99 lines
2.9 KiB
C++
99 lines
2.9 KiB
C++
#ifndef OSRM_UTIL_BIT_RANGE_HPP
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#define OSRM_UTIL_BIT_RANGE_HPP
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#include "util/msb.hpp"
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#include <boost/iterator/iterator_facade.hpp>
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#include <boost/range/iterator_range.hpp>
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namespace osrm
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{
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namespace util
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{
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namespace detail
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{
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template <typename T> std::size_t countOnes(T value)
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{
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static_assert(std::is_unsigned<T>::value, "Only unsigned types allowed");
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std::size_t number_of_ones = 0;
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while (value > 0)
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{
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auto index = msb(value);
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value = value & ~(T{1} << index);
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number_of_ones++;
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}
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return number_of_ones;
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}
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#if (defined(__clang__) || defined(__GNUC__) || defined(__GNUG__))
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inline std::size_t countOnes(std::uint8_t value)
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{
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return __builtin_popcount(std::uint32_t{value});
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}
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inline std::size_t countOnes(std::uint16_t value)
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{
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return __builtin_popcount(std::uint32_t{value});
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}
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inline std::size_t countOnes(unsigned int value) { return __builtin_popcount(value); }
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inline std::size_t countOnes(unsigned long value) { return __builtin_popcountl(value); }
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inline std::size_t countOnes(unsigned long long value) { return __builtin_popcountll(value); }
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#endif
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} // namespace detail
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// Investigate if we can replace this with
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// http://www.boost.org/doc/libs/1_64_0/libs/dynamic_bitset/dynamic_bitset.html
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template <typename DataT>
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class BitIterator : public boost::iterator_facade<BitIterator<DataT>,
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const std::size_t,
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boost::forward_traversal_tag,
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const std::size_t>
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{
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using base_t = boost::iterator_facade<BitIterator<DataT>,
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const std::size_t,
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boost::forward_traversal_tag,
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const std::size_t>;
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public:
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using value_type = typename base_t::value_type;
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using difference_type = typename base_t::difference_type;
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using reference = typename base_t::reference;
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using iterator_category = std::random_access_iterator_tag;
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explicit BitIterator() : m_value(0) {}
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explicit BitIterator(const DataT x) : m_value(std::move(x)) {}
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private:
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void increment()
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{
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auto index = msb(m_value);
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m_value = m_value & ~(DataT{1} << index);
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}
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difference_type distance_to(const BitIterator &other) const
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{
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return detail::countOnes(m_value) - detail::countOnes(other.m_value);
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}
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bool equal(const BitIterator &other) const { return m_value == other.m_value; }
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reference dereference() const
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{
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BOOST_ASSERT(m_value > 0);
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return msb(m_value);
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}
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friend class ::boost::iterator_core_access;
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DataT m_value;
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};
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// Returns range over all 1 bits of value
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template <typename T> auto makeBitRange(const T value)
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{
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return boost::make_iterator_range(BitIterator<T>{value}, BitIterator<T>{});
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}
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} // namespace util
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} // namespace osrm
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#endif
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