123 lines
3.4 KiB
C++
123 lines
3.4 KiB
C++
///////////////////////////////////////////////////////////////
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// Copyright 2018 John Maddock. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_
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#include <boost/multiprecision/cpp_int.hpp>
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#include <iostream>
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struct kiss_rand
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{
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typedef std::uint64_t result_type;
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constexpr kiss_rand() : x(0x8207ebe160468b32uLL), y(0x2871283e01d45bbduLL), z(0x9c80bfd5db9680c9uLL), c(0x2e2683c2abb878b8uLL) {}
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constexpr kiss_rand(std::uint64_t seed) : x(seed), y(0x2871283e01d45bbduLL), z(0x9c80bfd5db9680c9uLL), c(0x2e2683c2abb878b8uLL) {}
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constexpr kiss_rand(std::uint64_t seed_x, std::uint64_t seed_y) : x(seed_x), y(seed_y), z(0x9c80bfd5db9680c9uLL), c(0x2e2683c2abb878b8uLL) {}
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constexpr kiss_rand(std::uint64_t seed_x, std::uint64_t seed_y, std::uint64_t seed_z) : x(seed_x), y(seed_y), z(seed_z), c(0x2e2683c2abb878b8uLL) {}
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constexpr std::uint64_t operator()()
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{
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return MWC() + XSH() + CNG();
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}
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private:
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constexpr std::uint64_t MWC()
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{
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std::uint64_t t = (x << 58) + c;
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c = (x >> 6);
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x += t;
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c += (x < t);
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return x;
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}
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constexpr std::uint64_t XSH()
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{
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y ^= (y << 13);
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y ^= (y >> 17);
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return y ^= (y << 43);
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}
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constexpr std::uint64_t CNG()
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{
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return z = 6906969069LL * z + 1234567;
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}
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std::uint64_t x, y, z, c;
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};
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inline constexpr void hash_combine(std::uint64_t& h, std::uint64_t k)
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{
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constexpr const std::uint64_t m = 0xc6a4a7935bd1e995uLL;
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constexpr const int r = 47;
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k *= m;
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k ^= k >> r;
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k *= m;
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h ^= k;
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h *= m;
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// Completely arbitrary number, to prevent 0's
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// from hashing to 0.
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h += 0xe6546b64;
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}
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template <std::size_t N>
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inline constexpr std::uint64_t string_to_hash(const char (&s)[N])
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{
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std::uint64_t hash(0);
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for (unsigned i = 0; i < N; ++i)
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hash_combine(hash, s[i]);
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return hash;
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}
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template <class UnsignedInteger>
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struct multiprecision_generator
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{
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typedef UnsignedInteger result_type;
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constexpr multiprecision_generator(std::uint64_t seed1) : m_gen64(seed1) {}
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constexpr multiprecision_generator(std::uint64_t seed1, std::uint64_t seed2) : m_gen64(seed1, seed2) {}
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constexpr multiprecision_generator(std::uint64_t seed1, std::uint64_t seed2, std::uint64_t seed3) : m_gen64(seed1, seed2, seed3) {}
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static constexpr result_type (min)()
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{
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return 0u;
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}
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static constexpr result_type (max)()
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{
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return ~result_type(0u);
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}
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constexpr result_type operator()()
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{
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result_type result(m_gen64());
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unsigned digits = 64;
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while (digits < std::numeric_limits<result_type>::digits)
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{
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result <<= 64;
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result |= m_gen64();
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digits += 64;
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}
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return result;
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}
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private:
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kiss_rand m_gen64;
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};
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template <class UnsignedInteger>
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constexpr UnsignedInteger nth_random_value(unsigned count = 0)
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{
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std::uint64_t date_hash = string_to_hash(__DATE__);
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std::uint64_t time_hash = string_to_hash(__TIME__);
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multiprecision_generator<UnsignedInteger> big_gen(date_hash, time_hash);
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for (unsigned i = 0; i < count; ++i)
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big_gen();
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return big_gen();
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}
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int main()
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{
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using namespace boost::multiprecision;
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constexpr uint1024_t rand = nth_random_value<uint1024_t>(1000);
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std::cout << std::hex << rand << std::endl;
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return 0;
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}
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