wcsmbs/wcsncmp.c

   1 /* Copyright (C) 1995-2015 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    <http://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 (s1, s2, n)
  31      const wchar_t *s1;
  32      const wchar_t *s2;
  33      size_t n;
  34 {
  35   wchar_t c1 = L'\0';
  36   wchar_t c2 = L'\0';
  37
  38   if (n >= 4)
  39     {
  40       size_t n4 = n >> 2;
  41       do
  42         {
  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           c1 = *s1++;
  56           c2 = *s2++;
  57           if (c1 == L'\0' || c1 != c2)
  58             return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  59         } while (--n4 > 0);
  60       n &= 3;
  61     }
  62
  63   while (n > 0)
  64     {
  65       c1 = *s1++;
  66       c2 = *s2++;
  67       if (c1 == L'\0' || c1 != c2)
  68         return c1 > c2 ? 1 : (c1 < c2 ? -1 : 0);
  69       n--;
  70     }
  71
  72   return 0;
  73 }