From 5ab668ffae9b202918e052a8febdea9353838872 Mon Sep 17 00:00:00 2001 From: Xiang Xiao Date: Thu, 8 Nov 2018 08:37:34 -0600 Subject: [PATCH] libs/libc/string/lib_memrchr.c: Add memrchr() function --- include/string.h | 1 + libs/libc/string/Make.defs | 8 ++-- libs/libc/string/lib_memrchr.c | 75 ++++++++++++++++++++++++++++++++++ 3 files changed, 80 insertions(+), 4 deletions(-) create mode 100644 libs/libc/string/lib_memrchr.c diff --git a/include/string.h b/include/string.h index 2bf5c25f8b..9271dff631 100644 --- a/include/string.h +++ b/include/string.h @@ -89,6 +89,7 @@ FAR char *strtok_r(FAR char *, FAR const char *, FAR char **); size_t strxfrm(FAR char *, FAR const char *, size_t n); FAR void *memchr(FAR const void *s, int c, size_t n); +FAR void *memrchr(FAR const void *s, int c, size_t n); FAR void *memccpy(FAR void *s1, FAR const void *s2, int c, size_t n); int memcmp(FAR const void *s1, FAR const void *s2, size_t n); FAR void *memcpy(FAR void *dest, FAR const void *src, size_t n); diff --git a/libs/libc/string/Make.defs b/libs/libc/string/Make.defs index 550bb39ae5..5651137009 100644 --- a/libs/libc/string/Make.defs +++ b/libs/libc/string/Make.defs @@ -1,7 +1,7 @@ ############################################################################ # libs/libc/string/Make.defs # -# Copyright (C) 2011-2012, 2014, 2016-2017 Gregory Nutt. All rights reserved. +# Copyright (C) 2011-2012, 2014, 2016-2018 Gregory Nutt. All rights reserved. # Author: Gregory Nutt # # Redistribution and use in source and binary forms, with or without @@ -37,9 +37,9 @@ CSRCS += lib_ffs.c lib_ffsl.c lib_ffsll.c lib_fls.c lib_flsl.c CSRCS += lib_flsll.c lib_isbasedigit.c lib_memset.c lib_memchr.c -CSRCS += lib_memccpy.c lib_memcmp.c lib_memmove.c lib_skipspace.c -CSRCS += lib_stpcpy.c lib_stpncpy.c lib_strcasecmp.c lib_strcat.c -CSRCS += lib_strchr.c lib_strcpy.c lib_strcmp.c lib_strcspn.c +CSRCS += lib_memccpy.c lib_memcmp.c lib_memmove.c lib_memrchr.c +CSRCS += lib_skipspace.c lib_stpcpy.c lib_stpncpy.c lib_strcasecmp.c +CSRCS += lib_strcat.c lib_strchr.c lib_strcpy.c lib_strcmp.c lib_strcspn.c CSRCS += lib_strdup.c lib_strerror.c lib_strlen.c lib_strnlen.c CSRCS += lib_strncasecmp.c lib_strncat.c lib_strncmp.c lib_strncpy.c CSRCS += lib_strndup.c lib_strcasestr.c lib_strpbrk.c lib_strrchr.c diff --git a/libs/libc/string/lib_memrchr.c b/libs/libc/string/lib_memrchr.c new file mode 100644 index 0000000000..b7474d47a6 --- /dev/null +++ b/libs/libc/string/lib_memrchr.c @@ -0,0 +1,75 @@ +/**************************************************************************** + * libs/libc/string/lib_memchr.c + * + * Copyright (C) 2018 Pinecone Inc. All rights reserved. + * Author: Xiang Xiao + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include + +#include + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: memrchr + * + * Description: + * The memrchr() function locates the last occurrence of 'c' (converted to + * an unsigned char) in the initial 'n' bytes (each interpreted as + * unsigned char) of the object pointed to by s. + * + * Returned Value: + * The memrchr() function returns a pointer to the located byte, or a null + * pointer if the byte does not occur in the object. + * + ****************************************************************************/ + +FAR void *memrchr(FAR const void *s, int c, size_t n) +{ + FAR const unsigned char *p = (FAR const unsigned char *)s + n; + + while (n--) + { + if (*--p == (unsigned char)c) + { + return (FAR void *)p; + } + } + + return NULL; +}