/contrib/groff/src/libs/libgroff/strcasecmp.c

 1/* strcasecmp.c -- case insensitive string comparator
 2   Copyright (C) 1998, 1999 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., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301, USA.  */
17
18#if HAVE_CONFIG_H
19# include <config.h>
20#endif
21
22#ifdef LENGTH_LIMIT
23# define STRXCASECMP_FUNCTION strncasecmp
24# define STRXCASECMP_DECLARE_N , size_t n
25# define LENGTH_LIMIT_EXPR(Expr) Expr
26#else
27# define STRXCASECMP_FUNCTION strcasecmp
28# define STRXCASECMP_DECLARE_N /* empty */
29# define LENGTH_LIMIT_EXPR(Expr) 0
30#endif
31
32#include <stddef.h>
33#include <ctype.h>
34
35#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
36
37/* Compare {{no more than N characters of }}strings S1 and S2,
38   ignoring case, returning less than, equal to or
39   greater than zero if S1 is lexicographically less
40   than, equal to or greater than S2.  */
41
42int
43STRXCASECMP_FUNCTION (const char *s1, const char *s2 STRXCASECMP_DECLARE_N)
44{
45  register const unsigned char *p1 = (const unsigned char *) s1;
46  register const unsigned char *p2 = (const unsigned char *) s2;
47  unsigned char c1, c2;
48
49  if (p1 == p2 || LENGTH_LIMIT_EXPR (n == 0))
50    return 0;
51
52  do
53    {
54      c1 = TOLOWER (*p1);
55      c2 = TOLOWER (*p2);
56
57      if (LENGTH_LIMIT_EXPR (--n == 0) || c1 == '\0')
58	break;
59
60      ++p1;
61      ++p2;
62    }
63  while (c1 == c2);
64
65  return c1 - c2;
66}