120 lines
4.0 KiB
C
120 lines
4.0 KiB
C
/* Machine-independant string function optimizations.
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Copyright (C) 1997-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _STRING_H
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# error "Never use <bits/string2.h> directly; include <string.h> instead."
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#endif
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#ifndef __NO_STRING_INLINES
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/* Unlike the definitions in the header <bits/string.h> the
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definitions contained here are not optimized down to assembler
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level. Those optimizations are not always a good idea since this
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means the code size increases a lot. Instead the definitions here
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optimize some functions in a way which do not dramatically
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increase the code size and which do not use assembler. The main
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trick is to use GCC's `__builtin_constant_p' function.
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Every function XXX which has a defined version in
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<bits/string.h> must be accompanied by a symbol _HAVE_STRING_ARCH_XXX
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to make sure we don't get redefinitions.
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We must use here macros instead of inline functions since the
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trick won't work with the latter. */
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#ifndef __STRING_INLINE
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# ifdef __cplusplus
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# define __STRING_INLINE inline
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# else
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# define __STRING_INLINE __extern_inline
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# endif
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#endif
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/* Dereferencing a pointer arg to run sizeof on it fails for the void
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pointer case, so we use this instead.
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Note that __x is evaluated twice. */
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#define __string2_1bptr_p(__x) \
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((size_t)(const void *)((__x) + 1) - (size_t)(const void *)(__x) == 1)
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/* Set N bytes of S to 0. */
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#if !defined _HAVE_STRING_ARCH_memset
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# define __bzero(s, n) __builtin_memset (s, '\0', n)
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#endif
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/* Copy SRC to DEST, returning pointer to final NUL byte. */
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#ifdef __USE_GNU
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# ifndef _HAVE_STRING_ARCH_stpcpy
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# define __stpcpy(dest, src) __builtin_stpcpy (dest, src)
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/* In glibc we use this function frequently but for namespace reasons
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we have to use the name `__stpcpy'. */
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# define stpcpy(dest, src) __stpcpy (dest, src)
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# endif
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#endif
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/* Copy no more than N characters of SRC to DEST. */
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#ifndef _HAVE_STRING_ARCH_strncpy
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# define strncpy(dest, src, n) __builtin_strncpy (dest, src, n)
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#endif
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/* Append no more than N characters from SRC onto DEST. */
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#ifndef _HAVE_STRING_ARCH_strncat
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# ifdef _USE_STRING_ARCH_strchr
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# define strncat(dest, src, n) \
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(__extension__ ({ char *__dest = (dest); \
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__builtin_constant_p (src) && __builtin_constant_p (n) \
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? (strlen (src) < ((size_t) (n)) \
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? strcat (__dest, src) \
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: (*((char *) __mempcpy (strchr (__dest, '\0'), \
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src, n)) = '\0', __dest)) \
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: strncat (dest, src, n); }))
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# else
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# define strncat(dest, src, n) __builtin_strncat (dest, src, n)
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# endif
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#endif
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/* Return the length of the initial segment of S which
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consists entirely of characters not in REJECT. */
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#ifndef _HAVE_STRING_ARCH_strcspn
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# define strcspn(s, reject) __builtin_strcspn (s, reject)
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#endif
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/* Return the length of the initial segment of S which
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consists entirely of characters in ACCEPT. */
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#ifndef _HAVE_STRING_ARCH_strspn
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# define strspn(s, accept) __builtin_strspn (s, accept)
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#endif
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/* Find the first occurrence in S of any character in ACCEPT. */
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#ifndef _HAVE_STRING_ARCH_strpbrk
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# define strpbrk(s, accept) __builtin_strpbrk (s, accept)
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#endif
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#ifndef _FORCE_INLINES
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# undef __STRING_INLINE
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#endif
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#endif /* No string inlines. */
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