Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757846AbbKSGth (ORCPT ); Thu, 19 Nov 2015 01:49:37 -0500 Received: from mail-ig0-f193.google.com ([209.85.213.193]:33655 "EHLO mail-ig0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752981AbbKSGte (ORCPT ); Thu, 19 Nov 2015 01:49:34 -0500 From: Jia He To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Cc: Andrew Morton , Rasmus Villemoes , Denys Vlasenko , Kyungmin Park , Michal Nazarewicz , Yury Norov , Tejun Heo , Martin Kepplinger , George Spelvin , Ingo Molnar , Arnd Bergmann , Jia He Subject: [PATCH v2 2/3] lib: Introduce 2 bit ops api: all_is_bit_{one,zero} Date: Thu, 19 Nov 2015 14:48:43 +0800 Message-Id: <1447915724-29709-3-git-send-email-hejianet@gmail.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1447915724-29709-1-git-send-email-hejianet@gmail.com> References: <1447915724-29709-1-git-send-email-hejianet@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1977 Lines: 79 This patch introduces 2 lightweight bit api. all_bit_is_zero return 1 if the bit string is all zero. The addr is the start address, the size is the bit size of the bit string. all_bit_is_one is the opposite. Signed-off-by: Jia He --- lib/find_bit.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/lib/find_bit.c b/lib/find_bit.c index 18072ea..1d56d8d 100644 --- a/lib/find_bit.c +++ b/lib/find_bit.c @@ -131,6 +131,56 @@ unsigned long find_last_bit(const unsigned long *addr, unsigned long size) EXPORT_SYMBOL(find_last_bit); #endif +#ifndef all_bit_is_zero +/* + * return val: 1 means all bit is zero + */ +unsigned int all_bit_is_zero(const unsigned long *addr, unsigned size) +{ + unsigned long idx; + unsigned long mask = size; + + if (unlikely(size == 0)) + return 1; + + if (size > BITS_PER_LONG) { + for (idx = 0; idx * BITS_PER_LONG < size; idx++) + if (addr[idx]) + return 0; + + mask = size - (idx - 1) * BITS_PER_LONG; + } + + return !(*addr & BITMAP_LAST_WORD_MASK(mask)); +} +EXPORT_SYMBOL(all_bit_is_zero); +#endif + +#ifndef all_bit_is_one +/* + * return val: 1 means all bit is one + */ +unsigned int all_bit_is_one(const unsigned long *addr, unsigned size) +{ + unsigned long idx; + unsigned long mask = size; + + if (unlikely(size == 0)) + return 1; + + if (size > BITS_PER_LONG) { + for (idx = 0; idx * BITS_PER_LONG < size; idx++) + if (~addr[idx]) + return 0; + + mask = size - (idx - 1) * BITS_PER_LONG; + } + + return !(~(*addr) & BITMAP_LAST_WORD_MASK(mask)); +} +EXPORT_SYMBOL(all_bit_is_one); +#endif + #ifdef __BIG_ENDIAN /* include/linux/byteorder does not support "unsigned long" type */ -- 2.5.0 -- 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/