xref: /illumos-gate/usr/src/lib/libc/port/gen/ascii_strncasecmp.c (revision 6a634c9d)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

#include "lint.h"
#include <sys/types.h>
#include <strings.h>

/*
 * This array is designed for mapping upper and lower case letter
 * together for a case independent comparison.  The mappings are
 * based upon ascii character sequences.
 */

extern const char strcase_charmap[];

int
ascii_strncasecmp(const char *s1, const char *s2, size_t n)
{
	const unsigned char	*cm = (const unsigned char *)strcase_charmap;
	const unsigned char	*us1 = (const unsigned char *)s1;
	const unsigned char	*us2 = (const unsigned char *)s2;

	while (n != 0 && cm[*us1] == cm[*us2++]) {
		if (*us1++ == '\0')
			return (0);
		n--;
	}
	return (n == 0 ? 0 : cm[*us1] - cm[*(us2 - 1)]);
}