power_of_two.hh

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#ifndef POWER_OF_TWO_HH
#define POWER_OF_TWO_HH
 
#include "narrow.hh"
#include <bit>
#include <cassert>
#include <concepts>
#include <cstdint>
 
namespace openmsx {
 
template<std::unsigned_integral T>
struct power_of_two {
        constexpr power_of_two(T size)
                : exponent(narrow_cast<uint8_t>(std::bit_width(size - 1)))
        {
                assert(std::has_single_bit(size));
        };
 
        [[nodiscard]] constexpr operator T() const
        {
                return T{1} << exponent;
        }
 
        uint8_t exponent = 0;
};
 
} // namespace openmsx
 
#endif