xref: /illumos-gate/usr/src/lib/libc/port/gen/swab.c (revision 7257d1b4)
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 (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1988 AT&T	*/
28 /*	  All Rights Reserved  	*/
29 
30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
31 
32 /*
33  * Swab bytes
34  */
35 
36 #pragma weak _swab = swab
37 
38 #include "lint.h"
39 #include <sys/types.h>
40 #include <stdlib.h>
41 
42 
43 #define	STEP	(void)((temp = *from++), (*to++ = *from++), (*to++ = temp))
44 
45 void
swab(const char * src,char * dest,ssize_t n)46 swab(const char *src, char *dest, ssize_t n)
47 {
48 	char temp;
49 	const char *from = (const char *)src;
50 	char *to = (char *)dest;
51 
52 	if (n <= 1)
53 		return;
54 	n >>= 1; n++;
55 	/* round to multiple of 8 */
56 	while ((--n) & 07)
57 		STEP;
58 	n >>= 3;
59 	while (--n >= 0) {
60 		STEP; STEP; STEP; STEP;
61 		STEP; STEP; STEP; STEP;
62 	}
63 }
64