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      1 /*	$NetBSD: dkcksum.c,v 1.1 2021/05/17 08:50:36 mrg Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1991, 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  * from: NetBSD: dkcksum.c,v 1.14 2013/05/03 16:05:12 matt Exp
     32  */
     33 
     34 #include <sys/cdefs.h>
     35 #ifndef lint
     36 #if 0
     37 static char sccsid[] = "@(#)dkcksum.c	8.1 (Berkeley) 6/5/93";
     38 #else
     39 __RCSID("$NetBSD: dkcksum.c,v 1.1 2021/05/17 08:50:36 mrg Exp $");
     40 #endif
     41 #endif /* not lint */
     42 
     43 #include <sys/types.h>
     44 #include <sys/disklabel.h>
     45 #include <lib/libkern/libkern.h>
     46 
     47 uint16_t
     48 dkcksum(const struct disklabel *lp)
     49 {
     50 
     51 	return dkcksum_sized(lp, lp->d_npartitions);
     52 }
     53 
     54 uint16_t
     55 dkcksum_sized(const struct disklabel *lp, size_t npartitions)
     56 {
     57 	const uint16_t *start, *end;
     58 	uint16_t sum;
     59 
     60 	sum = 0;
     61 	start = (const uint16_t *)lp;
     62 	end = (const uint16_t *)&lp->d_partitions[npartitions];
     63 	while (start < end) {
     64 		sum ^= *start++;
     65 	}
     66 	return sum;
     67 }
     68