wcsmbs/wcsncmp.c

   1 /* Copyright (C) 1995, 1996 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3 Contributed by Ulrich Drepper, <drepper@gnu.ai.mit.edu>
   4
   5 The GNU C Library is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 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 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <wchar.h>
  21
  22
  23 /* Compare no more than N characters of S1 and S2,
  24    returning less than, equal to or greater than zero
  25    if S1 is lexiographically less than, equal to or
  26    greater than S2.  */
  27 int
  28 wcsncmp (s1, s2, n)
  29      const wchar_t *s1;
  30      const wchar_t *s2;
  31      size_t n;
  32 {
  33   uwchar_t c1 = L'\0';
  34   uwchar_t c2 = L'\0';
  35
  36   if (n >= 4)
  37     {
  38       size_t n4 = n >> 2;
  39       do
  40         {
  41           c1 = (uwchar_t) *s1++;
  42           c2 = (uwchar_t) *s2++;
  43           if (c1 == L'\0' || c1 != c2)
  44             return c1 - c2;
  45           c1 = (uwchar_t) *s1++;
  46           c2 = (uwchar_t) *s2++;
  47           if (c1 == L'\0' || c1 != c2)
  48             return c1 - c2;
  49           c1 = (uwchar_t) *s1++;
  50           c2 = (uwchar_t) *s2++;
  51           if (c1 == L'\0' || c1 != c2)
  52             return c1 - c2;
  53           c1 = (uwchar_t) *s1++;
  54           c2 = (uwchar_t) *s2++;
  55           if (c1 == L'\0' || c1 != c2)
  56             return c1 - c2;
  57         } while (--n4 > 0);
  58       n &= 3;
  59     }
  60
  61   while (n > 0)
  62     {
  63       c1 = (uwchar_t) *s1++;
  64       c2 = (uwchar_t) *s2++;
  65       if (c1 == L'\0' || c1 != c2)
  66         return c1 - c2;
  67       n--;
  68     }
  69
  70   return c1 - c2;
  71 }