1/* Compare at most N wide characters of two strings without taking care
2 for the case.
3 Copyright (C) 1992-2022 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#ifdef HAVE_CONFIG_H
21# include <config.h>
22#endif
23
24#include <wchar.h>
25#include <wctype.h>
26
27#ifndef weak_alias
28# define __wcsncasecmp wcsncasecmp
29# define TOLOWER(Ch) towlower (Ch)
30#else
31# ifdef USE_IN_EXTENDED_LOCALE_MODEL
32# define __wcsncasecmp __wcsncasecmp_l
33# define TOLOWER(Ch) __towlower_l ((Ch), loc)
34# else
35# define TOLOWER(Ch) towlower (Ch)
36# endif
37#endif
38
39#ifdef USE_IN_EXTENDED_LOCALE_MODEL
40# define LOCALE_PARAM , locale_t loc
41#else
42# define LOCALE_PARAM
43#endif
44
45/* Compare no more than N wide characters of S1 and S2,
46 ignoring case, returning less than, equal to or
47 greater than zero if S1 is lexicographically less
48 than, equal to or greater than S2. */
49int
50__wcsncasecmp (const wchar_t *s1, const wchar_t *s2, size_t n LOCALE_PARAM)
51{
52 wint_t c1, c2;
53
54 if (s1 == s2 || n == 0)
55 return 0;
56
57 do
58 {
59 c1 = (wint_t) TOLOWER (*s1++);
60 c2 = (wint_t) TOLOWER (*s2++);
61 if (c1 == L'\0' || c1 != c2)
62 return c1 - c2;
63 } while (--n > 0);
64
65 return c1 - c2;
66}
67#ifndef __wcsncasecmp
68weak_alias (__wcsncasecmp, wcsncasecmp)
69#endif
70

source code of glibc/wcsmbs/wcsncase.c