2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
5 Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
7 Stockfish is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 Stockfish is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
35 extern void benchmark(const Position& pos, istream& is);
39 // FEN string of the initial position, normal chess
40 const char* StartFEN = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
42 // Stack to keep track of the position states along the setup moves (from the
43 // start position to the position just before the search starts). Needed by
44 // 'draw by repetition' detection.
45 Search::StateStackPtr SetupStates;
48 // position() is called when engine receives the "position" UCI command.
49 // The function sets up the position described in the given FEN string ("fen")
50 // or the starting position ("startpos") and then makes the moves given in the
51 // following move list ("moves").
53 void position(Position& pos, istringstream& is) {
60 if (token == "startpos")
63 is >> token; // Consume "moves" token if any
65 else if (token == "fen")
66 while (is >> token && token != "moves")
71 pos.set(fen, Options["UCI_Chess960"], Threads.main());
72 SetupStates = Search::StateStackPtr(new std::stack<StateInfo>);
74 // Parse move list (if any)
75 while (is >> token && (m = UCI::to_move(pos, token)) != MOVE_NONE)
77 SetupStates->push(StateInfo());
78 pos.do_move(m, SetupStates->top(), pos.gives_check(m, CheckInfo(pos)));
83 // setoption() is called when engine receives the "setoption" UCI command. The
84 // function updates the UCI option ("name") to the given value ("value").
86 void setoption(istringstream& is) {
88 string token, name, value;
90 is >> token; // Consume "name" token
92 // Read option name (can contain spaces)
93 while (is >> token && token != "value")
94 name += string(" ", name.empty() ? 0 : 1) + token;
96 // Read option value (can contain spaces)
98 value += string(" ", value.empty() ? 0 : 1) + token;
100 if (Options.count(name))
101 Options[name] = value;
103 sync_cout << "No such option: " << name << sync_endl;
107 // go() is called when engine receives the "go" UCI command. The function sets
108 // the thinking time and other parameters from the input string, then starts
111 void go(const Position& pos, istringstream& is) {
113 Search::LimitsType limits;
116 limits.startTime = now(); // As early as possible!
119 if (token == "searchmoves")
121 limits.searchmoves.push_back(UCI::to_move(pos, token));
123 else if (token == "wtime") is >> limits.time[WHITE];
124 else if (token == "btime") is >> limits.time[BLACK];
125 else if (token == "winc") is >> limits.inc[WHITE];
126 else if (token == "binc") is >> limits.inc[BLACK];
127 else if (token == "movestogo") is >> limits.movestogo;
128 else if (token == "depth") is >> limits.depth;
129 else if (token == "nodes") is >> limits.nodes;
130 else if (token == "movetime") is >> limits.movetime;
131 else if (token == "mate") is >> limits.mate;
132 else if (token == "infinite") limits.infinite = 1;
133 else if (token == "ponder") limits.ponder = 1;
135 Threads.start_thinking(pos, limits, SetupStates);
141 /// UCI::loop() waits for a command from stdin, parses it and calls the appropriate
142 /// function. Also intercepts EOF from stdin to ensure gracefully exiting if the
143 /// GUI dies unexpectedly. When called with some command line arguments, e.g. to
144 /// run 'bench', once the command is executed the function returns immediately.
145 /// In addition to the UCI ones, also some additional debug commands are supported.
147 void UCI::loop(int argc, char* argv[]) {
149 Position pos(StartFEN, false, Threads.main()); // The root position
152 for (int i = 1; i < argc; ++i)
153 cmd += std::string(argv[i]) + " ";
156 if (argc == 1 && !getline(cin, cmd)) // Block here waiting for input or EOF
159 istringstream is(cmd);
161 token.clear(); // getline() could return empty or blank line
162 is >> skipws >> token;
164 // The GUI sends 'ponderhit' to tell us to ponder on the same move the
165 // opponent has played. In case Signals.stopOnPonderhit is set we are
166 // waiting for 'ponderhit' to stop the search (for instance because we
167 // already ran out of time), otherwise we should continue searching but
168 // switching from pondering to normal search.
171 || (token == "ponderhit" && Search::Signals.stopOnPonderhit))
173 Search::Signals.stop = true;
174 Threads.main()->start_searching(true); // Could be sleeping
176 else if (token == "ponderhit")
177 Search::Limits.ponder = 0; // Switch to normal search
179 else if (token == "uci")
180 sync_cout << "id name " << engine_info(true)
182 << "\nuciok" << sync_endl;
184 else if (token == "ucinewgame")
187 Time.availableNodes = 0;
189 else if (token == "isready") sync_cout << "readyok" << sync_endl;
190 else if (token == "go") go(pos, is);
191 else if (token == "position") position(pos, is);
192 else if (token == "setoption") setoption(is);
194 // Additional custom non-UCI commands, useful for debugging
195 else if (token == "flip") pos.flip();
196 else if (token == "bench") benchmark(pos, is);
197 else if (token == "d") sync_cout << pos << sync_endl;
198 else if (token == "eval") sync_cout << Eval::trace(pos) << sync_endl;
199 else if (token == "perft")
205 ss << Options["Hash"] << " "
206 << Options["Threads"] << " " << depth << " current perft";
211 sync_cout << "Unknown command: " << cmd << sync_endl;
213 } while (token != "quit" && argc == 1); // Passed args have one-shot behaviour
215 Threads.main()->wait_for_search_finished();
219 /// UCI::value() converts a Value to a string suitable for use with the UCI
220 /// protocol specification:
222 /// cp <x> The score from the engine's point of view in centipawns.
223 /// mate <y> Mate in y moves, not plies. If the engine is getting mated
224 /// use negative values for y.
226 string UCI::value(Value v) {
230 if (abs(v) < VALUE_MATE - MAX_PLY)
231 ss << "cp " << v * 100 / PawnValueEg;
233 ss << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
239 /// UCI::square() converts a Square to a string in algebraic notation (g1, a7, etc.)
241 std::string UCI::square(Square s) {
242 return std::string{ char('a' + file_of(s)), char('1' + rank_of(s)) };
246 /// UCI::move() converts a Move to a string in coordinate notation (g1f3, a7a8q).
247 /// The only special case is castling, where we print in the e1g1 notation in
248 /// normal chess mode, and in e1h1 notation in chess960 mode. Internally all
249 /// castling moves are always encoded as 'king captures rook'.
251 string UCI::move(Move m, bool chess960) {
253 Square from = from_sq(m);
254 Square to = to_sq(m);
262 if (type_of(m) == CASTLING && !chess960)
263 to = make_square(to > from ? FILE_G : FILE_C, rank_of(from));
265 string move = UCI::square(from) + UCI::square(to);
267 if (type_of(m) == PROMOTION)
268 move += " pnbrqk"[promotion_type(m)];
274 /// UCI::to_move() converts a string representing a move in coordinate notation
275 /// (g1f3, a7a8q) to the corresponding legal Move, if any.
277 Move UCI::to_move(const Position& pos, string& str) {
279 if (str.length() == 5) // Junior could send promotion piece in uppercase
280 str[4] = char(tolower(str[4]));
282 for (const auto& m : MoveList<LEGAL>(pos))
283 if (str == UCI::move(m, pos.is_chess960()))