lib/memcasecmp.c

   1 /* Case-insensitive buffer comparator.
   2    Copyright (C) 1996, 1997, 2000, 2003 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 /* Written by Jim Meyering.  */
  19
  20 #if HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <ctype.h>
  25
  26 #if defined STDC_HEADERS || (!defined isascii && !defined HAVE_ISASCII)
  27 # define IN_CTYPE_DOMAIN(Char) 1
  28 #else
  29 # define IN_CTYPE_DOMAIN(Char) isascii (Char)
  30 #endif
  31 #define ISLOWER(Char) (IN_CTYPE_DOMAIN (Char) && islower (Char))
  32
  33 #if _LIBC || STDC_HEADERS
  34 # define TOUPPER(Char) toupper (Char)
  35 #else
  36 # define TOUPPER(Char) (ISLOWER (Char) ? toupper (Char) : (Char))
  37 #endif
  38
  39 #include "memcasecmp.h"
  40
  41 /* Like memcmp, but ignore differences in case.
  42    Convert to upper case (not lower) before comparing so that
  43    join -i works with sort -f.  */
  44
  45 int
  46 memcasecmp (const void *vs1, const void *vs2, size_t n)
  47 {
  48   size_t i;
  49   char const *s1 = vs1;
  50   char const *s2 = vs2;
  51   for (i = 0; i < n; i++)
  52     {
  53       unsigned char u1 = s1[i];
  54       unsigned char u2 = s2[i];
  55       int diff = TOUPPER (u1) - TOUPPER (u2);
  56       if (diff)
  57         return diff;
  58     }
  59   return 0;
  60 }