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36 lines
1.2 KiB
C
36 lines
1.2 KiB
C
/* Determine the length of a string. For Intel 80x86, x>=3.
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Copyright (C) 1991-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Torbjorn Granlund (tege@sics.se).
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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 <string.h>
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size_t
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strlen (const char *str)
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{
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int cnt;
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asm("cld\n" /* Search forward. */
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/* Some old versions of gas need `repne' instead of `repnz'. */
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"repnz\n" /* Look for a zero byte. */
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"scasb" /* %0, %1, %3 */ :
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"=c" (cnt) : "D" (str), "0" (-1), "a" (0));
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return -2 - cnt;
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}
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libc_hidden_builtin_def (strlen)
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