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Independent SDK for the Sega Dreamcast
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byteorder.h
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1/* KallistiOS ##version##
2
3 arch/dreamcast/include/arch/byteorder.h
4 Copyright (C) 2015 Lawrence Sebald
5
6*/
7
8/** \file arch/byteorder.h
9 \brief Byte-order related macros.
10 \ingroup system_arch
11
12 This file contains architecture-specific byte-order related macros and/or
13 functions. Each platform should define six macros/functions in this file:
14 arch_swap16, arch_swap32, arch_ntohs, arch_ntohl, arch_htons, and
15 arch_htonl. The first two of these swap the byte order of 16-bit and 32-bit
16 integers, respectively. The other four macros will be used by the kernel to
17 implement the network-related byte order functions.
18
19 \author Lawrence Sebald
20*/
21
22#ifndef __ARCH_BYTEORDER_H
23#define __ARCH_BYTEORDER_H
24
25#include <sys/cdefs.h>
26__BEGIN_DECLS
27
28#include <sys/_types.h>
29
30#ifdef BYTE_ORDER
31/* If we've included <arch/types.h>, this might already be defined... */
32#undef BYTE_ORDER
33#endif
34
35/** \defgroup system_arch Byte Order
36 \brief Byte-order management for the SH4 architecture
37 \ingroup arch
38
39 @{
40*/
41
42/** \brief Define the byte-order of the platform in use. */
43#define BYTE_ORDER LITTLE_ENDIAN
44
45/** \brief Swap the byte order of a 16-bit integer.
46
47 This macro swaps the byte order of a 16-bit integer in an architecture-
48 defined manner.
49
50 \param x The value to be byte-swapped. This should be a uint16,
51 or equivalent.
52 \return The swapped value.
53*/
54#define arch_swap16(x) ({ \
55 uint16 __x = (x); \
56 __asm__ __volatile__("swap.b %0, %0" : "=r" (__x) : "0" (__x)); \
57 __x; \
58})
59
60/** \brief Swap the byte order of a 32-bit integer.
61
62 This macro swaps the byte order of a 32-bit integer in an architecture-
63 defined manner.
64
65 \param x The value to be byte-swapped. This should be a uint32,
66 or equivalent.
67 \return The swapped value.
68*/
69#define arch_swap32(x) ({ \
70 uint32 __x = (x); \
71 __asm__ __volatile__("swap.b %0, %0\n\t" \
72 "swap.w %0, %0\n\t" \
73 "swap.b %0, %0\n\t" : "=r"(__x) : "0" (__x)); \
74 __x; \
75})
76
77/** \brief Convert network-to-host short.
78
79 This macro converts a network byte order (big endian) value to the host's
80 native byte order. On a little endian system (like the Dreamcast), this
81 should just call arch_swap16(). On a big endian system, this should be a
82 no-op.
83
84 \param x The value to be converted. This should be a uint16,
85 or equivalent.
86 \return The converted value.
87*/
88#define arch_ntohs(x) arch_swap16(x)
89
90/** \brief Convert network-to-host long.
91
92 This macro converts a network byte order (big endian) value to the host's
93 native byte order. On a little endian system (like the Dreamcast), this
94 should just call arch_swap32(). On a big endian system, this should be a
95 no-op.
96
97 \param x The value to be converted. This should be a uint32,
98 or equivalent.
99 \return The converted value.
100*/
101#define arch_ntohl(x) arch_swap32(x)
102
103/** \brief Convert host-to-network short.
104
105 This macro converts a value in the host's native byte order to network byte
106 order (big endian). On a little endian system (like the Dreamcast), this
107 should just call arch_swap16(). On a big endian system, this should be a
108 no-op.
109
110 \param x The value to be converted. This should be a uint16,
111 or equivalent.
112 \return The converted value.
113*/
114#define arch_htons(x) arch_swap16(x)
115
116/** \brief Convert host-to-network long.
117
118 This macro converts a value in the host's native byte order to network byte
119 order (big endian). On a little endian system (like the Dreamcast), this
120 should just call arch_swap32(). On a big endian system, this should be a
121 no-op.
122
123 \param x The value to be converted. This should be a uint32,
124 or equivalent.
125 \return The converted value.
126*/
127#define arch_htonl(x) arch_swap32(x)
128
129/** @} */
130
131__END_DECLS
132
133#endif /* !__ARCH_BYTEORDER_H */
_types.h
Internal typedefs.