From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09809C43381 for ; Fri, 22 Mar 2019 18:22:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA4AE21917 for ; Fri, 22 Mar 2019 18:22:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727298AbfCVSWu (ORCPT ); Fri, 22 Mar 2019 14:22:50 -0400 Received: from mga06.intel.com ([134.134.136.31]:1681 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726875AbfCVSWt (ORCPT ); Fri, 22 Mar 2019 14:22:49 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Mar 2019 11:22:48 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,256,1549958400"; d="scan'208";a="331109085" Received: from smile.fi.intel.com (HELO smile) ([10.237.72.86]) by fmsmga005.fm.intel.com with ESMTP; 22 Mar 2019 11:22:45 -0700 Received: from andy by smile with local (Exim 4.92) (envelope-from ) id 1h7OoW-0005Wr-F7; Fri, 22 Mar 2019 20:22:44 +0200 Date: Fri, 22 Mar 2019 20:22:44 +0200 From: Andy Shevchenko To: William Breathitt Gray Cc: linus.walleij@linaro.org, akpm@linux-foundation.org, linux-gpio@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux@rasmusvillemoes.dk, yamada.masahiro@socionext.com, bgolaszewski@baylibre.com, linux-arm-kernel@lists.infradead.org, Arnd Bergmann Subject: Re: [PATCH v10 01/10] bitops: Introduce the for_each_set_clump8 macro Message-ID: <20190322182244.GZ9224@smile.fi.intel.com> References: <0e4d352418252d480dfc7d529604819f8ff88d9c.1552566113.git.vilhelm.gray@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0e4d352418252d480dfc7d529604819f8ff88d9c.1552566113.git.vilhelm.gray@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 14, 2019 at 09:30:02PM +0900, William Breathitt Gray wrote: > This macro iterates for each 8-bit group of bits (clump) with set bits, > within a bitmap memory region. For each iteration, "start" is set to the > bit offset of the found clump, while the respective clump value is > stored to the location pointed by "clump". Additionally, the > bitmap_get_value8 and bitmap_set_value8 functions are introduced to > respectively get and set an 8-bit value in a bitmap memory region. > +void bitmap_set_value8(unsigned long *const bitmap, const unsigned int size, > + const unsigned long value, const unsigned int start) > +{ > + const size_t index = BIT_WORD(start); > + const unsigned int offset = start % BITS_PER_LONG; > + const unsigned int low_width = (offset + 8 > BITS_PER_LONG) ? > + BITS_PER_LONG - offset : 8; > + const unsigned long low_mask = GENMASK(offset + low_width - 1, offset); I think unsigned long low_mask = GENMASK(low_width - 1, 0) << offset; will generate better code. > + const unsigned int high_width = 8 - low_width; > + const unsigned long high_mask = GENMASK(high_width - 1, 0); > + > + /* set lower portion */ > + bitmap[index] &= ~low_mask; > + bitmap[index] |= value << offset; > + > + /* set higher portion if space available in bitmap */ > + if (high_width && start + 8 <= size) { > + bitmap[index + 1] &= ~high_mask; > + bitmap[index + 1] |= value >> low_width; > + } > +} > +EXPORT_SYMBOL(bitmap_set_value8); -- With Best Regards, Andy Shevchenko