dd_swab.c revision 1.1 
1/*	$NetBSD: dd_swab.c,v 1.1 2019/10/04 08:57:38 mrg 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
42static char sccsid[] = "@(#)swab.c	8.1 (Berkeley) 6/4/93";
43#else
44__RCSID("$NetBSD: dd_swab.c,v 1.1 2019/10/04 08:57:38 mrg 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
53void
54dd_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	while ((--len % 8) != 0)
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