From: Tim Walberg <twalberg@comcast.net>
To: Michal Nazarewicz <mina86@tlen.pl>
Cc: ratheesh k <ratheesh.ksz@gmail.com>, linux-c-programming@vger.kernel.org
Subject: Re: union to get parts of integer
Date: Mon, 20 Dec 2010 09:30:08 -0600 [thread overview]
Message-ID: <20101220153008.GH16355@comcast.net> (raw)
In-Reply-To: <87aak0tsf3.fsf@erwin.mina86.com>
It's likely that either the union or direct pointer expressions yield
more efficient code, as they can probably be compiled to direct byte-width
load/store instructions, rather than shifts and logical ands... However,
if the code's not in a critical path for performance, it probably won't
matter. And on some architectures, there may not be byte-width operations,
I guess...
On 12/20/2010 15:44 +0100, Michal Nazarewicz wrote:
>>
>> ((char *)&i)[0].
>>
>> However, are you sure that you need this? Don't you need "(i & 255)",
>> "((i >> 8) & 255)", etc. instead?
>>
>> --
>> Best regards, _ _
>> .o. | Liege of Serenly Enlightened Majesty of o' \,=./ `o
>> ..o | Computer Science, Michal "mina86" Nazarewicz (o o)
>> ooo +--<mina86-tlen.pl>--<jid:mina86-jabber.org>--ooO--(_)--Ooo--
End of included message
--
+----------------------+
| Tim Walberg |
| 830 Carriage Dr. |
| Algonquin, IL 60102 |
| twalberg@comcast.net |
+----------------------+
next prev parent reply other threads:[~2010-12-20 15:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-20 10:40 union to get parts of integer ratheesh k
2010-12-20 12:03 ` Reza Hoorfar
2010-12-20 14:44 ` Michal Nazarewicz
2010-12-20 15:30 ` Tim Walberg [this message]
2010-12-20 15:40 ` Michal Nazarewicz
2010-12-21 16:22 ` 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=20101220153008.GH16355@comcast.net \
--to=twalberg@comcast.net \
--cc=linux-c-programming@vger.kernel.org \
--cc=mina86@tlen.pl \
--cc=ratheesh.ksz@gmail.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.