along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstring>
-#include <fstream>
+#include <iomanip>
#include <iostream>
#include <sstream>
#include <vector>
#include "evaluate.h"
#include "history.h"
#include "misc.h"
-#include "move.h"
#include "movegen.h"
#include "movepick.h"
#include "search.h"
#include "tt.h"
#include "ucioption.h"
+namespace Search {
+
+ volatile SignalsType Signals;
+ LimitsType Limits;
+ std::vector<Move> SearchMoves;
+ Position RootPosition;
+}
+
+using std::string;
using std::cout;
using std::endl;
+using namespace Search;
namespace {
const bool FakeSplit = false;
// Different node types, used as template parameter
- enum NodeType { Root, PV, NonPV, SplitPointPV, SplitPointNonPV };
+ enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV };
// RootMove struct is used for moves at the root of the tree. For each root
- // move, we store two scores, a node count, and a PV (really a refutation
- // in the case of moves which fail low). Value pv_score is normally set at
- // -VALUE_INFINITE for all non-pv moves, while non_pv_score is computed
- // according to the order in which moves are returned by MovePicker.
+ // 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();
- RootMove(const RootMove& rm) { *this = rm; }
- RootMove& operator=(const RootMove& rm);
-
- // RootMove::operator<() is the comparison function used when
- // sorting the moves. A move m1 is considered to be better
- // than a move m2 if it has an higher pv_score, or if it has
- // equal pv_score but m1 has the higher non_pv_score. In this way
- // we are guaranteed that PV moves are always sorted as first.
- bool operator<(const RootMove& m) const {
- return pv_score != m.pv_score ? pv_score < m.pv_score
- : non_pv_score < m.non_pv_score;
+ RootMove(){}
+ RootMove(Move m) {
+ nodes = 0;
+ score = prevScore = -VALUE_INFINITE;
+ pv.push_back(m);
+ pv.push_back(MOVE_NONE);
}
+ bool operator<(const RootMove& m) const { return score < m.score; }
+ bool operator==(const Move& m) const { return pv[0] == m; }
+
void extract_pv_from_tt(Position& pos);
void insert_pv_in_tt(Position& pos);
int64_t nodes;
- Value pv_score;
- Value non_pv_score;
- Move pv[PLY_MAX_PLUS_2];
- };
-
- // RootMoveList struct is mainly a std::vector of RootMove objects
- struct RootMoveList : public std::vector<RootMove> {
- void init(Position& pos, Move searchMoves[]);
- int bestMoveChanges;
+ Value score;
+ Value prevScore;
+ std::vector<Move> pv;
};
const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 };
inline bool piece_is_slider(Piece p) { return Slidings[p]; }
- // Step 6. Razoring
-
// Maximum depth for razoring
const Depth RazorDepth = 4 * ONE_PLY;
// Maximum depth for use of dynamic threat detection when null move fails low
const Depth ThreatDepth = 5 * ONE_PLY;
- // Step 9. Internal iterative deepening
-
// Minimum depth for use of internal iterative deepening
const Depth IIDDepth[] = { 8 * ONE_PLY, 5 * ONE_PLY };
// when the static evaluation is bigger then beta - IIDMargin.
const Value IIDMargin = Value(0x100);
- // Step 11. Decide the new search depth
-
- // Extensions. Array index 0 is used for non-PV nodes, index 1 for PV nodes
- const Depth CheckExtension[] = { ONE_PLY / 2, ONE_PLY / 1 };
- const Depth PawnEndgameExtension[] = { ONE_PLY / 1, ONE_PLY / 1 };
- const Depth PawnPushTo7thExtension[] = { ONE_PLY / 2, ONE_PLY / 2 };
- const Depth PassedPawnExtension[] = { DEPTH_ZERO, ONE_PLY / 2 };
-
// Minimum depth for use of singular extension
const Depth SingularExtensionDepth[] = { 8 * ONE_PLY, 6 * ONE_PLY };
- // Step 12. Futility pruning
-
// Futility margin for quiescence search
const Value FutilityMarginQS = Value(0x80);
inline Value futility_margin(Depth d, int mn) {
- return d < 7 * ONE_PLY ? FutilityMargins[Max(d, 1)][Min(mn, 63)]
+ return d < 7 * ONE_PLY ? FutilityMargins[std::max(int(d), 1)][std::min(mn, 63)]
: 2 * VALUE_INFINITE;
}
return d < 16 * ONE_PLY ? FutilityMoveCounts[d] : MAX_MOVES;
}
- // Step 14. Reduced search
-
// Reduction lookup tables (initialized at startup) and their access function
int8_t Reductions[2][64][64]; // [pv][depth][moveNumber]
template <bool PvNode> inline Depth reduction(Depth d, int mn) {
- return (Depth) Reductions[PvNode][Min(d / ONE_PLY, 63)][Min(mn, 63)];
+ return (Depth) Reductions[PvNode][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)];
}
// Easy move margin. An easy move candidate must be at least this much
// better than the second best move.
- const Value EasyMoveMargin = Value(0x200);
+ const Value EasyMoveMargin = Value(0x150);
/// Namespace variables
- // Root move list
- RootMoveList Rml;
-
- // MultiPV mode
- int MultiPV, UCIMultiPV;
-
- // Time management variables
- bool StopOnPonderhit, FirstRootMove, StopRequest, QuitRequest, AspirationFailLow;
+ std::vector<RootMove> RootMoves;
+ size_t MultiPV, UCIMultiPV, PVIdx;
TimeManager TimeMgr;
- SearchLimits Limits;
-
- // Log file
- std::ofstream LogFile;
-
- // Skill level adjustment
+ int BestMoveChanges;
int SkillLevel;
- bool SkillLevelEnabled;
-
- // Node counters, used only by thread[0] but try to keep in different cache
- // lines (64 bytes each) from the heavy multi-thread read accessed variables.
- bool SendSearchedNodes;
- int NodesSincePoll;
- int NodesBetweenPolls = 30000;
-
- // History table
+ bool SkillLevelEnabled, Chess960;
History H;
/// Local functions
- Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove);
-
template <NodeType NT>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
template <NodeType NT>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
+ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
+ void id_loop(Position& pos);
bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue);
bool connected_moves(const Position& pos, Move m1, Move m2);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
- bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
+ bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply);
bool connected_threat(const Position& pos, Move m, Move threat);
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
- void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
- void update_gains(const Position& pos, Move move, Value before, Value after);
- void do_skill_level(Move* best, Move* ponder);
-
- int current_search_time(int set = 0);
- std::string score_to_uci(Value v, Value alpha, Value beta);
- std::string speed_to_uci(int64_t nodes);
- std::string pv_to_uci(Move pv[], int pvNum);
- std::string depth_to_uci(Depth depth);
- void poll(const Position& pos);
- void wait_for_stop_or_ponderhit();
-
- // MovePickerExt template class extends MovePicker and allows to choose at compile
- // time the proper moves source according to the type of node. In the default case
- // we simply create and use a standard MovePicker object.
- template<NodeType> struct MovePickerExt : public MovePicker {
-
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ Move do_skill_level();
+ int elapsed_time(bool reset = false);
+ string score_to_uci(Value v, Value alpha = -VALUE_INFINITE, Value beta = VALUE_INFINITE);
+ void pv_info_to_log(Position& pos, int depth, Value score, int time, Move pv[]);
+ void pv_info_to_uci(const Position& pos, int depth, Value alpha, Value beta);
+
+ // MovePickerExt class template extends MovePicker and allows to choose at
+ // compile time the proper moves source according to the type of node. In the
+ // default case we simply create and use a standard MovePicker object.
+ template<bool SpNode> struct MovePickerExt : public MovePicker {
+
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
: MovePicker(p, ttm, d, h, ss, b) {}
-
- RootMove& current() { assert(false); return Rml[0]; } // Dummy, needed to compile
};
// In case of a SpNode we use split point's shared MovePicker object as moves source
- template<> struct MovePickerExt<SplitPointNonPV> : public MovePickerExt<NonPV> {
+ template<> struct MovePickerExt<true> : public MovePicker {
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
- : MovePickerExt<NonPV>(p, ttm, d, h, ss, b), mp(ss->sp->mp) {}
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
+ : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {}
- Move get_next_move() { return mp->get_next_move(); }
+ Move next_move() { return mp->next_move(); }
MovePicker* mp;
};
- template<> struct MovePickerExt<SplitPointPV> : public MovePickerExt<SplitPointNonPV> {
-
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
- : MovePickerExt<SplitPointNonPV>(p, ttm, d, h, ss, b) {}
- };
-
- // In case of a Root node we use RootMoveList as moves source
- template<> struct MovePickerExt<Root> : public MovePicker {
-
- MovePickerExt(const Position&, Move, Depth, const History&, SearchStack*, Value);
- RootMove& current() { return Rml[cur]; }
- Move get_next_move() { return ++cur < (int)Rml.size() ? Rml[cur].pv[0] : MOVE_NONE; }
-
- int cur;
- };
-
- // Overload operator<<() to make it easier to print moves in a coordinate
- // notation compatible with UCI protocol.
- std::ostream& operator<<(std::ostream& os, Move m) {
-
- bool chess960 = (os.iword(0) != 0); // See set960()
- return os << move_to_uci(m, chess960);
- }
+ // is_dangerous() checks whether a move belongs to some classes of known
+ // 'dangerous' moves so that we avoid to prune it.
+ FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) {
- // When formatting a move for std::cout we must know if we are in Chess960
- // or not. To keep using the handy operator<<() on the move the trick is to
- // embed this flag in the stream itself. Function-like named enum set960 is
- // used as a custom manipulator and the stream internal general-purpose array,
- // accessed through ios_base::iword(), is used to pass the flag to the move's
- // operator<<() that will read it to properly format castling moves.
- enum set960 {};
-
- std::ostream& operator<< (std::ostream& os, const set960& f) {
-
- os.iword(0) = int(f);
- return os;
- }
-
- // extension() decides whether a move should be searched with normal depth,
- // or with extended depth. Certain classes of moves (checking moves, in
- // particular) are searched with bigger depth than ordinary moves and in
- // any case are marked as 'dangerous'. Note that also if a move is not
- // extended, as example because the corresponding UCI option is set to zero,
- // the move is marked as 'dangerous' so, at least, we avoid to prune it.
- template <bool PvNode>
- FORCE_INLINE Depth extension(const Position& pos, Move m, bool captureOrPromotion,
- bool moveIsCheck, bool* dangerous) {
- assert(m != MOVE_NONE);
-
- Depth result = DEPTH_ZERO;
- *dangerous = moveIsCheck;
-
- if (moveIsCheck && pos.see_sign(m) >= 0)
- result += CheckExtension[PvNode];
-
- if (piece_type(pos.piece_on(move_from(m))) == PAWN)
+ // Test for a pawn pushed to 7th or a passed pawn move
+ if (type_of(pos.piece_on(move_from(m))) == PAWN)
{
Color c = pos.side_to_move();
- if (relative_rank(c, move_to(m)) == RANK_7)
- {
- result += PawnPushTo7thExtension[PvNode];
- *dangerous = true;
- }
- if (pos.pawn_is_passed(c, move_to(m)))
- {
- result += PassedPawnExtension[PvNode];
- *dangerous = true;
- }
+ if ( relative_rank(c, move_to(m)) == RANK_7
+ || pos.pawn_is_passed(c, move_to(m)))
+ return true;
}
+ // Test for a capture that triggers a pawn endgame
if ( captureOrPromotion
- && piece_type(pos.piece_on(move_to(m))) != PAWN
+ && type_of(pos.piece_on(move_to(m))) != PAWN
&& ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- - piece_value_midgame(pos.piece_on(move_to(m))) == VALUE_ZERO)
- && !move_is_special(m))
- {
- result += PawnEndgameExtension[PvNode];
- *dangerous = true;
- }
+ - PieceValueMidgame[pos.piece_on(move_to(m))] == VALUE_ZERO)
+ && !is_special(m))
+ return true;
- return Min(result, ONE_PLY);
+ return false;
}
} // namespace
-/// init_search() is called during startup to initialize various lookup tables
+/// Search::init() is called during startup to initialize various lookup tables
-void init_search() {
+void Search::init() {
int d; // depth (ONE_PLY == 2)
int hd; // half depth (ONE_PLY == 1)
}
-/// perft() is our utility to verify move generation. All the leaf nodes up to
-/// the given depth are generated and counted and the sum returned.
+/// Search::perft() is our utility to verify move generation. All the leaf nodes
+/// up to the given depth are generated and counted and the sum returned.
-int64_t perft(Position& pos, Depth depth) {
+int64_t Search::perft(Position& pos, Depth depth) {
StateInfo st;
int64_t sum = 0;
- // Generate all legal moves
MoveList<MV_LEGAL> ml(pos);
- // If we are at the last ply we don't need to do and undo
- // the moves, just to count them.
+ // At the last ply just return the number of moves (leaf nodes)
if (depth <= ONE_PLY)
return ml.size();
- // Loop through all legal moves
CheckInfo ci(pos);
for ( ; !ml.end(); ++ml)
{
}
-/// think() is the external interface to Stockfish's search, and is called when
-/// the program receives the UCI 'go' command. It initializes various global
-/// variables, and calls id_loop(). It returns false when a "quit" command is
-/// received during the search.
+/// Search::think() is the external interface to Stockfish's search, and is
+/// called by the main thread when the program receives the UCI 'go' command. It
+/// searches from RootPosition and at the end prints the "bestmove" to output.
-bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) {
+void Search::think() {
- static Book book;
+ static Book book; // Defined static to initialize the PRNG only once
- // Initialize global search-related variables
- StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = SendSearchedNodes = false;
- NodesSincePoll = 0;
- current_search_time(get_system_time());
- Limits = limits;
+ Position& pos = RootPosition;
+ Chess960 = pos.is_chess960();
+ elapsed_time(true);
TimeMgr.init(Limits, pos.startpos_ply_counter());
+ TT.new_search();
+ H.clear();
+ RootMoves.clear();
- // Set output steram in normal or chess960 mode
- cout << set960(pos.is_chess960());
+ // Populate RootMoves with all the legal moves (default) or, if a SearchMoves
+ // is given, with the subset of legal moves to search.
+ for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
+ if ( SearchMoves.empty()
+ || count(SearchMoves.begin(), SearchMoves.end(), ml.move()))
+ RootMoves.push_back(RootMove(ml.move()));
- // Set best NodesBetweenPolls interval to avoid lagging under time pressure
- if (Limits.maxNodes)
- NodesBetweenPolls = Min(Limits.maxNodes, 30000);
- else if (Limits.time && Limits.time < 1000)
- NodesBetweenPolls = 1000;
- else if (Limits.time && Limits.time < 5000)
- NodesBetweenPolls = 5000;
- else
- NodesBetweenPolls = 30000;
-
- // Look for a book move
if (Options["OwnBook"].value<bool>())
{
- if (Options["Book File"].value<std::string>() != book.name())
- book.open(Options["Book File"].value<std::string>());
+ if (Options["Book File"].value<string>() != book.name())
+ book.open(Options["Book File"].value<string>());
- Move bookMove = book.get_move(pos, Options["Best Book Move"].value<bool>());
- if (bookMove != MOVE_NONE)
- {
- if (Limits.ponder)
- wait_for_stop_or_ponderhit();
+ Move bookMove = book.probe(pos, Options["Best Book Move"].value<bool>());
- cout << "bestmove " << bookMove << endl;
- return !QuitRequest;
+ if ( bookMove != MOVE_NONE
+ && count(RootMoves.begin(), RootMoves.end(), bookMove))
+ {
+ std::swap(RootMoves[0], *find(RootMoves.begin(), RootMoves.end(), bookMove));
+ goto finish;
}
}
- // Read UCI options
- UCIMultiPV = Options["MultiPV"].value<int>();
- SkillLevel = Options["Skill Level"].value<int>();
-
+ // Read UCI options: GUI could change UCI parameters during the game
read_evaluation_uci_options(pos.side_to_move());
Threads.read_uci_options();
- // If needed allocate pawn and material hash tables and adjust TT size
- Threads.init_hash_tables();
TT.set_size(Options["Hash"].value<int>());
-
if (Options["Clear Hash"].value<bool>())
{
Options["Clear Hash"].set_value("false");
TT.clear();
}
+ UCIMultiPV = Options["MultiPV"].value<size_t>();
+ SkillLevel = Options["Skill Level"].value<int>();
+
// Do we have to play with skill handicap? In this case enable MultiPV that
// we will use behind the scenes to retrieve a set of possible moves.
SkillLevelEnabled = (SkillLevel < 20);
- MultiPV = (SkillLevelEnabled ? Max(UCIMultiPV, 4) : UCIMultiPV);
+ MultiPV = (SkillLevelEnabled ? std::max(UCIMultiPV, (size_t)4) : UCIMultiPV);
- // Wake up needed threads and reset maxPly counter
- for (int i = 0; i < Threads.size(); i++)
+ if (Options["Use Search Log"].value<bool>())
{
- Threads[i].wake_up();
- Threads[i].maxPly = 0;
+ Log log(Options["Search Log Filename"].value<string>());
+ log << "\nSearching: " << pos.to_fen()
+ << "\ninfinite: " << Limits.infinite
+ << " ponder: " << Limits.ponder
+ << " time: " << Limits.time
+ << " increment: " << Limits.increment
+ << " moves to go: " << Limits.movesToGo
+ << endl;
}
- // Write to log file and keep it open to be accessed during the search
- if (Options["Use Search Log"].value<bool>())
+ for (int i = 0; i < Threads.size(); i++)
{
- std::string name = Options["Search Log Filename"].value<std::string>();
- LogFile.open(name.c_str(), std::ios::out | std::ios::app);
-
- if (LogFile.is_open())
- LogFile << "\nSearching: " << pos.to_fen()
- << "\ninfinite: " << Limits.infinite
- << " ponder: " << Limits.ponder
- << " time: " << Limits.time
- << " increment: " << Limits.increment
- << " moves to go: " << Limits.movesToGo
- << endl;
+ Threads[i].maxPly = 0;
+ Threads[i].wake_up();
}
- // We're ready to start thinking. Call the iterative deepening loop function
- Move ponderMove = MOVE_NONE;
- Move bestMove = id_loop(pos, searchMoves, &ponderMove);
+ // Set best timer interval to avoid lagging under time pressure. Timer is
+ // used to check for remaining available thinking time.
+ if (TimeMgr.available_time())
+ Threads.set_timer(std::min(100, std::max(TimeMgr.available_time() / 8, 20)));
+ else
+ Threads.set_timer(100);
+
+ // We're ready to start searching. Call the iterative deepening loop function
+ id_loop(pos);
- // Write final search statistics and close log file
- if (LogFile.is_open())
+ // Stop timer and send all the slaves to sleep, if not already sleeping
+ Threads.set_timer(0);
+ Threads.set_size(1);
+
+ if (Options["Use Search Log"].value<bool>())
{
- int t = current_search_time();
+ int e = elapsed_time();
- LogFile << "Nodes: " << pos.nodes_searched()
- << "\nNodes/second: " << (t > 0 ? pos.nodes_searched() * 1000 / t : 0)
- << "\nBest move: " << move_to_san(pos, bestMove);
+ Log log(Options["Search Log Filename"].value<string>());
+ log << "Nodes: " << pos.nodes_searched()
+ << "\nNodes/second: " << (e > 0 ? pos.nodes_searched() * 1000 / e : 0)
+ << "\nBest move: " << move_to_san(pos, RootMoves[0].pv[0]);
StateInfo st;
- pos.do_move(bestMove, st);
- LogFile << "\nPonder move: " << move_to_san(pos, ponderMove) << endl;
- pos.undo_move(bestMove); // Return from think() with unchanged position
- LogFile.close();
+ pos.do_move(RootMoves[0].pv[0], st);
+ log << "\nPonder move: " << move_to_san(pos, RootMoves[0].pv[1]) << endl;
+ pos.undo_move(RootMoves[0].pv[0]);
}
- // This makes all the threads to go to sleep
- Threads.set_size(1);
-
- // If we are pondering or in infinite search, we shouldn't print the
- // best move before we are told to do so.
- if (!StopRequest && (Limits.ponder || Limits.infinite))
- wait_for_stop_or_ponderhit();
-
- // Could be MOVE_NONE when searching on a stalemate position
- cout << "bestmove " << bestMove;
+finish:
- // UCI protol is not clear on allowing sending an empty ponder move, instead
- // it is clear that ponder move is optional. So skip it if empty.
- if (ponderMove != MOVE_NONE)
- cout << " ponder " << ponderMove;
+ // When we reach max depth we arrive here even without a StopRequest, but if
+ // we are pondering or in infinite search, we shouldn't print the best move
+ // before we are told to do so.
+ if (!Signals.stop && (Limits.ponder || Limits.infinite))
+ Threads.wait_for_stop_or_ponderhit();
- cout << endl;
-
- return !QuitRequest;
+ // Best move could be MOVE_NONE when searching on a stalemate position
+ cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], Chess960)
+ << " ponder " << move_to_uci(RootMoves[0].pv[1], Chess960) << endl;
}
// with increasing depth until the allocated thinking time has been consumed,
// user stops the search, or the maximum search depth is reached.
- Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove) {
-
- SearchStack ss[PLY_MAX_PLUS_2];
- Value bestValues[PLY_MAX_PLUS_2];
- int bestMoveChanges[PLY_MAX_PLUS_2];
- int depth, aspirationDelta;
- Value value, alpha, beta;
- Move bestMove, easyMove, skillBest, skillPonder;
-
- // Initialize stuff before a new search
- memset(ss, 0, 4 * sizeof(SearchStack));
- TT.new_search();
- H.clear();
- *ponderMove = bestMove = easyMove = skillBest = skillPonder = MOVE_NONE;
- depth = aspirationDelta = 0;
- alpha = -VALUE_INFINITE, beta = VALUE_INFINITE;
- ss->currentMove = MOVE_NULL; // Hack to skip update_gains()
-
- // Moves to search are verified and copied
- Rml.init(pos, searchMoves);
-
- // Handle special case of searching on a mate/stalemate position
- if (!Rml.size())
+ void id_loop(Position& pos) {
+
+ Stack ss[PLY_MAX_PLUS_2];
+ int depth, prevBestMoveChanges;
+ Value bestValue, alpha, beta, delta;
+ bool bestMoveNeverChanged = true;
+ Move skillBest = MOVE_NONE;
+
+ memset(ss, 0, 4 * sizeof(Stack));
+ depth = BestMoveChanges = 0;
+ bestValue = delta = -VALUE_INFINITE;
+ ss->currentMove = MOVE_NULL; // Hack to skip update gains
+
+ // Handle the special case of a mate/stalemate position
+ if (RootMoves.empty())
{
- cout << "info" << depth_to_uci(DEPTH_ZERO)
- << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW, alpha, beta) << endl;
+ cout << "info depth 0"
+ << score_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW) << endl;
- return MOVE_NONE;
+ RootMoves.push_back(MOVE_NONE);
+ return;
}
// Iterative deepening loop until requested to stop or target depth reached
- while (!StopRequest && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth))
+ while (!Signals.stop && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth))
{
- Rml.bestMoveChanges = 0;
+ // Save last iteration's scores before first PV line is searched and all
+ // the move scores but the (new) PV are set to -VALUE_INFINITE.
+ for (size_t i = 0; i < RootMoves.size(); i++)
+ RootMoves[i].prevScore = RootMoves[i].score;
- // Calculate dynamic aspiration window based on previous iterations
- if (MultiPV == 1 && depth >= 5 && abs(bestValues[depth - 1]) < VALUE_KNOWN_WIN)
- {
- int prevDelta1 = bestValues[depth - 1] - bestValues[depth - 2];
- int prevDelta2 = bestValues[depth - 2] - bestValues[depth - 3];
+ prevBestMoveChanges = BestMoveChanges;
+ BestMoveChanges = 0;
- aspirationDelta = Min(Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16), 24);
- aspirationDelta = (aspirationDelta + 7) / 8 * 8; // Round to match grainSize
-
- alpha = Max(bestValues[depth - 1] - aspirationDelta, -VALUE_INFINITE);
- beta = Min(bestValues[depth - 1] + aspirationDelta, VALUE_INFINITE);
- }
-
- // Start with a small aspiration window and, in case of fail high/low,
- // research with bigger window until not failing high/low anymore.
- do {
- // Search starting from ss+1 to allow calling update_gains()
- value = search<Root>(pos, ss+1, alpha, beta, depth * ONE_PLY);
-
- // Write PV back to transposition table in case the relevant entries
- // have been overwritten during the search.
- for (int i = 0; i < Min(MultiPV, (int)Rml.size()); i++)
- Rml[i].insert_pv_in_tt(pos);
-
- // Value cannot be trusted. Break out immediately!
- if (StopRequest)
- break;
-
- // Send full PV info to GUI if we are going to leave the loop or
- // if we have a fail high/low and we are deep in the search.
- if ((value > alpha && value < beta) || current_search_time() > 2000)
- for (int i = 0; i < Min(UCIMultiPV, (int)Rml.size()); i++)
- cout << "info"
- << depth_to_uci(depth * ONE_PLY)
- << score_to_uci(Rml[i].pv_score, alpha, beta)
- << speed_to_uci(pos.nodes_searched())
- << pv_to_uci(Rml[i].pv, i + 1) << endl;
-
- // In case of failing high/low increase aspiration window and research,
- // otherwise exit the fail high/low loop.
- if (value >= beta)
+ // MultiPV loop. We perform a full root search for each PV line
+ for (PVIdx = 0; PVIdx < std::min(MultiPV, RootMoves.size()); PVIdx++)
+ {
+ // Set aspiration window default width
+ if (depth >= 5 && abs(RootMoves[PVIdx].prevScore) < VALUE_KNOWN_WIN)
{
- beta = Min(beta + aspirationDelta, VALUE_INFINITE);
- aspirationDelta += aspirationDelta / 2;
+ delta = Value(16);
+ alpha = RootMoves[PVIdx].prevScore - delta;
+ beta = RootMoves[PVIdx].prevScore + delta;
}
- else if (value <= alpha)
+ else
{
- AspirationFailLow = true;
- StopOnPonderhit = false;
-
- alpha = Max(alpha - aspirationDelta, -VALUE_INFINITE);
- aspirationDelta += aspirationDelta / 2;
+ alpha = -VALUE_INFINITE;
+ beta = VALUE_INFINITE;
}
- else
- break;
-
- } while (abs(value) < VALUE_KNOWN_WIN);
- // Collect info about search result
- bestMove = Rml[0].pv[0];
- *ponderMove = Rml[0].pv[1];
- bestValues[depth] = value;
- bestMoveChanges[depth] = Rml.bestMoveChanges;
+ // Start with a small aspiration window and, in case of fail high/low,
+ // research with bigger window until not failing high/low anymore.
+ do {
+ // Search starts from ss+1 to allow referencing (ss-1). This is
+ // needed by update gains and ss copy when splitting at Root.
+ bestValue = search<Root>(pos, ss+1, alpha, beta, depth * ONE_PLY);
+
+ // Bring to front the best move. It is critical that sorting is
+ // done with a stable algorithm because all the values but the first
+ // and eventually the new best one are set to -VALUE_INFINITE and
+ // we want to keep the same order for all the moves but the new
+ // PV that goes to the front. Note that in case of MultiPV search
+ // the already searched PV lines are preserved.
+ sort<RootMove>(RootMoves.begin() + PVIdx, RootMoves.end());
+
+ // In case we have found an exact score and we are going to leave
+ // the fail high/low loop then reorder the PV moves, otherwise
+ // leave the last PV move in its position so to be searched again.
+ // Of course this is needed only in MultiPV search.
+ if (PVIdx && bestValue > alpha && bestValue < beta)
+ sort<RootMove>(RootMoves.begin(), RootMoves.begin() + PVIdx);
+
+ // Write PV back to transposition table in case the relevant
+ // entries have been overwritten during the search.
+ for (size_t i = 0; i <= PVIdx; i++)
+ RootMoves[i].insert_pv_in_tt(pos);
+
+ // If search has been stopped exit the aspiration window loop.
+ // Sorting and writing PV back to TT is safe becuase RootMoves
+ // is still valid, although refers to previous iteration.
+ if (Signals.stop)
+ break;
+
+ // Send full PV info to GUI if we are going to leave the loop or
+ // if we have a fail high/low and we are deep in the search.
+ if ((bestValue > alpha && bestValue < beta) || elapsed_time() > 2000)
+ pv_info_to_uci(pos, depth, alpha, beta);
+
+ // In case of failing high/low increase aspiration window and
+ // research, otherwise exit the fail high/low loop.
+ if (bestValue >= beta)
+ {
+ beta += delta;
+ delta += delta / 2;
+ }
+ else if (bestValue <= alpha)
+ {
+ Signals.failedLowAtRoot = true;
+ Signals.stopOnPonderhit = false;
+
+ alpha -= delta;
+ delta += delta / 2;
+ }
+ else
+ break;
+
+ assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
+
+ } while (abs(bestValue) < VALUE_KNOWN_WIN);
+ }
- // Do we need to pick now the best and the ponder moves ?
+ // Skills: Do we need to pick now the best move ?
if (SkillLevelEnabled && depth == 1 + SkillLevel)
- do_skill_level(&skillBest, &skillPonder);
+ skillBest = do_skill_level();
- if (LogFile.is_open())
- LogFile << pretty_pv(pos, depth, value, current_search_time(), Rml[0].pv) << endl;
+ if (Options["Use Search Log"].value<bool>())
+ pv_info_to_log(pos, depth, bestValue, elapsed_time(), &RootMoves[0].pv[0]);
- // Init easyMove after first iteration or drop if differs from the best move
- if (depth == 1 && (Rml.size() == 1 || Rml[0].pv_score > Rml[1].pv_score + EasyMoveMargin))
- easyMove = bestMove;
- else if (bestMove != easyMove)
- easyMove = MOVE_NONE;
+ // Filter out startup noise when monitoring best move stability
+ if (depth > 2 && BestMoveChanges)
+ bestMoveNeverChanged = false;
- // Check for some early stop condition
- if (!StopRequest && Limits.useTimeManagement())
+ // Do we have time for the next iteration? Can we stop searching now?
+ if (!Signals.stop && !Signals.stopOnPonderhit && Limits.useTimeManagement())
{
- // Stop search early when the last two iterations returned a mate score
- if ( depth >= 5
- && abs(bestValues[depth]) >= VALUE_MATE_IN_PLY_MAX
- && abs(bestValues[depth - 1]) >= VALUE_MATE_IN_PLY_MAX)
- StopRequest = true;
-
- // Stop search early if one move seems to be much better than the
- // others or if there is only a single legal move. Also in the latter
- // case we search up to some depth anyway to get a proper score.
- if ( depth >= 7
- && easyMove == bestMove
- && ( Rml.size() == 1
- ||( Rml[0].nodes > (pos.nodes_searched() * 85) / 100
- && current_search_time() > TimeMgr.available_time() / 16)
- ||( Rml[0].nodes > (pos.nodes_searched() * 98) / 100
- && current_search_time() > TimeMgr.available_time() / 32)))
- StopRequest = true;
+ bool stop = false; // Local variable, not the volatile Signals.stop
// Take in account some extra time if the best move has changed
if (depth > 4 && depth < 50)
- TimeMgr.pv_instability(bestMoveChanges[depth], bestMoveChanges[depth - 1]);
-
- // Stop search if most of available time is already consumed. We probably don't
- // have enough time to search the first move at the next iteration anyway.
- if (current_search_time() > (TimeMgr.available_time() * 62) / 100)
- StopRequest = true;
+ TimeMgr.pv_instability(BestMoveChanges, prevBestMoveChanges);
+
+ // Stop search if most of available time is already consumed. We
+ // probably don't have enough time to search the first move at the
+ // next iteration anyway.
+ if (elapsed_time() > (TimeMgr.available_time() * 62) / 100)
+ stop = true;
+
+ // Stop search early if one move seems to be much better than others
+ if ( depth >= 10
+ && !stop
+ && ( bestMoveNeverChanged
+ || elapsed_time() > (TimeMgr.available_time() * 40) / 100))
+ {
+ Value rBeta = bestValue - EasyMoveMargin;
+ (ss+1)->excludedMove = RootMoves[0].pv[0];
+ (ss+1)->skipNullMove = true;
+ Value v = search<NonPV>(pos, ss+1, rBeta - 1, rBeta, (depth * ONE_PLY) / 2);
+ (ss+1)->skipNullMove = false;
+ (ss+1)->excludedMove = MOVE_NONE;
+
+ if (v < rBeta)
+ stop = true;
+ }
- // If we are allowed to ponder do not stop the search now but keep pondering
- if (StopRequest && Limits.ponder)
+ if (stop)
{
- StopRequest = false;
- StopOnPonderhit = true;
+ // If we are allowed to ponder do not stop the search now but
+ // keep pondering until GUI sends "ponderhit" or "stop".
+ if (Limits.ponder)
+ Signals.stopOnPonderhit = true;
+ else
+ Signals.stop = true;
}
}
}
- // When using skills overwrite best and ponder moves with the sub-optimal ones
+ // When using skills swap best PV line with the sub-optimal one
if (SkillLevelEnabled)
{
if (skillBest == MOVE_NONE) // Still unassigned ?
- do_skill_level(&skillBest, &skillPonder);
+ skillBest = do_skill_level();
- bestMove = skillBest;
- *ponderMove = skillPonder;
+ std::swap(RootMoves[0], *find(RootMoves.begin(), RootMoves.end(), skillBest));
}
-
- return bestMove;
}
// here: This is taken care of after we return from the split point.
template <NodeType NT>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
- const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV);
- const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV);
- const bool RootNode = (NT == Root);
+ const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot);
+ const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot);
+ const bool RootNode = (NT == Root || NT == SplitPointRoot);
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
Depth ext, newDepth;
ValueType vt;
Value bestValue, value, oldAlpha;
- Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific
- bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous;
+ Value refinedValue, nullValue, futilityBase, futilityValue;
+ bool isPvMove, inCheck, singularExtensionNode, givesCheck;
+ bool captureOrPromotion, dangerous, doFullDepthSearch;
int moveCount = 0, playedMoveCount = 0;
Thread& thread = Threads[pos.thread()];
SplitPoint* sp = NULL;
if (PvNode && thread.maxPly < ss->ply)
thread.maxPly = ss->ply;
- // Step 1. Initialize node and poll. Polling can abort search
+ // Step 1. Initialize node
if (!SpNode)
{
ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE;
goto split_point_start;
}
- if (pos.thread() == 0 && ++NodesSincePoll > NodesBetweenPolls)
- {
- NodesSincePoll = 0;
- poll(pos);
- }
-
// Step 2. Check for aborted search and immediate draw
- if (( StopRequest
+ if (( Signals.stop
|| pos.is_draw<false>()
|| ss->ply > PLY_MAX) && !RootNode)
return VALUE_DRAW;
// Step 3. Mate distance pruning
if (!RootNode)
{
- alpha = Max(value_mated_in(ss->ply), alpha);
- beta = Min(value_mate_in(ss->ply+1), beta);
+ alpha = std::max(value_mated_in(ss->ply), alpha);
+ beta = std::min(value_mate_in(ss->ply+1), beta);
if (alpha >= beta)
return alpha;
}
// We don't want the score of a partial search to overwrite a previous full search
// TT value, so we use a different position key in case of an excluded move.
excludedMove = ss->excludedMove;
- posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key();
+ posKey = excludedMove ? pos.exclusion_key() : pos.key();
tte = TT.probe(posKey);
- ttMove = tte ? tte->move() : MOVE_NONE;
+ ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
// At PV nodes we check for exact scores, while at non-PV nodes we check for
// a fail high/low. Biggest advantage at probing at PV nodes is to have a
- // smooth experience in analysis mode.
- if (tte && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT
- : ok_to_use_TT(tte, depth, beta, ss->ply)))
+ // smooth experience in analysis mode. We don't probe at Root nodes otherwise
+ // we should also update RootMoveList to avoid bogus output.
+ if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT
+ : can_return_tt(tte, depth, beta, ss->ply)))
{
TT.refresh(tte);
- ss->bestMove = ttMove; // Can be MOVE_NONE
- return value_from_tt(tte->value(), ss->ply);
+ ss->bestMove = move = ttMove; // Can be MOVE_NONE
+ value = value_from_tt(tte->value(), ss->ply);
+
+ if ( value >= beta
+ && move
+ && !pos.is_capture_or_promotion(move)
+ && move != ss->killers[0])
+ {
+ ss->killers[1] = ss->killers[0];
+ ss->killers[0] = move;
+ }
+ return value;
}
// Step 5. Evaluate the position statically and update parent's gain statistics
TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ss->evalMargin);
}
- // Save gain for the parent non-capture move
- update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval);
+ // Update gain for the parent non-capture move given the static position
+ // evaluation before and after the move.
+ if ( (move = (ss-1)->currentMove) != MOVE_NULL
+ && (ss-1)->eval != VALUE_NONE
+ && ss->eval != VALUE_NONE
+ && pos.captured_piece_type() == PIECE_TYPE_NONE
+ && !is_special(move))
+ {
+ Square to = move_to(move);
+ H.update_gain(pos.piece_on(to), to, -(ss-1)->eval - ss->eval);
+ }
// Step 6. Razoring (is omitted in PV nodes)
if ( !PvNode
if (refinedValue - PawnValueMidgame > beta)
R++;
- pos.do_null_move(st);
+ pos.do_null_move<true>(st);
(ss+1)->skipNullMove = true;
nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
: - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY);
(ss+1)->skipNullMove = false;
- pos.undo_null_move();
+ pos.do_null_move<false>(st);
if (nullValue >= beta)
{
MovePicker mp(pos, ttMove, H, pos.captured_piece_type());
CheckInfo ci(pos);
- while ((move = mp.get_next_move()) != MOVE_NONE)
+ while ((move = mp.next_move()) != MOVE_NONE)
if (pos.pl_move_is_legal(move, ci.pinned))
{
pos.do_move(move, st, ci, pos.move_gives_check(move, ci));
split_point_start: // At split points actual search starts from here
- // Initialize a MovePicker object for the current position
- MovePickerExt<NT> mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta);
+ MovePickerExt<SpNode> mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta);
CheckInfo ci(pos);
ss->bestMove = MOVE_NONE;
futilityBase = ss->eval + ss->evalMargin;
&& !SpNode
&& depth >= SingularExtensionDepth[PvNode]
&& ttMove != MOVE_NONE
- && !excludedMove // Do not allow recursive singular extension search
+ && !excludedMove // Recursive singular search is not allowed
&& (tte->type() & VALUE_TYPE_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY;
if (SpNode)
{
lock_grab(&(sp->lock));
bestValue = sp->bestValue;
+ moveCount = sp->moveCount;
+
+ assert(bestValue > -VALUE_INFINITE && moveCount > 0);
}
// Step 11. Loop through moves
// Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
- && (move = mp.get_next_move()) != MOVE_NONE
+ && (move = mp.next_move()) != MOVE_NONE
&& !thread.cutoff_occurred())
{
- assert(move_is_ok(move));
+ assert(is_ok(move));
if (move == excludedMove)
continue;
+ // At root obey the "searchmoves" option and skip moves not listed in Root
+ // Move List, as a consequence any illegal move is also skipped. In MultiPV
+ // mode we also skip PV moves which have been already searched.
+ if (RootNode && !count(RootMoves.begin() + PVIdx, RootMoves.end(), move))
+ continue;
+
// At PV and SpNode nodes we want all moves to be legal since the beginning
if ((PvNode || SpNode) && !pos.pl_move_is_legal(move, ci.pinned))
continue;
if (RootNode)
{
- // This is used by time management
- FirstRootMove = (moveCount == 1);
-
- // Save the current node count before the move is searched
+ Signals.firstRootMove = (moveCount == 1);
nodes = pos.nodes_searched();
- // If it's time to send nodes info, do it here where we have the
- // correct accumulated node counts searched by each thread.
- if (SendSearchedNodes)
- {
- SendSearchedNodes = false;
- cout << "info" << speed_to_uci(pos.nodes_searched()) << endl;
- }
-
- // For long searches send current move info to GUI
- if (current_search_time() > 2000)
- cout << "info" << depth_to_uci(depth)
- << " currmove " << move << " currmovenumber " << moveCount << endl;
+ if (pos.thread() == 0 && elapsed_time() > 2000)
+ cout << "info depth " << depth / ONE_PLY
+ << " currmove " << move_to_uci(move, Chess960)
+ << " currmovenumber " << moveCount + PVIdx << endl;
}
- // At Root and at first iteration do a PV search on all the moves to score root moves
- isPvMove = (PvNode && moveCount <= (!RootNode ? 1 : depth <= ONE_PLY ? MAX_MOVES : MultiPV));
+ isPvMove = (PvNode && moveCount <= 1);
+ captureOrPromotion = pos.is_capture_or_promotion(move);
givesCheck = pos.move_gives_check(move, ci);
- captureOrPromotion = pos.move_is_capture_or_promotion(move);
+ dangerous = givesCheck || is_dangerous(pos, move, captureOrPromotion);
+ ext = DEPTH_ZERO;
+
+ // Step 12. Extend checks and, in PV nodes, also dangerous moves
+ if (PvNode && dangerous)
+ ext = ONE_PLY;
- // Step 12. Decide the new search depth
- ext = extension<PvNode>(pos, move, captureOrPromotion, givesCheck, &dangerous);
+ else if (givesCheck && pos.see_sign(move) >= 0)
+ ext = PvNode ? ONE_PLY : ONE_PLY / 2;
// Singular extension search. If all moves but one fail low on a search of
// (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
// on all the other moves but the ttMove, if result is lower than ttValue minus
// a margin then we extend ttMove.
if ( singularExtensionNode
+ && !ext
&& move == ttMove
- && pos.pl_move_is_legal(move, ci.pinned)
- && ext < ONE_PLY)
+ && pos.pl_move_is_legal(move, ci.pinned))
{
Value ttValue = value_from_tt(tte->value(), ss->ply);
Value rBeta = ttValue - int(depth);
ss->excludedMove = move;
ss->skipNullMove = true;
- Value v = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2);
+ value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2);
ss->skipNullMove = false;
ss->excludedMove = MOVE_NONE;
ss->bestMove = MOVE_NONE;
- if (v < rBeta)
+ if (value < rBeta)
ext = ONE_PLY;
}
}
&& !inCheck
&& !dangerous
&& move != ttMove
- && !move_is_castle(move))
+ && !is_castle(move)
+ && (bestValue > VALUE_MATED_IN_PLY_MAX || bestValue == -VALUE_INFINITE))
{
// Move count based pruning
if ( moveCount >= futility_move_count(depth)
- && (!threatMove || !connected_threat(pos, move, threatMove))
- && bestValue > VALUE_MATED_IN_PLY_MAX) // FIXME bestValue is racy
+ && (!threatMove || !connected_threat(pos, move, threatMove)))
{
if (SpNode)
lock_grab(&(sp->lock));
// We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth,
// but fixing this made program slightly weaker.
Depth predictedDepth = newDepth - reduction<PvNode>(depth, moveCount);
- futilityValueScaled = futilityBase + futility_margin(predictedDepth, moveCount)
- + H.gain(pos.piece_on(move_from(move)), move_to(move));
+ futilityValue = futilityBase + futility_margin(predictedDepth, moveCount)
+ + H.gain(pos.piece_on(move_from(move)), move_to(move));
- if (futilityValueScaled < beta)
+ if (futilityValue < beta)
{
if (SpNode)
- {
lock_grab(&(sp->lock));
- if (futilityValueScaled > sp->bestValue)
- sp->bestValue = bestValue = futilityValueScaled;
- }
- else if (futilityValueScaled > bestValue)
- bestValue = futilityValueScaled;
continue;
}
// Prune moves with negative SEE at low depths
if ( predictedDepth < 2 * ONE_PLY
- && bestValue > VALUE_MATED_IN_PLY_MAX
&& pos.see_sign(move) < 0)
{
if (SpNode)
// Step 14. Make the move
pos.do_move(move, st, ci, givesCheck);
- // Step extra. pv search (only in PV nodes)
- // The first move in list is the expected PV
- if (isPvMove)
- value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
- else
+ // Step 15. Reduced depth search (LMR). If the move fails high will be
+ // re-searched at full depth.
+ if ( depth > 3 * ONE_PLY
+ && !isPvMove
+ && !captureOrPromotion
+ && !dangerous
+ && !is_castle(move)
+ && ss->killers[0] != move
+ && ss->killers[1] != move)
{
- // Step 15. Reduced depth search
- // If the move fails high will be re-searched at full depth.
- bool doFullDepthSearch = true;
-
- if ( depth > 3 * ONE_PLY
- && !captureOrPromotion
- && !dangerous
- && !move_is_castle(move)
- && ss->killers[0] != move
- && ss->killers[1] != move
- && (ss->reduction = reduction<PvNode>(depth, moveCount)) != DEPTH_ZERO)
- {
- Depth d = newDepth - ss->reduction;
- alpha = SpNode ? sp->alpha : alpha;
+ ss->reduction = reduction<PvNode>(depth, moveCount);
+ Depth d = newDepth - ss->reduction;
+ alpha = SpNode ? sp->alpha : alpha;
- value = d < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
+ value = d < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
- ss->reduction = DEPTH_ZERO;
- doFullDepthSearch = (value > alpha);
- }
+ doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
+ ss->reduction = DEPTH_ZERO;
+ }
+ else
+ doFullDepthSearch = !isPvMove;
- // Step 16. Full depth search
- if (doFullDepthSearch)
- {
- alpha = SpNode ? sp->alpha : alpha;
- value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
-
- // Step extra. pv search (only in PV nodes)
- // Search only for possible new PV nodes, if instead value >= beta then
- // parent node fails low with value <= alpha and tries another move.
- if (PvNode && value > alpha && (RootNode || value < beta))
- value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
- }
+ // Step 16. Full depth search, when LMR is skipped or fails high
+ if (doFullDepthSearch)
+ {
+ alpha = SpNode ? sp->alpha : alpha;
+ value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
}
+ // Only for PV nodes do a full PV search on the first move or after a fail
+ // high, in the latter case search only if value < beta, otherwise let the
+ // parent node to fail low with value <= alpha and to try another move.
+ if (PvNode && (isPvMove || (value > alpha && (RootNode || value < beta))))
+ value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
+
// Step 17. Undo move
pos.undo_move(move);
alpha = sp->alpha;
}
+ // Finished searching the move. If StopRequest is true, the search
+ // was aborted because the user interrupted the search or because we
+ // ran out of time. In this case, the return value of the search cannot
+ // be trusted, and we don't update the best move and/or PV.
+ if (RootNode && !Signals.stop)
+ {
+ RootMove& rm = *find(RootMoves.begin(), RootMoves.end(), move);
+ rm.nodes += pos.nodes_searched() - nodes;
+
+ // PV move or new best move ?
+ if (isPvMove || value > alpha)
+ {
+ rm.score = value;
+ rm.extract_pv_from_tt(pos);
+
+ // We record how often the best move has been changed in each
+ // iteration. This information is used for time management: When
+ // the best move changes frequently, we allocate some more time.
+ if (!isPvMove && MultiPV == 1)
+ BestMoveChanges++;
+ }
+ else
+ // All other moves but the PV are set to the lowest value, this
+ // is not a problem when sorting becuase sort is stable and move
+ // position in the list is preserved, just the PV is pushed up.
+ rm.score = -VALUE_INFINITE;
+
+ }
+
if (value > bestValue)
{
bestValue = value;
ss->bestMove = move;
- if ( !RootNode
- && PvNode
+ if ( PvNode
&& value > alpha
&& value < beta) // We want always alpha < beta
alpha = value;
}
}
- if (RootNode)
- {
- // Finished searching the move. If StopRequest is true, the search
- // was aborted because the user interrupted the search or because we
- // ran out of time. In this case, the return value of the search cannot
- // be trusted, and we break out of the loop without updating the best
- // move and/or PV.
- if (StopRequest)
- break;
-
- // Remember searched nodes counts for this move
- mp.current().nodes += pos.nodes_searched() - nodes;
-
- // PV move or new best move ?
- if (isPvMove || value > alpha)
- {
- // Update PV
- mp.current().pv_score = value;
- mp.current().extract_pv_from_tt(pos);
-
- // We record how often the best move has been changed in each
- // iteration. This information is used for time management: When
- // the best move changes frequently, we allocate some more time.
- if (!isPvMove && MultiPV == 1)
- Rml.bestMoveChanges++;
-
- // It is critical that sorting is done with a stable algorithm
- // because all the values but the first are usually set to
- // -VALUE_INFINITE and we want to keep the same order for all
- // the moves but the new PV that goes to head.
- sort<RootMove>(Rml.begin(), Rml.begin() + moveCount);
-
- // Update alpha. In multi-pv we don't use aspiration window, so set
- // alpha equal to minimum score among the PV lines searched so far.
- if (MultiPV > 1)
- alpha = Rml[Min(moveCount, MultiPV) - 1].pv_score;
- else if (value > alpha)
- alpha = value;
- }
- else
- // All other moves but the PV are set to the lowest value, this
- // is not a problem when sorting becuase sort is stable and move
- // position in the list is preserved, just the PV is pushed up.
- mp.current().pv_score = -VALUE_INFINITE;
-
- } // RootNode
-
// Step 19. Check for split
- if ( !RootNode
- && !SpNode
+ if ( !SpNode
&& depth >= Threads.min_split_depth()
&& bestValue < beta
&& Threads.available_slave_exists(pos.thread())
- && !StopRequest
+ && !Signals.stop
&& !thread.cutoff_occurred())
- Threads.split<FakeSplit>(pos, ss, &alpha, beta, &bestValue, depth,
- threatMove, moveCount, &mp, PvNode);
+ bestValue = Threads.split<FakeSplit>(pos, ss, alpha, beta, bestValue, depth,
+ threatMove, moveCount, &mp, NT);
}
// Step 20. Check for mate and stalemate
- // All legal moves have been searched and if there are
- // no legal moves, it must be mate or stalemate.
- // If one move was excluded return fail low score.
- if (!SpNode && !moveCount)
+ // All legal moves have been searched and if there are no legal moves, it
+ // must be mate or stalemate. Note that we can have a false positive in
+ // case of StopRequest or thread.cutoff_occurred() are set, but this is
+ // harmless because return value is discarded anyhow in the parent nodes.
+ // If we are in a singular extension search then return a fail low score.
+ if (!moveCount)
return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW;
+ // If we have pruned all the moves without searching return a fail-low score
+ if (bestValue == -VALUE_INFINITE)
+ {
+ assert(!playedMoveCount);
+
+ bestValue = alpha;
+ }
+
// Step 21. Update tables
- // If the search is not aborted, update the transposition table,
- // history counters, and killer moves.
- if (!SpNode && !StopRequest && !thread.cutoff_occurred())
+ // Update transposition table entry, killers and history
+ if (!SpNode && !Signals.stop && !thread.cutoff_occurred())
{
move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
TT.store(posKey, value_to_tt(bestValue, ss->ply), vt, depth, move, ss->eval, ss->evalMargin);
- // Update killers and history only for non capture moves that fails high
+ // Update killers and history for non capture cut-off moves
if ( bestValue >= beta
- && !pos.move_is_capture_or_promotion(move))
+ && !pos.is_capture_or_promotion(move)
+ && !inCheck)
{
if (move != ss->killers[0])
{
ss->killers[1] = ss->killers[0];
ss->killers[0] = move;
}
- update_history(pos, move, depth, movesSearched, playedMoveCount);
+
+ // Increase history value of the cut-off move
+ Value bonus = Value(int(depth) * int(depth));
+ H.add(pos.piece_on(move_from(move)), move_to(move), bonus);
+
+ // Decrease history of all the other played non-capture moves
+ for (int i = 0; i < playedMoveCount - 1; i++)
+ {
+ Move m = movesSearched[i];
+ H.add(pos.piece_on(move_from(m)), move_to(m), -bonus);
+ }
}
}
return bestValue;
}
+
// qsearch() is the quiescence search function, which is called by the main
// search function when the remaining depth is zero (or, to be more precise,
// less than ONE_PLY).
template <NodeType NT>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
const bool PvNode = (NT == PV);
bool inCheck, enoughMaterial, givesCheck, evasionPrunable;
const TTEntry* tte;
Depth ttDepth;
+ ValueType vt;
Value oldAlpha = alpha;
ss->bestMove = ss->currentMove = MOVE_NONE;
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
- tte = TT.probe(pos.get_key());
+ tte = TT.probe(pos.key());
ttMove = (tte ? tte->move() : MOVE_NONE);
- if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ss->ply))
+ if (!PvNode && tte && can_return_tt(tte, ttDepth, beta, ss->ply))
{
ss->bestMove = ttMove; // Can be MOVE_NONE
return value_from_tt(tte->value(), ss->ply);
if (bestValue >= beta)
{
if (!tte)
- TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), VALUE_TYPE_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin);
+ TT.store(pos.key(), value_to_tt(bestValue, ss->ply), VALUE_TYPE_LOWER, DEPTH_NONE, MOVE_NONE, ss->eval, evalMargin);
return bestValue;
}
if (PvNode && bestValue > alpha)
alpha = bestValue;
- // Futility pruning parameters, not needed when in check
futilityBase = ss->eval + evalMargin + FutilityMarginQS;
enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
}
CheckInfo ci(pos);
// Loop through the moves until no moves remain or a beta cutoff occurs
- while ( alpha < beta
- && (move = mp.get_next_move()) != MOVE_NONE)
+ while ( bestValue < beta
+ && (move = mp.next_move()) != MOVE_NONE)
{
- assert(move_is_ok(move));
+ assert(is_ok(move));
givesCheck = pos.move_gives_check(move, ci);
&& !givesCheck
&& move != ttMove
&& enoughMaterial
- && !move_is_promotion(move)
- && !pos.move_is_passed_pawn_push(move))
+ && !is_promotion(move)
+ && !pos.is_passed_pawn_push(move))
{
futilityValue = futilityBase
- + piece_value_endgame(pos.piece_on(move_to(move)))
- + (move_is_ep(move) ? PawnValueEndgame : VALUE_ZERO);
+ + PieceValueEndgame[pos.piece_on(move_to(move))]
+ + (is_enpassant(move) ? PawnValueEndgame : VALUE_ZERO);
- if (futilityValue < alpha)
+ if (futilityValue < beta)
{
if (futilityValue > bestValue)
bestValue = futilityValue;
+
continue;
}
evasionPrunable = !PvNode
&& inCheck
&& bestValue > VALUE_MATED_IN_PLY_MAX
- && !pos.move_is_capture(move)
+ && !pos.is_capture(move)
&& !pos.can_castle(pos.side_to_move());
// Don't search moves with negative SEE values
if ( !PvNode
&& (!inCheck || evasionPrunable)
&& move != ttMove
- && !move_is_promotion(move)
+ && !is_promotion(move)
&& pos.see_sign(move) < 0)
continue;
&& !inCheck
&& givesCheck
&& move != ttMove
- && !pos.move_is_capture_or_promotion(move)
+ && !pos.is_capture_or_promotion(move)
&& ss->eval + PawnValueMidgame / 4 < beta
&& !check_is_dangerous(pos, move, futilityBase, beta, &bestValue))
{
if (!pos.pl_move_is_legal(move, ci.pinned))
continue;
- // Update current move
ss->currentMove = move;
// Make and search the move
if (value > bestValue)
{
bestValue = value;
- if (value > alpha)
- {
+ ss->bestMove = move;
+
+ if ( PvNode
+ && value > alpha
+ && value < beta) // We want always alpha < beta
alpha = value;
- ss->bestMove = move;
- }
}
}
return value_mated_in(ss->ply);
// Update transposition table
- ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
- TT.store(pos.get_key(), value_to_tt(bestValue, ss->ply), vt, ttDepth, ss->bestMove, ss->eval, evalMargin);
+ move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
+ vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
+ : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT;
+
+ TT.store(pos.key(), value_to_tt(bestValue, ss->ply), vt, ttDepth, move, ss->eval, evalMargin);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
from = move_from(move);
to = move_to(move);
- them = opposite_color(pos.side_to_move());
+ them = flip(pos.side_to_move());
ksq = pos.king_square(them);
kingAtt = pos.attacks_from<KING>(ksq);
pc = pos.piece_on(from);
return true;
// Rule 2. Queen contact check is very dangerous
- if ( piece_type(pc) == QUEEN
+ if ( type_of(pc) == QUEEN
&& bit_is_set(kingAtt, to))
return true;
while (b)
{
victimSq = pop_1st_bit(&b);
- futilityValue = futilityBase + piece_value_endgame(pos.piece_on(victimSq));
+ futilityValue = futilityBase + PieceValueEndgame[pos.piece_on(victimSq)];
// Note that here we generate illegal "double move"!
if ( futilityValue >= beta
Square f1, t1, f2, t2;
Piece p1, p2;
+ Square ksq;
- assert(m1 && move_is_ok(m1));
- assert(m2 && move_is_ok(m2));
+ assert(is_ok(m1));
+ assert(is_ok(m2));
// Case 1: The moving piece is the same in both moves
f2 = move_from(m2);
return true;
// Case 5: Discovered check, checking piece is the piece moved in m1
+ ksq = pos.king_square(pos.side_to_move());
if ( piece_is_slider(p1)
- && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2)
- && !bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), t2))
+ && bit_is_set(squares_between(t1, ksq), f2))
{
- // discovered_check_candidates() works also if the Position's side to
- // move is the opposite of the checking piece.
- Color them = opposite_color(pos.side_to_move());
- Bitboard dcCandidates = pos.discovered_check_candidates(them);
-
- if (bit_is_set(dcCandidates, f2))
+ Bitboard occ = pos.occupied_squares();
+ clear_bit(&occ, f2);
+ if (bit_is_set(pos.attacks_from(p1, t1, occ), ksq))
return true;
}
return false;
// value_to_tt() adjusts a mate score from "plies to mate from the root" to
- // "plies to mate from the current ply". Non-mate scores are unchanged.
- // The function is called before storing a value to the transposition table.
+ // "plies to mate from the current ply". Non-mate scores are unchanged. The
+ // function is called before storing a value to the transposition table.
Value value_to_tt(Value v, int ply) {
bool connected_threat(const Position& pos, Move m, Move threat) {
- assert(move_is_ok(m));
- assert(threat && move_is_ok(threat));
- assert(!pos.move_is_capture_or_promotion(m));
- assert(!pos.move_is_passed_pawn_push(m));
+ assert(is_ok(m));
+ assert(is_ok(threat));
+ assert(!pos.is_capture_or_promotion(m));
+ assert(!pos.is_passed_pawn_push(m));
Square mfrom, mto, tfrom, tto;
// Case 2: If the threatened piece has value less than or equal to the
// value of the threatening piece, don't prune moves which defend it.
- if ( pos.move_is_capture(threat)
- && ( piece_value_midgame(pos.piece_on(tfrom)) >= piece_value_midgame(pos.piece_on(tto))
- || piece_type(pos.piece_on(tfrom)) == KING)
+ if ( pos.is_capture(threat)
+ && ( PieceValueMidgame[pos.piece_on(tfrom)] >= PieceValueMidgame[pos.piece_on(tto)]
+ || type_of(pos.piece_on(tfrom)) == KING)
&& pos.move_attacks_square(m, tto))
return true;
}
- // ok_to_use_TT() returns true if a transposition table score
- // can be used at a given point in search.
+ // can_return_tt() returns true if a transposition table score can be used to
+ // cut-off at a given point in search.
- bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply) {
+ bool can_return_tt(const TTEntry* tte, Depth depth, Value beta, int ply) {
Value v = value_from_tt(tte->value(), ply);
return ( tte->depth() >= depth
- || v >= Max(VALUE_MATE_IN_PLY_MAX, beta)
- || v < Min(VALUE_MATED_IN_PLY_MAX, beta))
+ || v >= std::max(VALUE_MATE_IN_PLY_MAX, beta)
+ || v < std::min(VALUE_MATED_IN_PLY_MAX, beta))
&& ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta)
|| ((tte->type() & VALUE_TYPE_UPPER) && v < beta));
}
- // refine_eval() returns the transposition table score if
- // possible otherwise falls back on static position evaluation.
+ // refine_eval() returns the transposition table score if possible, otherwise
+ // falls back on static position evaluation.
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) {
}
- // update_history() registers a good move that produced a beta-cutoff
- // in history and marks as failures all the other moves of that ply.
-
- void update_history(const Position& pos, Move move, Depth depth,
- Move movesSearched[], int moveCount) {
- Move m;
- Value bonus = Value(int(depth) * int(depth));
-
- H.update(pos.piece_on(move_from(move)), move_to(move), bonus);
-
- for (int i = 0; i < moveCount - 1; i++)
- {
- m = movesSearched[i];
-
- assert(m != move);
-
- H.update(pos.piece_on(move_from(m)), move_to(m), -bonus);
- }
- }
-
-
- // update_gains() updates the gains table of a non-capture move given
- // the static position evaluation before and after the move.
-
- void update_gains(const Position& pos, Move m, Value before, Value after) {
-
- if ( m != MOVE_NULL
- && before != VALUE_NONE
- && after != VALUE_NONE
- && pos.captured_piece_type() == PIECE_TYPE_NONE
- && !move_is_special(m))
- H.update_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after));
- }
-
-
// current_search_time() returns the number of milliseconds which have passed
// since the beginning of the current search.
- int current_search_time(int set) {
+ int elapsed_time(bool reset) {
static int searchStartTime;
- if (set)
- searchStartTime = set;
+ if (reset)
+ searchStartTime = system_time();
- return get_system_time() - searchStartTime;
+ return system_time() - searchStartTime;
}
// mate <y> Mate in y moves, not plies. If the engine is getting mated
// use negative values for y.
- std::string score_to_uci(Value v, Value alpha, Value beta) {
+ string score_to_uci(Value v, Value alpha, Value beta) {
std::stringstream s;
}
- // speed_to_uci() returns a string with time stats of current search suitable
- // to be sent to UCI gui.
+ // pv_info_to_uci() sends search info to GUI. UCI protocol requires to send all
+ // the PV lines also if are still to be searched and so refer to the previous
+ // search score.
- std::string speed_to_uci(int64_t nodes) {
-
- std::stringstream s;
- int t = current_search_time();
+ void pv_info_to_uci(const Position& pos, int depth, Value alpha, Value beta) {
- s << " nodes " << nodes
- << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0)
- << " time " << t;
+ int t = elapsed_time();
+ int selDepth = 0;
- return s.str();
- }
+ for (int i = 0; i < Threads.size(); i++)
+ if (Threads[i].maxPly > selDepth)
+ selDepth = Threads[i].maxPly;
- // pv_to_uci() returns a string with information on the current PV line
- // formatted according to UCI specification.
+ for (size_t i = 0; i < std::min(UCIMultiPV, RootMoves.size()); i++)
+ {
+ bool updated = (i <= PVIdx);
- std::string pv_to_uci(Move pv[], int pvNum) {
+ if (depth == 1 && !updated)
+ continue;
- std::stringstream s;
+ int d = (updated ? depth : depth - 1);
+ Value v = (updated ? RootMoves[i].score : RootMoves[i].prevScore);
+ std::stringstream s;
+
+ for (int j = 0; RootMoves[i].pv[j] != MOVE_NONE; j++)
+ s << " " << move_to_uci(RootMoves[i].pv[j], Chess960);
+
+ cout << "info depth " << d
+ << " seldepth " << selDepth
+ << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v))
+ << " nodes " << pos.nodes_searched()
+ << " nps " << (t > 0 ? pos.nodes_searched() * 1000 / t : 0)
+ << " time " << t
+ << " multipv " << i + 1
+ << " pv" << s.str() << endl;
+ }
+ }
- s << " multipv " << pvNum << " pv ";
- for ( ; *pv != MOVE_NONE; pv++)
- s << *pv << " ";
+ // pv_info_to_log() writes human-readable search information to the log file
+ // (which is created when the UCI parameter "Use Search Log" is "true"). It
+ // uses the two below helpers to pretty format time and score respectively.
- return s.str();
- }
+ string time_to_string(int millisecs) {
- // depth_to_uci() returns a string with information on the current depth and
- // seldepth formatted according to UCI specification.
+ const int MSecMinute = 1000 * 60;
+ const int MSecHour = 1000 * 60 * 60;
- std::string depth_to_uci(Depth depth) {
+ int hours = millisecs / MSecHour;
+ int minutes = (millisecs % MSecHour) / MSecMinute;
+ int seconds = ((millisecs % MSecHour) % MSecMinute) / 1000;
std::stringstream s;
- // Retrieve max searched depth among threads
- int selDepth = 0;
- for (int i = 0; i < Threads.size(); i++)
- if (Threads[i].maxPly > selDepth)
- selDepth = Threads[i].maxPly;
-
- s << " depth " << depth / ONE_PLY << " seldepth " << selDepth;
+ if (hours)
+ s << hours << ':';
+ s << std::setfill('0') << std::setw(2) << minutes << ':'
+ << std::setw(2) << seconds;
return s.str();
}
+ string score_to_string(Value v) {
- // poll() performs two different functions: It polls for user input, and it
- // looks at the time consumed so far and decides if it's time to abort the
- // search.
-
- void poll(const Position& pos) {
-
- static int lastInfoTime;
- int t = current_search_time();
-
- // Poll for input
- if (input_available())
- {
- // We are line oriented, don't read single chars
- std::string command;
-
- if (!std::getline(std::cin, command) || command == "quit")
- {
- // Quit the program as soon as possible
- Limits.ponder = false;
- QuitRequest = StopRequest = true;
- return;
- }
- else if (command == "stop")
- {
- // Stop calculating as soon as possible, but still send the "bestmove"
- // and possibly the "ponder" token when finishing the search.
- Limits.ponder = false;
- StopRequest = true;
- }
- else if (command == "ponderhit")
- {
- // The opponent has played the expected move. GUI sends "ponderhit" if
- // we were told to ponder on the same move the opponent has played. We
- // should continue searching but switching from pondering to normal search.
- Limits.ponder = false;
+ std::stringstream s;
- if (StopOnPonderhit)
- StopRequest = true;
- }
- }
+ if (v >= VALUE_MATE_IN_PLY_MAX)
+ s << "#" << (VALUE_MATE - v + 1) / 2;
+ else if (v <= VALUE_MATED_IN_PLY_MAX)
+ s << "-#" << (VALUE_MATE + v) / 2;
+ else
+ s << std::setprecision(2) << std::fixed << std::showpos
+ << float(v) / PawnValueMidgame;
- // Print search information
- if (t < 1000)
- lastInfoTime = 0;
+ return s.str();
+ }
- else if (lastInfoTime > t)
- // HACK: Must be a new search where we searched less than
- // NodesBetweenPolls nodes during the first second of search.
- lastInfoTime = 0;
+ void pv_info_to_log(Position& pos, int depth, Value value, int time, Move pv[]) {
- else if (t - lastInfoTime >= 1000)
- {
- lastInfoTime = t;
+ const int64_t K = 1000;
+ const int64_t M = 1000000;
- dbg_print_mean();
- dbg_print_hit_rate();
+ StateInfo state[PLY_MAX_PLUS_2], *st = state;
+ Move* m = pv;
+ string san, padding;
+ size_t length;
+ std::stringstream s;
- // Send info on searched nodes as soon as we return to root
- SendSearchedNodes = true;
- }
+ s << std::setw(2) << depth
+ << std::setw(8) << score_to_string(value)
+ << std::setw(8) << time_to_string(time);
- // Should we stop the search?
- if (Limits.ponder)
- return;
+ if (pos.nodes_searched() < M)
+ s << std::setw(8) << pos.nodes_searched() / 1 << " ";
- bool stillAtFirstMove = FirstRootMove
- && !AspirationFailLow
- && t > TimeMgr.available_time();
+ else if (pos.nodes_searched() < K * M)
+ s << std::setw(7) << pos.nodes_searched() / K << "K ";
- bool noMoreTime = t > TimeMgr.maximum_time()
- || stillAtFirstMove;
+ else
+ s << std::setw(7) << pos.nodes_searched() / M << "M ";
- if ( (Limits.useTimeManagement() && noMoreTime)
- || (Limits.maxTime && t >= Limits.maxTime)
- || (Limits.maxNodes && pos.nodes_searched() >= Limits.maxNodes)) // FIXME
- StopRequest = true;
- }
+ padding = string(s.str().length(), ' ');
+ length = padding.length();
+ while (*m != MOVE_NONE)
+ {
+ san = move_to_san(pos, *m);
- // wait_for_stop_or_ponderhit() is called when the maximum depth is reached
- // while the program is pondering. The point is to work around a wrinkle in
- // the UCI protocol: When pondering, the engine is not allowed to give a
- // "bestmove" before the GUI sends it a "stop" or "ponderhit" command.
- // We simply wait here until one of these commands is sent, and return,
- // after which the bestmove and pondermove will be printed.
+ if (length + san.length() > 80)
+ {
+ s << "\n" + padding;
+ length = padding.length();
+ }
- void wait_for_stop_or_ponderhit() {
+ s << san << ' ';
+ length += san.length() + 1;
- std::string command;
+ pos.do_move(*m++, *st++);
+ }
- // Wait for a command from stdin
- while ( std::getline(std::cin, command)
- && command != "ponderhit" && command != "stop" && command != "quit") {};
+ while (m != pv)
+ pos.undo_move(*--m);
- if (command != "ponderhit" && command != "stop")
- QuitRequest = true; // Must be "quit" or getline() returned false
+ Log l(Options["Search Log Filename"].value<string>());
+ l << s.str() << endl;
}
// When playing with strength handicap choose best move among the MultiPV set
// using a statistical rule dependent on SkillLevel. Idea by Heinz van Saanen.
- void do_skill_level(Move* best, Move* ponder) {
+
+ Move do_skill_level() {
assert(MultiPV > 1);
static RKISS rk;
- // Rml list is already sorted by pv_score in descending order
- int s;
- int max_s = -VALUE_INFINITE;
- int size = Min(MultiPV, (int)Rml.size());
- int max = Rml[0].pv_score;
- int var = Min(max - Rml[size - 1].pv_score, PawnValueMidgame);
- int wk = 120 - 2 * SkillLevel;
-
- // PRNG sequence should be non deterministic
- for (int i = abs(get_system_time() % 50); i > 0; i--)
+ // PRNG sequence should be not deterministic
+ for (int i = abs(system_time() % 50); i > 0; i--)
rk.rand<unsigned>();
- // Choose best move. For each move's score we add two terms both dependent
- // on wk, one deterministic and bigger for weaker moves, and one random,
+ // RootMoves are already sorted by score in descending order
+ size_t size = std::min(MultiPV, RootMoves.size());
+ int variance = std::min(RootMoves[0].score - RootMoves[size - 1].score, PawnValueMidgame);
+ int weakness = 120 - 2 * SkillLevel;
+ int max_s = -VALUE_INFINITE;
+ Move best = MOVE_NONE;
+
+ // Choose best move. For each move score we add two terms both dependent on
+ // weakness, one deterministic and bigger for weaker moves, and one random,
// then we choose the move with the resulting highest score.
- for (int i = 0; i < size; i++)
+ for (size_t i = 0; i < size; i++)
{
- s = Rml[i].pv_score;
+ int s = RootMoves[i].score;
// Don't allow crazy blunders even at very low skills
- if (i > 0 && Rml[i-1].pv_score > s + EasyMoveMargin)
+ if (i > 0 && RootMoves[i-1].score > s + EasyMoveMargin)
break;
- // This is our magical formula
- s += ((max - s) * wk + var * (rk.rand<unsigned>() % wk)) / 128;
+ // This is our magic formula
+ s += ( weakness * int(RootMoves[0].score - s)
+ + variance * (rk.rand<unsigned>() % weakness)) / 128;
if (s > max_s)
{
max_s = s;
- *best = Rml[i].pv[0];
- *ponder = Rml[i].pv[1];
+ best = RootMoves[i].pv[0];
}
}
+ return best;
}
- /// RootMove and RootMoveList method's definitions
-
- RootMove::RootMove() {
-
- nodes = 0;
- pv_score = non_pv_score = -VALUE_INFINITE;
- pv[0] = MOVE_NONE;
- }
-
- RootMove& RootMove::operator=(const RootMove& rm) {
-
- const Move* src = rm.pv;
- Move* dst = pv;
-
- // Avoid a costly full rm.pv[] copy
- do *dst++ = *src; while (*src++ != MOVE_NONE);
-
- nodes = rm.nodes;
- pv_score = rm.pv_score;
- non_pv_score = rm.non_pv_score;
- return *this;
- }
-
- void RootMoveList::init(Position& pos, Move searchMoves[]) {
-
- Move* sm;
- bestMoveChanges = 0;
- clear();
-
- // Generate all legal moves and add them to RootMoveList
- for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
- {
- // If we have a searchMoves[] list then verify the move
- // is in the list before to add it.
- for (sm = searchMoves; *sm && *sm != ml.move(); sm++) {}
-
- if (sm != searchMoves && *sm != ml.move())
- continue;
-
- RootMove rm;
- rm.pv[0] = ml.move();
- rm.pv[1] = MOVE_NONE;
- rm.pv_score = -VALUE_INFINITE;
- push_back(rm);
- }
- }
-
// extract_pv_from_tt() builds a PV by adding moves from the transposition table.
// We consider also failing high nodes and not only VALUE_TYPE_EXACT nodes. This
// allow to always have a ponder move even when we fail high at root and also a
StateInfo state[PLY_MAX_PLUS_2], *st = state;
TTEntry* tte;
int ply = 1;
+ Move m = pv[0];
- assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0]));
+ assert(m != MOVE_NONE && pos.is_pseudo_legal(m));
- pos.do_move(pv[0], *st++);
+ pv.clear();
+ pv.push_back(m);
+ pos.do_move(m, *st++);
- while ( (tte = TT.probe(pos.get_key())) != NULL
+ while ( (tte = TT.probe(pos.key())) != NULL
&& tte->move() != MOVE_NONE
- && pos.move_is_pl(tte->move())
- && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces(pos.side_to_move()))
+ && pos.is_pseudo_legal(tte->move())
+ && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces())
&& ply < PLY_MAX
&& (!pos.is_draw<false>() || ply < 2))
{
- pv[ply] = tte->move();
- pos.do_move(pv[ply++], *st++);
+ pv.push_back(tte->move());
+ pos.do_move(tte->move(), *st++);
+ ply++;
}
- pv[ply] = MOVE_NONE;
+ pv.push_back(MOVE_NONE);
do pos.undo_move(pv[--ply]); while (ply);
}
+
// insert_pv_in_tt() is called at the end of a search iteration, and inserts
// the PV back into the TT. This makes sure the old PV moves are searched
// first, even if the old TT entries have been overwritten.
Value v, m = VALUE_NONE;
int ply = 0;
- assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0]));
+ assert(pv[ply] != MOVE_NONE && pos.is_pseudo_legal(pv[ply]));
do {
- k = pos.get_key();
+ k = pos.key();
tte = TT.probe(k);
// Don't overwrite existing correct entries
do pos.undo_move(pv[--ply]); while (ply);
}
- // Specializations for MovePickerExt in case of Root node
- MovePickerExt<Root>::MovePickerExt(const Position& p, Move ttm, Depth d,
- const History& h, SearchStack* ss, Value b)
- : MovePicker(p, ttm, d, h, ss, b), cur(-1) {
- Move move;
- Value score = VALUE_ZERO;
-
- // Score root moves using standard ordering used in main search, the moves
- // are scored according to the order in which they are returned by MovePicker.
- // This is the second order score that is used to compare the moves when
- // the first orders pv_score of both moves are equal.
- while ((move = MovePicker::get_next_move()) != MOVE_NONE)
- for (RootMoveList::iterator rm = Rml.begin(); rm != Rml.end(); ++rm)
- if (rm->pv[0] == move)
- {
- rm->non_pv_score = score--;
- break;
- }
-
- sort<RootMove>(Rml.begin(), Rml.end());
- }
-
} // namespace
-// ThreadsManager::idle_loop() is where the threads are parked when they have no work
-// to do. The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint
-// object for which the current thread is the master.
-
-void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) {
+/// Thread::idle_loop() is where the thread is parked when it has no work to do.
+/// The parameter 'sp', if non-NULL, is a pointer to an active SplitPoint object
+/// for which the thread is the master.
- assert(threadID >= 0 && threadID < MAX_THREADS);
-
- int i;
- bool allFinished;
+void Thread::idle_loop(SplitPoint* sp) {
while (true)
{
- // Slave threads can exit as soon as AllThreadsShouldExit raises,
- // master should exit as last one.
- if (allThreadsShouldExit)
- {
- assert(!sp);
- threads[threadID].state = Thread::TERMINATED;
- return;
- }
-
- // If we are not thinking, wait for a condition to be signaled
+ // If we are not searching, wait for a condition to be signaled
// instead of wasting CPU time polling for work.
- while ( threadID >= activeThreads
- || threads[threadID].state == Thread::INITIALIZING
- || (useSleepingThreads && threads[threadID].state == Thread::AVAILABLE))
+ while ( do_sleep
+ || do_terminate
+ || (Threads.use_sleeping_threads() && !is_searching))
{
- assert(!sp || useSleepingThreads);
- assert(threadID != 0 || useSleepingThreads);
+ assert((!sp && threadID) || Threads.use_sleeping_threads());
- if (threads[threadID].state == Thread::INITIALIZING)
- threads[threadID].state = Thread::AVAILABLE;
+ if (do_terminate)
+ {
+ assert(!sp);
+ return;
+ }
// Grab the lock to avoid races with Thread::wake_up()
- lock_grab(&threads[threadID].sleepLock);
+ lock_grab(&sleepLock);
- // If we are master and all slaves have finished do not go to sleep
- for (i = 0; sp && i < activeThreads && !sp->is_slave[i]; i++) {}
- allFinished = (i == activeThreads);
-
- if (allFinished || allThreadsShouldExit)
+ // If we are master and all slaves have finished don't go to sleep
+ if (sp && Threads.split_point_finished(sp))
{
- lock_release(&threads[threadID].sleepLock);
+ lock_release(&sleepLock);
break;
}
- // Do sleep here after retesting sleep conditions
- if (threadID >= activeThreads || threads[threadID].state == Thread::AVAILABLE)
- cond_wait(&threads[threadID].sleepCond, &threads[threadID].sleepLock);
+ // Do sleep after retesting sleep conditions under lock protection, in
+ // particular we need to avoid a deadlock in case a master thread has,
+ // in the meanwhile, allocated us and sent the wake_up() call before we
+ // had the chance to grab the lock.
+ if (do_sleep || !is_searching)
+ cond_wait(&sleepCond, &sleepLock);
- lock_release(&threads[threadID].sleepLock);
+ lock_release(&sleepLock);
}
// If this thread has been assigned work, launch a search
- if (threads[threadID].state == Thread::WORKISWAITING)
+ if (is_searching)
{
- assert(!allThreadsShouldExit);
-
- threads[threadID].state = Thread::SEARCHING;
+ assert(!do_terminate);
// Copy split point position and search stack and call search()
- // with SplitPoint template parameter set to true.
- SearchStack ss[PLY_MAX_PLUS_2];
- SplitPoint* tsp = threads[threadID].splitPoint;
+ Stack ss[PLY_MAX_PLUS_2];
+ SplitPoint* tsp = splitPoint;
Position pos(*tsp->pos, threadID);
- memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack));
+ memcpy(ss, tsp->ss - 1, 4 * sizeof(Stack));
(ss+1)->sp = tsp;
- if (tsp->pvNode)
+ if (tsp->nodeType == Root)
+ search<SplitPointRoot>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ else if (tsp->nodeType == PV)
search<SplitPointPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
- else
+ else if (tsp->nodeType == NonPV)
search<SplitPointNonPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ else
+ assert(false);
- assert(threads[threadID].state == Thread::SEARCHING);
+ assert(is_searching);
- threads[threadID].state = Thread::AVAILABLE;
+ is_searching = false;
// Wake up master thread so to allow it to return from the idle loop in
// case we are the last slave of the split point.
- if ( useSleepingThreads
+ if ( Threads.use_sleeping_threads()
&& threadID != tsp->master
- && threads[tsp->master].state == Thread::AVAILABLE)
- threads[tsp->master].wake_up();
+ && !Threads[tsp->master].is_searching)
+ Threads[tsp->master].wake_up();
}
// If this thread is the master of a split point and all slaves have
// finished their work at this split point, return from the idle loop.
- for (i = 0; sp && i < activeThreads && !sp->is_slave[i]; i++) {}
- allFinished = (i == activeThreads);
-
- if (allFinished)
+ if (sp && Threads.split_point_finished(sp))
{
- // Because sp->slaves[] is reset under lock protection,
+ // Because sp->is_slave[] is reset under lock protection,
// be sure sp->lock has been released before to return.
lock_grab(&(sp->lock));
lock_release(&(sp->lock));
-
- // In helpful master concept a master can help only a sub-tree, and
- // because here is all finished is not possible master is booked.
- assert(threads[threadID].state == Thread::AVAILABLE);
-
- threads[threadID].state = Thread::SEARCHING;
return;
}
}
}
+
+
+/// do_timer_event() is called by the timer thread when the timer triggers. It
+/// is used to print debug info and, more important, to detect when we are out of
+/// available time and so stop the search.
+
+void do_timer_event() {
+
+ static int lastInfoTime;
+ int e = elapsed_time();
+
+ if (system_time() - lastInfoTime >= 1000 || !lastInfoTime)
+ {
+ lastInfoTime = system_time();
+
+ dbg_print_mean();
+ dbg_print_hit_rate();
+ }
+
+ if (Limits.ponder)
+ return;
+
+ bool stillAtFirstMove = Signals.firstRootMove
+ && !Signals.failedLowAtRoot
+ && e > TimeMgr.available_time();
+
+ bool noMoreTime = e > TimeMgr.maximum_time()
+ || stillAtFirstMove;
+
+ if ( (Limits.useTimeManagement() && noMoreTime)
+ || (Limits.maxTime && e >= Limits.maxTime)
+ /* missing nodes limit */ ) // FIXME
+ Signals.stop = true;
+}
projects / stockfish / blobdiff