1/* strncasecmp.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 Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
17#include <sys/cdefs.h>
18__RCSID("$NetBSD: strncasecmp.c,v 1.2 2016/05/17 14:00:09 christos Exp $");
19
20
21#ifdef HAVE_CONFIG_H
22# include <config.h>
23#endif
24
25/* Specification.  */
26#include "strcase.h"
27
28#include <ctype.h>
29
30#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
31
32/* Compare no more than N bytes of strings S1 and S2,
33   ignoring case, returning less than, equal to or
34   greater than zero if S1 is lexicographically less
35   than, equal to or greater than S2.  */
36
37int
38strncasecmp (const char *s1, const char *s2, size_t n)
39{
40  register const unsigned char *p1 = (const unsigned char *) s1;
41  register const unsigned char *p2 = (const unsigned char *) s2;
42  unsigned char c1, c2;
43
44  if (p1 == p2 || n == 0)
45    return 0;
46
47  do
48    {
49      c1 = TOLOWER (*p1);
50      c2 = TOLOWER (*p2);
51
52      if (--n == 0 || c1 == '\0')
53	break;
54
55      ++p1;
56      ++p2;
57    }
58  while (c1 == c2);
59
60  return c1 - c2;
61}
62