3FFFFFFF; #else return val; #endif Andy, can you test this, please?