From patchwork Tue Aug 24 13:33:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Shevchenko X-Patchwork-Id: 502605 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 3D539C4338F for ; Tue, 24 Aug 2021 13:34:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D4FF613B1 for ; Tue, 24 Aug 2021 13:34:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237591AbhHXNe4 (ORCPT ); Tue, 24 Aug 2021 09:34:56 -0400 Received: from mga18.intel.com ([134.134.136.126]:13438 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231237AbhHXNew (ORCPT ); Tue, 24 Aug 2021 09:34:52 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10085"; a="204444829" X-IronPort-AV: E=Sophos;i="5.84,347,1620716400"; d="scan'208";a="204444829" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2021 06:34:04 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,347,1620716400"; d="scan'208";a="685368422" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga005.fm.intel.com with ESMTP; 24 Aug 2021 06:33:55 -0700 Received: by black.fi.intel.com (Postfix, from userid 1003) id 5F4E4167; Tue, 24 Aug 2021 16:33:56 +0300 (EEST) From: Andy Shevchenko To: Mauro Carvalho Chehab , Sakari Ailus , Andy Shevchenko , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Yong Zhi , Bingbu Cao , Dan Scally , Tianshu Qiu , Mauro Carvalho Chehab Subject: [PATCH v1 2/3] lib/sort: Introduce rotate() to circular shift an array of elements Date: Tue, 24 Aug 2021 16:33:50 +0300 Message-Id: <20210824133351.88179-2-andriy.shevchenko@linux.intel.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210824133351.88179-1-andriy.shevchenko@linux.intel.com> References: <20210824133351.88179-1-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org In some cases we want to circular shift an array of elements. Introduce rotate() helper for that. Signed-off-by: Andy Shevchenko --- include/linux/sort.h | 3 +++ lib/sort.c | 61 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 64 insertions(+) diff --git a/include/linux/sort.h b/include/linux/sort.h index b5898725fe9d..c881acb12ffc 100644 --- a/include/linux/sort.h +++ b/include/linux/sort.h @@ -13,4 +13,7 @@ void sort(void *base, size_t num, size_t size, cmp_func_t cmp_func, swap_func_t swap_func); +void rotate(void *base, size_t num, size_t size, size_t by, + swap_func_t swap_func); + #endif diff --git a/lib/sort.c b/lib/sort.c index d9b2f5b73620..b9243f8db34b 100644 --- a/lib/sort.c +++ b/lib/sort.c @@ -14,6 +14,7 @@ #include #include +#include #include /** @@ -275,3 +276,63 @@ void sort(void *base, size_t num, size_t size, return sort_r(base, num, size, _CMP_WRAPPER, swap_func, cmp_func); } EXPORT_SYMBOL(sort); + +/** + * rotate - rotate an array of elements by a number of elements + * @base: pointer to data to sort + * @num: number of elements + * @size: size of each element + * @by: number of elements to rotate by + * @swap_func: pointer to swap function or NULL + * + * Helper function to advance all the elements of a circular buffer by + * @by positions. + */ +void rotate(void *base, size_t num, size_t size, size_t by, + swap_func_t swap_func) +{ + struct { + size_t begin, end; + } arr[2] = { + { .begin = 0, .end = by - 1 }, + { .begin = by, .end = num - 1 }, + }; + + swap_func = choose_swap_func(swap_func, base, size); + +#define CHUNK_SIZE(a) ((a)->end - (a)->begin + 1) + + /* Loop as long as we have out-of-place entries */ + while (CHUNK_SIZE(&arr[0]) && CHUNK_SIZE(&arr[1])) { + size_t size0, i; + + /* + * Find the number of entries that can be arranged on this + * iteration. + */ + size0 = min(CHUNK_SIZE(&arr[0]), CHUNK_SIZE(&arr[1])); + + /* Swap the entries in two parts of the array */ + for (i = 0; i < size0; i++) { + void *a = base + size * (arr[0].begin + i); + void *b = base + size * (arr[1].begin + i); + + do_swap(a, b, size, swap_func); + } + + if (CHUNK_SIZE(&arr[0]) > CHUNK_SIZE(&arr[1])) { + /* The end of the first array remains unarranged */ + arr[0].begin += size0; + } else { + /* + * The first array is fully arranged so we proceed + * handling the next one. + */ + arr[0].begin = arr[1].begin; + arr[0].end = arr[1].begin + size0 - 1; + arr[1].begin += size0; + } + } +#undef CHUNK_SIZE +} +EXPORT_SYMBOL(rotate);