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anjiahao
7c96537a58
This allows the compiler to automatically identify which string functions can be compiled into libraries, and the compiler's internal implementation is faster than libc functions. Signed-off-by: anjiahao <anjiahao@xiaomi.com>
71 lines
2.3 KiB
C
71 lines
2.3 KiB
C
/****************************************************************************
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* libs/libc/string/lib_memchr.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <string.h>
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#include "libc.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: memchr
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*
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* Description:
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* The memchr() function locates the first occurrence of 'c' (converted to
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* an unsigned char) in the initial 'n' bytes (each interpreted as
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* unsigned char) of the object pointed to by s.
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*
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* Returned Value:
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* The memchr() function returns a pointer to the located byte, or a null
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* pointer if the byte does not occur in the object.
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*
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****************************************************************************/
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#if !defined(CONFIG_LIBC_ARCH_MEMCHR) && defined(LIBC_BUILD_MEMCHR)
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#undef memchr
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no_builtin("memchr")
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FAR void *memchr(FAR const void *s, int c, size_t n)
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{
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FAR const unsigned char *p = (FAR const unsigned char *)s;
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while (n--)
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{
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if (*p == (unsigned char)c)
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{
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return (FAR void *)p;
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}
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p++;
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}
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return NULL;
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}
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#endif
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