sysdeps/generic/strncase.c

   1 /* Compare at most N characters of two strings without taking care for
   2    the case.
   3    Copyright (C) 1992, 1996, 1997 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include <string.h>
  26 #include <ctype.h>
  27
  28 #ifndef weak_alias
  29 # define __strncasecmp strncasecmp
  30 # define TOLOWER(Ch) tolower (Ch)
  31 #else
  32 # ifdef USE_IN_EXTENDED_LOCALE_MODEL
  33 #  define __strncasecmp __strncasecmp_l
  34 #  define TOLOWER(Ch) __tolower_l ((Ch), loc)
  35 # else
  36 #  define TOLOWER(Ch) tolower (Ch)
  37 # endif
  38 #endif
  39
  40 #ifdef USE_IN_EXTENDED_LOCALE_MODEL
  41 # define LOCALE_PARAM , loc
  42 # define LOCALE_PARAM_DECL __locale_t loc;
  43 #else
  44 # define LOCALE_PARAM
  45 # define LOCALE_PARAM_DECL
  46 #endif
  47
  48 /* Compare no more than N characters of S1 and S2,
  49    ignoring case, returning less than, equal to or
  50    greater than zero if S1 is lexicographically less
  51    than, equal to or greater than S2.  */
  52 int
  53 __strncasecmp (s1, s2, n LOCALE_PARAM)
  54      const char *s1;
  55      const char *s2;
  56      size_t n;
  57      LOCALE_PARAM_DECL
  58 {
  59   const unsigned char *p1 = (const unsigned char *) s1;
  60   const unsigned char *p2 = (const unsigned char *) s2;
  61   unsigned char c1, c2;
  62
  63   if (p1 == p2 || n == 0)
  64     return 0;
  65
  66   do
  67     {
  68       c1 = TOLOWER (*p1++);
  69       c2 = TOLOWER (*p2++);
  70       if (c1 == '\0' || c1 != c2)
  71         return c1 - c2;
  72     } while (--n > 0);
  73
  74   return c1 - c2;
  75 }
  76 #ifndef __strncasecmp
  77 weak_alias (__strncasecmp, strncasecmp)
  78 #endif