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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>
126 lines
3.9 KiB
C
126 lines
3.9 KiB
C
/****************************************************************************
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* libs/libc/string/lib_bsdstrncpy.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 <sys/types.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 LBLOCKSIZE (sizeof(long))
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/* Nonzero if either x or y is not aligned on a "long" boundary. */
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#define UNALIGNED(x, y) \
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(((long)(uintptr_t)(x) & (sizeof(long) - 1)) | ((long)(uintptr_t)(y) & (sizeof(long) - 1)))
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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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#define TOO_SMALL(len) ((len) < sizeof(long))
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: strncpy
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*
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* Description:
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* Copies the string pointed to by 'src' (including the terminating NUL
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* character) into the array pointed to by 'dest'. strncpy() will not
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* copy more than 'n' bytes from 'src' to 'dest' array (including the
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* NUL terminator).
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*
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* If the array pointed to by 'src' is a string that is shorter than 'n'
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* bytes, NUL characters will be appended to the copy in the array
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* pointed to by 'dest', until 'n' bytes in all are written.
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*
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* If copying takes place between objects that overlap, the behavior is
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* undefined.
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*
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* Returned Value:
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* The strncpy() function returns the pointer to 'dest'
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*
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****************************************************************************/
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#if !defined(CONFIG_LIBC_ARCH_STRNCPY) && defined(LIBC_BUILD_STRNCPY)
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#undef strncpy
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nosanitize_address
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no_builtin("strncpy")
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FAR char *strncpy(FAR char *dest, FAR const char *src, size_t n)
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{
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FAR char *dst0 = dest;
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FAR const char *src0 = src;
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FAR long *aligned_dst;
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FAR const long *aligned_src;
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/* If src and dest is aligned and n large enough, then copy words. */
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if (!UNALIGNED(src0, dst0) && !TOO_SMALL(n))
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{
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aligned_dst = (FAR long *)dst0;
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aligned_src = (FAR long *)src0;
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/* src and dest are both "long int" aligned, try to do "long int"
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* sized copies.
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*/
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while (n >= LBLOCKSIZE && !DETECTNULL(*aligned_src))
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{
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n -= LBLOCKSIZE;
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*aligned_dst++ = *aligned_src++;
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}
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dst0 = (FAR char *)aligned_dst;
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src0 = (FAR char *)aligned_src;
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}
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while (n > 0)
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{
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--n;
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if ((*dst0++ = *src0++) == '\0')
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{
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break;
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}
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}
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while (n-- > 0)
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{
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*dst0++ = '\0';
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}
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return dest;
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}
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#endif
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