X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=07700c6c2dd6cbdd27dd0a48cf985e0f4ddf74aa;hb=54f1c383d36f461a740eeaa93856b408e8d3faa3;hp=8cdd7a21323033bd46706ef5264bb1911eb4a385;hpb=6849f0800e82845271ad5888600c141857e744ec;p=stockfish
diff --git a/src/search.cpp b/src/search.cpp
index 8cdd7a21..07700c6c 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -17,11 +17,6 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
#include
#include
#include
@@ -47,27 +42,21 @@
using std::cout;
using std::endl;
-////
-//// Local definitions
-////
-
namespace {
- // Types
+ // Different node types, used as template parameter
enum NodeType { NonPV, PV };
- // Set to true to force running with one thread.
- // Used for debugging SMP code.
+ // Set to true to force running with one thread. Used for debugging.
const bool FakeSplit = false;
- // Fast lookup table of sliding pieces indexed by Piece
+ // Lookup table to check if a Piece is a slider and its access function
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]; }
- // ThreadsManager class is used to handle all the threads related stuff in search,
- // init, starting, parking and, the most important, launching a slave thread at a
- // split point are what this class does. All the access to shared thread data is
- // done through this class, so that we avoid using global variables instead.
+ // ThreadsManager class is used to handle all the threads related stuff like init,
+ // starting, parking and, the most important, launching a slave thread at a split
+ // point. All the access to shared thread data is done through this class.
class ThreadsManager {
/* As long as the single ThreadsManager object is defined as a global we don't
@@ -91,7 +80,7 @@ namespace {
template
void split(Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue,
- Depth depth, Move threatMove, bool mateThreat, int moveCount, MovePicker* mp, bool pvNode);
+ Depth depth, Move threatMove, int moveCount, MovePicker* mp, bool pvNode);
private:
Depth minimumSplitDepth;
@@ -105,7 +94,7 @@ namespace {
};
- // RootMove struct is used for moves at the root at the tree. For each root
+ // 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
@@ -120,8 +109,8 @@ namespace {
// 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.
+ // 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;
@@ -129,7 +118,7 @@ namespace {
void extract_pv_from_tt(Position& pos);
void insert_pv_in_tt(Position& pos);
- std::string pv_info_to_uci(Position& pos, Depth depth, Value alpha, Value beta, int pvLine = 0);
+ std::string pv_info_to_uci(Position& pos, int depth, Value alpha, Value beta, int pvIdx);
int64_t nodes;
Value pv_score;
@@ -138,7 +127,7 @@ namespace {
};
- // RootMoveList struct is essentially a std::vector<> of RootMove objects,
+ // RootMoveList struct is just a std::vector<> of RootMove objects,
// with an handful of methods above the standard ones.
struct RootMoveList : public std::vector {
@@ -153,12 +142,21 @@ namespace {
};
+ // 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);
+ }
+
+
// 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 use it to properly format castling moves.
+ // operator<<() that will read it to properly format castling moves.
enum set960 {};
std::ostream& operator<< (std::ostream& os, const set960& f) {
@@ -168,15 +166,6 @@ namespace {
}
- // Overload operator << for moves to make it easier to print moves in
- // 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);
- }
-
-
/// Adjustments
// Step 6. Razoring
@@ -203,22 +192,18 @@ namespace {
// Extensions. Configurable UCI options
// Array index 0 is used at non-PV nodes, index 1 at PV nodes.
- Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2];
- Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
+ Depth CheckExtension[2], PawnPushTo7thExtension[2];
+ Depth PassedPawnExtension[2], PawnEndgameExtension[2];
// Minimum depth for use of singular extension
const Depth SingularExtensionDepth[2] = { 8 * ONE_PLY /* non-PV */, 6 * ONE_PLY /* PV */};
- // If the TT move is at least SingularExtensionMargin better then the
- // remaining ones we will extend it.
- const Value SingularExtensionMargin = Value(0x20);
-
// Step 12. Futility pruning
// Futility margin for quiescence search
const Value FutilityMarginQS = Value(0x80);
- // Futility lookup tables (initialized at startup) and their getter functions
+ // Futility lookup tables (initialized at startup) and their access functions
Value FutilityMarginsMatrix[16][64]; // [depth][moveNumber]
int FutilityMoveCountArray[32]; // [depth]
@@ -240,16 +225,16 @@ namespace {
/// Namespace variables
- // Book object
+ // Book
Book OpeningBook;
// Root move list
RootMoveList Rml;
// MultiPV mode
- int MultiPV;
+ int MultiPV, UCIMultiPV;
- // Time managment variables
+ // Time management variables
int SearchStartTime, MaxNodes, MaxDepth, ExactMaxTime;
bool UseTimeManagement, InfiniteSearch, Pondering, StopOnPonderhit;
bool FirstRootMove, StopRequest, QuitRequest, AspirationFailLow;
@@ -259,7 +244,12 @@ namespace {
bool UseLogFile;
std::ofstream LogFile;
- // Multi-threads manager object
+ // Skill level adjustment
+ int SkillLevel;
+ bool SkillLevelEnabled;
+ RKISS RK;
+
+ // Multi-threads manager
ThreadsManager ThreadsMgr;
// Node counters, used only by thread[0] but try to keep in different cache
@@ -271,6 +261,7 @@ namespace {
// History table
History H;
+
/// Local functions
Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove);
@@ -284,28 +275,27 @@ namespace {
template
inline Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth, int ply) {
- return depth < ONE_PLY ? qsearch(pos, ss, alpha, beta, DEPTH_ZERO, ply)
- : search(pos, ss, alpha, beta, depth, ply);
+ return depth < ONE_PLY ? qsearch(pos, ss, alpha, beta, DEPTH_ZERO, ply)
+ : search(pos, ss, alpha, beta, depth, ply);
}
template
- Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous);
+ Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool* dangerous);
bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue);
bool connected_moves(const Position& pos, Move m1, Move m2);
- bool value_is_mate(Value value);
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 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_killers(Move m, Move killers[]);
void update_gains(const Position& pos, Move move, Value before, Value after);
+ void do_skill_level(Move* best, Move* ponder);
int current_search_time();
std::string value_to_uci(Value v);
- int nps(const Position& pos);
+ std::string speed_to_uci(int64_t nodes);
void poll(const Position& pos);
void wait_for_stop_or_ponderhit();
@@ -320,7 +310,7 @@ namespace {
// the proper move source according to the type of node.
template struct MovePickerExt;
- // In Root nodes use RootMoveList Rml as source. Score and sort the root moves
+ // In Root nodes use RootMoveList as source. Score and sort the root moves
// before to search them.
template<> struct MovePickerExt : public MovePicker {
@@ -329,10 +319,10 @@ namespace {
Move move;
Value score = VALUE_ZERO;
- // Score root moves using the standard way used in main search, the moves
- // are scored according to the order in which are returned by MovePicker.
+ // 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 order pv scores of both moves are equal.
+ // the first orders pv_score of both moves are equal.
while ((move = MovePicker::get_next_move()) != MOVE_NONE)
for (rm = Rml.begin(); rm != Rml.end(); ++rm)
if (rm->pv[0] == move)
@@ -354,7 +344,6 @@ namespace {
return rm != Rml.end() ? rm->pv[0] : MOVE_NONE;
}
- int number_of_evasions() const { return (int)Rml.size(); }
RootMoveList::iterator rm;
bool firstCall;
@@ -363,9 +352,8 @@ namespace {
// In SpNodes use split point's shared MovePicker object as move source
template<> struct MovePickerExt : public MovePicker {
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h,
- SearchStack* ss, Value b) : MovePicker(p, ttm, d, h, ss, b),
- mp(ss->sp->mp) {}
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {}
Move get_next_move() { return mp->get_next_move(); }
@@ -376,8 +364,8 @@ namespace {
// Default case, create and use a MovePicker object as source
template<> struct MovePickerExt : public MovePicker {
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h,
- SearchStack* ss, Value b) : MovePicker(p, ttm, d, h, ss, b) {}
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ : MovePicker(p, ttm, d, h, ss, b) {}
RootMoveList::iterator rm; // Dummy, needed to compile
};
@@ -385,20 +373,10 @@ namespace {
} // namespace
-////
-//// Functions
-////
+/// init_threads() is called during startup. It initializes various lookup tables
+/// and creates and launches search threads.
-/// init_threads(), exit_threads() and nodes_searched() are helpers to
-/// give accessibility to some TM methods from outside of current file.
-
-void init_threads() { ThreadsMgr.init_threads(); }
-void exit_threads() { ThreadsMgr.exit_threads(); }
-
-
-/// init_search() is called during startup. It initializes various lookup tables
-
-void init_search() {
+void init_threads() {
int d; // depth (ONE_PLY == 2)
int hd; // half depth (ONE_PLY == 1)
@@ -420,49 +398,56 @@ void init_search() {
// Init futility move count array
for (d = 0; d < 32; d++)
FutilityMoveCountArray[d] = int(3.001 + 0.25 * pow(d, 2.0));
+
+ // Create and startup threads
+ ThreadsMgr.init_threads();
}
-/// perft() is our utility to verify move generation is bug free. All the legal
-/// moves up to given depth are generated and counted and the sum returned.
+/// exit_threads() is a trampoline to access ThreadsMgr from outside of current file
+void exit_threads() { ThreadsMgr.exit_threads(); }
-int64_t perft(Position& pos, Depth depth)
-{
- MoveStack mlist[MOVES_MAX];
- StateInfo st;
- Move m;
- int64_t sum = 0;
- // Generate all legal moves
- MoveStack* last = generate(pos, mlist);
+/// perft() is our utility to verify move generation. All the legal moves up to
+/// given depth are generated and counted and the sum returned.
- // If we are at the last ply we don't need to do and undo
- // the moves, just to count them.
- if (depth <= ONE_PLY)
- return int(last - mlist);
+int64_t perft(Position& pos, Depth depth) {
- // Loop through all legal moves
- CheckInfo ci(pos);
- for (MoveStack* cur = mlist; cur != last; cur++)
- {
- m = cur->move;
- pos.do_move(m, st, ci, pos.move_is_check(m, ci));
- sum += perft(pos, depth - ONE_PLY);
- pos.undo_move(m);
- }
- return sum;
+ MoveStack mlist[MOVES_MAX];
+ StateInfo st;
+ Move m;
+ int64_t sum = 0;
+
+ // Generate all legal moves
+ MoveStack* last = generate(pos, mlist);
+
+ // If we are at the last ply we don't need to do and undo
+ // the moves, just to count them.
+ if (depth <= ONE_PLY)
+ return int(last - mlist);
+
+ // Loop through all legal moves
+ CheckInfo ci(pos);
+ for (MoveStack* cur = mlist; cur != last; cur++)
+ {
+ m = cur->move;
+ pos.do_move(m, st, ci, pos.move_is_check(m, ci));
+ sum += perft(pos, depth - ONE_PLY);
+ pos.undo_move(m);
+ }
+ return sum;
}
/// think() is the external interface to Stockfish's search, and is called when
-/// the program receives the UCI 'go' command. It initializes various
-/// search-related global variables, and calls id_loop(). It returns false
-/// when a quit command is received during the search.
+/// 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.
bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[],
int movesToGo, int maxDepth, int maxNodes, int maxTime, Move searchMoves[]) {
- // Initialize global search variables
+ // Initialize global search-related variables
StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = SendSearchedNodes = false;
NodesSincePoll = 0;
SearchStartTime = get_system_time();
@@ -490,36 +475,38 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[
}
}
- // Read UCI option values
- TT.set_size(Options["Hash"].value());
- if (Options["Clear Hash"].value())
- {
- Options["Clear Hash"].set_value("false");
- TT.clear();
- }
-
+ // Read UCI options
CheckExtension[1] = Options["Check Extension (PV nodes)"].value();
CheckExtension[0] = Options["Check Extension (non-PV nodes)"].value();
- SingleEvasionExtension[1] = Options["Single Evasion Extension (PV nodes)"].value();
- SingleEvasionExtension[0] = Options["Single Evasion Extension (non-PV nodes)"].value();
PawnPushTo7thExtension[1] = Options["Pawn Push to 7th Extension (PV nodes)"].value();
PawnPushTo7thExtension[0] = Options["Pawn Push to 7th Extension (non-PV nodes)"].value();
PassedPawnExtension[1] = Options["Passed Pawn Extension (PV nodes)"].value();
PassedPawnExtension[0] = Options["Passed Pawn Extension (non-PV nodes)"].value();
PawnEndgameExtension[1] = Options["Pawn Endgame Extension (PV nodes)"].value();
PawnEndgameExtension[0] = Options["Pawn Endgame Extension (non-PV nodes)"].value();
- MateThreatExtension[1] = Options["Mate Threat Extension (PV nodes)"].value();
- MateThreatExtension[0] = Options["Mate Threat Extension (non-PV nodes)"].value();
- MultiPV = Options["MultiPV"].value();
+ UCIMultiPV = Options["MultiPV"].value();
+ SkillLevel = Options["Skill level"].value();
UseLogFile = Options["Use Search Log"].value();
read_evaluation_uci_options(pos.side_to_move());
+ if (Options["Clear Hash"].value())
+ {
+ Options["Clear Hash"].set_value("false");
+ TT.clear();
+ }
+ TT.set_size(Options["Hash"].value());
+
+ // 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);
+
// Set the number of active threads
ThreadsMgr.read_uci_options();
init_eval(ThreadsMgr.active_threads());
- // Wake up needed threads
+ // Wake up needed threads. Main thread, with threadID == 0, is always active
for (int i = 1; i < ThreadsMgr.active_threads(); i++)
ThreadsMgr.wake_sleeping_thread(i);
@@ -529,8 +516,7 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[
if (UseTimeManagement)
TimeMgr.init(myTime, myIncrement, movesToGo, pos.startpos_ply_counter());
- // Set best NodesBetweenPolls interval to avoid lagging under
- // heavy time pressure.
+ // Set best NodesBetweenPolls interval to avoid lagging under time pressure
if (MaxNodes)
NodesBetweenPolls = Min(MaxNodes, 30000);
else if (myTime && myTime < 1000)
@@ -546,12 +532,13 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[
std::string name = Options["Search Log Filename"].value();
LogFile.open(name.c_str(), std::ios::out | std::ios::app);
- LogFile << "Searching: " << pos.to_fen()
- << "\ninfinite: " << infinite
- << " ponder: " << ponder
- << " time: " << myTime
- << " increment: " << myIncrement
- << " moves to go: " << movesToGo << endl;
+ LogFile << "\nSearching: " << pos.to_fen()
+ << "\ninfinite: " << infinite
+ << " ponder: " << ponder
+ << " time: " << myTime
+ << " increment: " << myIncrement
+ << " moves to go: " << movesToGo
+ << endl;
}
// We're ready to start thinking. Call the iterative deepening loop function
@@ -559,25 +546,20 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[
Move bestMove = id_loop(pos, searchMoves, &ponderMove);
// Print final search statistics
- cout << "info nodes " << pos.nodes_searched()
- << " nps " << nps(pos)
- << " time " << current_search_time() << endl;
+ cout << "info" << speed_to_uci(pos.nodes_searched()) << endl;
if (UseLogFile)
{
- LogFile << "\nNodes: " << pos.nodes_searched()
- << "\nNodes/second: " << nps(pos)
- << "\nBest move: " << move_to_san(pos, bestMove);
+ int t = current_search_time();
+
+ LogFile << "Nodes: " << pos.nodes_searched()
+ << "\nNodes/second: " << (t > 0 ? int(pos.nodes_searched() * 1000 / t) : 0)
+ << "\nBest move: " << move_to_san(pos, bestMove);
StateInfo st;
pos.do_move(bestMove, st);
- LogFile << "\nPonder move: "
- << move_to_san(pos, ponderMove) // Works also with MOVE_NONE
- << endl;
-
- // Return from think() with unchanged position
- pos.undo_move(bestMove);
-
+ LogFile << "\nPonder move: " << move_to_san(pos, ponderMove) << endl;
+ pos.undo_move(bestMove); // Return from think() with unchanged position
LogFile.close();
}
@@ -589,8 +571,15 @@ bool think(Position& pos, bool infinite, bool ponder, int time[], int increment[
if (!StopRequest && (Pondering || InfiniteSearch))
wait_for_stop_or_ponderhit();
- // Could be both MOVE_NONE when searching on a stalemate position
- cout << "bestmove " << bestMove << " ponder " << ponderMove << endl;
+ // Could be MOVE_NONE when searching on a stalemate position
+ cout << "bestmove " << bestMove;
+
+ // 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;
+
+ cout << endl;
return !QuitRequest;
}
@@ -607,73 +596,63 @@ namespace {
SearchStack ss[PLY_MAX_PLUS_2];
Value bestValues[PLY_MAX_PLUS_2];
int bestMoveChanges[PLY_MAX_PLUS_2];
- int iteration, researchCountFL, researchCountFH, aspirationDelta;
+ int depth, aspirationDelta, skillSamplingDepth;
Value value, alpha, beta;
- Depth depth;
- Move bestMove, easyMove;
-
- // Moves to search are verified, scored and sorted
- Rml.init(pos, searchMoves);
+ Move bestMove, easyMove, skillBest, skillPonder;
- // Initialize FIXME move before Rml.init()
+ // Initialize stuff before a new search
+ memset(ss, 0, 4 * sizeof(SearchStack));
TT.new_search();
H.clear();
- memset(ss, 0, PLY_MAX_PLUS_2 * sizeof(SearchStack));
+ *ponderMove = bestMove = easyMove = skillBest = skillPonder = MOVE_NONE;
+ depth = aspirationDelta = skillSamplingDepth = 0;
alpha = -VALUE_INFINITE, beta = VALUE_INFINITE;
- *ponderMove = bestMove = easyMove = MOVE_NONE;
- aspirationDelta = 0;
- iteration = 1;
ss->currentMove = MOVE_NULL; // Hack to skip update_gains()
- // Handle special case of searching on a mate/stale position
+ // Moves to search are verified and copied
+ Rml.init(pos, searchMoves);
+
+ // Handle special case of searching on a mate/stalemate position
if (Rml.size() == 0)
{
- cout << "info depth " << iteration << " score "
+ cout << "info depth 0 score "
<< value_to_uci(pos.is_check() ? -VALUE_MATE : VALUE_DRAW)
<< endl;
return MOVE_NONE;
}
- // Send initial scoring (iteration 1)
- cout << set960(pos.is_chess960()) // Is enough to set once at the beginning
- << "info depth " << iteration
- << "\n" << Rml[0].pv_info_to_uci(pos, ONE_PLY, alpha, beta) << endl;
-
- // Is one move significantly better than others after initial scoring ?
- if ( Rml.size() == 1
- || Rml[0].pv_score > Rml[1].pv_score + EasyMoveMargin)
- easyMove = Rml[0].pv[0];
+ // Choose a random sampling depth according to SkillLevel so that at low
+ // skills there is an higher risk to pick up a blunder.
+ if (SkillLevelEnabled)
+ skillSamplingDepth = 4 + SkillLevel + (RK.rand() % 4);
// Iterative deepening loop
- while (++iteration <= PLY_MAX && (!MaxDepth || iteration <= MaxDepth) && !StopRequest)
+ while (++depth <= PLY_MAX && (!MaxDepth || depth <= MaxDepth) && !StopRequest)
{
- cout << "info depth " << iteration << endl;
-
- Rml.bestMoveChanges = researchCountFL = researchCountFH = 0;
- depth = (iteration - 1) * ONE_PLY;
+ Rml.bestMoveChanges = 0;
+ cout << set960(pos.is_chess960()) << "info depth " << depth << endl;
// Calculate dynamic aspiration window based on previous iterations
- if (MultiPV == 1 && iteration >= 6 && abs(bestValues[iteration - 1]) < VALUE_KNOWN_WIN)
+ if (MultiPV == 1 && depth >= 5 && abs(bestValues[depth - 1]) < VALUE_KNOWN_WIN)
{
- int prevDelta1 = bestValues[iteration - 1] - bestValues[iteration - 2];
- int prevDelta2 = bestValues[iteration - 2] - bestValues[iteration - 3];
+ int prevDelta1 = bestValues[depth - 1] - bestValues[depth - 2];
+ int prevDelta2 = bestValues[depth - 2] - bestValues[depth - 3];
- aspirationDelta = Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16);
+ aspirationDelta = Min(Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16), 24);
aspirationDelta = (aspirationDelta + 7) / 8 * 8; // Round to match grainSize
- alpha = Max(bestValues[iteration - 1] - aspirationDelta, -VALUE_INFINITE);
- beta = Min(bestValues[iteration - 1] + aspirationDelta, VALUE_INFINITE);
+ 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.
- while (true)
- {
+ do {
// Search starting from ss+1 to allow calling update_gains()
- value = search(pos, ss+1, alpha, beta, depth, 0);
+ value = search(pos, ss+1, alpha, beta, depth * ONE_PLY, 0);
- // Write PV lines to transposition table, in case the relevant entries
+ // 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);
@@ -688,28 +667,43 @@ namespace {
// otherwise exit the fail high/low loop.
if (value >= beta)
{
- beta = Min(beta + aspirationDelta * (1 << researchCountFH), VALUE_INFINITE);
- researchCountFH++;
+ beta = Min(beta + aspirationDelta, VALUE_INFINITE);
+ aspirationDelta += aspirationDelta / 2;
}
else if (value <= alpha)
{
AspirationFailLow = true;
StopOnPonderhit = false;
- alpha = Max(alpha - aspirationDelta * (1 << researchCountFL), -VALUE_INFINITE);
- researchCountFL++;
+ alpha = Max(alpha - aspirationDelta, -VALUE_INFINITE);
+ aspirationDelta += aspirationDelta / 2;
}
else
break;
- }
+
+ } while (abs(value) < VALUE_KNOWN_WIN);
// Collect info about search result
bestMove = Rml[0].pv[0];
- bestValues[iteration] = value;
- bestMoveChanges[iteration] = Rml.bestMoveChanges;
+ *ponderMove = Rml[0].pv[1];
+ bestValues[depth] = value;
+ bestMoveChanges[depth] = Rml.bestMoveChanges;
+
+ // Do we need to pick now the best and the ponder moves ?
+ if (SkillLevelEnabled && depth == skillSamplingDepth)
+ do_skill_level(&skillBest, &skillPonder);
- // Drop the easy move if differs from the new best move
- if (bestMove != easyMove)
+ // Send PV line to GUI and to log file
+ for (int i = 0; i < Min(UCIMultiPV, (int)Rml.size()); i++)
+ cout << Rml[i].pv_info_to_uci(pos, depth, alpha, beta, i) << endl;
+
+ if (UseLogFile)
+ LogFile << pretty_pv(pos, depth, value, current_search_time(), Rml[0].pv) << endl;
+
+ // 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;
if (UseTimeManagement && !StopRequest)
@@ -718,15 +712,15 @@ namespace {
bool noMoreTime = false;
// Stop search early when the last two iterations returned a mate score
- if ( iteration >= 6
- && abs(bestValues[iteration]) >= abs(VALUE_MATE) - 100
- && abs(bestValues[iteration-1]) >= abs(VALUE_MATE) - 100)
+ if ( depth >= 5
+ && abs(bestValues[depth]) >= abs(VALUE_MATE) - 100
+ && abs(bestValues[depth - 1]) >= abs(VALUE_MATE) - 100)
noMoreTime = true;
// Stop search early if one move seems to be much better than the
// others or if there is only a single legal move. In this latter
// case we search up to Iteration 8 anyway to get a proper score.
- if ( iteration >= 8
+ if ( depth >= 7
&& easyMove == bestMove
&& ( Rml.size() == 1
||( Rml[0].nodes > (pos.nodes_searched() * 85) / 100
@@ -736,8 +730,8 @@ namespace {
noMoreTime = true;
// Add some extra time if the best move has changed during the last two iterations
- if (iteration > 5 && iteration <= 50)
- TimeMgr.pv_instability(bestMoveChanges[iteration], bestMoveChanges[iteration-1]);
+ if (depth > 4 && depth < 50)
+ TimeMgr.pv_instability(bestMoveChanges[depth], bestMoveChanges[depth-1]);
// Stop search if most of MaxSearchTime is consumed at the end of the
// iteration. We probably don't have enough time to search the first
@@ -755,7 +749,16 @@ namespace {
}
}
- *ponderMove = Rml[0].pv[1];
+ // When using skills fake best and ponder moves with the sub-optimal ones
+ if (SkillLevelEnabled)
+ {
+ if (skillBest == MOVE_NONE) // Still unassigned ?
+ do_skill_level(&skillBest, &skillPonder);
+
+ bestMove = skillBest;
+ *ponderMove = skillPonder;
+ }
+
return bestMove;
}
@@ -786,8 +789,7 @@ namespace {
ValueType vt;
Value bestValue, value, oldAlpha;
Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific
- bool isPvMove, isCheck, singleEvasion, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous;
- bool mateThreat = false;
+ bool isPvMove, isCheck, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous, isBadCap;
int moveCount = 0, playedMoveCount = 0;
int threadID = pos.thread();
SplitPoint* sp = NULL;
@@ -802,14 +804,14 @@ namespace {
tte = NULL;
ttMove = excludedMove = MOVE_NONE;
threatMove = sp->threatMove;
- mateThreat = sp->mateThreat;
goto split_point_start;
}
else if (Root)
bestValue = alpha;
// Step 1. Initialize node and poll. Polling can abort search
- ss->currentMove = ss->bestMove = threatMove = MOVE_NONE;
+ ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE;
+ (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
(ss+2)->killers[0] = (ss+2)->killers[1] = (ss+2)->mateKiller = MOVE_NONE;
if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls)
@@ -833,29 +835,27 @@ namespace {
// Step 4. Transposition table lookup
// 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 exists.
+ // 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();
tte = TT.retrieve(posKey);
ttMove = tte ? tte->move() : MOVE_NONE;
- // At PV nodes, we don't use the TT for pruning, but only for move ordering.
- // This is to avoid problems in the following areas:
- //
- // * Repetition draw detection
- // * Fifty move rule detection
- // * Searching for a mate
- // * Printing of full PV line
- if (!PvNode && tte && ok_to_use_TT(tte, depth, beta, ply))
+ // 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 ( !Root
+ && tte
+ && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT
+ : ok_to_use_TT(tte, depth, beta, ply)))
{
TT.refresh(tte);
ss->bestMove = ttMove; // Can be MOVE_NONE
return value_from_tt(tte->value(), ply);
}
- // Step 5. Evaluate the position statically and
- // update gain statistics of parent move.
+ // Step 5. Evaluate the position statically and update parent's gain statistics
if (isCheck)
ss->eval = ss->evalMargin = VALUE_NONE;
else if (tte)
@@ -879,9 +879,9 @@ namespace {
if ( !PvNode
&& depth < RazorDepth
&& !isCheck
- && refinedValue < beta - razor_margin(depth)
+ && refinedValue + razor_margin(depth) < beta
&& ttMove == MOVE_NONE
- && !value_is_mate(beta)
+ && abs(beta) < VALUE_MATE_IN_PLY_MAX
&& !pos.has_pawn_on_7th(pos.side_to_move()))
{
Value rbeta = beta - razor_margin(depth);
@@ -899,8 +899,8 @@ namespace {
&& !ss->skipNullMove
&& depth < RazorDepth
&& !isCheck
- && refinedValue >= beta + futility_margin(depth, 0)
- && !value_is_mate(beta)
+ && refinedValue - futility_margin(depth, 0) >= beta
+ && abs(beta) < VALUE_MATE_IN_PLY_MAX
&& pos.non_pawn_material(pos.side_to_move()))
return refinedValue - futility_margin(depth, 0);
@@ -910,7 +910,7 @@ namespace {
&& depth > ONE_PLY
&& !isCheck
&& refinedValue >= beta
- && !value_is_mate(beta)
+ && abs(beta) < VALUE_MATE_IN_PLY_MAX
&& pos.non_pawn_material(pos.side_to_move()))
{
ss->currentMove = MOVE_NULL;
@@ -919,7 +919,7 @@ namespace {
int R = 3 + (depth >= 5 * ONE_PLY ? depth / 8 : 0);
// Null move dynamic reduction based on value
- if (refinedValue - beta > PawnValueMidgame)
+ if (refinedValue - PawnValueMidgame > beta)
R++;
pos.do_null_move(st);
@@ -931,7 +931,7 @@ namespace {
if (nullValue >= beta)
{
// Do not return unproven mate scores
- if (nullValue >= value_mate_in(PLY_MAX))
+ if (nullValue >= VALUE_MATE_IN_PLY_MAX)
nullValue = beta;
if (depth < 6 * ONE_PLY)
@@ -953,10 +953,8 @@ namespace {
// move which was reduced. If a connection is found, return a fail
// low score (which will cause the reduced move to fail high in the
// parent node, which will trigger a re-search with full depth).
- if (nullValue == value_mated_in(ply + 2))
- mateThreat = true;
-
threatMove = (ss+1)->bestMove;
+
if ( depth < ThreatDepth
&& (ss-1)->reduction
&& threatMove != MOVE_NONE
@@ -968,7 +966,7 @@ namespace {
// Step 9. Internal iterative deepening
if ( depth >= IIDDepth[PvNode]
&& ttMove == MOVE_NONE
- && (PvNode || (!isCheck && ss->eval >= beta - IIDMargin)))
+ && (PvNode || (!isCheck && ss->eval + IIDMargin >= beta)))
{
Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2);
@@ -980,17 +978,12 @@ namespace {
tte = TT.retrieve(posKey);
}
- // Expensive mate threat detection (only for PV nodes)
- if (PvNode)
- mateThreat = pos.has_mate_threat();
-
split_point_start: // At split points actual search starts from here
// Initialize a MovePicker object for the current position
MovePickerExt mp(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta));
CheckInfo ci(pos);
ss->bestMove = MOVE_NONE;
- singleEvasion = !SpNode && isCheck && mp.number_of_evasions() == 1;
futilityBase = ss->eval + ss->evalMargin;
singularExtensionNode = !Root
&& !SpNode
@@ -1037,27 +1030,27 @@ split_point_start: // At split points actual search starts from here
if (SendSearchedNodes)
{
SendSearchedNodes = false;
- cout << "info nodes " << nodes
- << " nps " << nps(pos)
- << " time " << current_search_time() << endl;
+ cout << "info" << speed_to_uci(pos.nodes_searched()) << endl;
}
- if (current_search_time() >= 1000)
+ if (current_search_time() > 2000)
cout << "info currmove " << move
<< " currmovenumber " << moveCount << endl;
}
- isPvMove = (PvNode && moveCount <= (Root ? MultiPV : 1));
+ // At Root and at first iteration do a PV search on all the moves to score root moves
+ isPvMove = (PvNode && moveCount <= (Root ? depth <= ONE_PLY ? 1000 : MultiPV : 1));
moveIsCheck = pos.move_is_check(move, ci);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
// Step 11. Decide the new search depth
- ext = extension(pos, move, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous);
+ ext = extension(pos, move, captureOrPromotion, moveIsCheck, &dangerous);
- // 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 is singular and should be extended.
- // To verify this we do a reduced search on all the other moves but the ttMove, if result is
- // lower then ttValue minus a margin then we extend ttMove.
+ // 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
+ // is singular and should be extended. To verify this we do a reduced search
+ // on all the other moves but the ttMove, if result is lower than ttValue minus
+ // a margin then we extend ttMove.
if ( singularExtensionNode
&& move == tte->move()
&& ext < ONE_PLY)
@@ -1066,21 +1059,21 @@ split_point_start: // At split points actual search starts from here
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value b = ttValue - SingularExtensionMargin;
+ Value rBeta = ttValue - int(depth);
ss->excludedMove = move;
ss->skipNullMove = true;
- Value v = search(pos, ss, b - 1, b, depth / 2, ply);
+ Value v = search(pos, ss, rBeta - 1, rBeta, depth / 2, ply);
ss->skipNullMove = false;
ss->excludedMove = MOVE_NONE;
ss->bestMove = MOVE_NONE;
- if (v < b)
+ if (v < rBeta)
ext = ONE_PLY;
}
}
// Update current move (this must be done after singular extension search)
ss->currentMove = move;
- newDepth = depth - (!Root ? ONE_PLY : DEPTH_ZERO) + ext;
+ newDepth = depth - ONE_PLY + ext;
// Step 12. Futility pruning (is omitted in PV nodes)
if ( !PvNode
@@ -1092,8 +1085,8 @@ split_point_start: // At split points actual search starts from here
{
// 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))
+ && bestValue > VALUE_MATED_IN_PLY_MAX) // FIXME bestValue is racy
{
if (SpNode)
lock_grab(&(sp->lock));
@@ -1124,7 +1117,7 @@ split_point_start: // At split points actual search starts from here
// Prune moves with negative SEE at low depths
if ( predictedDepth < 2 * ONE_PLY
- && bestValue > value_mated_in(PLY_MAX)
+ && bestValue > VALUE_MATED_IN_PLY_MAX
&& pos.see_sign(move) < 0)
{
if (SpNode)
@@ -1134,6 +1127,16 @@ split_point_start: // At split points actual search starts from here
}
}
+ // Bad capture detection. Will be used by prob-cut search
+ isBadCap = depth >= 3 * ONE_PLY
+ && depth < 8 * ONE_PLY
+ && captureOrPromotion
+ && move != ttMove
+ && !dangerous
+ && !move_is_promotion(move)
+ && abs(alpha) < VALUE_MATE_IN_PLY_MAX
+ && pos.see_sign(move) < 0;
+
// Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
@@ -1155,6 +1158,7 @@ split_point_start: // At split points actual search starts from here
// Step 14. Reduced depth search
// If the move fails high will be re-searched at full depth.
bool doFullDepthSearch = true;
+ alpha = SpNode ? sp->alpha : alpha;
if ( depth >= 3 * ONE_PLY
&& !captureOrPromotion
@@ -1163,8 +1167,7 @@ split_point_start: // At split points actual search starts from here
&& ss->killers[0] != move
&& ss->killers[1] != move)
{
- ss->reduction = Root ? reduction(depth, moveCount - MultiPV + 1)
- : reduction(depth, moveCount);
+ ss->reduction = reduction(depth, moveCount);
if (ss->reduction)
{
alpha = SpNode ? sp->alpha : alpha;
@@ -1176,6 +1179,18 @@ split_point_start: // At split points actual search starts from here
ss->reduction = DEPTH_ZERO; // Restore original reduction
}
+ // Probcut search for bad captures. If a reduced search returns a value
+ // very below beta then we can (almost) safely prune the bad capture.
+ if (isBadCap)
+ {
+ ss->reduction = 3 * ONE_PLY;
+ Value rAlpha = alpha - 300;
+ Depth d = newDepth - ss->reduction;
+ value = -search(pos, ss+1, -(rAlpha+1), -rAlpha, d, ply+1);
+ doFullDepthSearch = (value > rAlpha);
+ ss->reduction = DEPTH_ZERO; // Restore original reduction
+ }
+
// Step 15. Full depth search
if (doFullDepthSearch)
{
@@ -1203,14 +1218,14 @@ split_point_start: // At split points actual search starts from here
alpha = sp->alpha;
}
- if (!Root && value > bestValue && !(SpNode && ThreadsMgr.cutoff_at_splitpoint(threadID)))
+ if (value > bestValue && !(SpNode && ThreadsMgr.cutoff_at_splitpoint(threadID)))
{
bestValue = value;
if (SpNode)
sp->bestValue = value;
- if (value > alpha)
+ if (!Root && value > alpha)
{
if (PvNode && value < beta) // We want always alpha < beta
{
@@ -1228,16 +1243,12 @@ split_point_start: // At split points actual search starts from here
ss->bestMove = move;
if (SpNode)
- sp->parentSstack->bestMove = move;
+ sp->ss->bestMove = move;
}
}
if (Root)
{
- // To avoid to exit with bestValue == -VALUE_INFINITE
- if (value > bestValue)
- bestValue = value;
-
// 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
@@ -1249,40 +1260,33 @@ split_point_start: // At split points actual search starts from here
// Remember searched nodes counts for this move
mp.rm->nodes += pos.nodes_searched() - nodes;
- // Step 17. Check for new best move
- if (!isPvMove && value <= alpha)
- mp.rm->pv_score = -VALUE_INFINITE;
- else
+ // PV move or new best move ?
+ if (isPvMove || value > alpha)
{
- // PV move or new best move!
-
// Update PV
ss->bestMove = move;
mp.rm->pv_score = value;
mp.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 managment: When
+ // 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++;
- // Inform GUI that PV has changed, in case of multi-pv UCI protocol
- // requires we send all the PV lines properly sorted.
Rml.sort_multipv(moveCount);
- for (int j = 0; j < Min(MultiPV, (int)Rml.size()); j++)
- cout << Rml[j].pv_info_to_uci(pos, depth, alpha, beta, j) << endl;
-
// Update alpha. In multi-pv we don't use aspiration window, so
// set alpha equal to minimum score among the PV lines.
if (MultiPV > 1)
alpha = Rml[Min(moveCount, MultiPV) - 1].pv_score; // FIXME why moveCount?
else if (value > alpha)
alpha = value;
+ }
+ else
+ mp.rm->pv_score = -VALUE_INFINITE;
- } // PV move or new best move
- }
+ } // Root
// Step 18. Check for split
if ( !Root
@@ -1294,7 +1298,7 @@ split_point_start: // At split points actual search starts from here
&& !StopRequest
&& !ThreadsMgr.cutoff_at_splitpoint(threadID))
ThreadsMgr.split(pos, ss, ply, &alpha, beta, &bestValue, depth,
- threatMove, mateThreat, moveCount, &mp, PvNode);
+ threatMove, moveCount, &mp, PvNode);
}
// Step 19. Check for mate and stalemate
@@ -1319,8 +1323,12 @@ split_point_start: // At split points actual search starts from here
if ( bestValue >= beta
&& !pos.move_is_capture_or_promotion(move))
{
+ if (move != ss->killers[0])
+ {
+ ss->killers[1] = ss->killers[0];
+ ss->killers[0] = move;
+ }
update_history(pos, move, depth, movesSearched, playedMoveCount);
- update_killers(move, ss->killers);
}
}
@@ -1454,11 +1462,17 @@ split_point_start: // At split points actual search starts from here
bestValue = futilityValue;
continue;
}
+
+ // Prune moves with negative or equal SEE
+ if ( futilityBase < beta
+ && depth < DEPTH_ZERO
+ && pos.see(move) <= 0)
+ continue;
}
// Detect non-capture evasions that are candidate to be pruned
evasionPrunable = isCheck
- && bestValue > value_mated_in(PLY_MAX)
+ && bestValue > VALUE_MATED_IN_PLY_MAX
&& !pos.move_is_capture(move)
&& !pos.can_castle(pos.side_to_move());
@@ -1632,28 +1646,16 @@ split_point_start: // At split points actual search starts from here
}
- // value_is_mate() checks if the given value is a mate one eventually
- // compensated for the ply.
-
- bool value_is_mate(Value value) {
-
- assert(abs(value) <= VALUE_INFINITE);
-
- return value <= value_mated_in(PLY_MAX)
- || value >= value_mate_in(PLY_MAX);
- }
-
-
// 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.
Value value_to_tt(Value v, int ply) {
- if (v >= value_mate_in(PLY_MAX))
+ if (v >= VALUE_MATE_IN_PLY_MAX)
return v + ply;
- if (v <= value_mated_in(PLY_MAX))
+ if (v <= VALUE_MATED_IN_PLY_MAX)
return v - ply;
return v;
@@ -1665,10 +1667,10 @@ split_point_start: // At split points actual search starts from here
Value value_from_tt(Value v, int ply) {
- if (v >= value_mate_in(PLY_MAX))
+ if (v >= VALUE_MATE_IN_PLY_MAX)
return v - ply;
- if (v <= value_mated_in(PLY_MAX))
+ if (v <= VALUE_MATED_IN_PLY_MAX)
return v + ply;
return v;
@@ -1682,25 +1684,16 @@ split_point_start: // At split points actual search starts from here
// 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
- Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck,
- bool singleEvasion, bool mateThreat, bool* dangerous) {
+ Depth extension(const Position& pos, Move m, bool captureOrPromotion,
+ bool moveIsCheck, bool* dangerous) {
assert(m != MOVE_NONE);
Depth result = DEPTH_ZERO;
- *dangerous = moveIsCheck | singleEvasion | mateThreat;
+ *dangerous = moveIsCheck;
- if (*dangerous)
- {
- if (moveIsCheck && pos.see_sign(m) >= 0)
- result += CheckExtension[PvNode];
-
- if (singleEvasion)
- result += SingleEvasionExtension[PvNode];
-
- if (mateThreat)
- result += MateThreatExtension[PvNode];
- }
+ if (moveIsCheck && pos.see_sign(m) >= 0)
+ result += CheckExtension[PvNode];
if (pos.type_of_piece_on(move_from(m)) == PAWN)
{
@@ -1728,21 +1721,12 @@ split_point_start: // At split points actual search starts from here
*dangerous = true;
}
- if ( PvNode
- && captureOrPromotion
- && pos.type_of_piece_on(move_to(m)) != PAWN
- && pos.see_sign(m) >= 0)
- {
- result += ONE_PLY / 2;
- *dangerous = true;
- }
-
return Min(result, ONE_PLY);
}
// connected_threat() tests whether it is safe to forward prune a move or if
- // is somehow coonected to the threat move returned by null search.
+ // is somehow connected to the threat move returned by null search.
bool connected_threat(const Position& pos, Move m, Move threat) {
@@ -1764,7 +1748,7 @@ split_point_start: // At split points actual search starts from here
return true;
// Case 2: If the threatened piece has value less than or equal to the
- // value of the threatening piece, don't prune move which defend it.
+ // value of the threatening piece, don't prune moves which defend it.
if ( pos.move_is_capture(threat)
&& ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
|| pos.type_of_piece_on(tfrom) == KING)
@@ -1790,8 +1774,8 @@ split_point_start: // At split points actual search starts from here
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 >= Max(VALUE_MATE_IN_PLY_MAX, beta)
+ || v < Min(VALUE_MATED_IN_PLY_MAX, beta))
&& ( ((tte->type() & VALUE_TYPE_LOWER) && v >= beta)
|| ((tte->type() & VALUE_TYPE_UPPER) && v < beta));
@@ -1836,19 +1820,6 @@ split_point_start: // At split points actual search starts from here
}
- // update_killers() add a good move that produced a beta-cutoff
- // among the killer moves of that ply.
-
- void update_killers(Move m, Move killers[]) {
-
- if (m != killers[0])
- {
- killers[1] = killers[0];
- killers[0] = m;
- }
- }
-
-
// update_gains() updates the gains table of a non-capture move given
// the static position evaluation before and after the move.
@@ -1863,6 +1834,15 @@ split_point_start: // At split points actual search starts from here
}
+ // current_search_time() returns the number of milliseconds which have passed
+ // since the beginning of the current search.
+
+ int current_search_time() {
+
+ return get_system_time() - SearchStartTime;
+ }
+
+
// value_to_uci() converts a value to a string suitable for use with the UCI
// protocol specifications:
//
@@ -1877,27 +1857,25 @@ split_point_start: // At split points actual search starts from here
if (abs(v) < VALUE_MATE - PLY_MAX * ONE_PLY)
s << "cp " << int(v) * 100 / int(PawnValueMidgame); // Scale to centipawns
else
- s << "mate " << (v > 0 ? (VALUE_MATE - v + 1) / 2 : -(VALUE_MATE + v) / 2 );
+ s << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;
return s.str();
}
- // current_search_time() returns the number of milliseconds which have passed
- // since the beginning of the current search.
-
- int current_search_time() {
-
- return get_system_time() - SearchStartTime;
- }
+ // speed_to_uci() returns a string with time stats of current search suitable
+ // to be sent to UCI gui.
+ std::string speed_to_uci(int64_t nodes) {
- // nps() computes the current nodes/second count
+ std::stringstream s;
+ int t = current_search_time();
- int nps(const Position& pos) {
+ s << " nodes " << nodes
+ << " nps " << (t > 0 ? int(nodes * 1000 / t) : 0)
+ << " time " << t;
- int t = current_search_time();
- return (t > 0 ? int((pos.nodes_searched() * 1000) / t) : 0);
+ return s.str();
}
@@ -1916,10 +1894,7 @@ split_point_start: // At split points actual search starts from here
// We are line oriented, don't read single chars
std::string command;
- if (!std::getline(std::cin, command))
- command = "quit";
-
- if (command == "quit")
+ if (!std::getline(std::cin, command) || command == "quit")
{
// Quit the program as soon as possible
Pondering = false;
@@ -1997,20 +1972,12 @@ split_point_start: // At split points actual search starts from here
std::string command;
- while (true)
- {
- // Wait for a command from stdin
- if (!std::getline(std::cin, command))
- command = "quit";
+ // Wait for a command from stdin
+ while ( std::getline(std::cin, command)
+ && command != "ponderhit" && command != "stop" && command != "quit") {};
- if (command == "quit")
- {
- QuitRequest = true;
- break;
- }
- else if (command == "ponderhit" || command == "stop")
- break;
- }
+ if (command != "ponderhit" && command != "stop")
+ QuitRequest = true; // Must be "quit" or getline() returned false
}
@@ -2114,16 +2081,19 @@ split_point_start: // At split points actual search starts from here
threads[threadID].state = THREAD_SEARCHING;
- // Here we call search() with SplitPoint template parameter set to true
+ // Copy SplitPoint 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;
Position pos(*tsp->pos, threadID);
- SearchStack* ss = tsp->sstack[threadID] + 1;
- ss->sp = tsp;
+
+ memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack));
+ (ss+1)->sp = tsp;
if (tsp->pvNode)
- search(pos, ss, tsp->alpha, tsp->beta, tsp->depth, tsp->ply);
+ search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth, tsp->ply);
else
- search(pos, ss, tsp->alpha, tsp->beta, tsp->depth, tsp->ply);
+ search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth, tsp->ply);
assert(threads[threadID].state == THREAD_SEARCHING);
@@ -2324,7 +2294,7 @@ split_point_start: // At split points actual search starts from here
template
void ThreadsManager::split(Position& pos, SearchStack* ss, int ply, Value* alpha,
const Value beta, Value* bestValue, Depth depth, Move threatMove,
- bool mateThreat, int moveCount, MovePicker* mp, bool pvNode) {
+ int moveCount, MovePicker* mp, bool pvNode) {
assert(pos.is_ok());
assert(ply > 0 && ply < PLY_MAX);
assert(*bestValue >= -VALUE_INFINITE);
@@ -2359,7 +2329,6 @@ split_point_start: // At split points actual search starts from here
splitPoint.ply = ply;
splitPoint.depth = depth;
splitPoint.threatMove = threatMove;
- splitPoint.mateThreat = mateThreat;
splitPoint.alpha = *alpha;
splitPoint.beta = beta;
splitPoint.pvNode = pvNode;
@@ -2368,7 +2337,7 @@ split_point_start: // At split points actual search starts from here
splitPoint.moveCount = moveCount;
splitPoint.pos = &pos;
splitPoint.nodes = 0;
- splitPoint.parentSstack = ss;
+ splitPoint.ss = ss;
for (i = 0; i < activeThreads; i++)
splitPoint.slaves[i] = 0;
@@ -2395,12 +2364,10 @@ split_point_start: // At split points actual search starts from here
lock_release(&mpLock);
// Tell the threads that they have work to do. This will make them leave
- // their idle loop. But before copy search stack tail for each thread.
+ // their idle loop.
for (i = 0; i < activeThreads; i++)
if (i == master || splitPoint.slaves[i])
{
- memcpy(splitPoint.sstack[i], ss - 1, 4 * sizeof(SearchStack));
-
assert(i == master || threads[i].state == THREAD_BOOKED);
threads[i].state = THREAD_WORKISWAITING; // This makes the slave to exit from idle_loop()
@@ -2475,13 +2442,13 @@ split_point_start: // At split points actual search starts from here
TTEntry* tte;
int ply = 1;
- assert(pv[0] != MOVE_NONE && move_is_legal(pos, pv[0]));
+ assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0]));
pos.do_move(pv[0], *st++);
while ( (tte = TT.retrieve(pos.get_key())) != NULL
&& tte->move() != MOVE_NONE
- && move_is_legal(pos, tte->move())
+ && pos.move_is_legal(tte->move())
&& ply < PLY_MAX
&& (!pos.is_draw() || ply < 2))
{
@@ -2505,13 +2472,13 @@ split_point_start: // At split points actual search starts from here
Value v, m = VALUE_NONE;
int ply = 0;
- assert(pv[0] != MOVE_NONE && move_is_legal(pos, pv[0]));
+ assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0]));
do {
k = pos.get_key();
tte = TT.retrieve(k);
- // Don't overwrite exsisting correct entries
+ // Don't overwrite existing correct entries
if (!tte || tte->move() != pv[ply])
{
v = (pos.is_check() ? VALUE_NONE : evaluate(pos, m));
@@ -2525,55 +2492,38 @@ split_point_start: // At split points actual search starts from here
}
// pv_info_to_uci() returns a string with information on the current PV line
- // formatted according to UCI specification and eventually writes the info
- // to a log file. It is called at each iteration or after a new pv is found.
-
- std::string RootMove::pv_info_to_uci(Position& pos, Depth depth, Value alpha, Value beta, int pvLine) {
+ // formatted according to UCI specification.
+ std::string RootMove::pv_info_to_uci(Position& pos, int depth, Value alpha,
+ Value beta, int pvIdx) {
std::stringstream s, l;
Move* m = pv;
while (*m != MOVE_NONE)
l << *m++ << " ";
- s << "info depth " << depth / ONE_PLY
+ s << "info depth " << depth
<< " seldepth " << int(m - pv)
- << " multipv " << pvLine + 1
+ << " multipv " << pvIdx + 1
<< " score " << value_to_uci(pv_score)
<< (pv_score >= beta ? " lowerbound" : pv_score <= alpha ? " upperbound" : "")
- << " time " << current_search_time()
- << " nodes " << pos.nodes_searched()
- << " nps " << nps(pos)
+ << speed_to_uci(pos.nodes_searched())
<< " pv " << l.str();
- if (UseLogFile && pvLine == 0)
- {
- ValueType t = pv_score >= beta ? VALUE_TYPE_LOWER :
- pv_score <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT;
-
- LogFile << pretty_pv(pos, current_search_time(), depth / ONE_PLY, pv_score, t, pv) << endl;
- }
return s.str();
}
void RootMoveList::init(Position& pos, Move searchMoves[]) {
- SearchStack ss[PLY_MAX_PLUS_2];
MoveStack mlist[MOVES_MAX];
- StateInfo st;
Move* sm;
- // Initialize search stack
- memset(ss, 0, PLY_MAX_PLUS_2 * sizeof(SearchStack));
- ss[0].eval = ss[0].evalMargin = VALUE_NONE;
- bestMoveChanges = 0;
clear();
+ bestMoveChanges = 0;
- // Generate all legal moves
+ // Generate all legal moves and add them to RootMoveList
MoveStack* last = generate(pos, mlist);
-
- // Add each move to the RootMoveList's vector
for (MoveStack* cur = mlist; cur != last; cur++)
{
// If we have a searchMoves[] list then verify cur->move
@@ -2583,18 +2533,54 @@ split_point_start: // At split points actual search starts from here
if (searchMoves[0] && *sm != cur->move)
continue;
- // Find a quick score for the move and add to the list
- pos.do_move(cur->move, st);
-
RootMove rm;
- rm.pv[0] = ss[0].currentMove = cur->move;
+ rm.pv[0] = cur->move;
rm.pv[1] = MOVE_NONE;
- rm.pv_score = -qsearch(pos, ss+1, -VALUE_INFINITE, VALUE_INFINITE, DEPTH_ZERO, 1);
+ rm.pv_score = -VALUE_INFINITE;
push_back(rm);
+ }
+ }
+
- pos.undo_move(cur->move);
+ // 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) {
+
+ assert(MultiPV > 1);
+
+ // 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--)
+ RK.rand();
+
+ // 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,
+ // then we choose the move with the resulting highest score.
+ for (int i = 0; i < size; i++)
+ {
+ s = Rml[i].pv_score;
+
+ // Don't allow crazy blunders even at very low skills
+ if (i > 0 && Rml[i-1].pv_score > s + EasyMoveMargin)
+ break;
+
+ // This is our magical formula
+ s += ((max - s) * wk + var * (RK.rand() % wk)) / 128;
+
+ if (s > max_s)
+ {
+ max_s = s;
+ *best = Rml[i].pv[0];
+ *ponder = Rml[i].pv[1];
+ }
}
- sort();
}
} // namespace