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{
99 T bmask = mask(first - last + 1) << last;
100 return ((bit_val << last) & bmask) | (val & ~bmask);
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
| 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{
99 T bmask = mask(first - last + 1) << last;
100 return ((bit_val << last) & bmask) | (val & ~bmask);
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 extensive use of
| 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
| 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
| 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
| 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.
| 142//stuff. Don't use any of these directly, except for the Bitfield classes in
143//the *BitfieldTypes class(es).
|
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.
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.
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.
165 inline void
166 setBits(int first, int last, uint64_t val)
167 {
168 replaceBits(__data, first, last, val);
169 }
170 };
171
| 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)
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
|
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 and explicitly making sure the assignment operator is blocked.
175 template<class Type, class Base>
176 class _BitfieldRO : public Base
| 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 {
| 177 {
|
178 private:
179 const Type
180 operator=(const Type & _data);
181
182 public:
183 operator const Type ()
| 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>
|
184 {
| 183 {
|
185 return *((Base *)this);
186 }
187 };
| 184 public:
185 operator const Type ()
186 {
187 return this->getBits(first, last);
188 }
|
188
| 189
|
189 //Similar to the above, but only allows writing.
190 template<class Type, class Base>
191 class _BitfieldWO : public Base
192 {
193 private:
194 operator const Type ();
| 190 const Type
191 operator=(const Type & _data)
192 {
193 this->setBits(first, last, _data);
194 return _data;
195 }
196 };
|
195
| 197
|
196 public:
197 const Type operator=(const Type & _data)
| 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>
|
198 {
| 205 {
|
199 *((Base *)this) = _data;
200 return _data;
201 }
202 };
| 206 private:
207 const Type
208 operator=(const Type & _data);
209 };
|
203
| 210
|
204 //This class implements ordinary bitfields, that is a span of bits
205 //who's msb is "first", and who's lsb is "last".
206 template<class Data, int first, int last=first>
207 class _Bitfield : public BitfieldBase<Data>
208 {
209 public:
210 operator const Data ()
| 211 //Similar to the above, but only allows writing.
212 template<int first, int last=first>
213 class BitfieldWO : public Bitfield<first, last>
|
211 {
| 214 {
|
212 return this->getBits(first, last);
213 }
| 215 private:
216 operator const Type ();
|
214
| 217
|
215 const Data
216 operator=(const Data & _data)
217 {
218 this->setBits(first, last, _data);
219 return _data;
220 }
| 218 public:
219 const Type operator=(const Type & _data)
220 {
221 *((Bitfield<first, last> *)this) = _data;
222 return _data;
223 }
224 };
|
221 };
222
| 225 };
226
|
| 227 template<class Type>
228 class BitfieldTypes : public RegularBitfieldTypes<Type>
229 {};
230
|
223 //When a BitUnion is set up, an underlying class is created which holds
224 //the actual union. This class then inherits from it, and provids the
225 //implementations for various operators. Setting things up this way
226 //prevents having to redefine these functions in every different BitUnion
227 //type. More operators could be implemented in the future, as the need
228 //arises.
229 template <class Type, class Base>
230 class BitUnionOperators : public Base
231 {
232 public:
233 operator const Type ()
234 {
235 return Base::__data;
236 }
237
238 const Type
239 operator=(const Type & _data)
240 {
241 Base::__data = _data;
242 }
243
244 bool
245 operator<(const Base & base)
246 {
247 return Base::__data < base.__data;
248 }
249
250 bool
251 operator==(const Base & base)
252 {
253 return Base::__data == base.__data;
254 }
255 };
256}
257
258//This macro is a backend for other macros that specialize it slightly.
259//First, it creates/extends a namespace "BitfieldUnderlyingClasses" and
260//sticks the class which has the actual union in it, which
261//BitfieldOperators above inherits from. Putting these classes in a special
262//namespace ensures that there will be no collisions with other names as long
263//as the BitUnion names themselves are all distinct and nothing else uses
264//the BitfieldUnderlyingClasses namespace, which is unlikely. The class itself
265//creates a typedef of the "type" parameter called __DataType. This allows
266//the type to propagate outside of the macro itself in a controlled way.
267//Finally, the base storage is defined which BitfieldOperators will refer to
268//in the operators it defines. This macro is intended to be followed by
269//bitfield definitions which will end up inside it's union. As explained
270//above, these is overlayed the __data member in its entirety by each of the
271//bitfields which are defined in the union, creating shared storage with no
272//overhead.
273#define __BitUnion(type, name) \
274 namespace BitfieldUnderlyingClasses \
275 { \
276 class name; \
277 } \
| 231 //When a BitUnion is set up, an underlying class is created which holds
232 //the actual union. This class then inherits from it, and provids the
233 //implementations for various operators. Setting things up this way
234 //prevents having to redefine these functions in every different BitUnion
235 //type. More operators could be implemented in the future, as the need
236 //arises.
237 template <class Type, class Base>
238 class BitUnionOperators : public Base
239 {
240 public:
241 operator const Type ()
242 {
243 return Base::__data;
244 }
245
246 const Type
247 operator=(const Type & _data)
248 {
249 Base::__data = _data;
250 }
251
252 bool
253 operator<(const Base & base)
254 {
255 return Base::__data < base.__data;
256 }
257
258 bool
259 operator==(const Base & base)
260 {
261 return Base::__data == base.__data;
262 }
263 };
264}
265
266//This macro is a backend for other macros that specialize it slightly.
267//First, it creates/extends a namespace "BitfieldUnderlyingClasses" and
268//sticks the class which has the actual union in it, which
269//BitfieldOperators above inherits from. Putting these classes in a special
270//namespace ensures that there will be no collisions with other names as long
271//as the BitUnion names themselves are all distinct and nothing else uses
272//the BitfieldUnderlyingClasses namespace, which is unlikely. The class itself
273//creates a typedef of the "type" parameter called __DataType. This allows
274//the type to propagate outside of the macro itself in a controlled way.
275//Finally, the base storage is defined which BitfieldOperators will refer to
276//in the operators it defines. This macro is intended to be followed by
277//bitfield definitions which will end up inside it's union. As explained
278//above, these is overlayed the __data member in its entirety by each of the
279//bitfields which are defined in the union, creating shared storage with no
280//overhead.
281#define __BitUnion(type, name) \
282 namespace BitfieldUnderlyingClasses \
283 { \
284 class name; \
285 } \
|
278 class BitfieldUnderlyingClasses::name { \
| 286 class BitfieldUnderlyingClasses::name : \
287 public BitfieldBackend::BitfieldTypes<type> \
288 { \
|
279 public: \
280 typedef type __DataType; \
281 union { \
282 type __data;\
283
284//This closes off the class and union started by the above macro. It is
285//followed by a typedef which makes "name" refer to a BitfieldOperator
286//class inheriting from the class and union just defined, which completes
287//building up the type for the user.
288#define EndBitUnion(name) \
289 }; \
290 }; \
291 typedef BitfieldBackend::BitUnionOperators< \
292 BitfieldUnderlyingClasses::name::__DataType, \
293 BitfieldUnderlyingClasses::name> name;
294
295//This sets up a bitfield which has other bitfields nested inside of it. The
296//__data member functions like the "underlying storage" of the top level
297//BitUnion. Like everything else, it overlays with the top level storage, so
298//making it a regular bitfield type makes the entire thing function as a
| 289 public: \
290 typedef type __DataType; \
291 union { \
292 type __data;\
293
294//This closes off the class and union started by the above macro. It is
295//followed by a typedef which makes "name" refer to a BitfieldOperator
296//class inheriting from the class and union just defined, which completes
297//building up the type for the user.
298#define EndBitUnion(name) \
299 }; \
300 }; \
301 typedef BitfieldBackend::BitUnionOperators< \
302 BitfieldUnderlyingClasses::name::__DataType, \
303 BitfieldUnderlyingClasses::name> name;
304
305//This sets up a bitfield which has other bitfields nested inside of it. The
306//__data member functions like the "underlying storage" of the top level
307//BitUnion. Like everything else, it overlays with the top level storage, so
308//making it a regular bitfield type makes the entire thing function as a
|
299//regular bitfield when referred to by itself. The operators are defined in
300//the macro itself instead of a class for technical reasons. If someone
301//determines a way to move them to one, please do so.
302#define __SubBitUnion(type, name) \
| 309//regular bitfield when referred to by itself.
310#define __SubBitUnion(fieldType, first, last, name) \
311 class : public BitfieldBackend::BitfieldTypes<__DataType> \
312 { \
313 public: \
|
303 union { \
| 314 union { \
|
304 type __data; \
305 inline operator const __DataType () \
306 { return __data; } \
307 \
308 inline const __DataType operator = (const __DataType & _data) \
309 { __data = _data; }
| 315 fieldType<first, last> __data;
|
310
311//This closes off the union created above and gives it a name. Unlike the top
312//level BitUnion, we're interested in creating an object instead of a type.
| 316
317//This closes off the union created above and gives it a name. Unlike the top
318//level BitUnion, we're interested in creating an object instead of a type.
|
313#define EndSubBitUnion(name) } name;
| 319//The operators are defined in the macro itself instead of a class for
320//technical reasons. If someone determines a way to move them to one, please
321//do so.
322#define EndSubBitUnion(name) \
323 }; \
324 inline operator const __DataType () \
325 { return __data; } \
326 \
327 inline const __DataType operator = (const __DataType & _data) \
328 { __data = _data; } \
329 } name;
|
314
| 330
|
315//The preprocessor will treat everything inside of parenthesis as a single
316//argument even if it has commas in it. This is used to pass in templated
317//classes which typically have commas to seperate their parameters.
318#define wrap(guts) guts
319
320//Read only bitfields
321//This wraps another bitfield class inside a _BitfieldRO class using
322//inheritance. As explained above, the _BitfieldRO class only passes through
323//the conversion operator, so the underlying bitfield can then only be read
324//from.
325#define __BitfieldRO(base) \
326 BitfieldBackend::_BitfieldRO<__DataType, base>
327#define __SubBitUnionRO(name, base) \
328 __SubBitUnion(wrap(_BitfieldRO<__DataType, base>), name)
329
330//Write only bitfields
331//Similar to above, but for making write only versions of bitfields with
332//_BitfieldWO.
333#define __BitfieldWO(base) \
334 BitfieldBackend::_BitfieldWO<__DataType, base>
335#define __SubBitUnionWO(name, base) \
336 __SubBitUnion(wrap(_BitfieldWO<__DataType, base>), name)
337
| |
338//Regular bitfields
| 331//Regular bitfields
|
339//This uses all of the above to define macros for read/write, read only, and
340//write only versions of regular bitfields.
341#define Bitfield(first, last) \
342 BitfieldBackend::_Bitfield<__DataType, first, last>
| 332//These define macros for read/write regular bitfield based subbitfields.
|
343#define SubBitUnion(name, first, last) \
| 333#define SubBitUnion(name, first, last) \
|
344 __SubBitUnion(Bitfield(first, last), name)
345#define BitfieldRO(first, last) __BitfieldRO(Bitfield(first, last))
346#define SubBitUnionRO(name, first, last) \
347 __SubBitUnionRO(Bitfield(first, last), name)
348#define BitfieldWO(first, last) __BitfieldWO(Bitfield(first, last))
349#define SubBitUnionWO(name, first, last) \
350 __SubBitUnionWO(Bitfield(first, last), name)
| 334 __SubBitUnion(Bitfield, first, last, name)
|
351
352//Use this to define an arbitrary type overlayed with bitfields.
353#define BitUnion(type, name) __BitUnion(type, name)
354
355//Use this to define conveniently sized values overlayed with bitfields.
356#define BitUnion64(name) __BitUnion(uint64_t, name)
357#define BitUnion32(name) __BitUnion(uint32_t, name)
358#define BitUnion16(name) __BitUnion(uint16_t, name)
359#define BitUnion8(name) __BitUnion(uint8_t, name)
360
361#endif // __BASE_BITFIELD_HH__
| 335
336//Use this to define an arbitrary type overlayed with bitfields.
337#define BitUnion(type, name) __BitUnion(type, name)
338
339//Use this to define conveniently sized values overlayed with bitfields.
340#define BitUnion64(name) __BitUnion(uint64_t, name)
341#define BitUnion32(name) __BitUnion(uint32_t, name)
342#define BitUnion16(name) __BitUnion(uint16_t, name)
343#define BitUnion8(name) __BitUnion(uint8_t, name)
344
345#endif // __BASE_BITFIELD_HH__
|