From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752294AbcDOQIq (ORCPT ); Fri, 15 Apr 2016 12:08:46 -0400 Received: from smtprelay0033.hostedemail.com ([216.40.44.33]:45220 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751581AbcDOQIp (ORCPT ); Fri, 15 Apr 2016 12:08:45 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1539:1568:1593:1594:1711:1714:1730:1747:1777:1792:2393:2559:2562:2828:3138:3139:3140:3141:3142:3151:3622:3865:3868:3871:4321:5007:6120:7514:7576:7901:10004:10400:10848:11232:11657:11658:11783:11914:12043:12517:12519:12740:13069:13311:13357:13439:13894:14181:14659:14721:21080:30054:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:3,LUA_SUMMARY:none X-HE-Tag: nose45_4c033ee59025b X-Filterd-Recvd-Size: 1584 Message-ID: <1460736514.19090.32.camel@perches.com> Subject: Re: [PATCH V3] blackfin: optimize ffz, __ffs, ffs, __fls, and fls functions From: Joe Perches To: zengzhaoxiu@163.com, linux-kernel@vger.kernel.org Cc: Zeng Zhaoxiu , Steven Miao , adi-buildroot-devel@lists.sourceforge.net Date: Fri, 15 Apr 2016 09:08:34 -0700 In-Reply-To: <1460733645-77406-1-git-send-email-zengzhaoxiu@163.com> References: <1460706724-15953-1-git-send-email-zengzhaoxiu@163.com> <1460733645-77406-1-git-send-email-zengzhaoxiu@163.com> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.18.5.2-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2016-04-15 at 23:20 +0800, zengzhaoxiu@163.com wrote: > From: Zeng Zhaoxiu > > blackfin has popcount instruction (ONES), we can do the efficient > computing (ffz, __ffs, ffs, __fls, and fls) use this instruction. [] > diff --git a/arch/blackfin/include/asm/bitops.h b/arch/blackfin/include/asm/bitops.h [] > +static inline unsigned int __arch_hweight64(__u64 w) > +{ > + return __arch_hweight32((unsigned int)(w >> 32)) + > +        __arch_hweight32((unsigned int)w); > +} trivia:  perhaps this is more readable as: return __arch_hweight32(upper_32_bits(w)) +        __arch_hweight32(lower_32_bits(w));