bitfield.hh (4258:a84b8cce90ce) bitfield.hh (4259:ca1ca13665ba)
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;

--- 116 unchanged lines hidden (view full) ---

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
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;

--- 116 unchanged lines hidden (view full) ---

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 extensive 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 know about 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 this directly! Use the macros at the end instead.
133namespace BitfieldBackend
134{
143namespace BitfieldBackend
144{
145 //A base class for all bitfields. It instantiates the actual storage,
146 //and provides getBits and setBits functions for manipulating it. The
147 //Data template parameter is type of the underlying storage.
135 template<class Data>
136 class BitfieldBase
137 {
138 protected:
139 Data __data;
140
148 template<class Data>
149 class BitfieldBase
150 {
151 protected:
152 Data __data;
153
154 //This function returns a range of bits from the underlying storage.
155 //It relies on the "bits" function above. It's the user's
156 //responsibility to make sure that there is a properly overloaded
157 //version of this function for whatever type they want to overlay.
141 inline uint64_t
142 getBits(int first, int last)
143 {
144 return bits(__data, first, last);
145 }
146
158 inline uint64_t
159 getBits(int first, int last)
160 {
161 return bits(__data, first, last);
162 }
163
164 //Similar to the above, but for settings bits with replaceBits.
147 inline void
148 setBits(int first, int last, uint64_t val)
149 {
150 replaceBits(__data, first, last, val);
151 }
152 };
153
165 inline void
166 setBits(int first, int last, uint64_t val)
167 {
168 replaceBits(__data, first, last, val);
169 }
170 };
171
172 //A class which specializes a given base so that it can only be read
173 //from. This is accomplished by only passing through the conversion
174 //operator.
154 template<class Type, class Base>
155 class _BitfieldRO : public Base
156 {
157 public:
158 operator const Type ()
159 {
160 return *((Base *)this);
161 }
162 };
163
175 template<class Type, class Base>
176 class _BitfieldRO : public Base
177 {
178 public:
179 operator const Type ()
180 {
181 return *((Base *)this);
182 }
183 };
184
185 //Similar to the above, but only allows writing.
164 template<class Type, class Base>
165 class _BitfieldWO : public Base
166 {
167 public:
168 const Type operator = (const Type & _data)
169 {
170 *((Base *)this) = _data;
171 return _data;
172 }
173 };
174
186 template<class Type, class Base>
187 class _BitfieldWO : public Base
188 {
189 public:
190 const Type operator = (const Type & _data)
191 {
192 *((Base *)this) = _data;
193 return _data;
194 }
195 };
196
197 //This class implements ordinary bitfields, that is a span of bits
198 //who's msb is "first", and who's lsb is "last".
175 template<class Data, int first, int last=first>
176 class _Bitfield : public BitfieldBase<Data>
177 {
178 public:
179 operator const Data ()
180 {
181 return this->getBits(first, last);
182 }
183
184 const Data
185 operator = (const Data & _data)
186 {
187 this->setBits(first, last, _data);
188 return _data;
189 }
190 };
191
199 template<class Data, int first, int last=first>
200 class _Bitfield : public BitfieldBase<Data>
201 {
202 public:
203 operator const Data ()
204 {
205 return this->getBits(first, last);
206 }
207
208 const Data
209 operator = (const Data & _data)
210 {
211 this->setBits(first, last, _data);
212 return _data;
213 }
214 };
215
216 //When a BitUnion is set up, an underlying class is created which holds
217 //the actual union. This class then inherits from it, and provids the
218 //implementations for various operators. Setting things up this way
219 //prevents having to redefine these functions in every different BitUnion
220 //type. More operators could be implemented in the future, as the need
221 //arises.
192 template <class Type, class Base>
193 class BitUnionOperators : public Base
194 {
195 public:
196 operator const Type ()
197 {
198 return Base::__data;
199 }

--- 13 unchanged lines hidden (view full) ---

213 bool
214 operator == (const Base & base)
215 {
216 return Base::__data == base.__data;
217 }
218 };
219}
220
222 template <class Type, class Base>
223 class BitUnionOperators : public Base
224 {
225 public:
226 operator const Type ()
227 {
228 return Base::__data;
229 }

--- 13 unchanged lines hidden (view full) ---

243 bool
244 operator == (const Base & base)
245 {
246 return Base::__data == base.__data;
247 }
248 };
249}
250
251//This macro is a backend for other macros that specialize it slightly.
252//First, it creates/extends a namespace "BitfieldUnderlyingClasses" and
253//sticks the class which has the actual union in it, which
254//BitfieldOperators above inherits from. Putting these classes in a special
255//namespace ensures that there will be no collisions with other names as long
256//as the BitUnion names themselves are all distinct and nothing else uses
257//the BitfieldUnderlyingClasses namespace, which is unlikely. The class itself
258//creates a typedef of the "type" parameter called __DataType. This allows
259//the type to propagate outside of the macro itself in a controlled way.
260//Finally, the base storage is defined which BitfieldOperators will refer to
261//in the operators it defines. This macro is intended to be followed by
262//bitfield definitions which will end up inside it's union. As explained
263//above, these is overlayed the __data member in its entirety by each of the
264//bitfields which are defined in the union, creating shared storage with no
265//overhead.
221#define __BitUnion(type, name) \
222 namespace BitfieldUnderlyingClasses \
223 { \
224 class name; \
225 } \
226 class BitfieldUnderlyingClasses::name { \
227 public: \
228 typedef type __DataType; \
229 union { \
230 type __data;\
231
266#define __BitUnion(type, name) \
267 namespace BitfieldUnderlyingClasses \
268 { \
269 class name; \
270 } \
271 class BitfieldUnderlyingClasses::name { \
272 public: \
273 typedef type __DataType; \
274 union { \
275 type __data;\
276
277//This closes off the class and union started by the above macro. It is
278//followed by a typedef which makes "name" refer to a BitfieldOperator
279//class inheriting from the class and union just defined, which completes
280//building up the type for the user.
232#define EndBitUnion(name) \
233 }; \
234 }; \
235 typedef BitfieldBackend::BitUnionOperators< \
236 BitfieldUnderlyingClasses::name::__DataType, \
237 BitfieldUnderlyingClasses::name> name;
238
281#define EndBitUnion(name) \
282 }; \
283 }; \
284 typedef BitfieldBackend::BitUnionOperators< \
285 BitfieldUnderlyingClasses::name::__DataType, \
286 BitfieldUnderlyingClasses::name> name;
287
288//This sets up a bitfield which has other bitfields nested inside of it. The
289//__data member functions like the "underlying storage" of the top level
290//BitUnion. Like everything else, it overlays with the top level storage, so
291//making it a regular bitfield type makes the entire thing function as a
292//regular bitfield when referred to by itself. The operators are defined in
293//the macro itself instead of a class for technical reasons. If someone
294//determines a way to move them to one, please do so.
239#define __SubBitUnion(type, name) \
240 union { \
241 type __data; \
242 inline operator const __DataType () \
243 { return __data; } \
244 \
245 inline const __DataType operator = (const __DataType & _data) \
246 { __data = _data; }
247
295#define __SubBitUnion(type, name) \
296 union { \
297 type __data; \
298 inline operator const __DataType () \
299 { return __data; } \
300 \
301 inline const __DataType operator = (const __DataType & _data) \
302 { __data = _data; }
303
304//This closes off the union created above and gives it a name. Unlike the top
305//level BitUnion, we're interested in creating an object instead of a type.
248#define EndSubBitUnion(name) } name;
249
306#define EndSubBitUnion(name) } name;
307
250//This is so we can send in parameters with commas
308//The preprocessor will treat everything inside of parenthesis as a single
309//argument even if it has commas in it. This is used to pass in templated
310//classes which typically have commas to seperate their parameters.
251#define wrap(guts) guts
252
253//Read only bitfields
311#define wrap(guts) guts
312
313//Read only bitfields
314//This wraps another bitfield class inside a _BitfieldRO class using
315//inheritance. As explained above, the _BitfieldRO class only passes through
316//the conversion operator, so the underlying bitfield can then only be read
317//from.
254#define __BitfieldRO(base) \
255 BitfieldBackend::_BitfieldRO<__DataType, base>
256#define __SubBitUnionRO(name, base) \
257 __SubBitUnion(wrap(_BitfieldRO<__DataType, base>), name)
258
259//Write only bitfields
318#define __BitfieldRO(base) \
319 BitfieldBackend::_BitfieldRO<__DataType, base>
320#define __SubBitUnionRO(name, base) \
321 __SubBitUnion(wrap(_BitfieldRO<__DataType, base>), name)
322
323//Write only bitfields
324//Similar to above, but for making write only versions of bitfields with
325//_BitfieldWO.
260#define __BitfieldWO(base) \
261 BitfieldBackend::_BitfieldWO<__DataType, base>
262#define __SubBitUnionWO(name, base) \
263 __SubBitUnion(wrap(_BitfieldWO<__DataType, base>), name)
264
265//Regular bitfields
326#define __BitfieldWO(base) \
327 BitfieldBackend::_BitfieldWO<__DataType, base>
328#define __SubBitUnionWO(name, base) \
329 __SubBitUnion(wrap(_BitfieldWO<__DataType, base>), name)
330
331//Regular bitfields
332//This uses all of the above to define macros for read/write, read only, and
333//write only versions of regular bitfields.
266#define Bitfield(first, last) \
267 BitfieldBackend::_Bitfield<__DataType, first, last>
268#define SubBitUnion(name, first, last) \
269 __SubBitUnion(Bitfield(first, last), name)
270#define BitfieldRO(first, last) __BitfieldRO(Bitfield(first, last))
271#define SubBitUnionRO(name, first, last) \
272 __SubBitUnionRO(Bitfield(first, last), name)
273#define BitfieldWO(first, last) __BitfieldWO(Bitfield(first, last))
274#define SubBitUnionWO(name, first, last) \
275 __SubBitUnionWO(Bitfield(first, last), name)
276
334#define Bitfield(first, last) \
335 BitfieldBackend::_Bitfield<__DataType, first, last>
336#define SubBitUnion(name, first, last) \
337 __SubBitUnion(Bitfield(first, last), name)
338#define BitfieldRO(first, last) __BitfieldRO(Bitfield(first, last))
339#define SubBitUnionRO(name, first, last) \
340 __SubBitUnionRO(Bitfield(first, last), name)
341#define BitfieldWO(first, last) __BitfieldWO(Bitfield(first, last))
342#define SubBitUnionWO(name, first, last) \
343 __SubBitUnionWO(Bitfield(first, last), name)
344
345//Use this to define an arbitrary type overlayed with bitfields.
277#define BitUnion(type, name) __BitUnion(type, name)
278
346#define BitUnion(type, name) __BitUnion(type, name)
347
348//Use this to define conveniently sized values overlayed with bitfields.
279#define BitUnion64(name) __BitUnion(uint64_t, name)
280#define BitUnion32(name) __BitUnion(uint32_t, name)
281#define BitUnion16(name) __BitUnion(uint16_t, name)
282#define BitUnion8(name) __BitUnion(uint8_t, name)
283
284#endif // __BASE_BITFIELD_HH__
349#define BitUnion64(name) __BitUnion(uint64_t, name)
350#define BitUnion32(name) __BitUnion(uint32_t, name)
351#define BitUnion16(name) __BitUnion(uint16_t, name)
352#define BitUnion8(name) __BitUnion(uint8_t, name)
353
354#endif // __BASE_BITFIELD_HH__