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 20 #include <stdbool.h> 21 #include <string.h> 22 #include <strings.h> 23 #include <sys/cdefs.h> 24 25 __BEGIN_DECLS 26 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 bitmask_init(unsigned int * bitmask,int num_bits)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 bitmask_ffz(unsigned int * bitmask,int num_bits)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 bitmask_weight(unsigned int * bitmask,int num_bits)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 bitmask_set(unsigned int * bitmask,int bit)88 static inline void bitmask_set(unsigned int *bitmask, int bit) 89 { 90 bitmask[BIT_WORD(bit)] |= BIT_MASK(bit); 91 } 92 bitmask_clear(unsigned int * bitmask,int bit)93 static inline void bitmask_clear(unsigned int *bitmask, int bit) 94 { 95 bitmask[BIT_WORD(bit)] &= ~BIT_MASK(bit); 96 } 97 bitmask_test(unsigned int * bitmask,int bit)98 static inline bool bitmask_test(unsigned int *bitmask, int bit) 99 { 100 return bitmask[BIT_WORD(bit)] & BIT_MASK(bit); 101 } 102 popcount(unsigned int x)103 static inline int popcount(unsigned int x) 104 { 105 return __builtin_popcount(x); 106 } 107 popcountl(unsigned long x)108 static inline int popcountl(unsigned long x) 109 { 110 return __builtin_popcountl(x); 111 } 112 popcountll(unsigned long long x)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 */ 121