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glibc  2.9
wcsncmp.c
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00001 /* Copyright (C) 1995, 1996 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <wchar.h>
00021 
00022 
00023 /* Compare no more than N characters of S1 and S2,
00024    returning less than, equal to or greater than zero
00025    if S1 is lexicographically less than, equal to or
00026    greater than S2.  */
00027 int
00028 wcsncmp (s1, s2, n)
00029      const wchar_t *s1;
00030      const wchar_t *s2;
00031      size_t n;
00032 {
00033   wint_t c1 = L'\0';
00034   wint_t c2 = L'\0';
00035 
00036   if (n >= 4)
00037     {
00038       size_t n4 = n >> 2;
00039       do
00040        {
00041          c1 = (wint_t) *s1++;
00042          c2 = (wint_t) *s2++;
00043          if (c1 == L'\0' || c1 != c2)
00044            return c1 - c2;
00045          c1 = (wint_t) *s1++;
00046          c2 = (wint_t) *s2++;
00047          if (c1 == L'\0' || c1 != c2)
00048            return c1 - c2;
00049          c1 = (wint_t) *s1++;
00050          c2 = (wint_t) *s2++;
00051          if (c1 == L'\0' || c1 != c2)
00052            return c1 - c2;
00053          c1 = (wint_t) *s1++;
00054          c2 = (wint_t) *s2++;
00055          if (c1 == L'\0' || c1 != c2)
00056            return c1 - c2;
00057        } while (--n4 > 0);
00058       n &= 3;
00059     }
00060 
00061   while (n > 0)
00062     {
00063       c1 = (wint_t) *s1++;
00064       c2 = (wint_t) *s2++;
00065       if (c1 == L'\0' || c1 != c2)
00066        return c1 - c2;
00067       n--;
00068     }
00069 
00070   return c1 - c2;
00071 }