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/*
* Created by Martin on 30/08/2017.
*
* Distributed under the Boost Software License, Version 1.0. (See accompanying
* file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
*/
#ifndef TWOBLUECUBES_CATCH_RANDOM_NUMBER_GENERATOR_H_INCLUDED
#define TWOBLUECUBES_CATCH_RANDOM_NUMBER_GENERATOR_H_INCLUDED
#include <cstdint>
namespace Catch {
// This is a simple implementation of C++11 Uniform Random Number
// Generator. It does not provide all operators, because Catch2
// does not use it, but it should behave as expected inside stdlib's
// distributions.
// The implementation is based on the PCG family (http://pcg-random.org)
class SimplePcg32 {
using state_type = std::uint64_t;
public:
using result_type = std::uint32_t;
static constexpr result_type (min)() {
return 0;
}
static constexpr result_type (max)() {
return static_cast<result_type>(-1);
}
// Provide some default initial state for the default constructor
SimplePcg32():SimplePcg32(0xed743cc4U) {}
explicit SimplePcg32(result_type seed_);
void seed(result_type seed_);
void discard(uint64_t skip);
result_type operator()();
private:
friend bool operator==(SimplePcg32 const& lhs, SimplePcg32 const& rhs);
friend bool operator!=(SimplePcg32 const& lhs, SimplePcg32 const& rhs);
// In theory we also need operator<< and operator>>
// In practice we do not use them, so we will skip them for now
std::uint64_t m_state;
// This part of the state determines which "stream" of the numbers
// is chosen -- we take it as a constant for Catch2, so we only
// need to deal with seeding the main state.
// Picked by reading 8 bytes from `/dev/random` :-)
static const std::uint64_t s_inc = (0x13ed0cc53f939476ULL << 1ULL) | 1ULL;
};
} // end namespace Catch
#endif // TWOBLUECUBES_CATCH_RANDOM_NUMBER_GENERATOR_H_INCLUDED
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