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53 lines
1.6 KiB
C
53 lines
1.6 KiB
C
/* Copyright (C) 1991-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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<https://www.gnu.org/licenses/>. */
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#include <libc-pointer-arith.h>
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#include <string-fzb.h>
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#include <string-fzc.h>
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#include <string-fzi.h>
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#include <string-shift.h>
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#include <string.h>
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#ifdef STRLEN
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# define __strlen STRLEN
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#endif
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/* Return the length of the null-terminated string STR. Scan for
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the null terminator quickly by testing four bytes at a time. */
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size_t
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__strlen (const char *str)
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{
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/* Align pointer to sizeof op_t. */
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const uintptr_t s_int = (uintptr_t) str;
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const op_t *word_ptr = (const op_t*) PTR_ALIGN_DOWN (str, sizeof (op_t));
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op_t word = *word_ptr;
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find_t mask = shift_find (find_zero_all (word), s_int);
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if (mask != 0)
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return index_first (mask);
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do
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word = *++word_ptr;
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while (! has_zero (word));
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return ((const char *) word_ptr) + index_first_zero (word) - str;
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}
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#ifndef STRLEN
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weak_alias (__strlen, strlen)
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libc_hidden_builtin_def (strlen)
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#endif
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