Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753466AbcDOIXd (ORCPT ); Fri, 15 Apr 2016 04:23:33 -0400 Received: from m50-135.163.com ([123.125.50.135]:53423 "EHLO m50-135.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752880AbcDOIXb (ORCPT ); Fri, 15 Apr 2016 04:23:31 -0400 From: zengzhaoxiu@163.com To: linux-kernel@vger.kernel.org Cc: Zhaoxiu Zeng , Steven Miao , adi-buildroot-devel@lists.sourceforge.net Subject: [PATCH V2] blackfin: optimize ffz, __ffs, ffs, __fls, and fls functions Date: Fri, 15 Apr 2016 16:23:08 +0800 Message-Id: <1460708588-16867-1-git-send-email-zengzhaoxiu@163.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1460706724-15953-1-git-send-email-zengzhaoxiu@163.com> References: <1460706724-15953-1-git-send-email-zengzhaoxiu@163.com> X-CM-TRANSID: D9GowAB3fqrxpBBXfLpMCg--.52911S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxXFyUtrW8GF13GFW3Aw18Xwb_yoW5WFy5pF 4v9as5JrWDta4xXFWakr1vvF13AFs3JF43JFyav3srJF17ta1DAFWvgr1qqw1DXayvvFya vrZrGry5Ga1xXaUanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jEBT5UUUUU= X-Originating-IP: [112.95.225.98] X-CM-SenderInfo: p2hqw6xkdr5xrx6rljoofrz/1tbiMBZMgFWBVZ9Q4AAAsE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2861 Lines: 115 From: Zhaoxiu Zeng blackfin has popcount instruction (ONES), we can do the efficient computing (ffz, __ffs, ffs, __fls, and fls) use this instruction. Adapted from "https://en.wikipedia.org/wiki/Find_first_set" and arch/ia64/include/asm/bitops.h. Changes to V1: - Use hweight32 instead __arch_hweight32 Signed-off-by: Zhaoxiu Zeng --- arch/blackfin/include/asm/bitops.h | 73 +++++++++++++++++++++++++++++++++++--- 1 file changed, 68 insertions(+), 5 deletions(-) diff --git a/arch/blackfin/include/asm/bitops.h b/arch/blackfin/include/asm/bitops.h index b298b65..602e7c0 100644 --- a/arch/blackfin/include/asm/bitops.h +++ b/arch/blackfin/include/asm/bitops.h @@ -9,10 +9,6 @@ #include -#include -#include -#include -#include #include #include @@ -21,7 +17,6 @@ #endif #include -#include #include #include @@ -137,4 +132,72 @@ static inline unsigned int __arch_hweight8(unsigned int w) return __arch_hweight32(w & 0xff); } +/** + * ffz - find the first zero bit in a long word + * @x: The long word to find the bit in + * + * Returns the bit-number (0..31) of the first (least significant) zero bit. + * Undefined if no zero exists, so code should check against ~0UL first... + */ +static inline unsigned long ffz(unsigned long x) +{ + return hweight32(x & (~x - 1)); +} + +/** + * ffs - find first bit set + * @x: the word to search + * + * This is defined the same way as + * the libc and compiler builtin ffs routines, therefore + * differs in spirit from the above ffz (man ffs). + */ +static inline int ffs(int x) +{ + if (!x) + return 0; + return hweight32(x ^ ((unsigned int)x - 1)); +} + +/** + * __ffs - find first bit in word. + * @x: The word to search + * + * Undefined if no bit exists, so code should check against 0 first. + */ +static inline unsigned long __ffs(unsigned long x) +{ + return hweight32(~x & (x - 1)); +} + +/* + * Find the last (most significant) bit set. Returns 0 for x==0 and + * bits are numbered from 1..32 (e.g., fls(9) == 4). + */ +static inline int fls(int x) +{ + if (!x) + return 0; + x |= x >> 1; + x |= x >> 2; + x |= x >> 4; + x |= x >> 8; + x |= x >> 16; + return hweight32(x); +} + +/* + * Find the last (most significant) bit set. Undefined for x==0. + * Bits are numbered from 0..31 (e.g., __fls(9) == 3). + */ +static inline unsigned long __fls(unsigned long x) +{ + x |= x >> 1; + x |= x >> 2; + x |= x >> 4; + x |= x >> 8; + x |= x >> 16; + return hweight32(x) - 1; +} + #endif /* _BLACKFIN_BITOPS_H */ -- 2.5.0