NetBSD/common/lib/libc/string/strncmp.c

66 lines
2.3 KiB
C

/* $NetBSD: strncmp.c,v 1.2 2007/06/04 18:19:27 christos Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)strncmp.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: strncmp.c,v 1.2 2007/06/04 18:19:27 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
#if !defined(_KERNEL) && !defined(_STANDALONE)
#include <assert.h>
#include <string.h>
#else
#include <lib/libkern/libkern.h>
#endif
int
strncmp(const char *s1, const char *s2, size_t n)
{
_DIAGASSERT(s1 != NULL);
_DIAGASSERT(s2 != NULL);
if (n == 0)
return (0);
do {
if (*s1 != *s2++)
return (*(const unsigned char *)s1 -
*(const unsigned char *)--s2);
if (*s1++ == 0)
break;
} while (--n != 0);
return (0);
}