1/*
2 * Copyright (c) 2017 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2003-2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Steve Reinhardt
41 * Nathan Binkert
42 * Giacomo Travaglini
43 */
44
45#ifndef __BASE_BITFIELD_HH__
46#define __BASE_BITFIELD_HH__
47
48#include <inttypes.h>
49#include <cassert>
50#include <cstddef>
51#include <type_traits>
52
53/** Lookup table used for High Speed bit reversing */
54extern const uint8_t reverseLookUpTable[];
55
56/**
57 * Generate a 64-bit mask of 'nbits' 1s, right justified.
58 */
59inline uint64_t
60mask(int nbits)
61{
62 return (nbits == 64) ? (uint64_t)-1LL : (1ULL << nbits) - 1;
63}
64
65/**
66 * Extract the bitfield from position 'first' to 'last' (inclusive)
67 * from 'val' and right justify it. MSB is numbered 63, LSB is 0.
68 */
69template <class T>
70inline
71T
72bits(T val, int first, int last)
73{
74 int nbits = first - last + 1;
75 return (val >> last) & mask(nbits);
76}
77
78/**
79 * Extract the bit from this position from 'val' and right justify it.
80 */
81template <class T>
82inline
83T
84bits(T val, int bit)
85{
86 return bits(val, bit, bit);
87}
88
89/**
90 * Mask off the given bits in place like bits() but without shifting.
91 * msb = 63, lsb = 0
92 */
93template <class T>
94inline
95T
96mbits(T val, int first, int last)
97{
98 return val & (mask(first+1) & ~mask(last));
99}
100
101inline uint64_t
102mask(int first, int last)
103{
104 return mbits((uint64_t)-1LL, first, last);
105}
106
107/**
108 * Sign-extend an N-bit value to 64 bits.
109 */
110template <int N>
111inline
112uint64_t
113sext(uint64_t val)
114{
115 int sign_bit = bits(val, N-1, N-1);
116 return sign_bit ? (val | ~mask(N)) : val;
117}
118
119/**
120 * Return val with bits first to last set to bit_val
121 */
122template <class T, class B>
123inline
124T
125insertBits(T val, int first, int last, B bit_val)
126{
127 T t_bit_val = bit_val;
128 T bmask = mask(first - last + 1) << last;
129 return ((t_bit_val << last) & bmask) | (val & ~bmask);
130}
131
132/**
133 * Overloaded for access to only one bit in value
134 */
135template <class T, class B>
136inline
137T
138insertBits(T val, int bit, B bit_val)
139{
140 return insertBits(val, bit, bit, bit_val);
141}
142
143/**
144 * A convenience function to replace bits first to last of val with bit_val
145 * in place.
146 */
147template <class T, class B>
148inline
149void
150replaceBits(T& val, int first, int last, B bit_val)
151{
152 val = insertBits(val, first, last, bit_val);
153}
154
155/** Overloaded function to allow to access only 1 bit*/
156template <class T, class B>
157inline
158void
159replaceBits(T& val, int bit, B bit_val)
160{
161 val = insertBits(val, bit, bit, bit_val);
162}
163
164/**
165 * Takes a variable lenght word and returns the mirrored version
166 * (Bit by bit, LSB=>MSB).
167 *
168 * algorithm from
169 * http://graphics.stanford.edu/~seander/bithacks.html
170 * #ReverseBitsByLookupTable
171 *
172 * @param val: variable lenght word
173 * @param size: number of bytes to mirror
174 * @return mirrored word
175 */
176template <class T>
177T
178reverseBits(T val, std::size_t size = sizeof(T))
179{
180 static_assert(std::is_integral<T>::value, "Expecting an integer type");
181
182 assert(size <= sizeof(T));
183
184 T output = 0;
185 for (auto byte = 0; byte < size; byte++, val >>= 8) {
186 output = (output << 8) | reverseLookUpTable[val & 0xFF];
187 }
188
189 return output;
190}
191
192/**
193 * Returns the bit position of the MSB that is set in the input
194 */
195inline
196int
197findMsbSet(uint64_t val) {
198 int msb = 0;
199 if (!val)
200 return 0;
201 if (bits(val, 63,32)) { msb += 32; val >>= 32; }
202 if (bits(val, 31,16)) { msb += 16; val >>= 16; }
203 if (bits(val, 15,8)) { msb += 8; val >>= 8; }
204 if (bits(val, 7,4)) { msb += 4; val >>= 4; }
205 if (bits(val, 3,2)) { msb += 2; val >>= 2; }
206 if (bits(val, 1,1)) { msb += 1; }
207 return msb;
208}
209
210/**
211 * Returns the bit position of the LSB that is set in the input
212 */
213inline int
214findLsbSet(uint64_t val) {
215 int lsb = 0;
216 if (!val)
217 return sizeof(val) * 8;
218 if (!bits(val, 31,0)) { lsb += 32; val >>= 32; }
219 if (!bits(val, 15,0)) { lsb += 16; val >>= 16; }
220 if (!bits(val, 7,0)) { lsb += 8; val >>= 8; }
221 if (!bits(val, 3,0)) { lsb += 4; val >>= 4; }
222 if (!bits(val, 1,0)) { lsb += 2; val >>= 2; }
223 if (!bits(val, 0,0)) { lsb += 1; }
224 return lsb;
225}
226
227/**
228 * Checks if a number is a power of two, or zero.
229 */
230template <class T>
231inline bool
232isPow2(T v) {
233 return (v & (v - 1)) == (T)0;
234}
235
236/**
237 * Returns the number of set ones in the provided value.
238 * PD algorithm from
239 * http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
240 */
241inline int
242popCount(uint64_t val) {
243#ifndef __has_builtin
244 #define __has_builtin(foo) 0
245#endif
246#if defined(__GNUC__) || (defined(__clang__) && __has_builtin(__builtin_popcountl))
247 return __builtin_popcountl(val);
248#else
249 const uint64_t m1 = 0x5555555555555555; // ..010101b
250 const uint64_t m2 = 0x3333333333333333; // ..110011b
251 const uint64_t m4 = 0x0f0f0f0f0f0f0f0f; // ..001111b
252 const uint64_t sum = 0x0101010101010101;
253
254 val -= (val >> 1) & m1; // 2 bits count -> 2 bits
255 val = (val & m2) + ((val >> 2) & m2); // 4 bits count -> 4 bits
256 val = (val + (val >> 4)) & m4; // 8 bits count -> 8 bits
257 return (val * sum) >> 56; // horizontal sum
258#endif // defined(__GNUC__) || (defined(__clang__) && __has_builtin(__builtin_popcountl))
259}
260
261/**
262 * Align to the next highest power of two.
263 *
264 * The number passed in is aligned to the next highest power of two,
265 * if it is not already a power of two. Please note that if 0 is
266 * passed in, 0 is returned.
267 *
268 * This code has been modified from the following:
269 * http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
270 */
271inline uint64_t alignToPowerOfTwo(uint64_t val)
272{
273 val--;
274 val |= val >> 1;
275 val |= val >> 2;
276 val |= val >> 4;
277 val |= val >> 8;
278 val |= val >> 16;
279 val |= val >> 32;
280 val++;
281
282 return val;
283};
284
| 1/*
2 * Copyright (c) 2017 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2003-2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Steve Reinhardt
41 * Nathan Binkert
42 * Giacomo Travaglini
43 */
44
45#ifndef __BASE_BITFIELD_HH__
46#define __BASE_BITFIELD_HH__
47
48#include <inttypes.h>
49#include <cassert>
50#include <cstddef>
51#include <type_traits>
52
53/** Lookup table used for High Speed bit reversing */
54extern const uint8_t reverseLookUpTable[];
55
56/**
57 * Generate a 64-bit mask of 'nbits' 1s, right justified.
58 */
59inline uint64_t
60mask(int nbits)
61{
62 return (nbits == 64) ? (uint64_t)-1LL : (1ULL << nbits) - 1;
63}
64
65/**
66 * Extract the bitfield from position 'first' to 'last' (inclusive)
67 * from 'val' and right justify it. MSB is numbered 63, LSB is 0.
68 */
69template <class T>
70inline
71T
72bits(T val, int first, int last)
73{
74 int nbits = first - last + 1;
75 return (val >> last) & mask(nbits);
76}
77
78/**
79 * Extract the bit from this position from 'val' and right justify it.
80 */
81template <class T>
82inline
83T
84bits(T val, int bit)
85{
86 return bits(val, bit, bit);
87}
88
89/**
90 * Mask off the given bits in place like bits() but without shifting.
91 * msb = 63, lsb = 0
92 */
93template <class T>
94inline
95T
96mbits(T val, int first, int last)
97{
98 return val & (mask(first+1) & ~mask(last));
99}
100
101inline uint64_t
102mask(int first, int last)
103{
104 return mbits((uint64_t)-1LL, first, last);
105}
106
107/**
108 * Sign-extend an N-bit value to 64 bits.
109 */
110template <int N>
111inline
112uint64_t
113sext(uint64_t val)
114{
115 int sign_bit = bits(val, N-1, N-1);
116 return sign_bit ? (val | ~mask(N)) : val;
117}
118
119/**
120 * Return val with bits first to last set to bit_val
121 */
122template <class T, class B>
123inline
124T
125insertBits(T val, int first, int last, B bit_val)
126{
127 T t_bit_val = bit_val;
128 T bmask = mask(first - last + 1) << last;
129 return ((t_bit_val << last) & bmask) | (val & ~bmask);
130}
131
132/**
133 * Overloaded for access to only one bit in value
134 */
135template <class T, class B>
136inline
137T
138insertBits(T val, int bit, B bit_val)
139{
140 return insertBits(val, bit, bit, bit_val);
141}
142
143/**
144 * A convenience function to replace bits first to last of val with bit_val
145 * in place.
146 */
147template <class T, class B>
148inline
149void
150replaceBits(T& val, int first, int last, B bit_val)
151{
152 val = insertBits(val, first, last, bit_val);
153}
154
155/** Overloaded function to allow to access only 1 bit*/
156template <class T, class B>
157inline
158void
159replaceBits(T& val, int bit, B bit_val)
160{
161 val = insertBits(val, bit, bit, bit_val);
162}
163
164/**
165 * Takes a variable lenght word and returns the mirrored version
166 * (Bit by bit, LSB=>MSB).
167 *
168 * algorithm from
169 * http://graphics.stanford.edu/~seander/bithacks.html
170 * #ReverseBitsByLookupTable
171 *
172 * @param val: variable lenght word
173 * @param size: number of bytes to mirror
174 * @return mirrored word
175 */
176template <class T>
177T
178reverseBits(T val, std::size_t size = sizeof(T))
179{
180 static_assert(std::is_integral<T>::value, "Expecting an integer type");
181
182 assert(size <= sizeof(T));
183
184 T output = 0;
185 for (auto byte = 0; byte < size; byte++, val >>= 8) {
186 output = (output << 8) | reverseLookUpTable[val & 0xFF];
187 }
188
189 return output;
190}
191
192/**
193 * Returns the bit position of the MSB that is set in the input
194 */
195inline
196int
197findMsbSet(uint64_t val) {
198 int msb = 0;
199 if (!val)
200 return 0;
201 if (bits(val, 63,32)) { msb += 32; val >>= 32; }
202 if (bits(val, 31,16)) { msb += 16; val >>= 16; }
203 if (bits(val, 15,8)) { msb += 8; val >>= 8; }
204 if (bits(val, 7,4)) { msb += 4; val >>= 4; }
205 if (bits(val, 3,2)) { msb += 2; val >>= 2; }
206 if (bits(val, 1,1)) { msb += 1; }
207 return msb;
208}
209
210/**
211 * Returns the bit position of the LSB that is set in the input
212 */
213inline int
214findLsbSet(uint64_t val) {
215 int lsb = 0;
216 if (!val)
217 return sizeof(val) * 8;
218 if (!bits(val, 31,0)) { lsb += 32; val >>= 32; }
219 if (!bits(val, 15,0)) { lsb += 16; val >>= 16; }
220 if (!bits(val, 7,0)) { lsb += 8; val >>= 8; }
221 if (!bits(val, 3,0)) { lsb += 4; val >>= 4; }
222 if (!bits(val, 1,0)) { lsb += 2; val >>= 2; }
223 if (!bits(val, 0,0)) { lsb += 1; }
224 return lsb;
225}
226
227/**
228 * Checks if a number is a power of two, or zero.
229 */
230template <class T>
231inline bool
232isPow2(T v) {
233 return (v & (v - 1)) == (T)0;
234}
235
236/**
237 * Returns the number of set ones in the provided value.
238 * PD algorithm from
239 * http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
240 */
241inline int
242popCount(uint64_t val) {
243#ifndef __has_builtin
244 #define __has_builtin(foo) 0
245#endif
246#if defined(__GNUC__) || (defined(__clang__) && __has_builtin(__builtin_popcountl))
247 return __builtin_popcountl(val);
248#else
249 const uint64_t m1 = 0x5555555555555555; // ..010101b
250 const uint64_t m2 = 0x3333333333333333; // ..110011b
251 const uint64_t m4 = 0x0f0f0f0f0f0f0f0f; // ..001111b
252 const uint64_t sum = 0x0101010101010101;
253
254 val -= (val >> 1) & m1; // 2 bits count -> 2 bits
255 val = (val & m2) + ((val >> 2) & m2); // 4 bits count -> 4 bits
256 val = (val + (val >> 4)) & m4; // 8 bits count -> 8 bits
257 return (val * sum) >> 56; // horizontal sum
258#endif // defined(__GNUC__) || (defined(__clang__) && __has_builtin(__builtin_popcountl))
259}
260
261/**
262 * Align to the next highest power of two.
263 *
264 * The number passed in is aligned to the next highest power of two,
265 * if it is not already a power of two. Please note that if 0 is
266 * passed in, 0 is returned.
267 *
268 * This code has been modified from the following:
269 * http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
270 */
271inline uint64_t alignToPowerOfTwo(uint64_t val)
272{
273 val--;
274 val |= val >> 1;
275 val |= val >> 2;
276 val |= val >> 4;
277 val |= val >> 8;
278 val |= val >> 16;
279 val |= val >> 32;
280 val++;
281
282 return val;
283};
284
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