Dima Zavin | 5a809b9 | 2011-03-10 15:06:27 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2011 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef __CUTILS_BITOPS_H |
| 18 | #define __CUTILS_BITOPS_H |
| 19 | |
Alex Ray | 81ec96d | 2013-01-07 16:58:01 -0800 | [diff] [blame] | 20 | #include <stdbool.h> |
Alex Ray | 2111bc7 | 2013-01-03 10:57:13 -0800 | [diff] [blame] | 21 | #include <string.h> |
| 22 | #include <strings.h> |
Dima Zavin | 5a809b9 | 2011-03-10 15:06:27 -0800 | [diff] [blame] | 23 | #include <sys/cdefs.h> |
| 24 | |
| 25 | __BEGIN_DECLS |
| 26 | |
Alex Ray | 2111bc7 | 2013-01-03 10:57:13 -0800 | [diff] [blame] | 27 | /* |
| 28 | * Bitmask Operations |
| 29 | * |
| 30 | * Note this doesn't provide any locking/exclusion, and isn't atomic. |
| 31 | * Additionally no bounds checking is done on the bitmask array. |
| 32 | * |
| 33 | * Example: |
| 34 | * |
| 35 | * int num_resources; |
| 36 | * unsigned int resource_bits[BITS_TO_WORDS(num_resources)]; |
| 37 | * bitmask_init(resource_bits, num_resources); |
| 38 | * ... |
| 39 | * int bit = bitmask_ffz(resource_bits, num_resources); |
| 40 | * bitmask_set(resource_bits, bit); |
| 41 | * ... |
| 42 | * if (bitmask_test(resource_bits, bit)) { ... } |
| 43 | * ... |
| 44 | * bitmask_clear(resource_bits, bit); |
| 45 | * |
| 46 | */ |
| 47 | |
| 48 | #define BITS_PER_WORD (sizeof(unsigned int) * 8) |
| 49 | #define BITS_TO_WORDS(x) (((x) + BITS_PER_WORD - 1) / BITS_PER_WORD) |
| 50 | #define BIT_IN_WORD(x) ((x) % BITS_PER_WORD) |
| 51 | #define BIT_WORD(x) ((x) / BITS_PER_WORD) |
| 52 | #define BIT_MASK(x) (1 << BIT_IN_WORD(x)) |
| 53 | |
| 54 | static inline void bitmask_init(unsigned int *bitmask, int num_bits) |
| 55 | { |
| 56 | memset(bitmask, 0, BITS_TO_WORDS(num_bits)*sizeof(unsigned int)); |
| 57 | } |
| 58 | |
| 59 | static inline int bitmask_ffz(unsigned int *bitmask, int num_bits) |
| 60 | { |
| 61 | int bit, result; |
| 62 | unsigned int i; |
| 63 | |
| 64 | for (i = 0; i < BITS_TO_WORDS(num_bits); i++) { |
| 65 | bit = ffs(~bitmask[i]); |
| 66 | if (bit) { |
| 67 | // ffs is 1-indexed, return 0-indexed result |
| 68 | bit--; |
| 69 | result = BITS_PER_WORD * i + bit; |
| 70 | if (result >= num_bits) |
| 71 | return -1; |
| 72 | return result; |
| 73 | } |
| 74 | } |
| 75 | return -1; |
| 76 | } |
| 77 | |
Alex Ray | f90fd9e | 2013-01-19 22:53:46 -0800 | [diff] [blame] | 78 | static inline int bitmask_weight(unsigned int *bitmask, int num_bits) |
| 79 | { |
| 80 | int i; |
| 81 | int weight = 0; |
| 82 | |
| 83 | for (i = 0; i < BITS_TO_WORDS(num_bits); i++) |
| 84 | weight += __builtin_popcount(bitmask[i]); |
| 85 | return weight; |
| 86 | } |
| 87 | |
Alex Ray | 2111bc7 | 2013-01-03 10:57:13 -0800 | [diff] [blame] | 88 | static inline void bitmask_set(unsigned int *bitmask, int bit) |
| 89 | { |
| 90 | bitmask[BIT_WORD(bit)] |= BIT_MASK(bit); |
| 91 | } |
| 92 | |
| 93 | static inline void bitmask_clear(unsigned int *bitmask, int bit) |
| 94 | { |
| 95 | bitmask[BIT_WORD(bit)] &= ~BIT_MASK(bit); |
| 96 | } |
| 97 | |
| 98 | static inline bool bitmask_test(unsigned int *bitmask, int bit) |
| 99 | { |
| 100 | return bitmask[BIT_WORD(bit)] & BIT_MASK(bit); |
| 101 | } |
| 102 | |
Dima Zavin | 5a809b9 | 2011-03-10 15:06:27 -0800 | [diff] [blame] | 103 | static inline int popcount(unsigned int x) |
| 104 | { |
| 105 | return __builtin_popcount(x); |
| 106 | } |
| 107 | |
| 108 | static inline int popcountl(unsigned long x) |
| 109 | { |
| 110 | return __builtin_popcountl(x); |
| 111 | } |
| 112 | |
| 113 | static inline int popcountll(unsigned long long x) |
| 114 | { |
| 115 | return __builtin_popcountll(x); |
| 116 | } |
| 117 | |
| 118 | __END_DECLS |
| 119 | |
| 120 | #endif /* __CUTILS_BITOPS_H */ |