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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)
*/
#include "catch_random_number_generator.h"
#include "catch_context.h"
#include "catch_run_context.h"
#include "catch_interfaces_config.h"
namespace Catch {
namespace {
#if defined(_MSC_VER)
#pragma warning(push)
#pragma warning(disable:4146) // we negate uint32 during the rotate
#endif
// Safe rotr implementation thanks to John Regehr
uint32_t rotate_right(uint32_t val, uint32_t count) {
const uint32_t mask = 31;
count &= mask;
return (val >> count) | (val << (-count & mask));
}
#if defined(_MSC_VER)
#pragma warning(pop)
#endif
}
SimplePcg32::SimplePcg32(result_type seed_) {
seed(seed_);
}
void SimplePcg32::seed(result_type seed_) {
m_state = 0;
(*this)();
m_state += seed_;
(*this)();
}
void SimplePcg32::discard(uint64_t skip) {
// We could implement this to run in O(log n) steps, but this
// should suffice for our use case.
for (uint64_t s = 0; s < skip; ++s) {
static_cast<void>((*this)());
}
}
SimplePcg32::result_type SimplePcg32::operator()() {
// prepare the output value
const uint32_t xorshifted = static_cast<uint32_t>(((m_state >> 18u) ^ m_state) >> 27u);
const auto output = rotate_right(xorshifted, m_state >> 59u);
// advance state
m_state = m_state * 6364136223846793005ULL + s_inc;
return output;
}
bool operator==(SimplePcg32 const& lhs, SimplePcg32 const& rhs) {
return lhs.m_state == rhs.m_state;
}
bool operator!=(SimplePcg32 const& lhs, SimplePcg32 const& rhs) {
return lhs.m_state != rhs.m_state;
}
}
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