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From: Szabolcs Nagy <nsz@port70.net>
To: musl@lists.openwall.com
Subject: Re: sign (in)consistency between architectures
Date: Thu, 2 May 2013 12:13:51 +0200	[thread overview]
Message-ID: <20130502101351.GO12689@port70.net> (raw)
In-Reply-To: <1367482359.28119.118.camel@eris.loria.fr>

* Jens Gustedt <jens.gustedt@inria.fr> [2013-05-02 10:12:39 +0200]:
> I would prefer to have both worlds by using uint64_t (or directly the
> underlying base type) uniformly. There is no reason to have it signed:
> 

yes probably that's the best solution

but note that even that can hurt: i've seen code like

  t = (double)clock();

(eg the time module in python does this) where interesting
low bits may get lost if clock_t is uint64_t

this might be common because clock_t is permitted to be
a floating-point type

of course this should not be a problem if the cast is
applied to the difference only
(other than uint64->double conversion is usually much
slower than int32->double conversion)
..but this issue is present on 64bit platforms anyway

siginfo is affected as well: clock_t is used in the union
in it which i think is aligned with glibc now

but i'm not against the uint64_t solution if we decide
breaking glibc abi here is ok


  reply	other threads:[~2013-05-02 10:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-05-01 17:05 Z. Gilboa
2013-05-01 18:00 ` Szabolcs Nagy
2013-05-01 20:00   ` Rich Felker
2013-05-01 22:41     ` Rich Felker
2013-05-02  1:39       ` Z. Gilboa
2013-05-02  2:47         ` Rich Felker
2013-05-02  8:12           ` Jens Gustedt
2013-05-02 10:13             ` Szabolcs Nagy [this message]
2013-05-02 12:12               ` Jens Gustedt
2013-05-02 13:08                 ` Szabolcs Nagy

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