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strncmp.c revision 1.1 
      1 /*	$NetBSD: strncmp.c,v 1.1 2005/12/20 19:28:52 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)strncmp.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: strncmp.c,v 1.1 2005/12/20 19:28:52 christos Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #if !defined(_KERNEL) && !defined(_STANDALONE)
     42 #include <assert.h>
     43 #include <string.h>
     44 #else
     45 #include <lib/libkern/libkern.h>
     46 #endif
     47 
     48 int
     49 strncmp(s1, s2, n)
     50 	const char *s1, *s2;
     51 	size_t n;
     52 {
     53 
     54 	_DIAGASSERT(s1 != NULL);
     55 	_DIAGASSERT(s2 != NULL);
     56 
     57 	if (n == 0)
     58 		return (0);
     59 	do {
     60 		if (*s1 != *s2++)
     61 			return (*(const unsigned char *)s1 -
     62 			    *(const unsigned char *)--s2);
     63 		if (*s1++ == 0)
     64 			break;
     65 	} while (--n != 0);
     66 	return (0);
     67 }
     68