From: Andy Moreton <andrewjmoreton@gmail.com>
To: 32605@debbugs.gnu.org
Subject: bug#32605: 26.1; (random) never returns negative
Date: Wed, 05 Sep 2018 14:20:48 +0100 [thread overview]
Message-ID: <vz1k1o05bdb.fsf@gmail.com> (raw)
In-Reply-To: <855zzpf86u.fsf@gmail.com>
On Tue 04 Sep 2018, Noam Postavsky wrote:
> retitle 32605 [w64] (random) never returns negative
> tags 32605 + confirmed
> quit
>
> Stephen Berman <stephen.berman@gmx.net> writes:
>
>> On Sat, 01 Sep 2018 18:18:01 +0100 Francis Wright <francis.j.wright@gmail.com> wrote:
>>> Therefore, it should return a negative integer
>>> half the time, but I have never yet seen it return a negative value.
>
>>> In GNU Emacs 26.1 (build 1, x86_64-w64-mingw32)
>
>> Prompted by this report, I just ran `M-: (random)' twice, with these
>> results:
>>
>> 1407814790132564328 (#o116114401367331100550, #x13899017bb648168)
>> -5902216973509885 (#o-247600437205762375, #x-14f808fa17e4fd)
>>
>> This was on a build from current master under GNU/Linux
>
> 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.
AndyM
next prev parent reply other threads:[~2018-09-05 13:20 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-01 17:18 bug#32605: 26.1; (random) never returns negative Francis Wright
2018-09-01 17:34 ` Stephen Berman
2018-09-04 22:27 ` Noam Postavsky
2018-09-05 13:20 ` Andy Moreton [this message]
2021-08-12 13:17 ` bug#32605: [w64] " Lars Ingebrigtsen
2021-08-12 13:42 ` Eli Zaretskii
2021-08-12 20:34 ` Andy Moreton
2021-08-13 6:29 ` Eli Zaretskii
2021-08-13 21:12 ` Andy Moreton
2021-08-14 5:54 ` Eli Zaretskii
2021-08-14 8:31 ` Andy Moreton
2021-08-14 8:57 ` Eli Zaretskii
2021-08-14 11:06 ` Andy Moreton
2021-08-14 11:33 ` Eli Zaretskii
2021-08-14 12:10 ` Andy Moreton
2021-08-14 12:36 ` Eli Zaretskii
2021-08-14 13:40 ` Andy Moreton
2021-08-14 14:43 ` Eli Zaretskii
2021-08-14 18:47 ` Andy Moreton
2021-08-15 6:07 ` Eli Zaretskii
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