xref: /dragonfly/lib/libc/string/swab.c (revision 2038fb68)
1 /*
2  * Copyright (c) 1988, 1993
3  *	The Regents of the University of California.  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  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  * @(#)swab.c	8.1 (Berkeley) 6/4/93
33  * $FreeBSD: src/lib/libc/string/swab.c,v 1.7 2007/01/09 00:28:12 imp Exp $
34  * $DragonFly: src/lib/libc/string/swab.c,v 1.4 2005/09/18 16:32:34 asmodai Exp $
35  */
36 
37 #include <unistd.h>
38 
39 void
40 swab(const void * __restrict from, void * __restrict to, ssize_t len)
41 {
42 	unsigned long temp;
43 	int n;
44 	char *fp, *tp;
45 
46 	n = len >> 1;
47 	fp = (char *)from;
48 	tp = (char *)to;
49 #define	STEP	temp = *fp++,*tp++ = *fp++,*tp++ = temp
50 	/* round to multiple of 8 */
51 	for (; n & 0x7; --n)
52 		STEP;
53 	for (n >>= 3; n > 0; --n) {
54 		STEP; STEP; STEP; STEP;
55 		STEP; STEP; STEP; STEP;
56 	}
57 }
58