1 /* $NetBSD: dd_swab.c,v 1.2 2021/10/08 14:44:48 christos Exp $ */
2
3 /*
4 * Copyright (c) 1988, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Jeffrey Mogul.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * from: NetBSD: swab.c,v 1.18 2011/01/04 17:14:07 martin Exp
35 */
36
37 /* This copy has no restrict on it, that dd wants */
38
39 #include <sys/cdefs.h>
40 #if defined(LIBC_SCCS) && !defined(lint)
41 #if 0
42 static char sccsid[] = "@(#)swab.c 8.1 (Berkeley) 6/4/93";
43 #else
44 __RCSID("$NetBSD: dd_swab.c,v 1.2 2021/10/08 14:44:48 christos Exp $");
45 #endif
46 #endif /* LIBC_SCCS and not lint */
47
48 #include <sys/types.h>
49
50 #include "dd.h"
51 #include "extern.h"
52
53 void
dd_swab(const void * from,void * to,ssize_t len)54 dd_swab(const void * from, void * to, ssize_t len)
55 {
56 char temp;
57 const char *fp;
58 char *tp;
59
60 if (len <= 1)
61 return;
62
63 len /= 2;
64 fp = (const char *)from;
65 tp = (char *)to;
66 #define STEP temp = *fp++,*tp++ = *fp++,*tp++ = temp
67
68 if (__predict_false(len == 1)) {
69 STEP;
70 return;
71 }
72
73 /* round to multiple of 8 */
74 for (; (len % 8) != 0; --len)
75 STEP;
76 len /= 8;
77 if (len == 0)
78 return;
79 while (len-- != 0) {
80 STEP; STEP; STEP; STEP;
81 STEP; STEP; STEP; STEP;
82 }
83 }
84