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/*
* Copyright (C) 2010-2020 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#pragma once
#include <array>
#include <wtf/Atomics.h>
#include <wtf/HashFunctions.h>
#include <wtf/MathExtras.h>
#include <wtf/StdIntExtras.h>
#include <string.h>
#include <type_traits>
namespace WTF {
template<size_t size>
using BitmapWordType = std::conditional_t<(size <= 32 && sizeof(UCPURegister) > sizeof(uint32_t)), uint32_t, UCPURegister>;
template<size_t bitmapSize, typename WordType = BitmapWordType<bitmapSize>>
class Bitmap final {
WTF_MAKE_FAST_ALLOCATED;
static_assert(sizeof(WordType) <= sizeof(UCPURegister), "WordType must not be bigger than the CPU atomic word size");
public:
constexpr Bitmap();
static constexpr size_t size()
{
return bitmapSize;
}
bool get(size_t, Dependency = Dependency()) const;
void set(size_t);
void set(size_t, bool);
bool testAndSet(size_t);
bool testAndClear(size_t);
bool concurrentTestAndSet(size_t, Dependency = Dependency());
bool concurrentTestAndClear(size_t, Dependency = Dependency());
size_t nextPossiblyUnset(size_t) const;
void clear(size_t);
void clearAll();
void invert();
int64_t findRunOfZeros(size_t runLength) const;
size_t count(size_t start = 0) const;
bool isEmpty() const;
bool isFull() const;
void merge(const Bitmap&);
void filter(const Bitmap&);
void exclude(const Bitmap&);
void concurrentFilter(const Bitmap&);
bool subsumes(const Bitmap&) const;
template<typename Func>
void forEachSetBit(const Func&) const;
size_t findBit(size_t startIndex, bool value) const;
class iterator {
WTF_MAKE_FAST_ALLOCATED;
public:
iterator()
: m_bitmap(nullptr)
, m_index(0)
{
}
iterator(const Bitmap& bitmap, size_t index)
: m_bitmap(&bitmap)
, m_index(index)
{
}
size_t operator*() const { return m_index; }
iterator& operator++()
{
m_index = m_bitmap->findBit(m_index + 1, true);
return *this;
}
bool operator==(const iterator& other) const
{
return m_index == other.m_index;
}
bool operator!=(const iterator& other) const
{
return !(*this == other);
}
private:
const Bitmap* m_bitmap;
size_t m_index;
};
// Use this to iterate over set bits.
iterator begin() const { return iterator(*this, findBit(0, true)); }
iterator end() const { return iterator(*this, bitmapSize); }
void mergeAndClear(Bitmap&);
void setAndClear(Bitmap&);
void setEachNthBit(size_t n, size_t start = 0, size_t end = bitmapSize);
bool operator==(const Bitmap&) const;
bool operator!=(const Bitmap&) const;
void operator|=(const Bitmap&);
void operator&=(const Bitmap&);
void operator^=(const Bitmap&);
unsigned hash() const;
private:
static constexpr unsigned wordSize = sizeof(WordType) * 8;
static constexpr unsigned words = (bitmapSize + wordSize - 1) / wordSize;
// the literal '1' is of type signed int. We want to use an unsigned
// version of the correct size when doing the calculations because if
// WordType is larger than int, '1 << 31' will first be sign extended
// and then casted to unsigned, meaning that set(31) when WordType is
// a 64 bit unsigned int would give 0xffff8000
static constexpr WordType one = 1;
std::array<WordType, words> bits;
};
template<size_t bitmapSize, typename WordType>
constexpr Bitmap<bitmapSize, WordType>::Bitmap()
{
clearAll();
}
template<size_t bitmapSize, typename WordType>
inline bool Bitmap<bitmapSize, WordType>::get(size_t n, Dependency dependency) const
{
return !!(dependency.consume(this)->bits[n / wordSize] & (one << (n % wordSize)));
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::set(size_t n)
{
bits[n / wordSize] |= (one << (n % wordSize));
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::set(size_t n, bool value)
{
if (value)
set(n);
else
clear(n);
}
template<size_t bitmapSize, typename WordType>
inline bool Bitmap<bitmapSize, WordType>::testAndSet(size_t n)
{
WordType mask = one << (n % wordSize);
size_t index = n / wordSize;
bool result = bits[index] & mask;
bits[index] |= mask;
return result;
}
template<size_t bitmapSize, typename WordType>
inline bool Bitmap<bitmapSize, WordType>::testAndClear(size_t n)
{
WordType mask = one << (n % wordSize);
size_t index = n / wordSize;
bool result = bits[index] & mask;
bits[index] &= ~mask;
return result;
}
template<size_t bitmapSize, typename WordType>
ALWAYS_INLINE bool Bitmap<bitmapSize, WordType>::concurrentTestAndSet(size_t n, Dependency dependency)
{
WordType mask = one << (n % wordSize);
size_t index = n / wordSize;
WordType* data = dependency.consume(bits.data()) + index;
return !bitwise_cast<Atomic<WordType>*>(data)->transactionRelaxed(
[&] (WordType& value) -> bool {
if (value & mask)
return false;
value |= mask;
return true;
});
}
template<size_t bitmapSize, typename WordType>
ALWAYS_INLINE bool Bitmap<bitmapSize, WordType>::concurrentTestAndClear(size_t n, Dependency dependency)
{
WordType mask = one << (n % wordSize);
size_t index = n / wordSize;
WordType* data = dependency.consume(bits.data()) + index;
return !bitwise_cast<Atomic<WordType>*>(data)->transactionRelaxed(
[&] (WordType& value) -> bool {
if (!(value & mask))
return false;
value &= ~mask;
return true;
});
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::clear(size_t n)
{
bits[n / wordSize] &= ~(one << (n % wordSize));
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::clearAll()
{
memset(bits.data(), 0, sizeof(bits));
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::invert()
{
for (size_t i = 0; i < words; ++i)
bits[i] = ~bits[i];
if constexpr (!!(bitmapSize % wordSize)) {
constexpr size_t remainingBits = bitmapSize % wordSize;
constexpr WordType mask = (static_cast<WordType>(1) << remainingBits) - 1;
bits[words - 1] &= mask;
}
}
template<size_t bitmapSize, typename WordType>
inline size_t Bitmap<bitmapSize, WordType>::nextPossiblyUnset(size_t start) const
{
if (!~bits[start / wordSize])
return ((start / wordSize) + 1) * wordSize;
return start + 1;
}
template<size_t bitmapSize, typename WordType>
inline int64_t Bitmap<bitmapSize, WordType>::findRunOfZeros(size_t runLength) const
{
if (!runLength)
runLength = 1;
if (runLength > bitmapSize)
return -1;
for (size_t i = 0; i <= (bitmapSize - runLength) ; i++) {
bool found = true;
for (size_t j = i; j <= (i + runLength - 1) ; j++) {
if (get(j)) {
found = false;
break;
}
}
if (found)
return i;
}
return -1;
}
template<size_t bitmapSize, typename WordType>
inline size_t Bitmap<bitmapSize, WordType>::count(size_t start) const
{
size_t result = 0;
for ( ; (start % wordSize); ++start) {
if (get(start))
++result;
}
for (size_t i = start / wordSize; i < words; ++i)
result += WTF::bitCount(bits[i]);
return result;
}
template<size_t bitmapSize, typename WordType>
inline bool Bitmap<bitmapSize, WordType>::isEmpty() const
{
for (size_t i = 0; i < words; ++i)
if (bits[i])
return false;
return true;
}
template<size_t bitmapSize, typename WordType>
inline bool Bitmap<bitmapSize, WordType>::isFull() const
{
for (size_t i = 0; i < words; ++i)
if (~bits[i]) {
if constexpr (!!(bitmapSize % wordSize)) {
if (i == words - 1) {
constexpr size_t remainingBits = bitmapSize % wordSize;
constexpr WordType mask = (static_cast<WordType>(1) << remainingBits) - 1;
if ((bits[i] & mask) == mask)
return true;
}
}
return false;
}
return true;
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::merge(const Bitmap& other)
{
for (size_t i = 0; i < words; ++i)
bits[i] |= other.bits[i];
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::filter(const Bitmap& other)
{
for (size_t i = 0; i < words; ++i)
bits[i] &= other.bits[i];
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::exclude(const Bitmap& other)
{
for (size_t i = 0; i < words; ++i)
bits[i] &= ~other.bits[i];
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::concurrentFilter(const Bitmap& other)
{
for (size_t i = 0; i < words; ++i) {
for (;;) {
WordType otherBits = other.bits[i];
if (!otherBits) {
bits[i] = 0;
break;
}
WordType oldBits = bits[i];
WordType filteredBits = oldBits & otherBits;
if (oldBits == filteredBits)
break;
if (atomicCompareExchangeWeakRelaxed(&bits[i], oldBits, filteredBits))
break;
}
}
}
template<size_t bitmapSize, typename WordType>
inline bool Bitmap<bitmapSize, WordType>::subsumes(const Bitmap& other) const
{
for (size_t i = 0; i < words; ++i) {
WordType myBits = bits[i];
WordType otherBits = other.bits[i];
if ((myBits | otherBits) != myBits)
return false;
}
return true;
}
template<size_t bitmapSize, typename WordType>
template<typename Func>
inline void Bitmap<bitmapSize, WordType>::forEachSetBit(const Func& func) const
{
for (size_t i = 0; i < words; ++i) {
WordType word = bits[i];
if (!word)
continue;
size_t base = i * wordSize;
for (size_t j = 0; j < wordSize; ++j) {
if (word & 1)
func(base + j);
word >>= 1;
}
}
}
template<size_t bitmapSize, typename WordType>
inline size_t Bitmap<bitmapSize, WordType>::findBit(size_t startIndex, bool value) const
{
WordType skipValue = -(static_cast<WordType>(value) ^ 1);
size_t wordIndex = startIndex / wordSize;
size_t startIndexInWord = startIndex - wordIndex * wordSize;
while (wordIndex < words) {
WordType word = bits[wordIndex];
if (word != skipValue) {
size_t index = startIndexInWord;
if (findBitInWord(word, index, wordSize, value))
return wordIndex * wordSize + index;
}
wordIndex++;
startIndexInWord = 0;
}
return bitmapSize;
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::mergeAndClear(Bitmap& other)
{
for (size_t i = 0; i < words; ++i) {
bits[i] |= other.bits[i];
other.bits[i] = 0;
}
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::setAndClear(Bitmap& other)
{
for (size_t i = 0; i < words; ++i) {
bits[i] = other.bits[i];
other.bits[i] = 0;
}
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::setEachNthBit(size_t n, size_t start, size_t end)
{
ASSERT(start <= end);
ASSERT(end <= bitmapSize);
size_t wordIndex = start / wordSize;
size_t endWordIndex = end / wordSize;
size_t index = start - wordIndex * wordSize;
while (wordIndex < endWordIndex) {
while (index < wordSize) {
bits[wordIndex] |= (one << index);
index += n;
}
index -= wordSize;
wordIndex++;
}
size_t endIndex = end - endWordIndex * wordSize;
while (index < endIndex) {
bits[wordIndex] |= (one << index);
index += n;
}
if constexpr (!!(bitmapSize % wordSize)) {
constexpr size_t remainingBits = bitmapSize % wordSize;
constexpr WordType mask = (static_cast<WordType>(1) << remainingBits) - 1;
bits[words - 1] &= mask;
}
}
template<size_t bitmapSize, typename WordType>
inline bool Bitmap<bitmapSize, WordType>::operator==(const Bitmap& other) const
{
for (size_t i = 0; i < words; ++i) {
if (bits[i] != other.bits[i])
return false;
}
return true;
}
template<size_t bitmapSize, typename WordType>
inline bool Bitmap<bitmapSize, WordType>::operator!=(const Bitmap& other) const
{
return !(*this == other);
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::operator|=(const Bitmap& other)
{
for (size_t i = 0; i < words; ++i)
bits[i] |= other.bits[i];
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::operator&=(const Bitmap& other)
{
for (size_t i = 0; i < words; ++i)
bits[i] &= other.bits[i];
}
template<size_t bitmapSize, typename WordType>
inline void Bitmap<bitmapSize, WordType>::operator^=(const Bitmap& other)
{
for (size_t i = 0; i < words; ++i)
bits[i] ^= other.bits[i];
}
template<size_t bitmapSize, typename WordType>
inline unsigned Bitmap<bitmapSize, WordType>::hash() const
{
unsigned result = 0;
for (size_t i = 0; i < words; ++i)
result ^= IntHash<WordType>::hash(bits[i]);
return result;
}
} // namespace WTF
using WTF::Bitmap;