xref: /illumos-gate/usr/src/lib/libc/port/gen/swab.c (revision 88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 /*	Copyright (c) 1988 AT&T	*/
30 /*	  All Rights Reserved  	*/
31 
32 
33 /*
34  * Swab bytes
35  */
36 
37 #pragma weak swab = _swab
38 
39 #include "synonyms.h"
40 #include <sys/types.h>
41 #include <stdlib.h>
42 
43 
44 #define	STEP	(void)((temp = *from++), (*to++ = *from++), (*to++ = temp))
45 
46 void
47 swab(const char *src, char *dest, ssize_t n)
48 {
49 	char temp;
50 	const char *from = (const char *)src;
51 	char *to = (char *)dest;
52 
53 	if (n <= 1)
54 		return;
55 	n >>= 1; n++;
56 	/* round to multiple of 8 */
57 	while ((--n) & 07)
58 		STEP;
59 	n >>= 3;
60 	while (--n >= 0) {
61 		STEP; STEP; STEP; STEP;
62 		STEP; STEP; STEP; STEP;
63 	}
64 }
65