Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932325AbWJFNg6 (ORCPT ); Fri, 6 Oct 2006 09:36:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932354AbWJFNg6 (ORCPT ); Fri, 6 Oct 2006 09:36:58 -0400 Received: from mx1.redhat.com ([66.187.233.31]:35490 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S932335AbWJFNfA (ORCPT ); Fri, 6 Oct 2006 09:35:00 -0400 From: David Howells Subject: [PATCH 2/4] LOG2: Alter roundup_pow_of_two() so that it can use a ilog2() on a constant [try #4] Date: Fri, 06 Oct 2006 14:34:17 +0100 To: torvalds@osdl.org, akpm@osdl.org, sfr@canb.auug.org.au Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, dhowells@redhat.com Message-Id: <20061006133417.9972.76941.stgit@warthog.cambridge.redhat.com> In-Reply-To: <20061006133414.9972.79007.stgit@warthog.cambridge.redhat.com> References: <20061006133414.9972.79007.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 Content-Length: 2206 Lines: 79 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 473101a..67ca3ad 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -156,12 +156,6 @@ #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 3979c60..d02e1a5 100644 --- a/include/linux/log2.h +++ b/include/linux/log2.h @@ -43,6 +43,15 @@ int __ilog2_u64(u64 n) } #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 - log of base 2 of 32-bit or a 64-bit unsigned value * @n - parameter @@ -128,4 +137,21 @@ ( \ __ilog2_u64(n) \ ) +/** + * 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 */ - 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/