1  /* Copyright (C) 1995-2023 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  }