atomic_bitset.h
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/****************************************************************************
*
* Copyright (c) 2020 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
#pragma once
#include "atomic.h"
namespace px4
{
template <size_t N>
class AtomicBitset
{
public:
AtomicBitset() = default;
size_t count() const
{
size_t total = 0;
for (const auto &x : _data) {
uint32_t y = x.load();
while (y) {
total += y & 1;
y >>= 1;
}
}
return total;
}
size_t size() const { return N; }
bool operator[](size_t position) const
{
return _data[array_index(position)].load() & element_mask(position);
}
void set(size_t pos, bool val = true)
{
const uint32_t bitmask = element_mask(pos);
if (val) {
_data[array_index(pos)].fetch_or(bitmask);
} else {
_data[array_index(pos)].fetch_and(~bitmask);
}
}
private:
static constexpr uint8_t BITS_PER_ELEMENT = 32;
static constexpr size_t ARRAY_SIZE = ((N % BITS_PER_ELEMENT) == 0) ? (N / BITS_PER_ELEMENT) :
(N / BITS_PER_ELEMENT + 1);
static constexpr size_t ALLOCATED_BITS = ARRAY_SIZE * BITS_PER_ELEMENT;
size_t array_index(size_t position) const { return position / BITS_PER_ELEMENT; }
uint32_t element_mask(size_t position) const { return (1 << (position % BITS_PER_ELEMENT)); }
px4::atomic<uint32_t> _data[ARRAY_SIZE];
};
} // namespace px4