From: wwp <subscript@free.fr>
To: linux-c-programming@vger.kernel.org
Subject: Re: bitfield array
Date: Mon, 12 Jan 2004 11:29:26 +0100 [thread overview]
Message-ID: <20040112112926.4e5794e3@tethys> (raw)
In-Reply-To: <20040112111016.000072cf.cialdi@firenze.net>
Hi Massimiliano Cialdi,
On Mon, 12 Jan 2004 11:10:16 +0100 Massimiliano Cialdi <cialdi@firenze.net> wrote:
> Is it possible to declare a bitfield array?
> I tried with
>
> typedef struct
> {
> u8_t busy[10]:1;
> }dummy;
>
> but I obtain an error:
> error: bit-field `busy' has invalid type
>
> I also tried with
>
> typedef struct
> {
> u8_t busy:1;
> }dummy;
> dummy a[10];
>
> but then a is as large as 10 bytes.
AFAIK, bitfields are stored in memory block which can only be allocated with
1-byte minimum.. Try to allocate 1 bit in memory, sounds not possible :-).
IOW, if you use a 1-bit bitfield, it will still be require an amount of memory
counted in bytes. That's partly why bitfields are not so used for
optimization, 'cause following the compiler you don't gaim memory space not
cpu time.
My 2cts.
Regards,
--
wwp
next prev parent reply other threads:[~2004-01-12 10:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-12 10:10 bitfield array Massimiliano Cialdi
2004-01-12 10:29 ` wwp [this message]
2004-01-12 10:56 ` Massimiliano Cialdi
2004-01-12 13:40 ` Mariano Moreyra
2004-01-13 1:02 ` James Stevenson
2004-01-12 21:06 ` Glynn Clements
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20040112112926.4e5794e3@tethys \
--to=subscript@free.fr \
--cc=linux-c-programming@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).