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 * Extract the bit from this position from 'val' and right justify it.
63 */
64template <class T>
65inline
66T
67bits(T val, int bit)
68{
69 return bits(val, bit, bit);
70}
71
72/**
73 * Mask off the given bits in place like bits() but without shifting.
74 * msb = 63, lsb = 0
75 */
76template <class T>
77inline
78T
79mbits(T val, int first, int last)
80{
81 return val & (mask(first+1) & ~mask(last));
82}
83
84inline uint64_t
85mask(int first, int last)
86{
87 return mbits((uint64_t)-1LL, first, last);
88}
89
90/**
91 * Sign-extend an N-bit value to 64 bits.
92 */
93template <int N>
94inline
95uint64_t
96sext(uint64_t val)
97{
98 int sign_bit = bits(val, N-1, N-1);
99 return sign_bit ? (val | ~mask(N)) : val;
100}
101
102/**
103 * Return val with bits first to last set to bit_val
104 */
105template <class T, class B>
106inline
107T
108insertBits(T val, int first, int last, B bit_val)
109{
110 T t_bit_val = bit_val;
111 T bmask = mask(first - last + 1) << last;
112 return ((t_bit_val << last) & bmask) | (val & ~bmask);
113}
114
115/**
116 * Overloaded for access to only one bit in value
117 */
118template <class T, class B>
119inline
120T
121insertBits(T val, int bit, B bit_val)
122{
123 return insertBits(val, bit, bit, bit_val);
124}
125
126/**
127 * A convenience function to replace bits first to last of val with bit_val
128 * in place.
129 */
130template <class T, class B>
131inline
132void
133replaceBits(T& val, int first, int last, B bit_val)
134{
135 val = insertBits(val, first, last, bit_val);
136}
137
138/** Overloaded function to allow to access only 1 bit*/
139template <class T, class B>
140inline
141void
142replaceBits(T& val, int bit, B bit_val)
143{
144 val = insertBits(val, bit, bit, bit_val);
145}
146/**
147 * Returns the bit position of the MSB that is set in the input
148 */
149inline
150int
151findMsbSet(uint64_t val) {
152 int msb = 0;
153 if (!val)
154 return 0;
155 if (bits(val, 63,32)) { msb += 32; val >>= 32; }
156 if (bits(val, 31,16)) { msb += 16; val >>= 16; }
157 if (bits(val, 15,8)) { msb += 8; val >>= 8; }
158 if (bits(val, 7,4)) { msb += 4; val >>= 4; }
159 if (bits(val, 3,2)) { msb += 2; val >>= 2; }
160 if (bits(val, 1,1)) { msb += 1; }
161 return msb;
162}
163
164/**
165 * Returns the bit position of the LSB that is set in the input
166 */
167inline int
168findLsbSet(uint64_t val) {
169 int lsb = 0;
170 if (!val)
171 return sizeof(val) * 8;
172 if (!bits(val, 31,0)) { lsb += 32; val >>= 32; }
173 if (!bits(val, 15,0)) { lsb += 16; val >>= 16; }
174 if (!bits(val, 7,0)) { lsb += 8; val >>= 8; }
175 if (!bits(val, 3,0)) { lsb += 4; val >>= 4; }
176 if (!bits(val, 1,0)) { lsb += 2; val >>= 2; }
177 if (!bits(val, 0,0)) { lsb += 1; }
178 return lsb;
179}
180
181/**
182 * Checks if a number is a power of two, or zero.
183 */
184template <class T>
185inline bool
186isPow2(T v) {
187 return (v & (v - 1)) == (T)0;
188}
189
190/**
191 * Returns the number of set ones in the provided value.
192 * PD algorithm from
193 * http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
194 */
195inline int
196popCount(uint64_t val) {
197#ifndef __has_builtin
198 #define __has_builtin(foo) 0
199#endif
200#if defined(__GNUC__) || (defined(__clang__) && __has_builtin(__builtin_popcountl))
201 return __builtin_popcountl(val);
202#else
203 const uint64_t m1 = 0x5555555555555555; // ..010101b
204 const uint64_t m2 = 0x3333333333333333; // ..110011b
205 const uint64_t m4 = 0x0f0f0f0f0f0f0f0f; // ..001111b
206 const uint64_t sum = 0x0101010101010101;
207
208 val -= (val >> 1) & m1; // 2 bits count -> 2 bits
209 val = (val & m2) + ((val >> 2) & m2); // 4 bits count -> 4 bits
210 val = (val + (val >> 4)) & m4; // 8 bits count -> 8 bits
211 return (val * sum) >> 56; // horizontal sum
212#endif // defined(__GNUC__) || (defined(__clang__) && __has_builtin(__builtin_popcountl))
213}
| 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 */
43
44#ifndef __BASE_BITFIELD_HH__
45#define __BASE_BITFIELD_HH__
46
47#include <inttypes.h>
48
49/**
50 * Generate a 64-bit mask of 'nbits' 1s, right justified.
51 */
52inline uint64_t
53mask(int nbits)
54{
55 return (nbits == 64) ? (uint64_t)-1LL : (1ULL << nbits) - 1;
56}
57
58
59
60/**
61 * Extract the bitfield from position 'first' to 'last' (inclusive)
62 * from 'val' and right justify it. MSB is numbered 63, LSB is 0.
63 */
64template <class T>
65inline
66T
67bits(T val, int first, int last)
68{
69 int nbits = first - last + 1;
70 return (val >> last) & mask(nbits);
71}
72
73/**
74 * Extract the bit from this position from 'val' and right justify it.
75 */
76template <class T>
77inline
78T
79bits(T val, int bit)
80{
81 return bits(val, bit, bit);
82}
83
84/**
85 * Mask off the given bits in place like bits() but without shifting.
86 * msb = 63, lsb = 0
87 */
88template <class T>
89inline
90T
91mbits(T val, int first, int last)
92{
93 return val & (mask(first+1) & ~mask(last));
94}
95
96inline uint64_t
97mask(int first, int last)
98{
99 return mbits((uint64_t)-1LL, first, last);
100}
101
102/**
103 * Sign-extend an N-bit value to 64 bits.
104 */
105template <int N>
106inline
107uint64_t
108sext(uint64_t val)
109{
110 int sign_bit = bits(val, N-1, N-1);
111 return sign_bit ? (val | ~mask(N)) : val;
112}
113
114/**
115 * Return val with bits first to last set to bit_val
116 */
117template <class T, class B>
118inline
119T
120insertBits(T val, int first, int last, B bit_val)
121{
122 T t_bit_val = bit_val;
123 T bmask = mask(first - last + 1) << last;
124 return ((t_bit_val << last) & bmask) | (val & ~bmask);
125}
126
127/**
128 * Overloaded for access to only one bit in value
129 */
130template <class T, class B>
131inline
132T
133insertBits(T val, int bit, B bit_val)
134{
135 return insertBits(val, bit, bit, bit_val);
136}
137
138/**
139 * A convenience function to replace bits first to last of val with bit_val
140 * in place.
141 */
142template <class T, class B>
143inline
144void
145replaceBits(T& val, int first, int last, B bit_val)
146{
147 val = insertBits(val, first, last, bit_val);
148}
149
150/** Overloaded function to allow to access only 1 bit*/
151template <class T, class B>
152inline
153void
154replaceBits(T& val, int bit, B bit_val)
155{
156 val = insertBits(val, bit, bit, bit_val);
157}
158/**
159 * Returns the bit position of the MSB that is set in the input
160 */
161inline
162int
163findMsbSet(uint64_t val) {
164 int msb = 0;
165 if (!val)
166 return 0;
167 if (bits(val, 63,32)) { msb += 32; val >>= 32; }
168 if (bits(val, 31,16)) { msb += 16; val >>= 16; }
169 if (bits(val, 15,8)) { msb += 8; val >>= 8; }
170 if (bits(val, 7,4)) { msb += 4; val >>= 4; }
171 if (bits(val, 3,2)) { msb += 2; val >>= 2; }
172 if (bits(val, 1,1)) { msb += 1; }
173 return msb;
174}
175
176/**
177 * Returns the bit position of the LSB that is set in the input
178 */
179inline int
180findLsbSet(uint64_t val) {
181 int lsb = 0;
182 if (!val)
183 return sizeof(val) * 8;
184 if (!bits(val, 31,0)) { lsb += 32; val >>= 32; }
185 if (!bits(val, 15,0)) { lsb += 16; val >>= 16; }
186 if (!bits(val, 7,0)) { lsb += 8; val >>= 8; }
187 if (!bits(val, 3,0)) { lsb += 4; val >>= 4; }
188 if (!bits(val, 1,0)) { lsb += 2; val >>= 2; }
189 if (!bits(val, 0,0)) { lsb += 1; }
190 return lsb;
191}
192
193/**
194 * Checks if a number is a power of two, or zero.
195 */
196template <class T>
197inline bool
198isPow2(T v) {
199 return (v & (v - 1)) == (T)0;
200}
201
202/**
203 * Returns the number of set ones in the provided value.
204 * PD algorithm from
205 * http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
206 */
207inline int
208popCount(uint64_t val) {
209#ifndef __has_builtin
210 #define __has_builtin(foo) 0
211#endif
212#if defined(__GNUC__) || (defined(__clang__) && __has_builtin(__builtin_popcountl))
213 return __builtin_popcountl(val);
214#else
215 const uint64_t m1 = 0x5555555555555555; // ..010101b
216 const uint64_t m2 = 0x3333333333333333; // ..110011b
217 const uint64_t m4 = 0x0f0f0f0f0f0f0f0f; // ..001111b
218 const uint64_t sum = 0x0101010101010101;
219
220 val -= (val >> 1) & m1; // 2 bits count -> 2 bits
221 val = (val & m2) + ((val >> 2) & m2); // 4 bits count -> 4 bits
222 val = (val + (val >> 4)) & m4; // 8 bits count -> 8 bits
223 return (val * sum) >> 56; // horizontal sum
224#endif // defined(__GNUC__) || (defined(__clang__) && __has_builtin(__builtin_popcountl))
225}
|