wcsmbs/wmemchr.c

   1 /* Copyright (C) 1996-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <wchar.h>
  19
  20 #ifdef WMEMCHR
  21 # define __wmemchr WMEMCHR
  22 #endif
  23
  24 wchar_t *
  25 __wmemchr (const wchar_t *s, wchar_t c, size_t n)
  26 {
  27   /* For performance reasons unfold the loop four times.  */
  28   while (n >= 4)
  29     {
  30       if (s[0] == c)
  31         return (wchar_t *) s;
  32       if (s[1] == c)
  33         return (wchar_t *) &s[1];
  34       if (s[2] == c)
  35         return (wchar_t *) &s[2];
  36       if (s[3] == c)
  37         return (wchar_t *) &s[3];
  38       s += 4;
  39       n -= 4;
  40     }
  41
  42   if (n > 0)
  43     {
  44       if (*s == c)
  45         return (wchar_t *) s;
  46       ++s;
  47       --n;
  48     }
  49   if (n > 0)
  50     {
  51       if (*s == c)
  52         return (wchar_t *) s;
  53       ++s;
  54       --n;
  55     }
  56   if (n > 0)
  57     if (*s == c)
  58       return (wchar_t *) s;
  59
  60   return NULL;
  61 }
  62 libc_hidden_def (__wmemchr)
  63 weak_alias (__wmemchr, wmemchr)
  64 libc_hidden_weak (wmemchr)