lfm16.cc

#include <cstdint>
template<uint16_t d> struct lfm16 { //lemire fast math for 16-bit space https://github.com/lemire/fastmod
    enum : uint32_t { M = uint32_t(-1) / d + 1 };
    static constexpr uint16_t mod(uint16_t a) { return uint16_t((uint64_t(d) * uint32_t(M * a)) >> 32); }
    static constexpr uint16_t div(uint16_t a) { return uint16_t((uint64_t(M) * a) >> 32); }
    static constexpr bool mod0(uint16_t a) { return a * M <= M - 1; }
};

#include <iostream>
#include <string>
#include <vector>
int main()
{
    std::cout
        << lfm16<32>::div(64) << std::endl
        << lfm16<32>::mod(64) << std::endl
        << lfm16<32>::mod(67) << std::endl
        << lfm16<32>::mod0(64) << std::endl
        << lfm16<32>::mod0(16) << std::endl
        << lfm16<32>::mod0(64*15) << std::endl
    ;
}