+/// RootMove struct is used for moves at the root of the tree. For each root
+/// move we store a score, a node count, and a PV (really a refutation in the
+/// case of moves which fail low). Score is normally set at -VALUE_INFINITE for
+/// all non-pv moves.
+struct RootMove {
+
+ RootMove(Move m) : score(-VALUE_INFINITE), prevScore(-VALUE_INFINITE) {
+ pv.push_back(m); pv.push_back(MOVE_NONE);
+ }
+
+ bool operator<(const RootMove& m) const { return score > m.score; } // Ascending sort
+ bool operator==(const Move& m) const { return pv[0] == m; }
+
+ void extract_pv_from_tt(Position& pos);
+ void insert_pv_in_tt(Position& pos);
+
+ Value score;
+ Value prevScore;
+ std::vector<Move> pv;
+};
+
+
+/// The LimitsType struct stores information sent by GUI about available time
+/// to search the current move, maximum depth/time, if we are in analysis mode
+/// or if we have to ponder while it's our opponent's turn to move.
+
+struct LimitsType {
+
+ LimitsType() { // Using memset on a std::vector is undefined behavior
+ nodes = time[WHITE] = time[BLACK] = inc[WHITE] = inc[BLACK] = movestogo =
+ depth = movetime = mate = infinite = ponder = 0;
+ }
+ bool use_time_management() const { return !(mate | movetime | depth | nodes | infinite); }
+
+ std::vector<Move> searchmoves;
+ int time[COLOR_NB], inc[COLOR_NB], movestogo, depth, movetime, mate, infinite, ponder;
+ int64_t nodes;
+};
+
+
+/// The SignalsType struct stores volatile flags updated during the search
+/// typically in an async fashion e.g. to stop the search by the GUI.
+
+struct SignalsType {
+ bool stop, stopOnPonderhit, firstRootMove, failedLowAtRoot;
+};
+
+typedef std::auto_ptr<std::stack<StateInfo> > StateStackPtr;
+
+extern volatile SignalsType Signals;
+extern LimitsType Limits;
+extern std::vector<RootMove> RootMoves;
+extern Position RootPos;
+extern Time::point SearchTime;
+extern StateStackPtr SetupStates;
+
+void init();
+void think();
+template<bool Root> uint64_t perft(Position& pos, Depth depth);