Bitset.h

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#ifndef INCLUDE_MOLASSEMBLER_TEMPLE_BITSET_H
#define INCLUDE_MOLASSEMBLER_TEMPLE_BITSET_H

#include "Molassembler/Temple/constexpr/Math.h"
#include "Molassembler/Temple/constexpr/Array.h"

namespace Scine {
namespace Molassembler {
namespace Temple {

template<std::size_t N>
class Bitset {
public:

  explicit constexpr Bitset() { zero(); }


  constexpr void zero() {
    for(auto& block : storage) {
      block = 0;
    }
  }

  constexpr void set(const std::size_t i) {
    std::size_t blockIndex = Math::floor(static_cast<double>(i) / bitsPerBlock);
    std::size_t bitIndex = i - bitsPerBlock * blockIndex;

    storage.at(blockIndex) |= (1ULL << bitIndex);
  }

  constexpr void unset(const std::size_t i) {
    std::size_t blockIndex = Math::floor(static_cast<double>(i) / bitsPerBlock);
    std::size_t bitIndex = i - bitsPerBlock * blockIndex;

    storage.at(blockIndex) ^= (1ULL << bitIndex);
  }

  constexpr void set(const std::size_t i, const bool value) {
    if(value) {
      set(i);
    } else {
      unset(i);
    }
  }


  constexpr bool test(const std::size_t i) const {
    std::size_t blockIndex = Math::floor(static_cast<double>(i) / bitsPerBlock);
    std::size_t bitIndex = i - bitsPerBlock * blockIndex;

    return (
      storage.at(blockIndex) & (1ULL << bitIndex)
    ) != 0;
  }

private:
  using Block = long long unsigned;

  static constexpr std::size_t bitsPerBlock = Math::floor(
    Math::log(
      static_cast<double>(std::numeric_limits<Block>::max()),
      2.0
    )
  );

  static constexpr std::size_t B = Math::ceil(
    static_cast<double>(N) / static_cast<double>(bitsPerBlock)
  );

  Array<Block, B> storage;

};

} // namespace Temple
} // namespace Molassembler
} // namespace Scine

#endif