lib/memcasecmp.c

   1 /* Case-insensitive buffer comparator.
   2    Copyright (C) 1996 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program 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
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 /* Jim Meyering (meyering@na-net.ornl.gov) */
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <sys/types.h>
  25 #include <ctype.h>
  26
  27 #if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
  28 #define ISASCII(c) 1
  29 #else
  30 #define ISASCII(c) isascii(c)
  31 #endif
  32 #define ISUPPER(c) (ISASCII (c) && isupper (c))
  33
  34 #if _LIBC || STDC_HEADERS
  35 # define TOLOWER(c) tolower (c)
  36 #else
  37 # define TOLOWER(c) (ISUPPER (c) ? tolower (c) : (c))
  38 #endif
  39
  40 #include "memcasecmp.h"
  41
  42 /* Like memcmp, but ignore differences in case.  */
  43
  44 int
  45 memcasecmp (vs1, vs2, n)
  46      const void *vs1;
  47      const void *vs2;
  48      size_t n;
  49 {
  50   unsigned int i;
  51   unsigned char *s1 = (unsigned char *) vs1;
  52   unsigned char *s2 = (unsigned char *) vs2;
  53   for (i = 0; i < n; i++)
  54     {
  55       unsigned char u1 = *s1++;
  56       unsigned char u2 = *s2++;
  57       if (TOLOWER (u1) != TOLOWER (u2))
  58         return TOLOWER (u1) - TOLOWER (u2);
  59     }
  60   return 0;
  61 }