c-strncasecmp.c

/* c-strncasecmp.c -- case insensitive string comparator in C locale
 * Copyright (C) 1998-1999, 2005-2006, 2009-2012 Free Software Foundation, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>

/* Specification: */
#include "c-strcase.h"

#include <limits.h>

#include "c-ctype.h"

int
c_strncasecmp(const char *s1, const char *s2, size_t n)
{
  register const unsigned char *p1 = (const unsigned char *)s1;
  register const unsigned char *p2 = (const unsigned char *)s2;
  unsigned char c1, c2;

  if ((p1 == p2) || (n == 0)) {
	  return 0;
  }

  do {
      c1 = (unsigned char)c_tolower(*p1);
      c2 = (unsigned char)c_tolower(*p2);

      if ((--n == 0) || (c1 == '\0')) {
		  break;
	  }

      ++p1;
      ++p2;
  } while (c1 == c2);

  if (UCHAR_MAX <= INT_MAX) {
	  return (c1 - c2);
  } else {
	  /* On machines where 'char' and 'int' are types of the same size, the
	   * difference of two 'unsigned char' values - including the sign bit -
	   * does NOT fit in an 'int'.  */
	  return ((c1 > c2) ? 1 : ((c1 < c2) ? -1 : 0));
  }
}

/* EOF */