1 /*
2 * Copyright (c) Ian F. Darwin 1986-1995.
3 * Software written by Ian F. Darwin and others;
4 * maintained 1995-present by Christos Zoulas and others.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice immediately at the beginning of the file, without modification,
11 * this list of conditions, and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
20 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28 /*
29 * apprentice - make one pass through /etc/magic, learning its secrets.
30 */
31
32 #include "file.h"
33
34 #ifndef lint
35 FILE_RCSID("@(#)$File: swap.c,v 1.1 2026/04/19 19:56:49 christos Exp $")
36 #endif /* lint */
37
38 #include "swap.h"
39
40 #if !defined(HAVE_BYTESWAP_H) && !defined(HAVE_SYS_BSWAP_H)
41 /*
42 * swap a short
43 */
44 file_protected uint16_t
file_swap2(uint16_t sv)45 file_swap2(uint16_t sv)
46 {
47 uint16_t rv;
48 uint8_t *s = RCAST(uint8_t *, RCAST(void *, &sv));
49 uint8_t *d = RCAST(uint8_t *, RCAST(void *, &rv));
50 d[0] = s[1];
51 d[1] = s[0];
52 return rv;
53 }
54
55 /*
56 * swap an int
57 */
58 file_protected uint32_t
file_swap4(uint32_t sv)59 file_swap4(uint32_t sv)
60 {
61 uint32_t rv;
62 uint8_t *s = RCAST(uint8_t *, RCAST(void *, &sv));
63 uint8_t *d = RCAST(uint8_t *, RCAST(void *, &rv));
64 d[0] = s[3];
65 d[1] = s[2];
66 d[2] = s[1];
67 d[3] = s[0];
68 return rv;
69 }
70
71 /*
72 * swap a quad
73 */
74 file_protected uint64_t
file_swap8(uint64_t sv)75 file_swap8(uint64_t sv)
76 {
77 uint64_t rv;
78 uint8_t *s = RCAST(uint8_t *, RCAST(void *, &sv));
79 uint8_t *d = RCAST(uint8_t *, RCAST(void *, &rv));
80 # if 0
81 d[0] = s[3];
82 d[1] = s[2];
83 d[2] = s[1];
84 d[3] = s[0];
85 d[4] = s[7];
86 d[5] = s[6];
87 d[6] = s[5];
88 d[7] = s[4];
89 # else
90 d[0] = s[7];
91 d[1] = s[6];
92 d[2] = s[5];
93 d[3] = s[4];
94 d[4] = s[3];
95 d[5] = s[2];
96 d[6] = s[1];
97 d[7] = s[0];
98 # endif
99 return rv;
100 }
101 #endif
102