| 1 | /* count-one-bits.h -- counts the number of 1-bits in a word. |
| 2 | Copyright (C) 2007-2014 Free Software Foundation, Inc. |
| 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 <http://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 | |
| 33 | /* Expand to code that computes the number of 1-bits of the local |
| 34 | variable 'x' of type TYPE (an unsigned integer type) and return it |
| 35 | from the current function. */ |
| 36 | #define COUNT_ONE_BITS_GENERIC(TYPE) \ |
| 37 | do \ |
| 38 | { \ |
| 39 | int count = 0; \ |
| 40 | int bits; \ |
| 41 | for (bits = 0; bits < sizeof (TYPE) * CHAR_BIT; bits += 32) \ |
| 42 | { \ |
| 43 | count += count_one_bits_32 (x); \ |
| 44 | x = x >> 31 >> 1; \ |
| 45 | } \ |
| 46 | return count; \ |
| 47 | } \ |
| 48 | while (0) |
| 49 | |
| 50 | /* Assuming the GCC builtin is BUILTIN and the MSC builtin is MSC_BUILTIN, |
| 51 | expand to code that computes the number of 1-bits of the local |
| 52 | variable 'x' of type TYPE (an unsigned integer type) and return it |
| 53 | from the current function. */ |
| 54 | #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) |
| 55 | # define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) return BUILTIN (x) |
| 56 | #else |
| 57 | |
| 58 | /* Compute and return the number of 1-bits set in the least |
| 59 | significant 32 bits of X. */ |
| 60 | COUNT_ONE_BITS_INLINE int |
| 61 | count_one_bits_32 (unsigned int x) |
| 62 | { |
| 63 | x = ((x & 0xaaaaaaaaU) >> 1) + (x & 0x55555555U); |
| 64 | x = ((x & 0xccccccccU) >> 2) + (x & 0x33333333U); |
| 65 | x = (x >> 16) + (x & 0xffff); |
| 66 | x = ((x & 0xf0f0) >> 4) + (x & 0x0f0f); |
| 67 | return (x >> 8) + (x & 0x00ff); |
| 68 | } |
| 69 | |
| 70 | # if 1500 <= _MSC_VER && (defined _M_IX86 || defined _M_X64) |
| 71 | |
| 72 | /* While gcc falls back to its own generic code if the machine |
| 73 | on which it's running doesn't support popcount, with Microsoft's |
| 74 | compiler we need to detect and fallback ourselves. */ |
| 75 | # pragma intrinsic __cpuid |
| 76 | # pragma intrinsic __popcnt |
| 77 | # pragma intrinsic __popcnt64 |
| 78 | |
| 79 | /* Return nonzero if popcount is supported. */ |
| 80 | |
| 81 | /* 1 if supported, 0 if not supported, -1 if unknown. */ |
| 82 | extern int popcount_support; |
| 83 | |
| 84 | COUNT_ONE_BITS_INLINE int |
| 85 | popcount_supported (void) |
| 86 | { |
| 87 | if (popcount_support < 0) |
| 88 | { |
| 89 | int cpu_info[4]; |
| 90 | __cpuid (cpu_info, 1); |
| 91 | popcount_support = (cpu_info[2] >> 23) & 1; /* See MSDN. */ |
| 92 | } |
| 93 | return popcount_support; |
| 94 | } |
| 95 | |
| 96 | # define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) \ |
| 97 | do \ |
| 98 | { \ |
| 99 | if (popcount_supported ()) \ |
| 100 | return MSC_BUILTIN (x); \ |
| 101 | else \ |
| 102 | COUNT_ONE_BITS_GENERIC (TYPE); \ |
| 103 | } \ |
| 104 | while (0) |
| 105 | # else |
| 106 | # define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) \ |
| 107 | COUNT_ONE_BITS_GENERIC (TYPE) |
| 108 | # endif |
| 109 | #endif |
| 110 | |
| 111 | /* Compute and return the number of 1-bits set in X. */ |
| 112 | COUNT_ONE_BITS_INLINE int |
| 113 | count_one_bits (unsigned int x) |
| 114 | { |
| 115 | COUNT_ONE_BITS (__builtin_popcount, __popcnt, unsigned int); |
| 116 | } |
| 117 | |
| 118 | /* Compute and return the number of 1-bits set in X. */ |
| 119 | COUNT_ONE_BITS_INLINE int |
| 120 | count_one_bits_l (unsigned long int x) |
| 121 | { |
| 122 | COUNT_ONE_BITS (__builtin_popcountl, __popcnt, unsigned long int); |
| 123 | } |
| 124 | |
| 125 | #if HAVE_UNSIGNED_LONG_LONG_INT |
| 126 | /* Compute and return the number of 1-bits set in X. */ |
| 127 | COUNT_ONE_BITS_INLINE int |
| 128 | count_one_bits_ll (unsigned long long int x) |
| 129 | { |
| 130 | COUNT_ONE_BITS (__builtin_popcountll, __popcnt64, unsigned long long int); |
| 131 | } |
| 132 | #endif |
| 133 | |
| 134 | _GL_INLINE_HEADER_END |
| 135 | |
| 136 | #endif /* COUNT_ONE_BITS_H */ |