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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>
89 lines
2.8 KiB
C
89 lines
2.8 KiB
C
/****************************************************************************
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* libs/libc/string/lib_bsdstrcat.c
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*
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* Copyright (c) 1994-2009 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the BSD License. This program is distributed in the hope that
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* it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
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* including the implied warranties of MERCHANTABILITY or FITNESS FOR
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* A PARTICULAR PURPOSE. A copy of this license is available at
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* http://www.opensource.org/licenses. Any Red Hat trademarks that are
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* incorporated in the source code or documentation are not subject to
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* the BSD License and may only be used or replicated with the express
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* permission of Red Hat, Inc.
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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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* Pre-processor Definitions
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****************************************************************************/
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#define ALIGNED(x) \
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(((long)(uintptr_t)(x) & (sizeof(long) - 1)) == 0)
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/* Macros for detecting endchar */
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#if LONG_MAX == 2147483647
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# define DETECTNULL(x) (((x) - 0x01010101) & ~(x) & 0x80808080)
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#elif LONG_MAX == 9223372036854775807
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/* Nonzero if x (a long int) contains a NULL byte. */
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# define DETECTNULL(x) (((x) - 0x0101010101010101) & ~(x) & 0x8080808080808080)
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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#if !defined(CONFIG_LIBC_ARCH_STRCAT) && defined(LIBC_BUILD_STRCAT)
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#undef strcat
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no_builtin("strcat")
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nosanitize_address
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FAR char *strcat(FAR char *dest, FAR const char *src)
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{
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FAR char *ret = dest;
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/* Skip over the data in dest as quickly as possible. */
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if (ALIGNED(dest))
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{
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FAR unsigned long *aligned_s1 = (FAR unsigned long *)dest;
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while (!DETECTNULL(*aligned_s1))
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{
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aligned_s1++;
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}
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dest = (FAR char *)aligned_s1;
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}
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while (*dest)
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{
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dest++;
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}
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/* dest now points to the its trailing null character, we can
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* just use strcpy to do the work for us now.
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* ?!? We might want to just include strcpy here.
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* Also, this will cause many more unaligned string copies because
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* dest is much less likely to be aligned. I don't know if its worth
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* tweaking strcpy to handle this better.
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*/
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strcpy(dest, src);
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return ret;
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}
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#endif
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