rotl.h

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#pragma once
 
#include "di/math/numeric_limits.h"
#include "di/meta/language.h"
 
namespace di::bit {
namespace detail {
    struct RotlFunction {
        template<concepts::UnsignedInteger T>
        constexpr auto operator()(T x, int s) const -> T {
            constexpr auto N = math::NumericLimits<T>::digits;
            int r = s % N;
            if (r == 0) {
                return x;
            }
            if (r > 0) {
                return (x << r) | (x >> (N - r));
            }
            return (x >> -r) | (x << (N + r));
        }
    };
}
 
constexpr inline auto rotl = detail::RotlFunction {};
}
 
namespace di {
using bit::rotl;
}