lib/memcasecmp.c

   1 /* Case-insensitive buffer comparator.
   2    Copyright (C) 1996, 1997 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 Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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 IN_CTYPE_DOMAIN(c) 1
  29 #else
  30 # define IN_CTYPE_DOMAIN(c) isascii(c)
  31 #endif
  32 #define ISLOWER(c) (IN_CTYPE_DOMAIN (c) && islower (c))
  33
  34 #if _LIBC || STDC_HEADERS
  35 # define TOUPPER(c) toupper (c)
  36 #else
  37 # define TOUPPER(c) (ISLOWER (c) ? toupper (c) : (c))
  38 #endif
  39
  40 #include "memcasecmp.h"
  41
  42 /* Like memcmp, but ignore differences in case.
  43    Convert to upper case (not lower) before comparing so that
  44    join -i works with sort -f.  */
  45
  46 int
  47 memcasecmp (vs1, vs2, n)
  48      const void *vs1;
  49      const void *vs2;
  50      size_t n;
  51 {
  52   unsigned int i;
  53   unsigned char *s1 = (unsigned char *) vs1;
  54   unsigned char *s2 = (unsigned char *) vs2;
  55   for (i = 0; i < n; i++)
  56     {
  57       unsigned char u1 = *s1++;
  58       unsigned char u2 = *s2++;
  59       if (TOUPPER (u1) != TOUPPER (u2))
  60         return TOUPPER (u1) - TOUPPER (u2);
  61     }
  62   return 0;
  63 }