BitArray.h (2136B)
1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- 2 * vim: set ts=8 sts=2 et sw=2 tw=80: 3 * This Source Code Form is subject to the terms of the Mozilla Public 4 * License, v. 2.0. If a copy of the MPL was not distributed with this 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 6 7 /* 8 * A bit array is an array of bits represented by an array of words (size_t). 9 */ 10 11 #ifndef util_BitArray_h 12 #define util_BitArray_h 13 14 #include "mozilla/Assertions.h" 15 16 #include <limits.h> 17 #include <stddef.h> 18 19 namespace js { 20 21 static const size_t BitArrayElementBits = sizeof(size_t) * CHAR_BIT; 22 23 static inline unsigned NumWordsForBitArrayOfLength(size_t length) { 24 return (length + (BitArrayElementBits - 1)) / BitArrayElementBits; 25 } 26 27 static inline unsigned BitArrayIndexToWordIndex(size_t length, 28 size_t bitIndex) { 29 unsigned wordIndex = bitIndex / BitArrayElementBits; 30 MOZ_ASSERT(wordIndex < length); 31 return wordIndex; 32 } 33 34 static inline size_t BitArrayIndexToWordMask(size_t i) { 35 return size_t(1) << (i % BitArrayElementBits); 36 } 37 38 static inline bool IsBitArrayElementSet(const size_t* array, size_t length, 39 size_t i) { 40 return array[BitArrayIndexToWordIndex(length, i)] & 41 BitArrayIndexToWordMask(i); 42 } 43 44 static inline bool IsAnyBitArrayElementSet(const size_t* array, size_t length) { 45 unsigned numWords = NumWordsForBitArrayOfLength(length); 46 for (unsigned i = 0; i < numWords; ++i) { 47 if (array[i]) { 48 return true; 49 } 50 } 51 return false; 52 } 53 54 static inline void SetBitArrayElement(size_t* array, size_t length, size_t i) { 55 array[BitArrayIndexToWordIndex(length, i)] |= BitArrayIndexToWordMask(i); 56 } 57 58 static inline void ClearBitArrayElement(size_t* array, size_t length, 59 size_t i) { 60 array[BitArrayIndexToWordIndex(length, i)] &= ~BitArrayIndexToWordMask(i); 61 } 62 63 static inline void ClearAllBitArrayElements(size_t* array, size_t length) { 64 for (unsigned i = 0; i < length; ++i) { 65 array[i] = 0; 66 } 67 } 68 69 } /* namespace js */ 70 71 #endif /* util_BitArray_h */