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/* Locate a substring in a wide string.
Copyright (C) 1999, 2011-2024 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Eric Blake, 2008. */
#define AVAILABLE(h, h_l, j, n_l) \
(!MEMCHR0 ((h) + (h_l), (j) + (n_l) - (h_l)) \
&& ((h_l) = (j) + (n_l)))
#include "wcs-two-way.h"
RETURN_TYPE
FUNC (const UNIT *haystack_start, const UNIT *needle_start)
{
const UNIT *haystack = haystack_start;
const UNIT *needle = needle_start;
size_t needle_len; /* Length of NEEDLE. */
size_t haystack_len; /* Known minimum length of HAYSTACK. */
bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */
/* Determine length of NEEDLE, and in the process, make sure
HAYSTACK is at least as long (no point processing all of a long
NEEDLE if HAYSTACK is too short). */
while (*haystack && *needle)
ok &= *haystack++ == *needle++;
if (*needle)
return NULL;
if (ok)
return (RETURN_TYPE) haystack_start;
/* Reduce the size of haystack using STRCHR, since it has a smaller
linear coefficient than the Two-Way algorithm. */
needle_len = needle - needle_start;
haystack = STRCHR (haystack_start + 1, *needle_start);
if (!haystack || __builtin_expect (needle_len == 1, 0))
return (RETURN_TYPE) haystack;
needle -= needle_len;
haystack_len = (haystack > haystack_start + needle_len ? 1
: needle_len + haystack_start - haystack);
/* Perform the search. */
return two_way_short_needle (haystack, haystack_len,
needle, needle_len);
}
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