1/* c-strncasecmp.c -- case insensitive string comparator in C locale
2   Copyright (C) 1998-1999, 2005-2006, 2009-2012 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 3, 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, see <http://www.gnu.org/licenses/>.  */
16
17#include <config.h>
18
19/* Specification.  */
20#include "c-strcase.h"
21
22#include <limits.h>
23
24#include "c-ctype.h"
25
26int
27c_strncasecmp (const char *s1, const char *s2, size_t n)
28{
29  register const unsigned char *p1 = (const unsigned char *) s1;
30  register const unsigned char *p2 = (const unsigned char *) s2;
31  unsigned char c1, c2;
32
33  if (p1 == p2 || n == 0)
34    return 0;
35
36  do
37    {
38      c1 = c_tolower (*p1);
39      c2 = c_tolower (*p2);
40
41      if (--n == 0 || c1 == '\0')
42        break;
43
44      ++p1;
45      ++p2;
46    }
47  while (c1 == c2);
48
49  if (UCHAR_MAX <= INT_MAX)
50    return c1 - c2;
51  else
52    /* On machines where 'char' and 'int' are types of the same size, the
53       difference of two 'unsigned char' values - including the sign bit -
54       doesn't fit in an 'int'.  */
55    return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
56}
57