45c2a5aa0e
previously it would write the wrong random state after advancing to a new scenario, so that the first reload after advancing to a new scenario would change the deteministic rng.
108 lines
2.9 KiB
C++
108 lines
2.9 KiB
C++
/*
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Copyright (C) 2014 - 2018 by Chris Beck <render787@gmail.com>
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Part of the Battle for Wesnoth Project https://www.wesnoth.org/
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY.
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See the COPYING file for more details.
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*/
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#include "mt_rng.hpp"
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#include "seed_rng.hpp"
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#include "config.hpp"
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#include "log.hpp"
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#include <sstream>
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#include <iomanip>
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static lg::log_domain log_random("random");
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#define DBG_RND LOG_STREAM(debug, log_random)
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#define LOG_RND LOG_STREAM(info, log_random)
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#define WRN_RND LOG_STREAM(warn, log_random)
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#define ERR_RND LOG_STREAM(err, log_random)
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namespace randomness
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{
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mt_rng::mt_rng() :
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random_seed_(seed_rng::next_seed()),
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mt_(random_seed_),
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random_calls_(0)
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{
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}
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mt_rng::mt_rng(uint32_t seed)
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: random_seed_(seed)
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, mt_(random_seed_)
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, random_calls_(0)
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{
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}
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mt_rng::mt_rng(const config& cfg) :
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random_seed_(42),
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mt_(random_seed_), //we don't have the seed at construction time, we have to seed after construction in this case. Constructing an mt19937 is somewhat expensive, apparently has about 2kb of private memory.
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random_calls_(0)
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{
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config::attribute_value seed = cfg["random_seed"];
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seed_random(seed.str(), cfg["random_calls"].to_int(0));
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}
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bool mt_rng::operator== (const mt_rng & other) const {
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return random_seed_ == other.random_seed_
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&& random_calls_ == other.random_calls_
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&& mt_ == other.mt_;
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}
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uint32_t mt_rng::get_next_random()
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{
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uint32_t result = mt_();
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++random_calls_;
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DBG_RND << "pulled user random " << result
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<< " for call " << random_calls_
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<< " with seed " << std::hex << random_seed_ << std::endl;
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return result;
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}
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void mt_rng::rotate_random()
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{
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seed_random(mt_(),0);
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}
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void mt_rng::seed_random(const uint32_t seed, const unsigned int call_count)
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{
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random_seed_ = seed;
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mt_.seed(random_seed_);
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mt_.discard(call_count);
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random_calls_ = call_count;
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DBG_RND << "Seeded random with " << std::hex << random_seed_ << std::dec << " with "
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<< random_calls_ << " calls." << std::endl;
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}
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void mt_rng::seed_random(const std::string & seed_str, const unsigned int call_count)
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{
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uint32_t new_seed;
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std::istringstream s(seed_str);
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if (!(s >> std::hex >> new_seed)) {
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new_seed = 42;
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DBG_RND << "Failed to seed a random number generator using seed string '" << seed_str << "', it could not be parsed to hex. Seeding with 42.\n";
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}
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seed_random(new_seed, call_count);
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}
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std::string mt_rng::get_random_seed_str() const {
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std::stringstream stream;
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stream << std::setfill('0');
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stream << std::setw(sizeof(uint32_t)*2);
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stream << std::hex;
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stream << random_seed_;
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return stream.str();
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}
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} // ends randomness namespace
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