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5f661e03 | 1 | /* count-one-bits.h -- counts the number of 1-bits in a word. |
9c9d63b1 | 2 | Copyright (C) 2007-2021 Free Software Foundation, Inc. |
5f661e03 SM |
3 | |
4 | This program is free software: you can redistribute it and/or modify | |
5 | it under the terms of the GNU General Public License as published by | |
6 | the Free Software Foundation; either version 3 of the License, or | |
7 | (at your option) any later version. | |
8 | ||
9 | This program is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | GNU General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU General Public License | |
15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ | |
16 | ||
17 | /* Written by Ben Pfaff. */ | |
18 | ||
19 | #ifndef COUNT_ONE_BITS_H | |
20 | #define COUNT_ONE_BITS_H 1 | |
21 | ||
22 | #include <limits.h> | |
23 | #include <stdlib.h> | |
24 | ||
25 | #ifndef _GL_INLINE_HEADER_BEGIN | |
26 | #error "Please include config.h first." | |
27 | #endif | |
28 | _GL_INLINE_HEADER_BEGIN | |
29 | #ifndef COUNT_ONE_BITS_INLINE | |
30 | # define COUNT_ONE_BITS_INLINE _GL_INLINE | |
31 | #endif | |
32 | ||
5df4cba6 SM |
33 | #ifdef __cplusplus |
34 | extern "C" { | |
35 | #endif | |
36 | ||
698be2d8 | 37 | /* Assuming the GCC builtin is GCC_BUILTIN and the MSC builtin is MSC_BUILTIN, |
5f661e03 SM |
38 | expand to code that computes the number of 1-bits of the local |
39 | variable 'x' of type TYPE (an unsigned integer type) and return it | |
40 | from the current function. */ | |
9c9d63b1 PM |
41 | #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) \ |
42 | || (__clang_major__ >= 4) | |
698be2d8 CB |
43 | # define COUNT_ONE_BITS(GCC_BUILTIN, MSC_BUILTIN, TYPE) \ |
44 | return GCC_BUILTIN (x) | |
5f661e03 SM |
45 | #else |
46 | ||
47 | /* Compute and return the number of 1-bits set in the least | |
48 | significant 32 bits of X. */ | |
49 | COUNT_ONE_BITS_INLINE int | |
50 | count_one_bits_32 (unsigned int x) | |
51 | { | |
52 | x = ((x & 0xaaaaaaaaU) >> 1) + (x & 0x55555555U); | |
53 | x = ((x & 0xccccccccU) >> 2) + (x & 0x33333333U); | |
54 | x = (x >> 16) + (x & 0xffff); | |
55 | x = ((x & 0xf0f0) >> 4) + (x & 0x0f0f); | |
56 | return (x >> 8) + (x & 0x00ff); | |
57 | } | |
58 | ||
698be2d8 CB |
59 | /* Expand to code that computes the number of 1-bits of the local |
60 | variable 'x' of type TYPE (an unsigned integer type) and return it | |
61 | from the current function. */ | |
62 | # define COUNT_ONE_BITS_GENERIC(TYPE) \ | |
63 | do \ | |
64 | { \ | |
65 | int count = 0; \ | |
66 | int bits; \ | |
67 | for (bits = 0; bits < sizeof (TYPE) * CHAR_BIT; bits += 32) \ | |
68 | { \ | |
69 | count += count_one_bits_32 (x); \ | |
70 | x = x >> 31 >> 1; \ | |
71 | } \ | |
72 | return count; \ | |
73 | } \ | |
74 | while (0) | |
75 | ||
5f661e03 SM |
76 | # if 1500 <= _MSC_VER && (defined _M_IX86 || defined _M_X64) |
77 | ||
78 | /* While gcc falls back to its own generic code if the machine | |
79 | on which it's running doesn't support popcount, with Microsoft's | |
80 | compiler we need to detect and fallback ourselves. */ | |
698be2d8 CB |
81 | |
82 | # if 0 | |
83 | # include <intrin.h> | |
84 | # else | |
85 | /* Don't pollute the namespace with too many MSVC intrinsics. */ | |
86 | # pragma intrinsic (__cpuid) | |
87 | # pragma intrinsic (__popcnt) | |
88 | # if defined _M_X64 | |
89 | # pragma intrinsic (__popcnt64) | |
90 | # endif | |
91 | # endif | |
92 | ||
93 | # if !defined _M_X64 | |
94 | static inline __popcnt64 (unsigned long long x) | |
95 | { | |
96 | return __popcnt ((unsigned int) (x >> 32)) + __popcnt ((unsigned int) x); | |
97 | } | |
98 | # endif | |
5f661e03 SM |
99 | |
100 | /* Return nonzero if popcount is supported. */ | |
101 | ||
102 | /* 1 if supported, 0 if not supported, -1 if unknown. */ | |
103 | extern int popcount_support; | |
104 | ||
105 | COUNT_ONE_BITS_INLINE int | |
106 | popcount_supported (void) | |
107 | { | |
108 | if (popcount_support < 0) | |
109 | { | |
698be2d8 CB |
110 | /* Do as described in |
111 | <https://docs.microsoft.com/en-us/cpp/intrinsics/popcnt16-popcnt-popcnt64> */ | |
5f661e03 SM |
112 | int cpu_info[4]; |
113 | __cpuid (cpu_info, 1); | |
698be2d8 | 114 | popcount_support = (cpu_info[2] >> 23) & 1; |
5f661e03 SM |
115 | } |
116 | return popcount_support; | |
117 | } | |
118 | ||
698be2d8 CB |
119 | # define COUNT_ONE_BITS(GCC_BUILTIN, MSC_BUILTIN, TYPE) \ |
120 | do \ | |
121 | { \ | |
122 | if (popcount_supported ()) \ | |
123 | return MSC_BUILTIN (x); \ | |
124 | else \ | |
125 | COUNT_ONE_BITS_GENERIC (TYPE); \ | |
126 | } \ | |
5f661e03 | 127 | while (0) |
698be2d8 | 128 | |
5f661e03 | 129 | # else |
698be2d8 CB |
130 | |
131 | # define COUNT_ONE_BITS(GCC_BUILTIN, MSC_BUILTIN, TYPE) \ | |
5f661e03 | 132 | COUNT_ONE_BITS_GENERIC (TYPE) |
698be2d8 | 133 | |
5f661e03 SM |
134 | # endif |
135 | #endif | |
136 | ||
137 | /* Compute and return the number of 1-bits set in X. */ | |
138 | COUNT_ONE_BITS_INLINE int | |
139 | count_one_bits (unsigned int x) | |
140 | { | |
141 | COUNT_ONE_BITS (__builtin_popcount, __popcnt, unsigned int); | |
142 | } | |
143 | ||
144 | /* Compute and return the number of 1-bits set in X. */ | |
145 | COUNT_ONE_BITS_INLINE int | |
146 | count_one_bits_l (unsigned long int x) | |
147 | { | |
148 | COUNT_ONE_BITS (__builtin_popcountl, __popcnt, unsigned long int); | |
149 | } | |
150 | ||
5f661e03 SM |
151 | /* Compute and return the number of 1-bits set in X. */ |
152 | COUNT_ONE_BITS_INLINE int | |
153 | count_one_bits_ll (unsigned long long int x) | |
154 | { | |
155 | COUNT_ONE_BITS (__builtin_popcountll, __popcnt64, unsigned long long int); | |
156 | } | |
5df4cba6 SM |
157 | |
158 | #ifdef __cplusplus | |
159 | } | |
5f661e03 SM |
160 | #endif |
161 | ||
162 | _GL_INLINE_HEADER_END | |
163 | ||
164 | #endif /* COUNT_ONE_BITS_H */ |