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
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
34 extern void benchmark(const Position& pos, istream& is);
38 // FEN string of the initial position, normal chess
39 const char* StartFEN = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
41 // Stack to keep track of the position states along the setup moves (from the
42 // start position to the position just before the search starts). Needed by
43 // 'draw by repetition' detection.
44 Search::StateStackPtr SetupStates;
47 // position() is called when engine receives the "position" UCI command.
48 // The function sets up the position described in the given FEN string ("fen")
49 // or the starting position ("startpos") and then makes the moves given in the
50 // following move list ("moves").
52 void position(Position& pos, istringstream& is) {
59 if (token == "startpos")
62 is >> token; // Consume "moves" token if any
64 else if (token == "fen")
65 while (is >> token && token != "moves")
70 pos.set(fen, Options["UCI_Chess960"], Threads.main());
71 SetupStates = Search::StateStackPtr(new std::stack<StateInfo>());
73 // Parse move list (if any)
74 while (is >> token && (m = UCI::to_move(pos, token)) != MOVE_NONE)
76 SetupStates->push(StateInfo());
77 pos.do_move(m, SetupStates->top());
82 // setoption() is called when engine receives the "setoption" UCI command. The
83 // function updates the UCI option ("name") to the given value ("value").
85 void setoption(istringstream& is) {
87 string token, name, value;
89 is >> token; // Consume "name" token
91 // Read option name (can contain spaces)
92 while (is >> token && token != "value")
93 name += string(" ", !name.empty()) + token;
95 // Read option value (can contain spaces)
97 value += string(" ", !value.empty()) + token;
99 if (Options.count(name))
100 Options[name] = value;
102 sync_cout << "No such option: " << name << sync_endl;
106 // go() is called when engine receives the "go" UCI command. The function sets
107 // the thinking time and other parameters from the input string, then starts
110 void go(const Position& pos, istringstream& is) {
112 Search::LimitsType limits;
116 if (token == "searchmoves")
118 limits.searchmoves.push_back(UCI::to_move(pos, token));
120 else if (token == "wtime") is >> limits.time[WHITE];
121 else if (token == "btime") is >> limits.time[BLACK];
122 else if (token == "winc") is >> limits.inc[WHITE];
123 else if (token == "binc") is >> limits.inc[BLACK];
124 else if (token == "movestogo") is >> limits.movestogo;
125 else if (token == "depth") is >> limits.depth;
126 else if (token == "nodes") is >> limits.nodes;
127 else if (token == "movetime") is >> limits.movetime;
128 else if (token == "mate") is >> limits.mate;
129 else if (token == "infinite") limits.infinite = true;
130 else if (token == "ponder") limits.ponder = true;
132 Threads.start_thinking(pos, limits, SetupStates);
138 /// UCI::loop() waits for a command from stdin, parses it and calls the appropriate
139 /// function. Also intercepts EOF from stdin to ensure gracefully exiting if the
140 /// GUI dies unexpectedly. When called with some command line arguments, e.g. to
141 /// run 'bench', once the command is executed the function returns immediately.
142 /// In addition to the UCI ones, also some additional debug commands are supported.
144 void UCI::loop(int argc, char* argv[]) {
146 Position pos(StartFEN, false, Threads.main()); // The root position
149 for (int i = 1; i < argc; ++i)
150 cmd += std::string(argv[i]) + " ";
153 if (argc == 1 && !getline(cin, cmd)) // Block here waiting for input or EOF
156 istringstream is(cmd);
158 token.clear(); // getline() could return empty or blank line
159 is >> skipws >> token;
161 // The GUI sends 'ponderhit' to tell us to ponder on the same move the
162 // opponent has played. In case Signals.stopOnPonderhit is set we are
163 // waiting for 'ponderhit' to stop the search (for instance because we
164 // already ran out of time), otherwise we should continue searching but
165 // switching from pondering to normal search.
168 || (token == "ponderhit" && Search::Signals.stopOnPonderhit))
170 Search::Signals.stop = true;
171 Threads.main()->notify_one(); // Could be sleeping
173 else if (token == "ponderhit")
174 Search::Limits.ponder = false; // Switch to normal search
176 else if (token == "uci")
177 sync_cout << "id name " << engine_info(true)
179 << "\nuciok" << sync_endl;
181 else if (token == "isready") sync_cout << "readyok" << sync_endl;
182 else if (token == "ucinewgame") TT.clear();
183 else if (token == "go") go(pos, is);
184 else if (token == "position") position(pos, is);
185 else if (token == "setoption") setoption(is);
187 // Additional custom non-UCI commands, useful for debugging
188 else if (token == "flip") pos.flip();
189 else if (token == "bench") benchmark(pos, is);
190 else if (token == "d") sync_cout << pos << sync_endl;
191 else if (token == "eval") sync_cout << Eval::trace(pos) << sync_endl;
192 else if (token == "perft")
198 ss << Options["Hash"] << " "
199 << Options["Threads"] << " " << depth << " current perft";
204 sync_cout << "Unknown command: " << cmd << sync_endl;
206 } while (token != "quit" && argc == 1); // Passed args have one-shot behaviour
208 Threads.wait_for_think_finished(); // Cannot quit whilst the search is running
212 /// UCI::value() converts a Value to a string suitable for use with the UCI
213 /// protocol specification:
215 /// cp <x> The score from the engine's point of view in centipawns.
216 /// mate <y> Mate in y moves, not plies. If the engine is getting mated
217 /// use negative values for y.
219 string UCI::value(Value v) {
223 if (abs(v) < VALUE_MATE - MAX_PLY)
224 ss << "cp " << v * 100 / PawnValueEg;
226 ss << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
232 /// UCI::square() converts a Square to a string in algebraic notation (g1, a7, etc.)
234 std::string UCI::square(Square s) {
235 return std::string{ char('a' + file_of(s)), char('1' + rank_of(s)) };
239 /// UCI::move() converts a Move to a string in coordinate notation (g1f3, a7a8q).
240 /// The only special case is castling, where we print in the e1g1 notation in
241 /// normal chess mode, and in e1h1 notation in chess960 mode. Internally all
242 /// castling moves are always encoded as 'king captures rook'.
244 string UCI::move(Move m, bool chess960) {
246 Square from = from_sq(m);
247 Square to = to_sq(m);
255 if (type_of(m) == CASTLING && !chess960)
256 to = make_square(to > from ? FILE_G : FILE_C, rank_of(from));
258 string move = UCI::square(from) + UCI::square(to);
260 if (type_of(m) == PROMOTION)
261 move += " pnbrqk"[promotion_type(m)];
267 /// UCI::to_move() converts a string representing a move in coordinate notation
268 /// (g1f3, a7a8q) to the corresponding legal Move, if any.
270 Move UCI::to_move(const Position& pos, string& str) {
272 if (str.length() == 5) // Junior could send promotion piece in uppercase
273 str[4] = char(tolower(str[4]));
275 for (const auto& m : MoveList<LEGAL>(pos))
276 if (str == UCI::move(m, pos.is_chess960()))