From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754854AbbATMbk (ORCPT ); Tue, 20 Jan 2015 07:31:40 -0500 Received: from mx02.posteo.de ([89.146.194.165]:55619 "EHLO mx02.posteo.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753389AbbATMbh (ORCPT ); Tue, 20 Jan 2015 07:31:37 -0500 From: Martin Kepplinger To: torvalds@linux-foundation.org, jsrhbz@kanargh.force9.co.uk, christoph.muellner@theobroma-systems.com, linux@roeck-us.net, linux@rasmusvillemoes.dk, paulmck@linux.vnet.ibm.com, tglx@linutronix.de, mingo@kernel.org, akpm@linux-foundation.org, hpa@zytor.com, maxime.coquelin@st.com, linux-kernel@vger.kernel.org, peterz@infradead.org, tytso@mit.edu Cc: linux-tip-commits@vger.kernel.org, Martin Kepplinger Subject: [PATCH 2/2] bitops.h: Add sign_extend64() API Date: Tue, 20 Jan 2015 13:30:55 +0100 Message-Id: <1421757055-8234-3-git-send-email-martink@posteo.de> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1421757055-8234-1-git-send-email-martink@posteo.de> References: <1421757055-8234-1-git-send-email-martink@posteo.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add sign_extend64() for sign extending any (hardware-)given signed value greater than 32 bits to s64. Suggested-by: Christoph Muellner Suggested-by: Peter Zijlstra Signed-off-by: Martin Kepplinger --- include/linux/bitops.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 336f22b..2fd47c8 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -173,6 +173,17 @@ static inline __s32 sign_extend32(__u32 value, int index) return (__s32)(value << shift) >> shift; } +/** + * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit + * @value: value to sign extend + * @index: 0 based bit index (0<=index<64) to sign bit + */ +static inline __s64 sign_extend64(__u64 value, int index) +{ + __u8 shift = 63 - index; + return (__s64)(value << shift) >> shift; +} + static inline unsigned fls_long(unsigned long l) { if (sizeof(l) == 4) -- 2.1.4