/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
* A bit array is an array of bits represented by an array of words (size_t).
*/
#ifndef util_BitArray_h
#define util_BitArray_h
#include "mozilla/Assertions.h"
#include <limits.h>
#include <stddef.h>
namespace js {
static const size_t BitArrayElementBits =
sizeof(size_t) * CHAR_BIT;
static inline unsigned NumWordsForBitArrayOfLength(size_t length) {
return (length + (BitArrayElementBits - 1)) / BitArrayElementBits;
}
static inline unsigned BitArrayIndexToWordIndex(size_t length,
size_t bitIndex) {
unsigned wordIndex = bitIndex / BitArrayElementBits;
MOZ_ASSERT(wordIndex < length);
return wordIndex;
}
static inline size_t BitArrayIndexToWordMask(size_t i) {
return size_t(1) << (i % BitArrayElementBits);
}
static inline bool IsBitArrayElementSet(
const size_t* array, size_t length,
size_t i) {
return array[BitArrayIndexToWordIndex(length, i)] &
BitArrayIndexToWordMask(i);
}
static inline bool IsAnyBitArrayElementSet(
const size_t* array, size_t length) {
unsigned numWords = NumWordsForBitArrayOfLength(length);
for (
unsigned i = 0; i < numWords; ++i) {
if (array[i]) {
return true;
}
}
return false;
}
static inline void SetBitArrayElement(size_t* array, size_t length, size_t i) {
array[BitArrayIndexToWordIndex(length, i)] |= BitArrayIndexToWordMask(i);
}
static inline void ClearBitArrayElement(size_t* array, size_t length,
size_t i) {
array[BitArrayIndexToWordIndex(length, i)] &= ~BitArrayIndexToWordMask(i);
}
static inline void ClearAllBitArrayElements(size_t* array, size_t length) {
for (
unsigned i = 0; i < length; ++i) {
array[i] = 0;
}
}
}
/* namespace js */
#endif /* util_BitArray_h */
