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5f661e03 | 1 | /* count-one-bits.h -- counts the number of 1-bits in a word. |
5df4cba6 | 2 | Copyright (C) 2007-2020 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. */ | |
41 | #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) | |
698be2d8 CB |
42 | # define COUNT_ONE_BITS(GCC_BUILTIN, MSC_BUILTIN, TYPE) \ |
43 | return GCC_BUILTIN (x) | |
5f661e03 SM |
44 | #else |
45 | ||
46 | /* Compute and return the number of 1-bits set in the least | |
47 | significant 32 bits of X. */ | |
48 | COUNT_ONE_BITS_INLINE int | |
49 | count_one_bits_32 (unsigned int x) | |
50 | { | |
51 | x = ((x & 0xaaaaaaaaU) >> 1) + (x & 0x55555555U); | |
52 | x = ((x & 0xccccccccU) >> 2) + (x & 0x33333333U); | |
53 | x = (x >> 16) + (x & 0xffff); | |
54 | x = ((x & 0xf0f0) >> 4) + (x & 0x0f0f); | |
55 | return (x >> 8) + (x & 0x00ff); | |
56 | } | |
57 | ||
698be2d8 CB |
58 | /* Expand to code that computes the number of 1-bits of the local |
59 | variable 'x' of type TYPE (an unsigned integer type) and return it | |
60 | from the current function. */ | |
61 | # define COUNT_ONE_BITS_GENERIC(TYPE) \ | |
62 | do \ | |
63 | { \ | |
64 | int count = 0; \ | |
65 | int bits; \ | |
66 | for (bits = 0; bits < sizeof (TYPE) * CHAR_BIT; bits += 32) \ | |
67 | { \ | |
68 | count += count_one_bits_32 (x); \ | |
69 | x = x >> 31 >> 1; \ | |
70 | } \ | |
71 | return count; \ | |
72 | } \ | |
73 | while (0) | |
74 | ||
5f661e03 SM |
75 | # if 1500 <= _MSC_VER && (defined _M_IX86 || defined _M_X64) |
76 | ||
77 | /* While gcc falls back to its own generic code if the machine | |
78 | on which it's running doesn't support popcount, with Microsoft's | |
79 | compiler we need to detect and fallback ourselves. */ | |
698be2d8 CB |
80 | |
81 | # if 0 | |
82 | # include <intrin.h> | |
83 | # else | |
84 | /* Don't pollute the namespace with too many MSVC intrinsics. */ | |
85 | # pragma intrinsic (__cpuid) | |
86 | # pragma intrinsic (__popcnt) | |
87 | # if defined _M_X64 | |
88 | # pragma intrinsic (__popcnt64) | |
89 | # endif | |
90 | # endif | |
91 | ||
92 | # if !defined _M_X64 | |
93 | static inline __popcnt64 (unsigned long long x) | |
94 | { | |
95 | return __popcnt ((unsigned int) (x >> 32)) + __popcnt ((unsigned int) x); | |
96 | } | |
97 | # endif | |
5f661e03 SM |
98 | |
99 | /* Return nonzero if popcount is supported. */ | |
100 | ||
101 | /* 1 if supported, 0 if not supported, -1 if unknown. */ | |
102 | extern int popcount_support; | |
103 | ||
104 | COUNT_ONE_BITS_INLINE int | |
105 | popcount_supported (void) | |
106 | { | |
107 | if (popcount_support < 0) | |
108 | { | |
698be2d8 CB |
109 | /* Do as described in |
110 | <https://docs.microsoft.com/en-us/cpp/intrinsics/popcnt16-popcnt-popcnt64> */ | |
5f661e03 SM |
111 | int cpu_info[4]; |
112 | __cpuid (cpu_info, 1); | |
698be2d8 | 113 | popcount_support = (cpu_info[2] >> 23) & 1; |
5f661e03 SM |
114 | } |
115 | return popcount_support; | |
116 | } | |
117 | ||
698be2d8 CB |
118 | # define COUNT_ONE_BITS(GCC_BUILTIN, MSC_BUILTIN, TYPE) \ |
119 | do \ | |
120 | { \ | |
121 | if (popcount_supported ()) \ | |
122 | return MSC_BUILTIN (x); \ | |
123 | else \ | |
124 | COUNT_ONE_BITS_GENERIC (TYPE); \ | |
125 | } \ | |
5f661e03 | 126 | while (0) |
698be2d8 | 127 | |
5f661e03 | 128 | # else |
698be2d8 CB |
129 | |
130 | # define COUNT_ONE_BITS(GCC_BUILTIN, MSC_BUILTIN, TYPE) \ | |
5f661e03 | 131 | COUNT_ONE_BITS_GENERIC (TYPE) |
698be2d8 | 132 | |
5f661e03 SM |
133 | # endif |
134 | #endif | |
135 | ||
136 | /* Compute and return the number of 1-bits set in X. */ | |
137 | COUNT_ONE_BITS_INLINE int | |
138 | count_one_bits (unsigned int x) | |
139 | { | |
140 | COUNT_ONE_BITS (__builtin_popcount, __popcnt, unsigned int); | |
141 | } | |
142 | ||
143 | /* Compute and return the number of 1-bits set in X. */ | |
144 | COUNT_ONE_BITS_INLINE int | |
145 | count_one_bits_l (unsigned long int x) | |
146 | { | |
147 | COUNT_ONE_BITS (__builtin_popcountl, __popcnt, unsigned long int); | |
148 | } | |
149 | ||
5f661e03 SM |
150 | /* Compute and return the number of 1-bits set in X. */ |
151 | COUNT_ONE_BITS_INLINE int | |
152 | count_one_bits_ll (unsigned long long int x) | |
153 | { | |
154 | COUNT_ONE_BITS (__builtin_popcountll, __popcnt64, unsigned long long int); | |
155 | } | |
5df4cba6 SM |
156 | |
157 | #ifdef __cplusplus | |
158 | } | |
5f661e03 SM |
159 | #endif |
160 | ||
161 | _GL_INLINE_HEADER_END | |
162 | ||
163 | #endif /* COUNT_ONE_BITS_H */ |