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swab.c revision 1.1.1.1 
      1 /*
      2  * Copyright (c) 1988 Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * This code is derived from software contributed to Berkeley by
      6  * Jeffrey Mogul.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *	This product includes software developed by the University of
     19  *	California, Berkeley and its contributors.
     20  * 4. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  */
     36 
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 static char sccsid[] = "@(#)swab.c	5.10 (Berkeley) 3/6/91";
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include <string.h>
     42 
     43 void
     44 swab(from, to, len)
     45 	const void *from;
     46 	void *to;
     47 	size_t len;
     48 {
     49 	register unsigned long temp;
     50 	register int n;
     51 	register char *fp, *tp;
     52 
     53 	n = (len >> 1) + 1;
     54 	fp = (char *)from;
     55 	tp = (char *)to;
     56 #define	STEP	temp = *fp++,*tp++ = *fp++,*tp++ = temp
     57 	/* round to multiple of 8 */
     58 	while ((--n) & 07)
     59 		STEP;
     60 	n >>= 3;
     61 	while (--n >= 0) {
     62 		STEP; STEP; STEP; STEP;
     63 		STEP; STEP; STEP; STEP;
     64 	}
     65 }
     66