namespace {
- // Different node types, used as template parameter
- enum NodeType { NonPV, PV };
-
- // Set to true to force running with one thread. Used for debugging.
+ // Set to true to force running with one thread. Used for debugging
const bool FakeSplit = false;
- // 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]; }
+ // Different node types, used as template parameter
+ enum NodeType { Root, PV, NonPV, 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.
-
struct RootMove {
RootMove();
Move pv[PLY_MAX_PLUS_2];
};
-
// RootMoveList struct is just a vector of RootMove objects,
// with an handful of methods above the standard ones.
-
struct RootMoveList : public std::vector<RootMove> {
typedef std::vector<RootMove> Base;
int bestMoveChanges;
};
+ // 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 {
- // 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) {
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ : MovePicker(p, ttm, d, h, ss, b) {}
- bool chess960 = (os.iword(0) != 0); // See set960()
- return os << move_to_uci(m, chess960);
- }
+ RootMoveList::iterator rm; // 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> {
- // 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 {};
+ 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) {}
- std::ostream& operator<< (std::ostream& os, const set960& f) {
+ Move get_next_move() { return mp->get_next_move(); }
+ MovePicker* mp;
+ };
- os.iword(0) = int(f);
- return os;
- }
+ 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) {}
+ };
- /// Adjustments
+ // 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);
+ Move get_next_move();
+
+ RootMoveList::iterator rm;
+ bool firstCall;
+ };
+
+
+ /// Constants
+
+ // 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]; }
// Step 6. Razoring
// Reduction lookup tables (initialized at startup) and their access function
int8_t Reductions[2][64][64]; // [pv][depth][moveNumber]
- template <NodeType PV> inline Depth reduction(Depth d, int mn) {
+ template <bool PvNode> inline Depth reduction(Depth d, int mn) {
- return (Depth) Reductions[PV][Min(d / ONE_PLY, 63)][Min(mn, 63)];
+ return (Depth) Reductions[PvNode][Min(d / ONE_PLY, 63)][Min(mn, 63)];
}
// Easy move margin. An easy move candidate must be at least this much
/// Namespace variables
- // Book
- Book OpeningBook;
-
// Root move list
RootMoveList Rml;
// Skill level adjustment
int SkillLevel;
bool SkillLevelEnabled;
- RKISS RK;
// 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.
Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove);
- template <NodeType PvNode, bool SpNode, bool Root>
+ template <NodeType NT>
Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
- template <NodeType PvNode>
+ template <NodeType NT>
Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
- template <NodeType PvNode>
- inline Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
-
- return depth < ONE_PLY ? qsearch<PvNode>(pos, ss, alpha, beta, DEPTH_ZERO)
- : search<PvNode, false, false>(pos, ss, alpha, beta, depth);
- }
-
- template <NodeType PvNode>
+ template <bool PvNode>
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);
void poll(const Position& pos);
void wait_for_stop_or_ponderhit();
+ // 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) {
- // MovePickerExt is an extended MovePicker class used to choose at compile time
- // the proper move source according to the type of node.
- template<bool SpNode, bool Root> struct MovePickerExt;
-
- // In Root nodes use RootMoveList as source. Score and sort the root moves
- // before to search them.
- template<> struct MovePickerExt<false, true> : public MovePicker {
-
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
- : MovePicker(p, ttm, d, h, ss, b), firstCall(true) {
- 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 (rm = Rml.begin(); rm != Rml.end(); ++rm)
- if (rm->pv[0] == move)
- {
- rm->non_pv_score = score--;
- break;
- }
-
- Rml.sort();
- rm = Rml.begin();
- }
-
- Move get_next_move() {
-
- if (!firstCall)
- ++rm;
- else
- firstCall = false;
-
- return rm != Rml.end() ? rm->pv[0] : MOVE_NONE;
- }
-
- RootMoveList::iterator rm;
- bool firstCall;
- };
-
- // In SpNodes use split point's shared MovePicker object as move source
- template<> struct MovePickerExt<true, false> : 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) {}
-
- Move get_next_move() { return mp->get_next_move(); }
-
- RootMoveList::iterator rm; // Dummy, needed to compile
- MovePicker* mp;
- };
+ bool chess960 = (os.iword(0) != 0); // See set960()
+ return os << move_to_uci(m, chess960);
+ }
- // Default case, create and use a MovePicker object as source
- template<> struct MovePickerExt<false, false> : public MovePicker {
+ // 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 {};
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
- : MovePicker(p, ttm, d, h, ss, b) {}
+ std::ostream& operator<< (std::ostream& os, const set960& f) {
- RootMoveList::iterator rm; // Dummy, needed to compile
- };
+ os.iword(0) = int(f);
+ return os;
+ }
} // namespace
{
double pvRed = log(double(hd)) * log(double(mc)) / 3.0;
double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25;
- Reductions[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0);
- Reductions[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0);
+ Reductions[1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0);
+ Reductions[0][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0);
}
// Init futility margins array
}
-/// perft() is our utility to verify move generation. All the legal moves up to
-/// given depth are generated and counted and the sum returned.
+/// 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) {
for (MoveStack* cur = mlist; cur != last; cur++)
{
m = cur->move;
- pos.do_move(m, st, ci, pos.move_is_check(m, ci));
+ pos.do_move(m, st, ci, pos.move_gives_check(m, ci));
sum += perft(pos, depth - ONE_PLY);
pos.undo_move(m);
}
bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) {
+ static Book book;
+
// Initialize global search-related variables
StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = SendSearchedNodes = false;
NodesSincePoll = 0;
// Look for a book move
if (Options["OwnBook"].value<bool>())
{
- if (Options["Book File"].value<std::string>() != OpeningBook.name())
- OpeningBook.open(Options["Book File"].value<std::string>());
+ if (Options["Book File"].value<std::string>() != book.name())
+ book.open(Options["Book File"].value<std::string>());
- Move bookMove = OpeningBook.get_move(pos, Options["Best Book Move"].value<bool>());
+ Move bookMove = book.get_move(pos, Options["Best Book Move"].value<bool>());
if (bookMove != MOVE_NONE)
{
if (Limits.ponder)
// Read UCI options
UCIMultiPV = Options["MultiPV"].value<int>();
- SkillLevel = Options["Skill level"].value<int>();
+ SkillLevel = Options["Skill Level"].value<int>();
read_evaluation_uci_options(pos.side_to_move());
Threads.read_uci_options();
if (Rml.size() == 0)
{
cout << "info depth 0 score "
- << value_to_uci(pos.is_check() ? -VALUE_MATE : VALUE_DRAW)
+ << value_to_uci(pos.in_check() ? -VALUE_MATE : VALUE_DRAW)
<< endl;
return MOVE_NONE;
// research with bigger window until not failing high/low anymore.
do {
// Search starting from ss+1 to allow calling update_gains()
- value = search<PV, false, true>(pos, ss+1, alpha, beta, depth * ONE_PLY);
+ 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.
// all this work again. We also don't need to store anything to the hash table
// here: This is taken care of after we return from the split point.
- template <NodeType PvNode, bool SpNode, bool Root>
+ template <NodeType NT>
Value search(Position& pos, SearchStack* 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);
+
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
assert(PvNode || alpha == beta - 1);
StateInfo st;
const TTEntry *tte;
Key posKey;
+ Bitboard pinned;
Move ttMove, move, excludedMove, threatMove;
Depth ext, newDepth;
ValueType vt;
Value bestValue, value, oldAlpha;
Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific
- bool isPvMove, isCheck, singularExtensionNode, moveIsCheck, captureOrPromotion, dangerous, isBadCap;
+ bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous;
int moveCount = 0, playedMoveCount = 0;
int threadID = pos.thread();
SplitPoint* sp = NULL;
refinedValue = bestValue = value = -VALUE_INFINITE;
oldAlpha = alpha;
- isCheck = pos.is_check();
+ inCheck = pos.in_check();
ss->ply = (ss-1)->ply + 1;
// Used to send selDepth info to GUI
threatMove = sp->threatMove;
goto split_point_start;
}
- else if (Root)
+ else if (RootNode)
bestValue = alpha;
// Step 1. Initialize node and poll. Polling can abort search
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;
+ (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls)
{
if (( StopRequest
|| Threads[threadID].cutoff_occurred()
|| pos.is_draw()
- || ss->ply > PLY_MAX) && !Root)
+ || ss->ply > PLY_MAX) && !RootNode)
return VALUE_DRAW;
// Step 3. Mate distance pruning
excludedMove = ss->excludedMove;
posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key();
- tte = TT.retrieve(posKey);
+ tte = TT.probe(posKey);
ttMove = 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 ( !Root
+ if ( !RootNode
&& tte
&& (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT
: ok_to_use_TT(tte, depth, beta, ss->ply)))
}
// Step 5. Evaluate the position statically and update parent's gain statistics
- if (isCheck)
+ if (inCheck)
ss->eval = ss->evalMargin = VALUE_NONE;
else if (tte)
{
// Step 6. Razoring (is omitted in PV nodes)
if ( !PvNode
&& depth < RazorDepth
- && !isCheck
+ && !inCheck
&& refinedValue + razor_margin(depth) < beta
&& ttMove == MOVE_NONE
&& abs(beta) < VALUE_MATE_IN_PLY_MAX
if ( !PvNode
&& !ss->skipNullMove
&& depth < RazorDepth
- && !isCheck
+ && !inCheck
&& refinedValue - futility_margin(depth, 0) >= beta
&& abs(beta) < VALUE_MATE_IN_PLY_MAX
&& pos.non_pawn_material(pos.side_to_move()))
if ( !PvNode
&& !ss->skipNullMove
&& depth > ONE_PLY
- && !isCheck
+ && !inCheck
&& refinedValue >= beta
&& abs(beta) < VALUE_MATE_IN_PLY_MAX
&& pos.non_pawn_material(pos.side_to_move()))
pos.do_null_move(st);
(ss+1)->skipNullMove = true;
- nullValue = -search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY);
+ 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();
}
}
- // Step 9. Internal iterative deepening
+ // Step 9. ProbCut (is omitted in PV nodes)
+ // If we have a very good capture (i.e. SEE > seeValues[captured_piece_type])
+ // and a reduced search returns a value much above beta, we can (almost) safely
+ // prune the previous move.
+ if ( !PvNode
+ && depth >= RazorDepth + ONE_PLY
+ && !inCheck
+ && !ss->skipNullMove
+ && excludedMove == MOVE_NONE
+ && abs(beta) < VALUE_MATE_IN_PLY_MAX)
+ {
+ Value rbeta = beta + 200;
+ Depth rdepth = depth - ONE_PLY - 3 * ONE_PLY;
+
+ assert(rdepth >= ONE_PLY);
+
+ MovePicker mp(pos, ttMove, H, Position::see_value(pos.captured_piece_type()));
+ pinned = pos.pinned_pieces(pos.side_to_move());
+
+ while ((move = mp.get_next_move()) != MOVE_NONE)
+ if (pos.pl_move_is_legal(move, pinned))
+ {
+ pos.do_move(move, st);
+ value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth);
+ pos.undo_move(move);
+ if (value >= rbeta)
+ return value;
+ }
+ }
+
+ // Step 10. Internal iterative deepening
if ( depth >= IIDDepth[PvNode]
&& ttMove == MOVE_NONE
- && (PvNode || (!isCheck && ss->eval + IIDMargin >= beta)))
+ && (PvNode || (!inCheck && ss->eval + IIDMargin >= beta)))
{
Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2);
ss->skipNullMove = true;
- search<PvNode>(pos, ss, alpha, beta, d);
+ search<PvNode ? PV : NonPV>(pos, ss, alpha, beta, d);
ss->skipNullMove = false;
- ttMove = ss->bestMove;
- tte = TT.retrieve(posKey);
+ tte = TT.probe(posKey);
+ ttMove = tte ? tte->move() : MOVE_NONE;
}
split_point_start: // At split points actual search starts from here
// Initialize a MovePicker object for the current position
- MovePickerExt<SpNode, Root> mp(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta));
+ MovePickerExt<NT> mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta);
CheckInfo ci(pos);
+ pinned = pos.pinned_pieces(pos.side_to_move());
ss->bestMove = MOVE_NONE;
futilityBase = ss->eval + ss->evalMargin;
- singularExtensionNode = !Root
+ singularExtensionNode = !RootNode
&& !SpNode
&& depth >= SingularExtensionDepth[PvNode]
- && tte
- && tte->move()
+ && ttMove != MOVE_NONE
&& !excludedMove // Do not allow recursive singular extension search
&& (tte->type() & VALUE_TYPE_LOWER)
&& tte->depth() >= depth - 3 * ONE_PLY;
bestValue = sp->bestValue;
}
- // Step 10. Loop through moves
- // Loop through all legal moves until no moves remain or a beta cutoff occurs
+ // 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
&& !Threads[threadID].cutoff_occurred())
{
assert(move_is_ok(move));
+ if (move == excludedMove)
+ continue;
+
+ // At PV and SpNode nodes we want the moves to be legal
+ if ((PvNode || SpNode) && !pos.pl_move_is_legal(move, pinned))
+ continue;
+
if (SpNode)
{
moveCount = ++sp->moveCount;
lock_release(&(sp->lock));
}
- else if (move == excludedMove)
- continue;
else
moveCount++;
- if (Root)
+ if (RootNode)
{
// This is used by time management
FirstRootMove = (moveCount == 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);
+ isPvMove = (PvNode && moveCount <= (RootNode ? depth <= ONE_PLY ? 1000 : MultiPV : 1));
+ givesCheck = pos.move_gives_check(move, ci);
+ captureOrPromotion = pos.move_is_capture(move) || move_is_promotion(move);
- // Step 11. Decide the new search depth
- ext = extension<PvNode>(pos, move, captureOrPromotion, moveIsCheck, &dangerous);
+ // Step 12. Decide the new search depth
+ ext = extension<PvNode>(pos, move, captureOrPromotion, givesCheck, &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
// 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()
+ && move == ttMove
+ && pos.pl_move_is_legal(move, pinned)
&& ext < ONE_PLY)
{
Value ttValue = value_from_tt(tte->value(), ss->ply);
}
// Update current move (this must be done after singular extension search)
- ss->currentMove = move;
newDepth = depth - ONE_PLY + ext;
- // Step 12. Futility pruning (is omitted in PV nodes)
+ // Step 13. Futility pruning (is omitted in PV nodes)
if ( !PvNode
&& !captureOrPromotion
- && !isCheck
+ && !inCheck
&& !dangerous
&& move != ttMove
&& !move_is_castle(move))
// Value based pruning
// We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth,
// but fixing this made program slightly weaker.
- Depth predictedDepth = newDepth - reduction<NonPV>(depth, moveCount);
+ Depth predictedDepth = newDepth - reduction<PvNode>(depth, moveCount);
futilityValueScaled = futilityBase + futility_margin(predictedDepth, moveCount)
+ H.gain(pos.piece_on(move_from(move)), move_to(move));
}
}
- // 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;
+ // Check for legality only before to do the move
+ if (!pos.pl_move_is_legal(move, pinned))
+ {
+ moveCount--;
+ continue;
+ }
+
+ ss->currentMove = move;
- // Step 13. Make the move
- pos.do_move(move, st, ci, moveIsCheck);
+ // Step 14. Make the move
+ pos.do_move(move, st, ci, givesCheck);
if (!SpNode && !captureOrPromotion)
movesSearched[playedMoveCount++] = move;
if (isPvMove)
{
// Aspiration window is disabled in multi-pv case
- if (Root && MultiPV > 1)
+ if (RootNode && MultiPV > 1)
alpha = -VALUE_INFINITE;
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth);
+ value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
}
else
{
- // Step 14. Reduced depth search
+ // Step 15. Reduced depth search
// If the move fails high will be re-searched at full depth.
bool doFullDepthSearch = true;
alpha = SpNode ? sp->alpha : alpha;
ss->reduction = reduction<PvNode>(depth, moveCount);
if (ss->reduction)
{
- alpha = SpNode ? sp->alpha : alpha;
Depth d = newDepth - ss->reduction;
- value = -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);
doFullDepthSearch = (value > alpha);
}
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<NonPV>(pos, ss+1, -(rAlpha+1), -rAlpha, d);
- doFullDepthSearch = (value > rAlpha);
- ss->reduction = DEPTH_ZERO; // Restore original reduction
- }
-
- // Step 15. Full depth search
+ // Step 16. Full depth search
if (doFullDepthSearch)
{
alpha = SpNode ? sp->alpha : alpha;
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
+ 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 && (Root || value < beta))
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth);
+ 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. Undo move
+ // Step 17. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- // Step 17. Check for new best move
+ // Step 18. Check for new best move
if (SpNode)
{
lock_grab(&(sp->lock));
if (SpNode)
sp->bestValue = value;
- if (!Root && value > alpha)
+ if (!RootNode && value > alpha)
{
if (PvNode && value < beta) // We want always alpha < beta
{
else if (SpNode)
sp->is_betaCutoff = true;
- if (value == value_mate_in(ss->ply + 1))
- ss->mateKiller = move;
-
ss->bestMove = move;
if (SpNode)
}
}
- if (Root)
+ if (RootNode)
{
// Finished searching the move. If StopRequest is true, the search
// was aborted because the user interrupted the search or because we
else
mp.rm->pv_score = -VALUE_INFINITE;
- } // Root
+ } // RootNode
- // Step 18. Check for split
- if ( !Root
+ // Step 19. Check for split
+ if ( !RootNode
&& !SpNode
&& depth >= Threads.min_split_depth()
&& bestValue < beta
threatMove, moveCount, &mp, PvNode);
}
- // Step 19. Check for mate and stalemate
+ // 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)
- return excludedMove ? oldAlpha : isCheck ? value_mated_in(ss->ply) : VALUE_DRAW;
+ return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW;
- // Step 20. Update tables
+ // Step 21. Update tables
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
if (!SpNode && !StopRequest && !Threads[threadID].cutoff_occurred())
// Update killers and history only for non capture moves that fails high
if ( bestValue >= beta
- && !pos.move_is_capture_or_promotion(move))
+ && !pos.move_is_capture(move)
+ && !move_is_promotion(move))
{
if (move != ss->killers[0])
{
// search function when the remaining depth is zero (or, to be more precise,
// less than ONE_PLY).
- template <NodeType PvNode>
+ template <NodeType NT>
Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ const bool PvNode = (NT == PV);
+
+ assert(NT == PV || NT == NonPV);
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(PvNode || alpha == beta - 1);
StateInfo st;
Move ttMove, move;
Value bestValue, value, evalMargin, futilityValue, futilityBase;
- bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
+ bool inCheck, enoughMaterial, givesCheck, evasionPrunable;
const TTEntry* tte;
Depth ttDepth;
Value oldAlpha = alpha;
// Decide whether or not to include checks, this fixes also the type of
// TT entry depth that we are going to use. Note that in qsearch we use
// only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
- isCheck = pos.is_check();
- ttDepth = (isCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS);
+ inCheck = pos.in_check();
+ ttDepth = (inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS);
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
- tte = TT.retrieve(pos.get_key());
+ tte = TT.probe(pos.get_key());
ttMove = (tte ? tte->move() : MOVE_NONE);
if (!PvNode && tte && ok_to_use_TT(tte, ttDepth, beta, ss->ply))
}
// Evaluate the position statically
- if (isCheck)
+ if (inCheck)
{
bestValue = futilityBase = -VALUE_INFINITE;
ss->eval = evalMargin = VALUE_NONE;
// be generated.
MovePicker mp(pos, ttMove, depth, H);
CheckInfo ci(pos);
+ Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
// Loop through the moves until no moves remain or a beta cutoff occurs
while ( alpha < beta
{
assert(move_is_ok(move));
- moveIsCheck = pos.move_is_check(move, ci);
+ givesCheck = pos.move_gives_check(move, ci);
// Futility pruning
if ( !PvNode
- && !isCheck
- && !moveIsCheck
+ && !inCheck
+ && !givesCheck
&& move != ttMove
&& enoughMaterial
&& !move_is_promotion(move)
}
// Detect non-capture evasions that are candidate to be pruned
- evasionPrunable = isCheck
+ evasionPrunable = !PvNode
+ && inCheck
&& bestValue > VALUE_MATED_IN_PLY_MAX
&& !pos.move_is_capture(move)
&& !pos.can_castle(pos.side_to_move());
// Don't search moves with negative SEE values
if ( !PvNode
- && (!isCheck || evasionPrunable)
+ && (!inCheck || evasionPrunable)
&& move != ttMove
&& !move_is_promotion(move)
&& pos.see_sign(move) < 0)
// Don't search useless checks
if ( !PvNode
- && !isCheck
- && moveIsCheck
+ && !inCheck
+ && givesCheck
&& move != ttMove
- && !pos.move_is_capture_or_promotion(move)
+ && !pos.move_is_capture(move)
+ && !move_is_promotion(move)
&& ss->eval + PawnValueMidgame / 4 < beta
&& !check_is_dangerous(pos, move, futilityBase, beta, &bestValue))
{
continue;
}
+ // Check for legality only before to do the move
+ if (!pos.pl_move_is_legal(move, pinned))
+ continue;
+
// Update current move
ss->currentMove = move;
// Make and search the move
- pos.do_move(move, st, ci, moveIsCheck);
- value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-ONE_PLY);
+ pos.do_move(move, st, ci, givesCheck);
+ value = -qsearch<NT>(pos, ss+1, -beta, -alpha, depth-ONE_PLY);
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
// All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
- if (isCheck && bestValue == -VALUE_INFINITE)
+ if (inCheck && bestValue == -VALUE_INFINITE)
return value_mated_in(ss->ply);
// Update transposition table
// 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 <NodeType PvNode>
+ template <bool PvNode>
Depth extension(const Position& pos, Move m, bool captureOrPromotion,
bool moveIsCheck, bool* dangerous) {
assert(move_is_ok(m));
assert(threat && move_is_ok(threat));
- assert(!pos.move_is_check(m));
- assert(!pos.move_is_capture_or_promotion(m));
+ assert(!pos.move_gives_check(m));
+ assert(!pos.move_is_capture(m) && !move_is_promotion(m));
assert(!pos.move_is_passed_pawn_push(m));
Square mfrom, mto, tfrom, tto;
assert(MultiPV > 1);
+ static RKISS rk;
+
// Rml list is already sorted by pv_score in descending order
int s;
int max_s = -VALUE_INFINITE;
// PRNG sequence should be non deterministic
for (int i = abs(get_system_time() % 50); i > 0; i--)
- RK.rand<unsigned>();
+ 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,
break;
// This is our magical formula
- s += ((max - s) * wk + var * (RK.rand<unsigned>() % wk)) / 128;
+ s += ((max - s) * wk + var * (rk.rand<unsigned>() % wk)) / 128;
if (s > max_s)
{
TTEntry* tte;
int ply = 1;
- assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0]));
+ assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0]));
pos.do_move(pv[0], *st++);
- while ( (tte = TT.retrieve(pos.get_key())) != NULL
+ while ( (tte = TT.probe(pos.get_key())) != NULL
&& tte->move() != MOVE_NONE
- && pos.move_is_legal(tte->move())
+ && pos.move_is_pl(tte->move())
+ && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces(pos.side_to_move()))
&& ply < PLY_MAX
&& (!pos.is_draw() || ply < 2))
{
Value v, m = VALUE_NONE;
int ply = 0;
- assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0]));
+ assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0]));
do {
k = pos.get_key();
- tte = TT.retrieve(k);
+ tte = TT.probe(k);
// Don't overwrite existing correct entries
if (!tte || tte->move() != pv[ply])
{
- v = (pos.is_check() ? VALUE_NONE : evaluate(pos, m));
+ v = (pos.in_check() ? VALUE_NONE : evaluate(pos, m));
TT.store(k, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, pv[ply], v, m);
}
pos.do_move(pv[ply], *st++);
return s.str();
}
+ // 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), firstCall(true) {
+ 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 (rm = Rml.begin(); rm != Rml.end(); ++rm)
+ if (rm->pv[0] == move)
+ {
+ rm->non_pv_score = score--;
+ break;
+ }
+
+ Rml.sort();
+ rm = Rml.begin();
+ }
+
+ Move MovePickerExt<Root>::get_next_move() {
+
+ if (!firstCall)
+ ++rm;
+ else
+ firstCall = false;
+
+ return rm != Rml.end() ? rm->pv[0] : MOVE_NONE;
+ }
+
} // namespace
(ss+1)->sp = tsp;
if (tsp->pvNode)
- search<PV, true, false>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ search<SplitPointPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
else
- search<NonPV, true, false>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
+ search<SplitPointNonPV>(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth);
assert(threads[threadID].state == Thread::SEARCHING);
projects / stockfish / blobdiff