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swab.c revision 1.4 
      1 /*	$NetBSD: swab.c,v 1.4 1997/07/13 20:24:37 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1988 Regents of the University of California.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Jeffrey Mogul.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #if defined(LIBC_SCCS) && !defined(lint)
     41 #if 0
     42 static char *sccsid = "@(#)swab.c	5.10 (Berkeley) 3/6/91";
     43 #else
     44 __RCSID("$NetBSD: swab.c,v 1.4 1997/07/13 20:24:37 christos Exp $");
     45 #endif
     46 #endif /* LIBC_SCCS and not lint */
     47 
     48 #include <string.h>
     49 
     50 void
     51 swab(from, to, len)
     52 	const void *from;
     53 	void *to;
     54 	size_t len;
     55 {
     56 	register unsigned long temp;
     57 	register int n;
     58 	register char *fp, *tp;
     59 
     60 	n = (len >> 1) + 1;
     61 	fp = (char *)from;
     62 	tp = (char *)to;
     63 #define	STEP	temp = *fp++,*tp++ = *fp++,*tp++ = temp
     64 	/* round to multiple of 8 */
     65 	while ((--n) & 07)
     66 		STEP;
     67 	n >>= 3;
     68 	while (--n >= 0) {
     69 		STEP; STEP; STEP; STEP;
     70 		STEP; STEP; STEP; STEP;
     71 	}
     72 }
     73