From patchwork Thu Feb 14 03:48:16 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiang Xiao X-Patchwork-Id: 10811701 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1DB6013BF for ; Thu, 14 Feb 2019 03:48:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 081872DFD2 for ; Thu, 14 Feb 2019 03:48:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F05A82DFD6; Thu, 14 Feb 2019 03:48:34 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2553E2DFD4 for ; Thu, 14 Feb 2019 03:48:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390208AbfBNDsc (ORCPT ); Wed, 13 Feb 2019 22:48:32 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:38215 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387562AbfBNDsc (ORCPT ); Wed, 13 Feb 2019 22:48:32 -0500 Received: by mail-pg1-f196.google.com with SMTP id m2so42519pgl.5; Wed, 13 Feb 2019 19:48:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=i3gc5E2H5s0Z0cU1Rtar6FigVqhI90HZ+Cw+llye4LQ=; b=hmjjxacKBDS9YSm5KMm6z8uRO8UrEEmxpP/0bBUbPN2Z+JcbUTkn5nrFePQ/PIPLGO VmHLb+f9y3v4A7lQBcujsXn8Pd7fKmC9SpecuwiMLh7TIwCqd6wISNXHqYA82nt+3pUS OyYRY5zDvPvh6k6hpgxUOsg/it+ev6KL26RCydyAoxA7edeQhl+V3L8UZZ0RQ6Um0SWM 8/TbN5StyisOXhNJTaJHL1BvgCkYjeJTtP3plDjS6itg2D3/5+p94p/Yljo77JHC6HiW lOkdAVd7AJIii2ORTCAOmcKVD7jb6ZWYAHTs4td/mAQ7mtx9Wn7btXxYfIpvCeHBJM6/ 9IZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=i3gc5E2H5s0Z0cU1Rtar6FigVqhI90HZ+Cw+llye4LQ=; b=DfEbZ1DWDrz0mxyAdwCBbbYV+Dn2arK2NN6Zvg5Y+H8Fkhz05wSNQ/KJe6YUnTE6PE QtJSXtqnulJsGR3k5wN58MOuJUGRnnZte7vVskmkr2vz+TjvIAuhvxac9WFDX/88TG0J w5XNPgug/YjsSe0nC7+tMQ9ypE7qQxkL8nwoAp1p0xBSGt78T/xSy+7H37fcTpRn86Xs KDReTWkP5vsvjTAHC5TySNjJyVNXkMzm7LoghWoLKBWxXTfmOSnZHMvBggzZG+VgiEWP QsN+pjBUb3Al+v7aj9f4+xut5BnNbi87fIztverrv0JOtviKbT2vtglRMEr2FLQcK/jd qMzw== X-Gm-Message-State: AHQUAuaspDENX5240+g9uUwbqvf1GeGtygsJ2F7o/o+2ZPDuLKWsYuAc /HFLAhb+LAga3lqSZy4JQbg= X-Google-Smtp-Source: AHgI3IY3GudN4kJXsQMH44OWMPdjekvfDuIPMiRDW0lFbe93LBhROkACL86nSS+VprfLsH4EIJdP3A== X-Received: by 2002:a63:fc4d:: with SMTP id r13mr1740786pgk.242.1550116111584; Wed, 13 Feb 2019 19:48:31 -0800 (PST) Received: from localhost.localdomain ([43.224.245.179]) by smtp.gmail.com with ESMTPSA id g7sm969962pfi.187.2019.02.13.19.48.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 13 Feb 2019 19:48:31 -0800 (PST) From: Xiang Xiao X-Google-Original-From: Xiang Xiao To: gregkh@linuxfoundation.org, alexander.shishkin@linux.intel.com, andriy.shevchenko@linux.intel.com, ohad@wizery.com, bjorn.andersson@linaro.org, wendy.liang@xilinx.com, arnaud.pouliquen@st.com, kumar.gala@linaro.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Xiang Xiao Subject: [PATCH 1/2] lib/string: add memrchr function Date: Thu, 14 Feb 2019 11:48:16 +0800 Message-Id: <1550116097-29710-1-git-send-email-xiaoxiang@xiaomi.com> X-Mailer: git-send-email 2.7.4 Sender: linux-remoteproc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Here is the detailed description for memrchr: void *memrchr(const void *s, int c, size_t n); The memrchr() function is like the memchr() function, except that it searches backward from the end of the n bytes pointed to by s instead of forward from the beginning. The memrchr() functions return a pointer to the matching byte or NULL if the character does not occur in the given memory area. Signed-off-by: Xiang Xiao --- include/linux/string.h | 1 + lib/string.c | 21 +++++++++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/include/linux/string.h b/include/linux/string.h index 7927b87..f380f4b 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -167,6 +167,7 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt) memcpy(dst, src, cnt); } #endif +void *memrchr(const void *s, int c, size_t n); void *memchr_inv(const void *s, int c, size_t n); char *strreplace(char *s, char old, char new); diff --git a/lib/string.c b/lib/string.c index 38e4ca0..92914f6 100644 --- a/lib/string.c +++ b/lib/string.c @@ -964,6 +964,27 @@ void *memchr(const void *s, int c, size_t n) EXPORT_SYMBOL(memchr); #endif +/** + * memrchr - Find a character in an area of memory. + * @s: The memory area + * @c: The byte to search for + * @n: The size of the area. + * + * returns the address of the last occurrence of @c, or %NULL + * if @c is not found + */ +void *memrchr(const void *s, int c, size_t n) +{ + const unsigned char *p = s + n; + + while (n-- != 0) { + if ((unsigned char)c == *--p) + return (void *)p; + } + return NULL; +} +EXPORT_SYMBOL(memrchr); + static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes) { while (bytes) {