newlib/libc/string/wcsncmp.c

   1 /*
   2 FUNCTION
   3         <<wcsncmp>>---compare part of two wide-character strings
   4
   5 SYNOPSIS
   6         #include <wchar.h>
   7         int wcsncmp(const wchar_t *<[s1]>, const wchar_t *<[s2]>, size_t <[n]>);
   8
   9 DESCRIPTION
  10         The <<wcsncmp>> function compares not more than <[n]> wide-character
  11         codes (wide-character codes that follow a null wide-character code are
  12         not compared) from the array pointed to by <[s1]> to the array pointed
  13         to by <[s2]>.
  14
  15         The sign of a non-zero return value is determined by the sign of the
  16         difference between the values of the first pair of wide-character codes
  17         that differ in the objects being compared.
  18
  19 RETURNS
  20         Upon successful completion, <<wcsncmp>> returns an integer greater than,
  21         equal to or less than 0, if the possibly null-terminated array pointed
  22         to by <[s1]> is greater than, equal to or less than the possibly
  23         null-terminated array pointed to by <[s2]> respectively.
  24
  25 PORTABILITY
  26 <<wcsncmp>> is ISO/IEC 9899/AMD1:1995 (ISO C).
  27
  28 No supporting OS subroutines are required.
  29 */
  30
  31 /*      $NetBSD$        */
  32
  33 /*
  34  * Copyright (c) 1989, 1993
  35  *      The Regents of the University of California.  All rights reserved.
  36  *
  37  * Redistribution and use in source and binary forms, with or without
  38  * modification, are permitted provided that the following conditions
  39  * are met:
  40  * 1. Redistributions of source code must retain the above copyright
  41  *    notice, this list of conditions and the following disclaimer.
  42  * 2. Redistributions in binary form must reproduce the above copyright
  43  *    notice, this list of conditions and the following disclaimer in the
  44  *    documentation and/or other materials provided with the distribution.
  45  * 3. Neither the name of the University nor the names of its contributors
  46  *    may be used to endorse or promote products derived from this software
  47  *    without specific prior written permission.
  48  *
  49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  59  * SUCH DAMAGE.
  60  */
  61
  62 #include <_ansi.h>
  63 #include <wchar.h>
  64
  65 int
  66 wcsncmp (const wchar_t * s1,
  67         const wchar_t * s2,
  68         size_t n)
  69 {
  70
  71   if (n == 0)
  72     return (0);
  73   do
  74     {
  75       if (*s1 != *s2++)
  76         {
  77           return (*s1 - *--s2);
  78         }
  79       if (*s1++ == 0)
  80         break;
  81     }
  82   while (--n != 0);
  83   return (0);
  84 }