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cf11e74b0d
It uses the same two-way algorithm used on strstr, strcasestr, and memmem. Different than strstr, neither the "shift table" optimization nor the self-adapting filtering check is used because it would result in a too-large shift table (and it also simplifies the implementation bit). Checked on x86_64-linux-gnu and aarch64-linux-gnu. Reviewed-by: DJ Delorie <dj@redhat.com>
53 lines
1.9 KiB
C
53 lines
1.9 KiB
C
/* Locate a substring in a wide-character string.
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Copyright (C) 1995-2024 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 <wchar.h>
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#include <string.h>
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#define AVAILABLE(h, h_l, j, n_l) \
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(((j) + (n_l) <= (h_l)) \
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|| ((h_l) += __wcsnlen ((void*)((h) + (h_l)), (n_l) + 128), \
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(j) + (n_l) <= (h_l)))
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#include "wcs-two-way.h"
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#ifndef WCSSTR
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# define WCSSTR wcsstr
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#endif
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wchar_t *
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WCSSTR (const wchar_t *haystack, const wchar_t *needle)
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{
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/* Ensure haystack length is at least as long as needle length.
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Since a match may occur early on in a huge haystack, use strnlen
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and read ahead a few cachelines for improved performance. */
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size_t ne_len = __wcslen (needle);
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size_t hs_len = __wcsnlen (haystack, ne_len | 128);
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if (hs_len < ne_len)
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return NULL;
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/* Check whether we have a match. This improves performance since we
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avoid initialization overheads. */
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if (__wmemcmp (haystack, needle, ne_len) == 0)
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return (wchar_t *) haystack;
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return two_way_short_needle (haystack, hs_len, needle, ne_len);
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}
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/* This alias is for backward compatibility with drafts of the ISO C
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standard. Unfortunately the Unix(TM) standard requires this name. */
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weak_alias (wcsstr, wcswcs)
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