From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751040AbWIMSgk (ORCPT ); Wed, 13 Sep 2006 14:36:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751079AbWIMSfo (ORCPT ); Wed, 13 Sep 2006 14:35:44 -0400 Received: from mx1.redhat.com ([66.187.233.31]:1423 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1751076AbWIMSfj (ORCPT ); Wed, 13 Sep 2006 14:35:39 -0400 From: David Howells Subject: [PATCH 6/7] Alter roundup_pow_of_two() so that it can make use of ilog2() on a constant [try #3] Date: Wed, 13 Sep 2006 19:35:33 +0100 To: torvalds@osdl.org, akpm@osdl.org Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, dhowells@redhat.com Message-Id: <20060913183533.22109.85070.stgit@warthog.cambridge.redhat.com> In-Reply-To: <20060913183522.22109.10565.stgit@warthog.cambridge.redhat.com> References: <20060913183522.22109.10565.stgit@warthog.cambridge.redhat.com> Content-Type: text/plain; charset=utf-8; format=fixed Content-Transfer-Encoding: 8bit User-Agent: StGIT/0.10 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: David Howells Alter roundup_pow_of_two() so that it can make use of ilog2() on a constant to produce a constant value, retaining the ability for an arch to override it in the non-const case. This permits the function to be used to initialise variables. Signed-Off-By: David Howells --- include/linux/kernel.h | 6 ------ include/linux/log2.h | 26 ++++++++++++++++++++++++++ 2 files changed, 26 insertions(+), 6 deletions(-) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index e8c6c66..e5947fb 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -155,12 +155,6 @@ #endif unsigned long int_sqrt(unsigned long); -static inline unsigned long -__attribute_const__ roundup_pow_of_two(unsigned long x) -{ - return 1UL << fls_long(x - 1); -} - extern int printk_ratelimit(void); extern int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst); diff --git a/include/linux/log2.h b/include/linux/log2.h index 88b7b0e..c7574a6 100644 --- a/include/linux/log2.h +++ b/include/linux/log2.h @@ -73,6 +73,15 @@ #endif } #endif +/* + * round up to nearest power of two + */ +static inline __attribute__((const)) +unsigned long __roundup_pow_of_two(unsigned long n) +{ + return 1UL << fls_long(n - 1); +} + /** * ilog2_u32 - log of base 2 of 32-bit unsigned value * @n - parameter @@ -230,4 +239,21 @@ ( \ __get_order(n, PAGE_SHIFT) \ ) +/** + * roundup_pow_of_two - round the given value up to nearest power of two + * @n - parameter + * + * round the given balue up to the nearest power of two + * - the result is undefined when n == 0 + * - this can be used to initialise global variables from constant data + */ +#define roundup_pow_of_two(n) \ +( \ + __builtin_constant_p(n) ? ( \ + (n == 1) ? 0 : \ + (1UL << (ilog2((n) - 1) + 1)) \ + ) : \ + __roundup_pow_of_two(n) \ + ) + #endif /* _LINUX_LOG2_H */