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
60static __inline__ unsigned int byte_reverse_word(unsigned int word);
61static __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
83unsigned short	ntohs(), htons();
84unsigned 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_ */
94