xref: /netbsd-src/lib/libc/string/swab.c (revision d9158b13b5dfe46201430699a3f7a235ecf28df3)
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 = "from: @(#)swab.c	5.10 (Berkeley) 3/6/91";*/
39 static char *rcsid = "$Id: swab.c,v 1.3 1993/08/26 00:52:03 jtc Exp $";
40 #endif /* LIBC_SCCS and not lint */
41 
42 #include <string.h>
43 
44 void
45 swab(from, to, len)
46 	const void *from;
47 	void *to;
48 	size_t len;
49 {
50 	register unsigned long temp;
51 	register int n;
52 	register char *fp, *tp;
53 
54 	n = (len >> 1) + 1;
55 	fp = (char *)from;
56 	tp = (char *)to;
57 #define	STEP	temp = *fp++,*tp++ = *fp++,*tp++ = temp
58 	/* round to multiple of 8 */
59 	while ((--n) & 07)
60 		STEP;
61 	n >>= 3;
62 	while (--n >= 0) {
63 		STEP; STEP; STEP; STEP;
64 		STEP; STEP; STEP; STEP;
65 	}
66 }
67