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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 | ||
5f661e03 SM |
37 | /* Expand to code that computes the number of 1-bits of the local |
38 | variable 'x' of type TYPE (an unsigned integer type) and return it | |
39 | from the current function. */ | |
40 | #define COUNT_ONE_BITS_GENERIC(TYPE) \ | |
41 | do \ | |
42 | { \ | |
43 | int count = 0; \ | |
44 | int bits; \ | |
45 | for (bits = 0; bits < sizeof (TYPE) * CHAR_BIT; bits += 32) \ | |
46 | { \ | |
47 | count += count_one_bits_32 (x); \ | |
48 | x = x >> 31 >> 1; \ | |
49 | } \ | |
50 | return count; \ | |
51 | } \ | |
52 | while (0) | |
53 | ||
54 | /* Assuming the GCC builtin is BUILTIN and the MSC builtin is MSC_BUILTIN, | |
55 | expand to code that computes the number of 1-bits of the local | |
56 | variable 'x' of type TYPE (an unsigned integer type) and return it | |
57 | from the current function. */ | |
58 | #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) | |
59 | # define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) return BUILTIN (x) | |
60 | #else | |
61 | ||
62 | /* Compute and return the number of 1-bits set in the least | |
63 | significant 32 bits of X. */ | |
64 | COUNT_ONE_BITS_INLINE int | |
65 | count_one_bits_32 (unsigned int x) | |
66 | { | |
67 | x = ((x & 0xaaaaaaaaU) >> 1) + (x & 0x55555555U); | |
68 | x = ((x & 0xccccccccU) >> 2) + (x & 0x33333333U); | |
69 | x = (x >> 16) + (x & 0xffff); | |
70 | x = ((x & 0xf0f0) >> 4) + (x & 0x0f0f); | |
71 | return (x >> 8) + (x & 0x00ff); | |
72 | } | |
73 | ||
74 | # if 1500 <= _MSC_VER && (defined _M_IX86 || defined _M_X64) | |
75 | ||
76 | /* While gcc falls back to its own generic code if the machine | |
77 | on which it's running doesn't support popcount, with Microsoft's | |
78 | compiler we need to detect and fallback ourselves. */ | |
79 | # pragma intrinsic __cpuid | |
80 | # pragma intrinsic __popcnt | |
81 | # pragma intrinsic __popcnt64 | |
82 | ||
83 | /* Return nonzero if popcount is supported. */ | |
84 | ||
85 | /* 1 if supported, 0 if not supported, -1 if unknown. */ | |
86 | extern int popcount_support; | |
87 | ||
88 | COUNT_ONE_BITS_INLINE int | |
89 | popcount_supported (void) | |
90 | { | |
91 | if (popcount_support < 0) | |
92 | { | |
93 | int cpu_info[4]; | |
94 | __cpuid (cpu_info, 1); | |
95 | popcount_support = (cpu_info[2] >> 23) & 1; /* See MSDN. */ | |
96 | } | |
97 | return popcount_support; | |
98 | } | |
99 | ||
100 | # define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) \ | |
101 | do \ | |
102 | { \ | |
103 | if (popcount_supported ()) \ | |
104 | return MSC_BUILTIN (x); \ | |
105 | else \ | |
106 | COUNT_ONE_BITS_GENERIC (TYPE); \ | |
107 | } \ | |
108 | while (0) | |
109 | # else | |
110 | # define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) \ | |
111 | COUNT_ONE_BITS_GENERIC (TYPE) | |
112 | # endif | |
113 | #endif | |
114 | ||
115 | /* Compute and return the number of 1-bits set in X. */ | |
116 | COUNT_ONE_BITS_INLINE int | |
117 | count_one_bits (unsigned int x) | |
118 | { | |
119 | COUNT_ONE_BITS (__builtin_popcount, __popcnt, unsigned int); | |
120 | } | |
121 | ||
122 | /* Compute and return the number of 1-bits set in X. */ | |
123 | COUNT_ONE_BITS_INLINE int | |
124 | count_one_bits_l (unsigned long int x) | |
125 | { | |
126 | COUNT_ONE_BITS (__builtin_popcountl, __popcnt, unsigned long int); | |
127 | } | |
128 | ||
5f661e03 SM |
129 | /* Compute and return the number of 1-bits set in X. */ |
130 | COUNT_ONE_BITS_INLINE int | |
131 | count_one_bits_ll (unsigned long long int x) | |
132 | { | |
133 | COUNT_ONE_BITS (__builtin_popcountll, __popcnt64, unsigned long long int); | |
134 | } | |
5df4cba6 SM |
135 | |
136 | #ifdef __cplusplus | |
137 | } | |
5f661e03 SM |
138 | #endif |
139 | ||
140 | _GL_INLINE_HEADER_END | |
141 | ||
142 | #endif /* COUNT_ONE_BITS_H */ |