[bpt/guile.git] / lib / strncasecmp.c

/* strncasecmp.c -- case insensitive string comparator
   Copyright (C) 1998-1999, 2005-2007, 2009-2010 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser 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 Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <config.h>

/* Specification.  */
#include <string.h>

#include <ctype.h>
#include <limits.h>

#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))

/* Compare no more than N bytes of strings S1 and S2, ignoring case,
   returning less than, equal to or greater than zero if S1 is
   lexicographically less than, equal to or greater than S2.
   Note: This function cannot work correctly in multibyte locales.  */

int
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 = TOLOWER (*p1);
      c2 = 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 -
       doesn't fit in an 'int'.  */
    return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
}
Commit	Line	Data
103dc4d4	1	/* strncasecmp.c -- case insensitive string comparator
61cd9dc9	2	Copyright (C) 1998-1999, 2005-2007, 2009-2010 Free Software Foundation, Inc.
103dc4d4 LC	3
	4	This program is free software; you can redistribute it and/or modify
	5	it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
	13
	14	You should have received a copy of the GNU Lesser 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
	18	#include <config.h>
	19
	20	/* Specification. */
	21	#include <string.h>
	22
	23	#include <ctype.h>
	24	#include <limits.h>
	25
	26	#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
	27
	28	/* Compare no more than N bytes of strings S1 and S2, ignoring case,
	29	returning less than, equal to or greater than zero if S1 is
	30	lexicographically less than, equal to or greater than S2.
	31	Note: This function cannot work correctly in multibyte locales. */
	32
	33	int
	34	strncasecmp (const char s1, const char s2, size_t n)
	35	{
	36	register const unsigned char p1 = (const unsigned char ) s1;
	37	register const unsigned char p2 = (const unsigned char ) s2;
	38	unsigned char c1, c2;
	39
	40	if (p1 == p2 \|\| n == 0)
	41	return 0;
	42
	43	do
	44	{
	45	c1 = TOLOWER (*p1);
	46	c2 = TOLOWER (*p2);
	47
	48	if (--n == 0 \|\| c1 == '\0')
1cd4fffc	49	break;
103dc4d4 LC	50
	51	++p1;
	52	++p2;
	53	}
	54	while (c1 == c2);
	55
	56	if (UCHAR_MAX <= INT_MAX)
	57	return c1 - c2;
	58	else
	59	/* On machines where 'char' and 'int' are types of the same size, the
	60	difference of two 'unsigned char' values - including the sign bit -
	61	doesn't fit in an 'int'. */
	62	return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
	63	}