xref: /illumos-gate/usr/src/lib/libc/port/gen/swab.c (revision f37b3cbb6f67aaea5eec1c335bdc7bf432867d64)
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 /*
31  * Swab bytes
32  */
33 
34 #pragma weak _swab = swab
35 
36 #include "lint.h"
37 #include <sys/types.h>
38 #include <stdlib.h>
39 
40 
41 #define	STEP	(void)((temp = *from++), (*to++ = *from++), (*to++ = temp))
42 
43 void
44 swab(const char *src, char *dest, ssize_t n)
45 {
46 	char temp;
47 	const char *from = (const char *)src;
48 	char *to = (char *)dest;
49 
50 	if (n <= 1)
51 		return;
52 	n >>= 1; n++;
53 	/* round to multiple of 8 */
54 	while ((--n) & 07)
55 		STEP;
56 	n >>= 3;
57 	while (--n >= 0) {
58 		STEP; STEP; STEP; STEP;
59 		STEP; STEP; STEP; STEP;
60 	}
61 }
62