/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#include <iomanip>
+#include <cassert>
+#include <cmath>
#include <iostream>
#include <sstream>
#include <string>
#include "position.h"
#include "search.h"
#include "thread.h"
+#include "timeman.h"
#include "tt.h"
#include "uci.h"
+#include "syzygy/tbprobe.h"
using namespace std;
-extern void benchmark(const Position& pos, istream& is);
+namespace Stockfish {
+
+vector<string> setup_bench(const Position&, istream&);
namespace {
- // FEN string of the initial position, normal chess
+ // FEN string for the initial position in standard chess
const char* StartFEN = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
- // Keep a track of the position keys along the setup moves (from the start position
- // to the position just before the search starts). This is needed by the repetition
- // draw detection code.
- Search::StateStackPtr SetupStates;
-
- // position() is called when engine receives the "position" UCI command.
- // The function sets up the position described in the given FEN string ("fen")
- // or the starting position ("startpos") and then makes the moves given in the
- // following move list ("moves").
+ // position() is called when the engine receives the "position" UCI command.
+ // It sets up the position that is described in the given FEN string ("fen") or
+ // the initial position ("startpos") and then makes the moves given in the following
+ // move list ("moves").
- void position(Position& pos, istringstream& is) {
+ void position(Position& pos, istringstream& is, StateListPtr& states) {
Move m;
string token, fen;
if (token == "startpos")
{
fen = StartFEN;
- is >> token; // Consume "moves" token if any
+ is >> token; // Consume the "moves" token, if any
}
else if (token == "fen")
while (is >> token && token != "moves")
else
return;
- pos.set(fen, Options["UCI_Chess960"], Threads.main());
- SetupStates = Search::StateStackPtr(new std::stack<StateInfo>());
+ states = StateListPtr(new std::deque<StateInfo>(1)); // Drop the old state and create a new one
+ pos.set(fen, Options["UCI_Chess960"], &states->back(), Threads.main());
- // Parse move list (if any)
+ // Parse the move list, if any
while (is >> token && (m = UCI::to_move(pos, token)) != MOVE_NONE)
{
- SetupStates->push(StateInfo());
- pos.do_move(m, SetupStates->top());
+ states->emplace_back();
+ pos.do_move(m, states->back());
}
}
+ // trace_eval() prints the evaluation of the current position, consistent with
+ // the UCI options set so far.
+
+ void trace_eval(Position& pos) {
+
+ StateListPtr states(new std::deque<StateInfo>(1));
+ Position p;
+ p.set(pos.fen(), Options["UCI_Chess960"], &states->back(), Threads.main());
+
+ Eval::NNUE::verify();
+
+ sync_cout << "\n" << Eval::trace(p) << sync_endl;
+ }
- // setoption() is called when engine receives the "setoption" UCI command. The
- // function updates the UCI option ("name") to the given value ("value").
+
+ // setoption() is called when the engine receives the "setoption" UCI command.
+ // The function updates the UCI option ("name") to the given value ("value").
void setoption(istringstream& is) {
string token, name, value;
- is >> token; // Consume "name" token
+ is >> token; // Consume the "name" token
- // Read option name (can contain spaces)
+ // Read the option name (can contain spaces)
while (is >> token && token != "value")
- name += string(" ", !name.empty()) + token;
+ name += (name.empty() ? "" : " ") + token;
- // Read option value (can contain spaces)
+ // Read the option value (can contain spaces)
while (is >> token)
- value += string(" ", !value.empty()) + token;
+ value += (value.empty() ? "" : " ") + token;
if (Options.count(name))
Options[name] = value;
}
- // go() is called when engine receives the "go" UCI command. The function sets
- // the thinking time and other parameters from the input string, and starts
- // the search.
+ // go() is called when the engine receives the "go" UCI command. The function
+ // sets the thinking time and other parameters from the input string, then starts
+ // with a search.
- void go(const Position& pos, istringstream& is) {
+ void go(Position& pos, istringstream& is, StateListPtr& states) {
Search::LimitsType limits;
string token;
+ bool ponderMode = false;
+
+ limits.startTime = now(); // The search starts as early as possible
while (is >> token)
- {
- if (token == "searchmoves")
+ if (token == "searchmoves") // Needs to be the last command on the line
while (is >> token)
limits.searchmoves.push_back(UCI::to_move(pos, token));
else if (token == "nodes") is >> limits.nodes;
else if (token == "movetime") is >> limits.movetime;
else if (token == "mate") is >> limits.mate;
- else if (token == "infinite") limits.infinite = true;
- else if (token == "ponder") limits.ponder = true;
+ else if (token == "perft") is >> limits.perft;
+ else if (token == "infinite") limits.infinite = 1;
+ else if (token == "ponder") ponderMode = true;
+
+ Threads.start_thinking(pos, states, limits, ponderMode);
+ }
+
+
+ // bench() is called when the engine receives the "bench" command.
+ // Firstly, a list of UCI commands is set up according to the bench
+ // parameters, then it is run one by one, printing a summary at the end.
+
+ void bench(Position& pos, istream& args, StateListPtr& states) {
+
+ string token;
+ uint64_t num, nodes = 0, cnt = 1;
+
+ vector<string> list = setup_bench(pos, args);
+ num = count_if(list.begin(), list.end(), [](string s) { return s.find("go ") == 0 || s.find("eval") == 0; });
+
+ TimePoint elapsed = now();
+
+ for (const auto& cmd : list)
+ {
+ istringstream is(cmd);
+ is >> skipws >> token;
+
+ if (token == "go" || token == "eval")
+ {
+ cerr << "\nPosition: " << cnt++ << '/' << num << " (" << pos.fen() << ")" << endl;
+ if (token == "go")
+ {
+ go(pos, is, states);
+ Threads.main()->wait_for_search_finished();
+ nodes += Threads.nodes_searched();
+ }
+ else
+ trace_eval(pos);
+ }
+ else if (token == "setoption") setoption(is);
+ else if (token == "position") position(pos, is, states);
+ else if (token == "ucinewgame") { Search::clear(); elapsed = now(); } // Search::clear() may take a while
}
- Threads.start_thinking(pos, limits, SetupStates);
+ elapsed = now() - elapsed + 1; // Ensure positivity to avoid a 'divide by zero'
+
+ dbg_print();
+
+ cerr << "\n==========================="
+ << "\nTotal time (ms) : " << elapsed
+ << "\nNodes searched : " << nodes
+ << "\nNodes/second : " << 1000 * nodes / elapsed << endl;
+ }
+
+ // 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[] = { -0.58270499, 2.68512549, 15.24638015, 344.49745382};
+ constexpr double bs[] = { -2.65734562, 15.96509799, -20.69040836, 73.61029937 };
+
+ // 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
-/// Wait for a command from the user, parse this text string as an UCI command,
-/// and call the appropriate functions. Also intercepts EOF from stdin to ensure
-/// that we exit gracefully if the GUI dies unexpectedly. In addition to the UCI
-/// commands, the function also supports a few debug commands.
+/// 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(StartFEN, false, Threads.main()); // The root position
+ Position pos;
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(cin, cmd)) // Block here waiting for input
+ if (argc == 1 && !getline(cin, cmd)) // Wait for an input or an end-of-file (EOF) indication
cmd = "quit";
istringstream is(cmd);
+ token.clear(); // Avoid a stale if getline() returns nothing or a blank line
is >> skipws >> token;
- if (token == "quit" || token == "stop" || token == "ponderhit")
- {
- // The GUI sends 'ponderhit' to tell us to ponder on the same move the
- // opponent has played. In case Signals.stopOnPonderhit is set we are
- // waiting for 'ponderhit' to stop the search (for instance because we
- // already ran out of time), otherwise we should continue searching but
- // switch from pondering to normal search.
- if (token != "ponderhit" || Search::Signals.stopOnPonderhit)
- {
- Search::Signals.stop = true;
- Threads.main()->notify_one(); // Could be sleeping
- }
- else
- Search::Limits.ponder = false;
- }
- else if (token == "perft")
- {
- int depth;
- stringstream ss;
-
- is >> depth;
- ss << Options["Hash"] << " "
- << Options["Threads"] << " " << depth << " current " << token;
+ if ( token == "quit"
+ || token == "stop")
+ Threads.stop = true;
- benchmark(pos, ss);
- }
- else if (token == "key")
- sync_cout << hex << uppercase << setfill('0')
- << "position key: " << setw(16) << pos.key()
- << "\nmaterial key: " << setw(16) << pos.material_key()
- << "\npawn key: " << setw(16) << pos.pawn_key()
- << dec << nouppercase << setfill(' ') << sync_endl;
+ // 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 == "ucinewgame") TT.clear();
- else if (token == "go") go(pos, is);
- else if (token == "position") position(pos, is);
else if (token == "setoption") setoption(is);
- else if (token == "flip") pos.flip();
- else if (token == "bench") benchmark(pos, is);
- else if (token == "d") sync_cout << pos.pretty() << sync_endl;
+ 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;
- else if (token == "eval") sync_cout << Eval::trace(pos) << sync_endl;
- else
- sync_cout << "Unknown command: " << cmd << sync_endl;
-
- } while (token != "quit" && argc == 1); // Passed args have one-shot behaviour
- Threads.wait_for_think_finished(); // Cannot quit whilst the search is running
+ // 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 >> 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
}
-/// format_value() converts a Value to a string suitable for use with the UCI
-/// protocol specifications:
+/// UCI::value() converts a Value to a string by adhering to the UCI protocol specification:
///
-/// cp <x> The score from the engine's point of view in centipawns.
-/// mate <y> Mate in y moves, not plies. If the engine is getting mated
-/// use negative values for y.
+/// cp <x> The score from the engine's point of view in centipawns.
+/// mate <y> Mate in 'y' moves (not plies). If the engine is getting mated,
+/// uses negative values for 'y'.
+
+string UCI::value(Value v) {
-string UCI::format_value(Value v, Value alpha, Value beta) {
+ assert(-VALUE_INFINITE < v && v < VALUE_INFINITE);
stringstream ss;
if (abs(v) < VALUE_MATE_IN_MAX_PLY)
- ss << "cp " << v * 100 / PawnValueEg;
+ ss << "cp " << v * 100 / NormalizeToPawnValue;
else
ss << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
- ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");
-
return ss.str();
}
-/// format_square() converts a Square to a string (g1, a7, etc.)
+/// UCI::wdl() reports the win-draw-loss (WDL) statistics given an evaluation
+/// and a game ply based on the data gathered for fishtest LTC games.
+
+string UCI::wdl(Value v, int ply) {
+
+ stringstream ss;
+
+ int wdl_w = win_rate_model( v, ply);
+ int wdl_l = win_rate_model(-v, ply);
+ int wdl_d = 1000 - wdl_w - wdl_l;
+ ss << " wdl " << wdl_w << " " << wdl_d << " " << wdl_l;
+
+ return ss.str();
+}
+
-std::string UCI::format_square(Square s) {
+/// UCI::square() converts a Square to a string in algebraic notation (g1, a7, etc.)
- char ch[] = { char('a' + file_of(s)),
- char('1' + rank_of(s)), 0 }; // Zero-terminating
- return ch;
+std::string UCI::square(Square s) {
+ return std::string{ char('a' + file_of(s)), char('1' + rank_of(s)) };
}
-/// format_move() converts a Move to a string in coordinate notation
-/// (g1f3, a7a8q, etc.). The only special case is castling moves, where we print
-/// in the e1g1 notation in normal chess mode, and in e1h1 notation in chess960
-/// mode. Internally castling moves are always encoded as "king captures rook".
+/// UCI::move() converts a Move to a string in coordinate notation (g1f3, a7a8q).
+/// The only special case is castling where the e1g1 notation is printed in
+/// standard chess mode and in e1h1 notation it is printed in Chess960 mode.
+/// Internally, all castling moves are always encoded as 'king captures rook'.
-string UCI::format_move(Move m, bool chess960) {
+string UCI::move(Move m, bool chess960) {
Square from = from_sq(m);
Square to = to_sq(m);
if (type_of(m) == CASTLING && !chess960)
to = make_square(to > from ? FILE_G : FILE_C, rank_of(from));
- string move = format_square(from) + format_square(to);
+ string move = UCI::square(from) + UCI::square(to);
if (type_of(m) == PROMOTION)
move += " pnbrqk"[promotion_type(m)];
}
-/// to_move() takes a position and a string representing a move in
-/// simple coordinate notation and returns an equivalent legal Move if any.
+/// UCI::to_move() converts a string representing a move in coordinate notation
+/// (g1f3, a7a8q) to the corresponding legal Move, if any.
Move UCI::to_move(const Position& pos, string& str) {
- if (str.length() == 5) // Junior could send promotion piece in uppercase
- str[4] = char(tolower(str[4]));
+ if (str.length() == 5)
+ str[4] = char(tolower(str[4])); // The promotion piece character must be lowercased
- for (MoveList<LEGAL> it(pos); *it; ++it)
- if (str == format_move(*it, pos.is_chess960()))
- return *it;
+ for (const auto& m : MoveList<LEGAL>(pos))
+ if (str == UCI::move(m, pos.is_chess960()))
+ return m;
return MOVE_NONE;
}
+
+} // namespace Stockfish
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