- }
-
- // The win rate model returns the probability of winning (in per mille units) given an
- // eval and a game ply. It fits the LTC fishtest statistics rather accurately.
- int win_rate_model(Value v, int ply) {
-
- // The model only captures up to 240 plies, so limit the input and then rescale
- double m = std::min(240, ply) / 64.0;
-
- // The coefficients of a third-order polynomial fit is based on the fishtest data
- // for two parameters that need to transform eval to the argument of a logistic
- // function.
- constexpr double as[] = { 0.38036525, -2.82015070, 23.17882135, 307.36768407};
- constexpr double bs[] = { -2.29434733, 13.27689788, -14.26828904, 63.45318330 };
-
- // Enforce that NormalizeToPawnValue corresponds to a 50% win rate at ply 64
- static_assert(UCI::NormalizeToPawnValue == int(as[0] + as[1] + as[2] + as[3]));
-
- double a = (((as[0] * m + as[1]) * m + as[2]) * m) + as[3];
- double b = (((bs[0] * m + bs[1]) * m + bs[2]) * m) + bs[3];
-
- // Transform the eval to centipawns with limited range
- double x = std::clamp(double(v), -4000.0, 4000.0);
-
- // Return the win rate in per mille units rounded to the nearest value
- return int(0.5 + 1000 / (1 + std::exp((a - x) / b)));
- }
-
-} // namespace
-
-
-/// UCI::loop() waits for a command from the stdin, parses it and then calls the appropriate
-/// function. It also intercepts an end-of-file (EOF) indication from the stdin to ensure a
-/// graceful exit if the GUI dies unexpectedly. When called with some command-line arguments,
-/// like running 'bench', the function returns immediately after the command is executed.
-/// In addition to the UCI ones, some additional debug commands are also supported.
-
-void UCI::loop(int argc, char* argv[]) {
-
- Position pos;
- std::string token, cmd;
- StateListPtr states(new std::deque<StateInfo>(1));
-
- pos.set(StartFEN, false, &states->back(), Threads.main());
-
- for (int i = 1; i < argc; ++i)
- cmd += std::string(argv[i]) + " ";
-
- do {
- if (argc == 1 && !getline(std::cin, cmd)) // Wait for an input or an end-of-file (EOF) indication
- cmd = "quit";
-
- std::istringstream is(cmd);
-
- token.clear(); // Avoid a stale if getline() returns nothing or a blank line
- is >> std::skipws >> token;
-
- if ( token == "quit"
- || token == "stop")
- Threads.stop = true;
-
- // The GUI sends 'ponderhit' to tell that the user has played the expected move.
- // So, 'ponderhit' is sent if pondering was done on the same move that the user
- // has played. The search should continue, but should also switch from pondering
- // to the normal search.
- else if (token == "ponderhit")
- Threads.main()->ponder = false; // Switch to the normal search
-
- else if (token == "uci")
- sync_cout << "id name " << engine_info(true)
- << "\n" << Options
- << "\nuciok" << sync_endl;
-
- else if (token == "setoption") setoption(is);
- else if (token == "go") go(pos, is, states);
- else if (token == "position") position(pos, is, states);
- else if (token == "ucinewgame") Search::clear();
- else if (token == "isready") sync_cout << "readyok" << sync_endl;
-
- // Add custom non-UCI commands, mainly for debugging purposes.
- // These commands must not be used during a search!
- else if (token == "flip") pos.flip();
- else if (token == "bench") bench(pos, is, states);
- else if (token == "d") sync_cout << pos << sync_endl;
- else if (token == "eval") trace_eval(pos);
- else if (token == "compiler") sync_cout << compiler_info() << sync_endl;
- else if (token == "export_net")
- {
- std::optional<std::string> filename;
- std::string f;
- if (is >> std::skipws >> f)
- filename = f;
- Eval::NNUE::save_eval(filename);
- }
- else if (token == "--help" || token == "help" || token == "--license" || token == "license")
- sync_cout << "\nStockfish is a powerful chess engine for playing and analyzing."
- "\nIt is released as free software licensed under the GNU GPLv3 License."
- "\nStockfish is normally used with a graphical user interface (GUI) and implements"
- "\nthe Universal Chess Interface (UCI) protocol to communicate with a GUI, an API, etc."
- "\nFor any further information, visit https://github.com/official-stockfish/Stockfish#readme"
- "\nor read the corresponding README.md and Copying.txt files distributed along with this program.\n" << sync_endl;
- else if (!token.empty() && token[0] != '#')
- sync_cout << "Unknown command: '" << cmd << "'. Type help for more information." << sync_endl;
-
- } while (token != "quit" && argc == 1); // The command-line arguments are one-shot