1/*
2 * Copyright (c) 2003-2005 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Steve Reinhardt
29 * Nathan Binkert
30 */
31
32#ifndef __BASE_BITFIELD_HH__
33#define __BASE_BITFIELD_HH__
34
35#include <inttypes.h>
36
37/**
38 * Generate a 64-bit mask of 'nbits' 1s, right justified.
39 */
40inline uint64_t
41mask(int nbits)
42{
43 return (nbits == 64) ? (uint64_t)-1LL : (1ULL << nbits) - 1;
44}
45
46
47
48/**
49 * Extract the bitfield from position 'first' to 'last' (inclusive)
50 * from 'val' and right justify it. MSB is numbered 63, LSB is 0.
51 */
52template <class T>
53inline
54T
55bits(T val, int first, int last)
56{
57 int nbits = first - last + 1;
58 return (val >> last) & mask(nbits);
59}
60
61/**
62 * Mask off the given bits in place like bits() but without shifting.
63 * msb = 63, lsb = 0
64 */
65template <class T>
66inline
67T
68mbits(T val, int first, int last)
69{
70 return val & (mask(first+1) & ~mask(last));
71}
72
73inline uint64_t
74mask(int first, int last)
75{
76 return mbits((uint64_t)-1LL, first, last);
77}
78
79/**
80 * Sign-extend an N-bit value to 64 bits.
81 */
82template <int N>
83inline
84int64_t
85sext(uint64_t val)
86{
87 int sign_bit = bits(val, N-1, N-1);
88 return sign_bit ? (val | ~mask(N)) : val;
89}
90
91/**
92 * Return val with bits first to last set to bit_val
93 */
94template <class T, class B>
95inline
96T
97insertBits(T val, int first, int last, B bit_val)
98{
| 1/*
2 * Copyright (c) 2003-2005 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Steve Reinhardt
29 * Nathan Binkert
30 */
31
32#ifndef __BASE_BITFIELD_HH__
33#define __BASE_BITFIELD_HH__
34
35#include <inttypes.h>
36
37/**
38 * Generate a 64-bit mask of 'nbits' 1s, right justified.
39 */
40inline uint64_t
41mask(int nbits)
42{
43 return (nbits == 64) ? (uint64_t)-1LL : (1ULL << nbits) - 1;
44}
45
46
47
48/**
49 * Extract the bitfield from position 'first' to 'last' (inclusive)
50 * from 'val' and right justify it. MSB is numbered 63, LSB is 0.
51 */
52template <class T>
53inline
54T
55bits(T val, int first, int last)
56{
57 int nbits = first - last + 1;
58 return (val >> last) & mask(nbits);
59}
60
61/**
62 * Mask off the given bits in place like bits() but without shifting.
63 * msb = 63, lsb = 0
64 */
65template <class T>
66inline
67T
68mbits(T val, int first, int last)
69{
70 return val & (mask(first+1) & ~mask(last));
71}
72
73inline uint64_t
74mask(int first, int last)
75{
76 return mbits((uint64_t)-1LL, first, last);
77}
78
79/**
80 * Sign-extend an N-bit value to 64 bits.
81 */
82template <int N>
83inline
84int64_t
85sext(uint64_t val)
86{
87 int sign_bit = bits(val, N-1, N-1);
88 return sign_bit ? (val | ~mask(N)) : val;
89}
90
91/**
92 * Return val with bits first to last set to bit_val
93 */
94template <class T, class B>
95inline
96T
97insertBits(T val, int first, int last, B bit_val)
98{
|
101}
102
103/**
104 * A convenience function to replace bits first to last of val with bit_val
105 * in place.
106 */
107template <class T, class B>
108inline
109void
110replaceBits(T& val, int first, int last, B bit_val)
111{
112 val = insertBits(val, first, last, bit_val);
113}
114
115/**
116 * Returns the bit position of the MSB that is set in the input
117 */
118inline
119int
120findMsbSet(uint64_t val) {
121 int msb = 0;
122 if (!val)
123 return 0;
124 if (bits(val, 63,32)) { msb += 32; val >>= 32; }
125 if (bits(val, 31,16)) { msb += 16; val >>= 16; }
126 if (bits(val, 15,8)) { msb += 8; val >>= 8; }
127 if (bits(val, 7,4)) { msb += 4; val >>= 4; }
128 if (bits(val, 3,2)) { msb += 2; val >>= 2; }
129 if (bits(val, 1,1)) { msb += 1; }
130 return msb;
131}
132
133// The following implements the BitUnion system of defining bitfields
134//on top of an underlying class. This is done through the pervasive use of
135//both named and unnamed unions which all contain the same actual storage.
136//Since they're unioned with each other, all of these storage locations
137//overlap. This allows all of the bitfields to manipulate the same data
138//without having to have access to each other. More details are provided with the
139//individual components.
140
141//This namespace is for classes which implement the backend of the BitUnion
142//stuff. Don't use any of these directly, except for the Bitfield classes in
143//the *BitfieldTypes class(es).
144namespace BitfieldBackend
145{
146 //A base class for all bitfields. It instantiates the actual storage,
147 //and provides getBits and setBits functions for manipulating it. The
148 //Data template parameter is type of the underlying storage.
149 template<class Data>
150 class BitfieldBase
151 {
152 protected:
153 Data __data;
154
155 //This function returns a range of bits from the underlying storage.
156 //It relies on the "bits" function above. It's the user's
157 //responsibility to make sure that there is a properly overloaded
158 //version of this function for whatever type they want to overlay.
159 inline uint64_t
160 getBits(int first, int last) const
161 {
162 return bits(__data, first, last);
163 }
164
165 //Similar to the above, but for settings bits with replaceBits.
166 inline void
167 setBits(int first, int last, uint64_t val)
168 {
169 replaceBits(__data, first, last, val);
170 }
171 };
172
173 //This class contains all the "regular" bitfield classes. It is inherited
174 //by all BitUnions which give them access to those types.
175 template<class Type>
176 class RegularBitfieldTypes
177 {
178 protected:
179 //This class implements ordinary bitfields, that is a span of bits
180 //who's msb is "first", and who's lsb is "last".
181 template<int first, int last=first>
182 class Bitfield : public BitfieldBase<Type>
183 {
184 public:
185 operator uint64_t () const
186 {
187 return this->getBits(first, last);
188 }
189
190 uint64_t
191 operator=(const uint64_t _data)
192 {
193 this->setBits(first, last, _data);
194 return _data;
195 }
196 };
197
198 //A class which specializes the above so that it can only be read
199 //from. This is accomplished explicitly making sure the assignment
200 //operator is blocked. The conversion operator is carried through
201 //inheritance. This will unfortunately need to be copied into each
202 //bitfield type due to limitations with how templates work
203 template<int first, int last=first>
204 class BitfieldRO : public Bitfield<first, last>
205 {
206 private:
207 uint64_t
208 operator=(const uint64_t _data);
209 };
210
211 //Similar to the above, but only allows writing.
212 template<int first, int last=first>
213 class BitfieldWO : public Bitfield<first, last>
214 {
215 private:
216 operator uint64_t () const;
217
218 public:
219 using Bitfield<first, last>::operator=;
220 };
221 };
222
223 //This class contains all the "regular" bitfield classes. It is inherited
224 //by all BitUnions which give them access to those types.
225 template<class Type>
226 class SignedBitfieldTypes
227 {
228 protected:
229 //This class implements ordinary bitfields, that is a span of bits
230 //who's msb is "first", and who's lsb is "last".
231 template<int first, int last=first>
232 class SignedBitfield : public BitfieldBase<Type>
233 {
234 public:
235 operator int64_t () const
236 {
237 return sext<first - last + 1>(this->getBits(first, last));
238 }
239
240 int64_t
241 operator=(const int64_t _data)
242 {
243 this->setBits(first, last, _data);
244 return _data;
245 }
246 };
247
248 //A class which specializes the above so that it can only be read
249 //from. This is accomplished explicitly making sure the assignment
250 //operator is blocked. The conversion operator is carried through
251 //inheritance. This will unfortunately need to be copied into each
252 //bitfield type due to limitations with how templates work
253 template<int first, int last=first>
254 class SignedBitfieldRO : public SignedBitfield<first, last>
255 {
256 private:
257 int64_t
258 operator=(const int64_t _data);
259 };
260
261 //Similar to the above, but only allows writing.
262 template<int first, int last=first>
263 class SignedBitfieldWO : public SignedBitfield<first, last>
264 {
265 private:
266 operator int64_t () const;
267
268 public:
269 int64_t operator=(const int64_t _data)
270 {
271 *((SignedBitfield<first, last> *)this) = _data;
272 return _data;
273 }
274 };
275 };
276
277 template<class Type>
278 class BitfieldTypes : public RegularBitfieldTypes<Type>,
279 public SignedBitfieldTypes<Type>
280 {};
281
282 //When a BitUnion is set up, an underlying class is created which holds
283 //the actual union. This class then inherits from it, and provids the
284 //implementations for various operators. Setting things up this way
285 //prevents having to redefine these functions in every different BitUnion
286 //type. More operators could be implemented in the future, as the need
287 //arises.
288 template <class Type, class Base>
289 class BitUnionOperators : public Base
290 {
291 public:
292 operator Type () const
293 {
294 return Base::__data;
295 }
296
297 Type
298 operator=(const Type & _data)
299 {
300 Base::__data = _data;
301 return _data;
302 }
303
304 bool
305 operator<(const Base & base) const
306 {
307 return Base::__data < base.__data;
308 }
309
310 bool
311 operator==(const Base & base) const
312 {
313 return Base::__data == base.__data;
314 }
315 };
316}
317
318//This macro is a backend for other macros that specialize it slightly.
319//First, it creates/extends a namespace "BitfieldUnderlyingClasses" and
320//sticks the class which has the actual union in it, which
321//BitfieldOperators above inherits from. Putting these classes in a special
322//namespace ensures that there will be no collisions with other names as long
323//as the BitUnion names themselves are all distinct and nothing else uses
324//the BitfieldUnderlyingClasses namespace, which is unlikely. The class itself
325//creates a typedef of the "type" parameter called __DataType. This allows
326//the type to propagate outside of the macro itself in a controlled way.
327//Finally, the base storage is defined which BitfieldOperators will refer to
328//in the operators it defines. This macro is intended to be followed by
329//bitfield definitions which will end up inside it's union. As explained
330//above, these is overlayed the __data member in its entirety by each of the
331//bitfields which are defined in the union, creating shared storage with no
332//overhead.
333#define __BitUnion(type, name) \
334 namespace BitfieldUnderlyingClasses \
335 { \
336 class name; \
337 } \
338 class BitfieldUnderlyingClasses::name : \
339 public BitfieldBackend::BitfieldTypes<type> \
340 { \
341 public: \
342 typedef type __DataType; \
343 union { \
344 type __data;\
345
346//This closes off the class and union started by the above macro. It is
347//followed by a typedef which makes "name" refer to a BitfieldOperator
348//class inheriting from the class and union just defined, which completes
349//building up the type for the user.
350#define EndBitUnion(name) \
351 }; \
352 }; \
353 typedef BitfieldBackend::BitUnionOperators< \
354 BitfieldUnderlyingClasses::name::__DataType, \
355 BitfieldUnderlyingClasses::name> name;
356
357//This sets up a bitfield which has other bitfields nested inside of it. The
358//__data member functions like the "underlying storage" of the top level
359//BitUnion. Like everything else, it overlays with the top level storage, so
360//making it a regular bitfield type makes the entire thing function as a
361//regular bitfield when referred to by itself.
362#define __SubBitUnion(fieldType, first, last, name) \
363 class : public BitfieldBackend::BitfieldTypes<__DataType> \
364 { \
365 public: \
366 union { \
367 fieldType<first, last> __data;
368
369//This closes off the union created above and gives it a name. Unlike the top
370//level BitUnion, we're interested in creating an object instead of a type.
371//The operators are defined in the macro itself instead of a class for
372//technical reasons. If someone determines a way to move them to one, please
373//do so.
374#define EndSubBitUnion(name) \
375 }; \
376 inline operator const __DataType () \
377 { return __data; } \
378 \
379 inline const __DataType operator = (const __DataType & _data) \
380 { __data = _data; } \
381 } name;
382
383//Regular bitfields
384//These define macros for read/write regular bitfield based subbitfields.
385#define SubBitUnion(name, first, last) \
386 __SubBitUnion(Bitfield, first, last, name)
387
388//Regular bitfields
389//These define macros for read/write regular bitfield based subbitfields.
390#define SignedSubBitUnion(name, first, last) \
391 __SubBitUnion(SignedBitfield, first, last, name)
392
393//Use this to define an arbitrary type overlayed with bitfields.
394#define BitUnion(type, name) __BitUnion(type, name)
395
396//Use this to define conveniently sized values overlayed with bitfields.
397#define BitUnion64(name) __BitUnion(uint64_t, name)
398#define BitUnion32(name) __BitUnion(uint32_t, name)
399#define BitUnion16(name) __BitUnion(uint16_t, name)
400#define BitUnion8(name) __BitUnion(uint8_t, name)
401
402#endif // __BASE_BITFIELD_HH__
| 102}
103
104/**
105 * A convenience function to replace bits first to last of val with bit_val
106 * in place.
107 */
108template <class T, class B>
109inline
110void
111replaceBits(T& val, int first, int last, B bit_val)
112{
113 val = insertBits(val, first, last, bit_val);
114}
115
116/**
117 * Returns the bit position of the MSB that is set in the input
118 */
119inline
120int
121findMsbSet(uint64_t val) {
122 int msb = 0;
123 if (!val)
124 return 0;
125 if (bits(val, 63,32)) { msb += 32; val >>= 32; }
126 if (bits(val, 31,16)) { msb += 16; val >>= 16; }
127 if (bits(val, 15,8)) { msb += 8; val >>= 8; }
128 if (bits(val, 7,4)) { msb += 4; val >>= 4; }
129 if (bits(val, 3,2)) { msb += 2; val >>= 2; }
130 if (bits(val, 1,1)) { msb += 1; }
131 return msb;
132}
133
134// The following implements the BitUnion system of defining bitfields
135//on top of an underlying class. This is done through the pervasive use of
136//both named and unnamed unions which all contain the same actual storage.
137//Since they're unioned with each other, all of these storage locations
138//overlap. This allows all of the bitfields to manipulate the same data
139//without having to have access to each other. More details are provided with the
140//individual components.
141
142//This namespace is for classes which implement the backend of the BitUnion
143//stuff. Don't use any of these directly, except for the Bitfield classes in
144//the *BitfieldTypes class(es).
145namespace BitfieldBackend
146{
147 //A base class for all bitfields. It instantiates the actual storage,
148 //and provides getBits and setBits functions for manipulating it. The
149 //Data template parameter is type of the underlying storage.
150 template<class Data>
151 class BitfieldBase
152 {
153 protected:
154 Data __data;
155
156 //This function returns a range of bits from the underlying storage.
157 //It relies on the "bits" function above. It's the user's
158 //responsibility to make sure that there is a properly overloaded
159 //version of this function for whatever type they want to overlay.
160 inline uint64_t
161 getBits(int first, int last) const
162 {
163 return bits(__data, first, last);
164 }
165
166 //Similar to the above, but for settings bits with replaceBits.
167 inline void
168 setBits(int first, int last, uint64_t val)
169 {
170 replaceBits(__data, first, last, val);
171 }
172 };
173
174 //This class contains all the "regular" bitfield classes. It is inherited
175 //by all BitUnions which give them access to those types.
176 template<class Type>
177 class RegularBitfieldTypes
178 {
179 protected:
180 //This class implements ordinary bitfields, that is a span of bits
181 //who's msb is "first", and who's lsb is "last".
182 template<int first, int last=first>
183 class Bitfield : public BitfieldBase<Type>
184 {
185 public:
186 operator uint64_t () const
187 {
188 return this->getBits(first, last);
189 }
190
191 uint64_t
192 operator=(const uint64_t _data)
193 {
194 this->setBits(first, last, _data);
195 return _data;
196 }
197 };
198
199 //A class which specializes the above so that it can only be read
200 //from. This is accomplished explicitly making sure the assignment
201 //operator is blocked. The conversion operator is carried through
202 //inheritance. This will unfortunately need to be copied into each
203 //bitfield type due to limitations with how templates work
204 template<int first, int last=first>
205 class BitfieldRO : public Bitfield<first, last>
206 {
207 private:
208 uint64_t
209 operator=(const uint64_t _data);
210 };
211
212 //Similar to the above, but only allows writing.
213 template<int first, int last=first>
214 class BitfieldWO : public Bitfield<first, last>
215 {
216 private:
217 operator uint64_t () const;
218
219 public:
220 using Bitfield<first, last>::operator=;
221 };
222 };
223
224 //This class contains all the "regular" bitfield classes. It is inherited
225 //by all BitUnions which give them access to those types.
226 template<class Type>
227 class SignedBitfieldTypes
228 {
229 protected:
230 //This class implements ordinary bitfields, that is a span of bits
231 //who's msb is "first", and who's lsb is "last".
232 template<int first, int last=first>
233 class SignedBitfield : public BitfieldBase<Type>
234 {
235 public:
236 operator int64_t () const
237 {
238 return sext<first - last + 1>(this->getBits(first, last));
239 }
240
241 int64_t
242 operator=(const int64_t _data)
243 {
244 this->setBits(first, last, _data);
245 return _data;
246 }
247 };
248
249 //A class which specializes the above so that it can only be read
250 //from. This is accomplished explicitly making sure the assignment
251 //operator is blocked. The conversion operator is carried through
252 //inheritance. This will unfortunately need to be copied into each
253 //bitfield type due to limitations with how templates work
254 template<int first, int last=first>
255 class SignedBitfieldRO : public SignedBitfield<first, last>
256 {
257 private:
258 int64_t
259 operator=(const int64_t _data);
260 };
261
262 //Similar to the above, but only allows writing.
263 template<int first, int last=first>
264 class SignedBitfieldWO : public SignedBitfield<first, last>
265 {
266 private:
267 operator int64_t () const;
268
269 public:
270 int64_t operator=(const int64_t _data)
271 {
272 *((SignedBitfield<first, last> *)this) = _data;
273 return _data;
274 }
275 };
276 };
277
278 template<class Type>
279 class BitfieldTypes : public RegularBitfieldTypes<Type>,
280 public SignedBitfieldTypes<Type>
281 {};
282
283 //When a BitUnion is set up, an underlying class is created which holds
284 //the actual union. This class then inherits from it, and provids the
285 //implementations for various operators. Setting things up this way
286 //prevents having to redefine these functions in every different BitUnion
287 //type. More operators could be implemented in the future, as the need
288 //arises.
289 template <class Type, class Base>
290 class BitUnionOperators : public Base
291 {
292 public:
293 operator Type () const
294 {
295 return Base::__data;
296 }
297
298 Type
299 operator=(const Type & _data)
300 {
301 Base::__data = _data;
302 return _data;
303 }
304
305 bool
306 operator<(const Base & base) const
307 {
308 return Base::__data < base.__data;
309 }
310
311 bool
312 operator==(const Base & base) const
313 {
314 return Base::__data == base.__data;
315 }
316 };
317}
318
319//This macro is a backend for other macros that specialize it slightly.
320//First, it creates/extends a namespace "BitfieldUnderlyingClasses" and
321//sticks the class which has the actual union in it, which
322//BitfieldOperators above inherits from. Putting these classes in a special
323//namespace ensures that there will be no collisions with other names as long
324//as the BitUnion names themselves are all distinct and nothing else uses
325//the BitfieldUnderlyingClasses namespace, which is unlikely. The class itself
326//creates a typedef of the "type" parameter called __DataType. This allows
327//the type to propagate outside of the macro itself in a controlled way.
328//Finally, the base storage is defined which BitfieldOperators will refer to
329//in the operators it defines. This macro is intended to be followed by
330//bitfield definitions which will end up inside it's union. As explained
331//above, these is overlayed the __data member in its entirety by each of the
332//bitfields which are defined in the union, creating shared storage with no
333//overhead.
334#define __BitUnion(type, name) \
335 namespace BitfieldUnderlyingClasses \
336 { \
337 class name; \
338 } \
339 class BitfieldUnderlyingClasses::name : \
340 public BitfieldBackend::BitfieldTypes<type> \
341 { \
342 public: \
343 typedef type __DataType; \
344 union { \
345 type __data;\
346
347//This closes off the class and union started by the above macro. It is
348//followed by a typedef which makes "name" refer to a BitfieldOperator
349//class inheriting from the class and union just defined, which completes
350//building up the type for the user.
351#define EndBitUnion(name) \
352 }; \
353 }; \
354 typedef BitfieldBackend::BitUnionOperators< \
355 BitfieldUnderlyingClasses::name::__DataType, \
356 BitfieldUnderlyingClasses::name> name;
357
358//This sets up a bitfield which has other bitfields nested inside of it. The
359//__data member functions like the "underlying storage" of the top level
360//BitUnion. Like everything else, it overlays with the top level storage, so
361//making it a regular bitfield type makes the entire thing function as a
362//regular bitfield when referred to by itself.
363#define __SubBitUnion(fieldType, first, last, name) \
364 class : public BitfieldBackend::BitfieldTypes<__DataType> \
365 { \
366 public: \
367 union { \
368 fieldType<first, last> __data;
369
370//This closes off the union created above and gives it a name. Unlike the top
371//level BitUnion, we're interested in creating an object instead of a type.
372//The operators are defined in the macro itself instead of a class for
373//technical reasons. If someone determines a way to move them to one, please
374//do so.
375#define EndSubBitUnion(name) \
376 }; \
377 inline operator const __DataType () \
378 { return __data; } \
379 \
380 inline const __DataType operator = (const __DataType & _data) \
381 { __data = _data; } \
382 } name;
383
384//Regular bitfields
385//These define macros for read/write regular bitfield based subbitfields.
386#define SubBitUnion(name, first, last) \
387 __SubBitUnion(Bitfield, first, last, name)
388
389//Regular bitfields
390//These define macros for read/write regular bitfield based subbitfields.
391#define SignedSubBitUnion(name, first, last) \
392 __SubBitUnion(SignedBitfield, first, last, name)
393
394//Use this to define an arbitrary type overlayed with bitfields.
395#define BitUnion(type, name) __BitUnion(type, name)
396
397//Use this to define conveniently sized values overlayed with bitfields.
398#define BitUnion64(name) __BitUnion(uint64_t, name)
399#define BitUnion32(name) __BitUnion(uint32_t, name)
400#define BitUnion16(name) __BitUnion(uint16_t, name)
401#define BitUnion8(name) __BitUnion(uint8_t, name)
402
403#endif // __BASE_BITFIELD_HH__
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