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1 /*
2 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 /*
29 * @OSF_COPYRIGHT@
30 *
31 */
32
33 #ifndef _MACHINE_ENDIAN_H_
34 #define _MACHINE_ENDIAN_H_
35
36 /*
37 * Definitions for byte order,
38 * according to byte significance from low address to high.
39 */
40 #define LITTLE_ENDIAN 1234 /* least-significant byte first (vax) */
41 #define BIG_ENDIAN 4321 /* most-significant byte first (IBM, net) */
42 #define PDP_ENDIAN 3412 /* LSB first in word, MSW first in long (pdp) */
43
44 #ifdef __BIG_ENDIAN__ /* Predefined by compiler */
45 #define BYTE_ORDER BIG_ENDIAN /* byte order we use on ppc */
46 #define ENDIAN BIG
47 #else
48 #error code has not been ported to little endian targets yet
49 #endif
50
51 /*
52 * Macros for network/external number representation conversion.
53 */
54 #if BYTE_ORDER == BIG_ENDIAN && !defined(lint)
55 #define ntohl(x) (x)
56 #define ntohs(x) (x)
57 #define htonl(x) (x)
58 #define htons(x) (x)
59
60 static __inline__ unsigned int byte_reverse_word(unsigned int word);
61 static __inline__ unsigned int byte_reverse_word(unsigned int word) {
62 unsigned int result;
63 __asm__ volatile("lwbrx %0, 0, %1" : "=r" (result) : "r" (&word));
64 return result;
65 }
66
67 /* The above function is commutative, so we can use it for
68 * translations in both directions (to/from little endianness)
69 * Note that htolx and ltohx are probably identical, they are
70 * included for completeness.
71 */
72 #define htoll(x) byte_reverse_word(x)
73 #define htols(x) (byte_reverse_word(x) >> 16)
74 #define ltohl(x) htoll(x)
75 #define ltohs(x) htols(x)
76
77 #define htobl(x) (x)
78 #define htobs(x) (x)
79 #define btohl(x) (x)
80 #define btohs(x) (x)
81
82 #else
83 unsigned short ntohs(), htons();
84 unsigned long ntohl(), htonl();
85 #endif
86
87 /* This defines the order of elements in a bitfield,
88 * it is principally used by the SCSI subsystem in
89 * the definitions of mapped registers
90 */
91 #define BYTE_MSF 1
92
93 #endif /* _MACHINE_ENDIAN_H_ */