wcsmbs/wcsncmp.c

   1 /* Copyright (C) 1995-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <wchar.h>
  20
  21 #ifndef WCSNCMP
  22 # define WCSNCMP wcsncmp
  23 #endif
  24
  25 /* Compare no more than N characters of S1 and S2,
  26    returning less than, equal to or greater than zero
  27    if S1 is lexicographically less than, equal to or
  28    greater than S2.  */
  29 int
  30 WCSNCMP (const wchar_t *s1, const wchar_t *s2, size_t n)
  31 {
  32   wchar_t c1 = L'\0';
  33   wchar_t c2 = L'\0';
  34
  35   if (n >= 4)
  36     {
  37       size_t n4 = n >> 2;
  38       do
  39         {
  40           c1 = *s1++;
  41           c2 = *s2++;
  42           if (c1 == L'\0' || c1 != c2)
  43             return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  44           c1 = *s1++;
  45           c2 = *s2++;
  46           if (c1 == L'\0' || c1 != c2)
  47             return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  48           c1 = *s1++;
  49           c2 = *s2++;
  50           if (c1 == L'\0' || c1 != c2)
  51             return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  52           c1 = *s1++;
  53           c2 = *s2++;
  54           if (c1 == L'\0' || c1 != c2)
  55             return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  56         } while (--n4 > 0);
  57       n &= 3;
  58     }
  59
  60   while (n > 0)
  61     {
  62       c1 = *s1++;
  63       c2 = *s2++;
  64       if (c1 == L'\0' || c1 != c2)
  65         return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  66       n--;
  67     }
  68
  69   return 0;
  70 }