linux-kernel - Re: [patch/rfc 2/4] pcf875x I2C GPIO expander driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <47500A4A.10006@billgatliff.com>
Date:	Fri, 30 Nov 2007 07:04:10 -0600
From:	Bill Gatliff <bgat@...lgatliff.com>
To:	Jean Delvare <khali@...ux-fr.org>
CC:	David Brownell <david-b@...bell.net>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Felipe Balbi <felipebalbi@...rs.sourceforge.net>,
	Haavard Skinnemoen <hskinnemoen@...el.com>,
	Andrew Victor <andrew@...people.com>,
	Tony Lindgren <tony@...mide.com>,
	eric miao <eric.y.miao@...il.com>,
	Kevin Hilman <khilman@...sta.com>,
	Paul Mundt <lethal@...ux-sh.org>,
	Ben Dooks <ben@...nity.fluff.org>
Subject: Re: [patch/rfc 2/4] pcf875x I2C GPIO expander driver

Jean Delvare wrote:
> !!(value & (1 << offset))
> is more efficiently written
> (value >> offset) & 1
>   

... but not more efficiently implemented.

Your version requires code to do the shift on live data at runtime.  
David's version lets the compiler create the mask once, at compile-time.



b.g.

-- 
Bill Gatliff
bgat@...lgatliff.com

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/