ReverseBits.hpp

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namespace duds { namespace general {

template <typename Integer>
constexpr inline bool IsPowerOf2(Integer i) {
    return i && !(i & (i - 1));
}

template <typename Integer>
inline Integer ReverseBits(Integer i) {
    static_assert(
        IsPowerOf2(sizeof(Integer)),
        "Size must be a power of 2 for this algorithm."
    );
    std::size_t s = sizeof(Integer) * 8;
    Integer m = -1;
    while (s >>= 1) {
            m ^= (m << s);
            i = ((i >> s) & m) | ((i << s) & ~m);
    }
    return i;
}

constexpr inline std::uint8_t ReverseBits(const std::uint8_t i) {
    return (i * 0x0202020202ULL & 0x010884422010ULL) % 1023;
}

} }