Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758029AbXKLHfT (ORCPT ); Mon, 12 Nov 2007 02:35:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753913AbXKLHfG (ORCPT ); Mon, 12 Nov 2007 02:35:06 -0500 Received: from astoria.ccjclearline.com ([64.235.106.9]:36938 "EHLO astoria.ccjclearline.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753902AbXKLHfE (ORCPT ); Mon, 12 Nov 2007 02:35:04 -0500 Date: Mon, 12 Nov 2007 02:32:04 -0500 (EST) From: "Robert P. J. Day" X-X-Sender: rpjday@localhost.localdomain To: Linux Kernel Mailing List cc: Andrew Morton Subject: [PATCH] log2.h: Define order_base_2() macro for convenience. Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - astoria.ccjclearline.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - crashcourse.ca X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1557 Lines: 51 Given a number of places in the tree that need to calculate this value explicitly, might as well just create a macro for it. Signed-off-by: Robert P. J. Day --- run-time tested for the first several values. note that this macro is defined strictly in terms of rounding *up* -- i've seen no places in the tree that require this expression to be rounded down, so i'm not drawing that distinction. diff --git a/include/linux/log2.h b/include/linux/log2.h index c8cf5e8..ed121c0 100644 --- a/include/linux/log2.h +++ b/include/linux/log2.h @@ -190,4 +190,20 @@ unsigned long __rounddown_pow_of_two(unsigned long n) __rounddown_pow_of_two(n) \ ) +/** + * order_base_2 - calculate the (rounded up) base 2 order of the argument + * @n: parameter + * + * The first few values calculated by this routine: + * ob2(0) = 0 + * ob2(1) = 0 + * ob2(2) = 1 + * ob2(3) = 2 + * ob2(4) = 2 + * ob2(5) = 3 + * ... and so on. + */ + +#define order_base_2(n) ilog2(roundup_pow_of_two(n)) + #endif /* _LINUX_LOG2_H */ -- ======================================================================== Robert P. J. Day Linux Consulting, Training and Annoying Kernel Pedantry Waterloo, Ontario, CANADA http://crashcourse.ca ======================================================================== - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/