From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753606AbbBXRmw (ORCPT ); Tue, 24 Feb 2015 12:42:52 -0500 Received: from mail-we0-f173.google.com ([74.125.82.173]:39970 "EHLO mail-we0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753467AbbBXRmD (ORCPT ); Tue, 24 Feb 2015 12:42:03 -0500 From: Bartosz Golaszewski To: LKML Cc: Guenter Roeck , Jean Delvare , lm-sensors , Bartosz Golaszewski Subject: [PATCH 1/4] kernel.h: add find_closest() macro Date: Tue, 24 Feb 2015 18:42:11 +0100 Message-Id: <1424799734-2170-2-git-send-email-bgolaszewski@baylibre.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1424799734-2170-1-git-send-email-bgolaszewski@baylibre.com> References: <1424799734-2170-1-git-send-email-bgolaszewski@baylibre.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Searching for the member of an array closest to 'x' is duplicated in several places. Add two macros that implement this algorithm for arrays sorted both in ascending and descending order. Signed-off-by: Bartosz Golaszewski --- include/linux/kernel.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index d6d630d..f4294da 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -116,6 +116,29 @@ } \ ) +#define __find_closest(x, a, as, op)( \ +{ \ + typeof(as) _i, _as = (as) - 1; \ + typeof(x) _x = (x); \ + typeof(*a) *_a = (a); \ + for (_i = 0; _i < _as; _i++) { \ + if (_x op DIV_ROUND_CLOSEST(_a[_i] + _a[_i + 1], 2)) \ + break; \ + } \ + (_i); \ +} \ +) + +/* + * Given an array 'a' (sorted in ascending order) of size 'as' return + * the index of the element in that array closest to 'x'. + */ +#define find_closest(x, a, as) __find_closest(x, a, as, <=) +/* + * Similar to find_closest(), but 'a' is expected to be sorted + * in descending order. + */ +#define find_closest_desc(x, a, as) __find_closest(x, a, as, >) #define _RET_IP_ (unsigned long)__builtin_return_address(0) #define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; }) -- 2.1.4