wcsmbs/wcsncmp.c

   1 /* Copyright (C) 1995-2022 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 #ifndef WCSNCMP
  21 # define WCSNCMP wcsncmp
  22 #endif
  23
  24 /* Compare no more than N characters of S1 and S2,
  25    returning less than, equal to or greater than zero
  26    if S1 is lexicographically less than, equal to or
  27    greater than S2.  */
  28 int
  29 WCSNCMP (const wchar_t *s1, const wchar_t *s2, size_t n)
  30 {
  31   wchar_t c1 = L'\0';
  32   wchar_t c2 = L'\0';
  33
  34   if (n >= 4)
  35     {
  36       size_t n4 = n >> 2;
  37       do
  38         {
  39           c1 = *s1++;
  40           c2 = *s2++;
  41           if (c1 == L'\0' || c1 != c2)
  42             return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  43           c1 = *s1++;
  44           c2 = *s2++;
  45           if (c1 == L'\0' || c1 != c2)
  46             return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  47           c1 = *s1++;
  48           c2 = *s2++;
  49           if (c1 == L'\0' || c1 != c2)
  50             return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  51           c1 = *s1++;
  52           c2 = *s2++;
  53           if (c1 == L'\0' || c1 != c2)
  54             return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  55         } while (--n4 > 0);
  56       n &= 3;
  57     }
  58
  59   while (n > 0)
  60     {
  61       c1 = *s1++;
  62       c2 = *s2++;
  63       if (c1 == L'\0' || c1 != c2)
  64         return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  65       n--;
  66     }
  67
  68   return 0;
  69 }