From: Thomas Hood <jdthood@mail.com>
To: linux-kernel@vger.kernel.org
Subject: Re: RFC: booleans and the kernel
Date: 25 Jan 2002 06:28:37 -0500 [thread overview]
Message-ID: <1011958120.1219.2.camel@thanatos> (raw)
Jeff Garzik wrote:
> A small issue...
... bound therefore to generate the most discussion ...
> C99 introduced _Bool as a builtin type. The gcc patch for
> it went into cvs around Dec 2000. Any objections to
> propagating this type and usage of 'true' and 'false' around
> the kernel?
What concerns me is the question of casting. Will truth always
cast to integer value 1 and falsehood always cast to integer
value 0, and vice versa? If so then the bool type is a lot
like a "bit" type would be if C had one, i.e., a very short
integer variable limited to the values 0 and 1. If the casts
are not guaranteed then bool is a lot like an enumerated type
where the compiler is free to choose whatever representations
it wants for truth and falsehood.
I assume the casts are guaranteed. E.g., I take it that the
result of a logical comparison is considered to be of type
bool, but that the following will increment val by 1 if a > b
val += (a > b)
In that case, perhaps it would be more perspicuous to define
a "bit" type rather than a "bool" type, and to use 0 and 1 as
its values rather than 'true' and 'false'. (A "bit" type
would have all the advantages mentioned earlier by Peter Anvin
http://marc.theaimsgroup.com/?l=linux-kernel&m=101191106124169&w=2 .)
--
Thomas Hood
next reply other threads:[~2002-01-25 11:28 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-25 11:28 Thomas Hood [this message]
2002-01-25 11:39 ` RFC: booleans and the kernel Xavier Bestel
-- strict thread matches above, loose matches on Subject: below --
2002-01-26 15:48 Ben Bridgwater
2002-01-25 11:09 Helge Hafting
2002-01-26 3:08 ` Jamie Lokier
2002-01-26 9:13 ` Mark Zealey
2002-01-27 19:58 ` Jamie Lokier
2002-01-26 10:51 ` Gábor Lénárt
2002-01-26 16:27 ` Jamie Lokier
2002-01-24 17:42 Jeff Garzik
2002-01-24 18:22 ` Anton Altaparmakov
2002-01-24 18:33 ` Arnaldo Carvalho de Melo
2002-01-24 19:28 ` H. Peter Anvin
2002-01-24 19:34 ` Arnaldo Carvalho de Melo
2002-01-24 19:43 ` H. Peter Anvin
2002-01-24 19:47 ` Arnaldo Carvalho de Melo
2002-01-24 19:46 ` Ingo Oeser
2002-01-24 19:52 ` Oliver Xymoron
2002-01-24 20:03 ` Jeff Garzik
2002-01-24 20:06 ` Oliver Xymoron
2002-01-24 20:14 ` Jeff Garzik
2002-01-24 20:23 ` Alexander Viro
2002-01-24 20:25 ` Oliver Xymoron
2002-01-24 20:35 ` John Levon
2002-01-24 20:15 ` Alexander Viro
2002-01-24 20:21 ` Richard B. Johnson
2002-01-24 20:39 ` Oliver Xymoron
2002-01-24 21:55 ` Richard B. Johnson
2002-01-24 21:57 ` Jeff Garzik
2002-01-24 22:05 ` H. Peter Anvin
2002-01-24 22:13 ` Robert Love
2002-01-24 22:33 ` Xavier Bestel
2002-01-24 22:53 ` Xavier Bestel
2002-01-24 22:59 ` Robert Love
2002-01-24 23:27 ` Xavier Bestel
2002-01-25 6:13 ` Alexander Viro
2002-01-25 8:00 ` Momchil Velikov
2002-01-25 10:51 ` Xavier Bestel
2002-01-25 16:11 ` Olivier Galibert
2002-01-26 7:22 ` Timothy Covell
2002-01-25 7:48 ` Alexander Viro
2002-01-25 23:49 ` J.A. Magallon
2002-01-27 11:27 ` Kai Henningsen
2002-01-25 23:09 ` Timothy Covell
2002-01-25 1:16 ` John Levon
2002-01-25 22:47 ` Timothy Covell
2002-01-25 21:24 ` Timothy Covell
2002-01-24 21:31 ` Oliver Xymoron
2002-01-24 22:19 ` Robert Love
2002-01-24 22:38 ` Robert Love
2002-01-25 22:44 ` Timothy Covell
2002-01-25 3:52 ` Ragnar Hojland Espinosa
2002-01-25 20:39 ` Calin A. Culianu
2002-01-25 23:07 ` Rick Stevens
2002-01-25 19:02 ` Kai Henningsen
2002-01-27 1:33 ` Timothy Covell
2002-01-26 2:56 ` Jamie Lokier
2002-01-27 11:18 ` Kai Henningsen
2002-01-25 22:30 ` Timothy Covell
2002-01-24 22:36 ` Alexander Viro
2002-01-25 6:36 ` Kai Henningsen
[not found] ` <200201250900.g0P8xoL10082@home.ashavan.org.>
2002-01-29 6:36 ` Nix N. Nix
2002-01-25 21:43 ` Timothy Covell
2002-01-24 21:50 ` Oliver Xymoron
2002-01-24 22:21 ` H. Peter Anvin
2002-01-25 15:07 ` Werner Almesberger
2002-01-25 15:21 ` Jakub Jelinek
2002-01-25 16:45 ` H. Peter Anvin
2002-01-25 11:07 ` Helge Hafting
2002-01-24 22:33 ` Chris Wedgwood
2002-01-24 22:44 ` H. Peter Anvin
2002-01-26 10:22 ` Chris Wedgwood
2002-01-25 2:00 ` Erik Andersen
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