toolchain/gcc/newlib/libc/string/wcsncmp.c

   1 /*
   2 FUNCTION
   3         <<wcsncmp>>---compare part of two wide-character strings
   4
   5 ANSI_SYNOPSIS
   6         #include <wchar.h>
   7         int wcsncmp(const wchar_t *<[s1]>, const wchar_t *<[s2]>, size_t <[n]>);
   8
   9 TRAD_SYNOPSIS
  10         int wcsncmp(<[s1]>, <[s2]>, <[n]>
  11         const wchar_t *<[s1]>;
  12         const wchar_t *<[s2]>;
  13         size_t <[n]>;
  14
  15 DESCRIPTION
  16         The <<wcsncmp>> function compares not more than <[n]> wide-character
  17         codes (wide-character codes that follow a null wide-character code are
  18         not compared) from the array pointed to by <[s1]> to the array pointed
  19         to by <[s2]>.
  20
  21         The sign of a non-zero return value is determined by the sign of the
  22         difference between the values of the first pair of wide-character codes
  23         that differ in the objects being compared.
  24
  25 RETURNS
  26         Upon successful completion, <<wcsncmp>> returns an integer greater than,
  27         equal to or less than 0, if the possibly null-terminated array pointed
  28         to by <[s1]> is greater than, equal to or less than the possibly
  29         null-terminated array pointed to by <[s2]> respectively.
  30
  31 PORTABILITY
  32 <<wcsncmp>> is ISO/IEC 9899/AMD1:1995 (ISO C).
  33 No supporting OS subroutines are required.
  34 */
  35
  36 /*      $NetBSD$        */
  37
  38 /*
  39  * Copyright (c) 1989, 1993
  40  *      The Regents of the University of California.  All rights reserved.
  41  *
  42  * Redistribution and use in source and binary forms, with or without
  43  * modification, are permitted provided that the following conditions
  44  * are met:
  45  * 1. Redistributions of source code must retain the above copyright
  46  *    notice, this list of conditions and the following disclaimer.
  47  * 2. Redistributions in binary form must reproduce the above copyright
  48  *    notice, this list of conditions and the following disclaimer in the
  49  *    documentation and/or other materials provided with the distribution.
  50  * 3. Neither the name of the University nor the names of its contributors
  51  *    may be used to endorse or promote products derived from this software
  52  *    without specific prior written permission.
  53  *
  54  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  55  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  56  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  57  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  58  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  59  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  60  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  61  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  62  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  63  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  64  * SUCH DAMAGE.
  65  */
  66
  67 #include <_ansi.h>
  68 #include <wchar.h>
  69
  70 int
  71 _DEFUN (wcsncmp, (s1, s2, n),
  72         _CONST wchar_t * s1 _AND
  73         _CONST wchar_t * s2 _AND
  74         size_t n)
  75 {
  76
  77   if (n == 0)
  78     return (0);
  79   do
  80     {
  81       if (*s1 != *s2++)
  82         {
  83           return (*s1 - *--s2);
  84         }
  85       if (*s1++ == 0)
  86         break;
  87     }
  88   while (--n != 0);
  89   return (0);
  90 }