From: Eli Zaretskii <eliz@gnu.org>
To: Andy Moreton <andrewjmoreton@gmail.com>
Cc: 32605@debbugs.gnu.org
Subject: bug#32605: [w64] (random) never returns negative
Date: Sat, 14 Aug 2021 14:33:00 +0300 [thread overview]
Message-ID: <835yw8b6s3.fsf@gnu.org> (raw)
In-Reply-To: <86sfzcjnfr.fsf@gmail.com> (message from Andy Moreton on Sat, 14 Aug 2021 12:06:00 +0100)
> From: Andy Moreton <andrewjmoreton@gmail.com>
> 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?
next prev parent reply other threads:[~2021-08-14 11:33 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
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 [this message]
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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