From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [RFC] enhanced version of net_random() Date: Sun, 22 Aug 2004 17:04:14 +0200 Sender: netdev-bounce@oss.sgi.com Message-ID: <20040822170414.3ecab1e5.ak@suse.de> References: <20040812104835.3b179f5a@dell_ss3.pdx.osdl.net> <20040820175952.GI5806@certainkey.com> <20040820185956.GV8967@schnapps.adilger.int> <20040820124823.071ac1d9.davem@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: root@chaos.analogic.com, adilger@clusterfs.com, jlcooke@certainkey.com, shemminger@osdl.org, alan@lxorguk.ukuu.org.uk, tytso@mit.edu, netdev@oss.sgi.com, linux-kernel@vger.kernel.org Return-path: To: "David S. Miller" In-Reply-To: <20040820124823.071ac1d9.davem@redhat.com> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org On Fri, 20 Aug 2004 12:48:23 -0700 "David S. Miller" wrote: > > I wouldn't suggest converting it to 'C' because the rotation > > takes many CPU instructions when one tries to do the test, shift, > > and OR in 'C', > > You only need 2 'shifts' and an 'or' to do a rotate in C. > No tests are needed. gcc is clever enough to detect the common C patterns for rotate and generate a real ROL when the CPU supports it. -Andi