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endian.h
説明を見る。
1 //
2 // Copyright (c) 2003-2011, MIST Project, Nagoya University
3 // All rights reserved.
4 //
5 // Redistribution and use in source and binary forms, with or without modification,
6 // are permitted provided that the following conditions are met:
7 //
8 // 1. Redistributions of source code must retain the above copyright notice,
9 // this list of conditions and the following disclaimer.
10 //
11 // 2. Redistributions in binary form must reproduce the above copyright notice,
12 // this list of conditions and the following disclaimer in the documentation
13 // and/or other materials provided with the distribution.
14 //
15 // 3. Neither the name of the Nagoya University nor the names of its contributors
16 // may be used to endorse or promote products derived from this software
17 // without specific prior written permission.
18 //
19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
20 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
21 // FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
22 // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
25 // IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
26 // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 //
28
33
34 #ifndef __INCLUDE_MIST_ENDIAN__
35 #define __INCLUDE_MIST_ENDIAN__
36
37 #ifndef __INCLUDE_MIST_CONF_H__
38 #include "mist_conf.h"
39 #endif
40
41
42 // mist名前空間の始まり
43 _MIST_BEGIN
44
45
53
54
55
56
63 template < class T >
64 union byte_array
65 {
66 public:
67 typedef T value_type;
68 typedef size_t size_type;
69
70 private:
71 value_type value;
72 unsigned char byte[ sizeof( value_type ) ];
73
74 public:
76 byte_array( ) : value( 0 ){ }
77
78
80 byte_array( const value_type v ) : value( v ){ }
81
82
84 byte_array( const byte_array &v ) : value( v.value ){ }
85
86
91 byte_array( const unsigned char *b )
92 {
93 for( size_type i = 0 ; i < sizeof( value_type ) ; i++ )
94 {
95 byte[ i ] = b[ i ];
96 }
97 }
98
100 size_type length( ) const { return( sizeof( value_type ) ); }
101
103 unsigned char &operator[]( size_type index ){ return( byte[ index ] ); }
104
106 const unsigned char &operator[]( size_type index ) const { return( byte[ index ] ); }
107
109 const value_type get_value( ) const { return( value ); }
110
112 value_type set_value( const value_type &v ) { return( value = v ); }
113
115 const unsigned char * get_bytes( ) const { return( byte ); }
116 };
117
118
124 inline bool _is_little_endian_( )
125 {
126 return( byte_array< unsigned short >( 1 )[ 0 ] == 1 );
127 }
128
129
137 inline bool _is_big_endian_( )
138 {
139 return( byte_array< unsigned short >( 1 )[ 0 ] == 0 );
140 }
141
142
147 template < class T >
148 inline void swap_bytes( byte_array< T > &bytes )
149 {
150 typedef typename byte_array< T >::size_type size_type;
151 byte_array< T > tmp( bytes );
152 for( size_type i = 0 ; i < sizeof( T ) ; ++i )
153 {
154 bytes[ i ] = tmp[ sizeof( T ) - i - 1 ];
155 }
156 }
157
158
170 template < class T >
171 inline byte_array< T > to_current_endian( const byte_array< T > &bytes, bool from_little_endian )
172 {
173 static bool current_endian = _is_little_endian_( );
174 if( current_endian != from_little_endian )
175 {
176 byte_array< T > tmp( bytes );
177 swap_bytes( tmp );
178 return( tmp );
179 }
180 else
181 {
182 return( bytes );
183 }
184 }
185
186
198 template < class T >
199 inline byte_array< T > from_current_endian( const byte_array< T > &bytes, bool to_little_endian )
200 {
201 static bool current_endian = _is_little_endian_( );
202 if( current_endian != to_little_endian )
203 {
204 byte_array< T > tmp( bytes );
205 swap_bytes( tmp );
206 return( tmp );
207 }
208 else
209 {
210 return( bytes );
211 }
212 }
213
214
215
217 // エンディアンに関する情報の取得及び変換グループの終わり
218
219
220 // mist名前空間の終わり
221 _MIST_END
222
223
224 #endif // __INCLUDE_MIST_ENDIAN__
225