WebSVN – Games.Chess Giants – Diff – //engine-stockfish/search.cpp

 #include "evaluate.h"
 #include "misc.h"
 #include "movegen.h"
 #include "movepick.h"
+#include "position.h"
 #include "search.h"
 #include "timeman.h"
 #include "thread.h"
 #include "tt.h"
 #include "uci.h"
 namespace Search {
   SignalsType Signals;
   LimitsType Limits;
-  StateStackPtr SetupStates;
+}
 namespace Tablebases {
   int Cardinality;
-  uint64_t Hits;
   bool RootInTB;
   bool UseRule50;
   Depth ProbeDepth;
   Value Score;
+}
   // Different node types, used as a template parameter
   enum NodeType { NonPV, PV };
   // Razoring and futility margin based on depth
   const int razor_margin[4] = { 483, 570, 603, 554 };
-  Value futility_margin(Depth d) { return Value(200 * d); }
+  Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
   // Futility and reductions lookup tables, initialized at startup
-  int FutilityMoveCounts[2][16];  // [improving][depth]
+  int FutilityMoveCounts[2][16]; // [improving][depth]
-  Depth Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber]
+  int Reductions[2][2][64][64];  // [pv][improving][depth][moveNumber]
   template <bool PvNode> Depth reduction(bool i, Depth d, int mn) {
-    return Reductions[PvNode][i][std::min(d, 63 * ONE_PLY)][std::min(mn, 63)];
+    return Reductions[PvNode][i][std::min(d / ONE_PLY, 63)][std::min(mn, 63)] * ONE_PLY;
+  }
   // Skill structure is used to implement strength limit
   struct Skill {
     Skill(int l) : level(l) {}
       if (!std::equal(newPv.begin(), newPv.begin() + 3, pv))
+      {
           std::copy(newPv.begin(), newPv.begin() + 3, pv);
           StateInfo st[2];
-          pos.do_move(newPv[0], st[0], pos.gives_check(newPv[0], CheckInfo(pos)));
+          pos.do_move(newPv[0], st[0], pos.gives_check(newPv[0]));
-          pos.do_move(newPv[1], st[1], pos.gives_check(newPv[1], CheckInfo(pos)));
+          pos.do_move(newPv[1], st[1], pos.gives_check(newPv[1]));
           expectedPosKey = pos.key();
           pos.undo_move(newPv[1]);
           pos.undo_move(newPv[0]);
+      }
+    }
   const size_t HalfDensitySize = std::extent<decltype(HalfDensity)>::value;
   EasyMoveManager EasyMove;
   Value DrawValue[COLOR_NB];
-  CounterMoveHistoryStats CounterMoveHistory;
   template <NodeType NT>
   Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
   template <NodeType NT, bool InCheck>
   Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
   Value value_to_tt(Value v, int ply);
   Value value_from_tt(Value v, int ply);
   void update_pv(Move* pv, Move move, Move* childPv);
+  void update_cm_stats(Stack* ss, Piece pc, Square s, Value bonus);
-  void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
+  void update_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, Value bonus);
   void check_time();
 } // namespace
 /// Search::init() is called during startup to initialize various lookup tables
 void Search::init() {
+  for (int imp = 0; imp <= 1; ++imp)
+      for (int d = 1; d < 64; ++d)
+          for (int mc = 1; mc < 64; ++mc)
+          {
-  const double K[][2] = {{ 0.799, 2.281 }, { 0.484, 3.023 }};
+              double r = log(d) * log(mc) / 2;
+              if (r < 0.80)
+                continue;
-  for (int pv = 0; pv <= 1; ++pv)
-      for (int imp = 0; imp <= 1; ++imp)
-          for (int d = 1; d < 64; ++d)
-              for (int mc = 1; mc < 64; ++mc)
+              Reductions[NonPV][imp][d][mc] = int(std::round(r));
-              {
-                  double r = K[pv][0] + log(d) * log(mc) / K[pv][1];
+              Reductions[PV][imp][d][mc] = std::max(Reductions[NonPV][imp][d][mc] - 1, 0);
-                  if (r >= 1.5)
-                      Reductions[pv][imp][d][mc] = int(r) * ONE_PLY;
-                  // Increase reduction when eval is not improving
+              // Increase reduction for non-PV nodes when eval is not improving
-                  if (!pv && !imp && Reductions[pv][imp][d][mc] >= 2 * ONE_PLY)
+              if (!imp && Reductions[NonPV][imp][d][mc] >= 2)
-                      Reductions[pv][imp][d][mc] += ONE_PLY;
+                Reductions[NonPV][imp][d][mc]++;
-              }
+          }
   for (int d = 0; d < 16; ++d)
+  {
       FutilityMoveCounts[0][d] = int(2.4 + 0.773 * pow(d + 0.00, 1.8));
       FutilityMoveCounts[1][d] = int(2.9 + 1.045 * pow(d + 0.49, 1.8));
 /// Search::clear() resets search state to zero, to obtain reproducible results
 void Search::clear() {
   TT.clear();
-  CounterMoveHistory.clear();
   for (Thread* th : Threads)
+  {
       th->history.clear();
       th->counterMoves.clear();
+      th->fromTo.clear();
+      th->counterMoveHistory.clear();
+  }
   Threads.main()->previousScore = VALUE_INFINITE;
+}
 template<bool Root>
 uint64_t Search::perft(Position& pos, Depth depth) {
   StateInfo st;
   uint64_t cnt, nodes = 0;
-  CheckInfo ci(pos);
   const bool leaf = (depth == 2 * ONE_PLY);
   for (const auto& m : MoveList<LEGAL>(pos))
+  {
       if (Root && depth <= ONE_PLY)
           cnt = 1, nodes++;
       else
+      {
-          pos.do_move(m, st, pos.gives_check(m, ci));
+          pos.do_move(m, st, pos.gives_check(m));
           cnt = leaf ? MoveList<LEGAL>(pos).size() : perft<false>(pos, depth - ONE_PLY);
           nodes += cnt;
           pos.undo_move(m);
+      }
       if (Root)
   Time.init(Limits, us, rootPos.game_ply());
   int contempt = Options["Contempt"] * PawnValueEg / 100; // From centipawns
   DrawValue[ us] = VALUE_DRAW - Value(contempt);
   DrawValue[~us] = VALUE_DRAW + Value(contempt);
-  TB::Hits = 0;
-  TB::RootInTB = false;
-  TB::UseRule50 = Options["Syzygy50MoveRule"];
-  TB::ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
-  TB::Cardinality = Options["SyzygyProbeLimit"];
-  // Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality
-  if (TB::Cardinality > TB::MaxCardinality)
-  {
-      TB::Cardinality = TB::MaxCardinality;
-      TB::ProbeDepth = DEPTH_ZERO;
-  }
   if (rootMoves.empty())
+  {
       rootMoves.push_back(RootMove(MOVE_NONE));
       sync_cout << "info depth 0 score "
                 << UCI::value(rootPos.checkers() ? -VALUE_MATE : VALUE_DRAW)
                 << sync_endl;
+  }
   else
+  {
-      if (    TB::Cardinality >=  rootPos.count<ALL_PIECES>(WHITE)
-                                + rootPos.count<ALL_PIECES>(BLACK)
-          && !rootPos.can_castle(ANY_CASTLING))
-      {
-          // If the current root position is in the tablebases, then RootMoves
-          // contains only moves that preserve the draw or the win.
-          TB::RootInTB = Tablebases::root_probe(rootPos, rootMoves, TB::Score);
-          if (TB::RootInTB)
-              TB::Cardinality = 0; // Do not probe tablebases during the search
-          else // If DTZ tables are missing, use WDL tables as a fallback
-          {
-              // Filter out moves that do not preserve the draw or the win.
-              TB::RootInTB = Tablebases::root_probe_wdl(rootPos, rootMoves, TB::Score);
-              // Only probe during search if winning
-              if (TB::Score <= VALUE_DRAW)
-                  TB::Cardinality = 0;
-          }
-          if (TB::RootInTB)
-          {
-              TB::Hits = rootMoves.size();
-              if (!TB::UseRule50)
-                  TB::Score =  TB::Score > VALUE_DRAW ?  VALUE_MATE - MAX_PLY - 1
-                             : TB::Score < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1
-                                                      :  VALUE_DRAW;
-          }
-      }
       for (Thread* th : Threads)
-      {
-          th->maxPly = 0;
-          th->rootDepth = DEPTH_ZERO;
           if (th != this)
-          {
-              th->rootPos = Position(rootPos, th);
-              th->rootMoves = rootMoves;
               th->start_searching();
-          }
-      }
       Thread::search(); // Let's start searching!
+  }
   // When playing in 'nodes as time' mode, subtract the searched nodes from
   // Check if there are threads with a better score than main thread
   Thread* bestThread = this;
   if (   !this->easyMovePlayed
       &&  Options["MultiPV"] == 1
+      && !Limits.depth
-      && !Skill(Options["Skill Level"]).enabled())
+      && !Skill(Options["Skill Level"]).enabled()
+      &&  rootMoves[0].pv[0] != MOVE_NONE)
+  {
       for (Thread* th : Threads)
           if (   th->completedDepth > bestThread->completedDepth
               && th->rootMoves[0].score > bestThread->rootMoves[0].score)
               bestThread = th;
 // repeatedly with increasing depth until the allocated thinking time has been
 // consumed, the user stops the search, or the maximum search depth is reached.
 void Thread::search() {
-  Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2)
+  Stack stack[MAX_PLY+7], *ss = stack+5; // To allow referencing (ss-5) and (ss+2)
   Value bestValue, alpha, beta, delta;
   Move easyMove = MOVE_NONE;
   MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
-  std::memset(ss-2, 0, 5 * sizeof(Stack));
+  std::memset(ss-5, 0, 8 * sizeof(Stack));
   bestValue = delta = alpha = -VALUE_INFINITE;
   beta = VALUE_INFINITE;
   completedDepth = DEPTH_ZERO;
   if (skill.enabled())
       multiPV = std::max(multiPV, (size_t)4);
   multiPV = std::min(multiPV, rootMoves.size());
-  // Iterative deepening loop until requested to stop or the target depth is reached.
+  // Iterative deepening loop until requested to stop or the target depth is reached
+  while (   (rootDepth += ONE_PLY) < DEPTH_MAX
+         && !Signals.stop
-  while (++rootDepth < DEPTH_MAX && !Signals.stop && (!Limits.depth || rootDepth <= Limits.depth))
+         && (!Limits.depth || Threads.main()->rootDepth / ONE_PLY <= Limits.depth))
+  {
       // Set up the new depths for the helper threads skipping on average every
       // 2nd ply (using a half-density matrix).
       if (!mainThread)
+      {
           const Row& row = HalfDensity[(idx - 1) % HalfDensitySize];
-          if (row[(rootDepth + rootPos.game_ply()) % row.size()])
+          if (row[(rootDepth / ONE_PLY + rootPos.game_ply()) % row.size()])
              continue;
+      }
       // Age out PV variability metric
       if (mainThread)
               // first and eventually the new best one are set to -VALUE_INFINITE
               // and we want to keep the same order for all the moves except the
               // new PV that goes to the front. Note that in case of MultiPV
               // search the already searched PV lines are preserved.
               std::stable_sort(rootMoves.begin() + PVIdx, rootMoves.end());
-              // Write PV back to the 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(rootPos);
               // If search has been stopped, break immediately. Sorting and
               // writing PV back to TT is safe because RootMoves is still
               // valid, although it refers to the previous iteration.
               if (Signals.stop)
           // Sort the PV lines searched so far and update the GUI
           std::stable_sort(rootMoves.begin(), rootMoves.begin() + PVIdx + 1);
           if (!mainThread)
-              break;
+              continue;
-          if (Signals.stop)
-              sync_cout << "info nodes " << Threads.nodes_searched()
-                        << " time " << Time.elapsed() << sync_endl;
-          else if (PVIdx + 1 == multiPV || Time.elapsed() > 3000)
+          if (Signals.stop || PVIdx + 1 == multiPV || Time.elapsed() > 3000)
               sync_cout << UCI::pv(rootPos, rootDepth, alpha, beta) << sync_endl;
+      }
       if (!Signals.stop)
           completedDepth = rootDepth;
           if (!Signals.stop && !Signals.stopOnPonderhit)
+          {
               // Stop the search if only one legal move is available, or if all
               // of the available time has been used, or if we matched an easyMove
               // from the previous search and just did a fast verification.
-              const bool F[] = { !mainThread->failedLow,
+              const int F[] = { mainThread->failedLow,
-                                 bestValue >= mainThread->previousScore };
+                                bestValue - mainThread->previousScore };
-              int improvingFactor = 640 - 160*F[0] - 126*F[1] - 124*F[0]*F[1];
+              int improvingFactor = std::max(229, std::min(715, 357 + 119 * F[0] - 6 * F[1]));
               double unstablePvFactor = 1 + mainThread->bestMoveChanges;
               bool doEasyMove =   rootMoves[0].pv[0] == easyMove
                                && mainThread->bestMoveChanges < 0.03
-                               && Time.elapsed() > Time.optimum() * 25 / 204;
+                               && Time.elapsed() > Time.optimum() * 5 / 42;
               if (   rootMoves.size() == 1
-                  || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 634
+                  || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 628
-                  || (mainThread->easyMovePlayed = doEasyMove))
+                  || (mainThread->easyMovePlayed = doEasyMove, doEasyMove))
+              {
                   // If we are allowed to ponder do not stop the search now but
                   // keep pondering until the GUI sends "ponderhit" or "stop".
                   if (Limits.ponder)
                       Signals.stopOnPonderhit = true;
     const bool rootNode = PvNode && (ss-1)->ply == 0;
     assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE);
     assert(PvNode || (alpha == beta - 1));
     assert(DEPTH_ZERO < depth && depth < DEPTH_MAX);
+    assert(!(PvNode && cutNode));
+    assert(depth / ONE_PLY * ONE_PLY == depth);
     Move pv[MAX_PLY+1], quietsSearched[64];
     StateInfo st;
     TTEntry* tte;
     Key posKey;
     Move ttMove, move, excludedMove, bestMove;
-    Depth extension, newDepth, predictedDepth;
+    Depth extension, newDepth;
-    Value bestValue, value, ttValue, eval, nullValue, futilityValue;
+    Value bestValue, value, ttValue, eval, nullValue;
     bool ttHit, inCheck, givesCheck, singularExtensionNode, improving;
-    bool captureOrPromotion, doFullDepthSearch;
+    bool captureOrPromotion, doFullDepthSearch, moveCountPruning;
+    Piece moved_piece;
     int moveCount, quietCount;
     // Step 1. Initialize node
     Thread* thisThread = pos.this_thread();
     inCheck = pos.checkers();
     moveCount = quietCount =  ss->moveCount = 0;
+    ss->history = VALUE_ZERO;
     bestValue = -VALUE_INFINITE;
     ss->ply = (ss-1)->ply + 1;
     // Check for the available remaining time
     if (thisThread->resetCalls.load(std::memory_order_relaxed))
+    }
     assert(0 <= ss->ply && ss->ply < MAX_PLY);
     ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
+    ss->counterMoves = nullptr;
     (ss+1)->skipEarlyPruning = false;
     (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
     // 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.
     excludedMove = ss->excludedMove;
-    posKey = excludedMove ? pos.exclusion_key() : pos.key();
+    posKey = pos.key() ^ Key(excludedMove);
     tte = TT.probe(posKey, ttHit);
     ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
     ttMove =  rootNode ? thisThread->rootMoves[thisThread->PVIdx].pv[0]
             : ttHit    ? tte->move() : MOVE_NONE;
         && tte->depth() >= depth
         && ttValue != VALUE_NONE // Possible in case of TT access race
         && (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
                             : (tte->bound() & BOUND_UPPER)))
+    {
-        ss->currentMove = ttMove; // Can be MOVE_NONE
         // If ttMove is quiet, update killers, history, counter move on TT hit
-        if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove))
+        if (ttValue >= beta && ttMove)
+        {
-            update_stats(pos, ss, ttMove, depth, nullptr, 0);
+            int d = depth / ONE_PLY;
+            if (!pos.capture_or_promotion(ttMove))
+            {
+                Value bonus = Value(d * d + 2 * d - 2);
+                update_stats(pos, ss, ttMove, nullptr, 0, bonus);
+            }
+            // Extra penalty for a quiet TT move in previous ply when it gets refuted
+            if ((ss-1)->moveCount == 1 && !pos.captured_piece())
+            {
+                Value penalty = Value(d * d + 4 * d + 1);
+                Square prevSq = to_sq((ss-1)->currentMove);
+                update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -penalty);
+            }
+        }
         return ttValue;
+    }
     // Step 4a. Tablebase probe
     if (!rootNode && TB::Cardinality)
+        {
             int found, v = Tablebases::probe_wdl(pos, &found);
             if (found)
+            {
-                TB::Hits++;
+                thisThread->tbHits++;
                 int drawScore = TB::UseRule50 ? 1 : 0;
                 value =  v < -drawScore ? -VALUE_MATE + MAX_PLY + ss->ply
                        : v >  drawScore ?  VALUE_MATE - MAX_PLY - ss->ply
         goto moves_loop;
     // Step 6. Razoring (skipped when in check)
     if (   !PvNode
         &&  depth < 4 * ONE_PLY
-        &&  eval + razor_margin[depth] <= alpha
-        &&  ttMove == MOVE_NONE)
+        &&  ttMove == MOVE_NONE
+        &&  eval + razor_margin[depth / ONE_PLY] <= alpha)
+    {
-        if (   depth <= ONE_PLY
+        if (depth <= ONE_PLY)
-            && eval + razor_margin[3 * ONE_PLY] <= alpha)
             return qsearch<NonPV, false>(pos, ss, alpha, beta, DEPTH_ZERO);
-        Value ralpha = alpha - razor_margin[depth];
+        Value ralpha = alpha - razor_margin[depth / ONE_PLY];
         Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1, DEPTH_ZERO);
         if (v <= ralpha)
             return v;
+    }
     if (   !rootNode
         &&  depth < 7 * ONE_PLY
         &&  eval - futility_margin(depth) >= beta
         &&  eval < VALUE_KNOWN_WIN  // Do not return unproven wins
         &&  pos.non_pawn_material(pos.side_to_move()))
-        return eval - futility_margin(depth);
+        return eval;
     // Step 8. Null move search with verification search (is omitted in PV nodes)
     if (   !PvNode
-        &&  depth >= 2 * ONE_PLY
         &&  eval >= beta
+        && (ss->staticEval >= beta - 35 * (depth / ONE_PLY - 6) || depth >= 13 * ONE_PLY)
         &&  pos.non_pawn_material(pos.side_to_move()))
+    {
         ss->currentMove = MOVE_NULL;
+        ss->counterMoves = nullptr;
         assert(eval - beta >= 0);
         // Null move dynamic reduction based on depth and value
-        Depth R = ((823 + 67 * depth) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
+        Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
         pos.do_null_move(st);
         (ss+1)->skipEarlyPruning = true;
         nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1, DEPTH_ZERO)
                                       : - search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode);
                 return nullValue;
+        }
+    }
     // Step 9. ProbCut (skipped when in check)
-    // If we have a very good capture (i.e. SEE > seeValues[captured_piece_type])
+    // If we have a good enough capture and a reduced search returns a value
-    // and a reduced search returns a value much above beta, we can (almost)
-    // safely prune the previous move.
+    // much above beta, we can (almost) safely prune the previous move.
     if (   !PvNode
         &&  depth >= 5 * ONE_PLY
         &&  abs(beta) < VALUE_MATE_IN_MAX_PLY)
+    {
         Value rbeta = std::min(beta + 200, VALUE_INFINITE);
         assert(rdepth >= ONE_PLY);
         assert((ss-1)->currentMove != MOVE_NONE);
         assert((ss-1)->currentMove != MOVE_NULL);
-        MovePicker mp(pos, ttMove, thisThread->history, PieceValue[MG][pos.captured_piece_type()]);
+        MovePicker mp(pos, ttMove, rbeta - ss->staticEval);
-        CheckInfo ci(pos);
         while ((move = mp.next_move()) != MOVE_NONE)
-            if (pos.legal(move, ci.pinned))
+            if (pos.legal(move))
+            {
                 ss->currentMove = move;
+                ss->counterMoves = &thisThread->counterMoveHistory[pos.moved_piece(move)][to_sq(move)];
-                pos.do_move(move, st, pos.gives_check(move, ci));
+                pos.do_move(move, st, pos.gives_check(move));
                 value = -search<NonPV>(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode);
                 pos.undo_move(move);
                 if (value >= rbeta)
                     return value;
+            }
+    }
     // Step 10. Internal iterative deepening (skipped when in check)
-    if (    depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY)
+    if (    depth >= 6 * ONE_PLY
         && !ttMove
         && (PvNode || ss->staticEval + 256 >= beta))
+    {
-        Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4);
+        Depth d = (3 * depth / (4 * ONE_PLY) - 2) * ONE_PLY;
         ss->skipEarlyPruning = true;
-        search<NT>(pos, ss, alpha, beta, d, true);
+        search<NT>(pos, ss, alpha, beta, d, cutNode);
         ss->skipEarlyPruning = false;
         tte = TT.probe(posKey, ttHit);
         ttMove = ttHit ? tte->move() : MOVE_NONE;
+    }
 moves_loop: // When in check search starts from here
-    Square prevSq = to_sq((ss-1)->currentMove);
+    const CounterMoveStats* cmh  = (ss-1)->counterMoves;
-    Move cm = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
+    const CounterMoveStats* fmh  = (ss-2)->counterMoves;
-    const CounterMoveStats& cmh = CounterMoveHistory[pos.piece_on(prevSq)][prevSq];
+    const CounterMoveStats* fmh2 = (ss-4)->counterMoves;
-    MovePicker mp(pos, ttMove, depth, thisThread->history, cmh, cm, ss);
+    MovePicker mp(pos, ttMove, depth, ss);
-    CheckInfo ci(pos);
     value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
     improving =   ss->staticEval >= (ss-2)->staticEval
-               || ss->staticEval == VALUE_NONE
+            /* || ss->staticEval == VALUE_NONE Already implicit in the previous condition */
                ||(ss-2)->staticEval == VALUE_NONE;
     singularExtensionNode =   !rootNode
                            &&  depth >= 8 * ONE_PLY
                            &&  ttMove != MOVE_NONE
-                       /*  &&  ttValue != VALUE_NONE Already implicit in the next condition */
-                           &&  abs(ttValue) < VALUE_KNOWN_WIN
+                           &&  ttValue != VALUE_NONE
                            && !excludedMove // Recursive singular search is not allowed
                            && (tte->bound() & BOUND_LOWER)
                            &&  tte->depth() >= depth - 3 * ONE_PLY;
     // Step 11. Loop through moves
       if (PvNode)
           (ss+1)->pv = nullptr;
       extension = DEPTH_ZERO;
       captureOrPromotion = pos.capture_or_promotion(move);
+      moved_piece = pos.moved_piece(move);
-      givesCheck =  type_of(move) == NORMAL && !ci.dcCandidates
+      givesCheck =  type_of(move) == NORMAL && !pos.discovered_check_candidates()
-                  ? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
+                  ? pos.check_squares(type_of(pos.piece_on(from_sq(move)))) & to_sq(move)
-                  : pos.gives_check(move, ci);
+                  : pos.gives_check(move);
+      moveCountPruning =   depth < 16 * ONE_PLY
+                        && moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
       // Step 12. Extend checks
+      if (    givesCheck
+          && !moveCountPruning
-      if (givesCheck && pos.see_sign(move) >= VALUE_ZERO)
+          &&  pos.see_ge(move, VALUE_ZERO))
           extension = ONE_PLY;
       // 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 and if the result is lower than
       // ttValue minus a margin then we extend the ttMove.
       if (    singularExtensionNode
           &&  move == ttMove
           && !extension
-          &&  pos.legal(move, ci.pinned))
+          &&  pos.legal(move))
+      {
-          Value rBeta = ttValue - 2 * depth / ONE_PLY;
+          Value rBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE);
+          Depth d = (depth / (2 * ONE_PLY)) * ONE_PLY;
           ss->excludedMove = move;
           ss->skipEarlyPruning = true;
-          value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
+          value = search<NonPV>(pos, ss, rBeta - 1, rBeta, d, cutNode);
           ss->skipEarlyPruning = false;
           ss->excludedMove = MOVE_NONE;
           if (value < rBeta)
               extension = ONE_PLY;
       // Update the current move (this must be done after singular extension search)
       newDepth = depth - ONE_PLY + extension;
       // Step 13. Pruning at shallow depth
-      if (   !rootNode
+      if (  !rootNode
-          && !captureOrPromotion
-          && !inCheck
-          && !givesCheck
-          && !pos.advanced_pawn_push(move)
-          &&  bestValue > VALUE_MATED_IN_MAX_PLY)
+          && bestValue > VALUE_MATED_IN_MAX_PLY)
+      {
-          // Move count based pruning
+          if (   !captureOrPromotion
-          if (   depth < 16 * ONE_PLY
+              && !givesCheck
+              && !pos.advanced_pawn_push(move))
+          {
-              && moveCount >= FutilityMoveCounts[improving][depth])
+              // Move count based pruning
+              if (moveCountPruning)
-              continue;
+                  continue;
-          // History based pruning
-          if (   depth <= 4 * ONE_PLY
+              // Reduced depth of the next LMR search
-              && move != ss->killers[0]
-              && thisThread->history[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO
+              int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY;
-              && cmh[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO)
-              continue;
+              // Countermoves based pruning
+              if (   lmrDepth < 3
+                  && (!cmh  || (*cmh )[moved_piece][to_sq(move)] < VALUE_ZERO)
-          predictedDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO);
+                  && (!fmh  || (*fmh )[moved_piece][to_sq(move)] < VALUE_ZERO)
+                  && (!fmh2 || (*fmh2)[moved_piece][to_sq(move)] < VALUE_ZERO || (cmh && fmh)))
+                  continue;
-          // Futility pruning: parent node
+              // Futility pruning: parent node
-          if (predictedDepth < 7 * ONE_PLY)
+              if (   lmrDepth < 7
-          {
+                  && !inCheck
-              futilityValue = ss->staticEval + futility_margin(predictedDepth) + 256;
+                  && ss->staticEval + 256 + 200 * lmrDepth <= alpha)
+                  continue;
-              if (futilityValue <= alpha)
+              // Prune moves with negative SEE
-              {
+              if (   lmrDepth < 8
-                  bestValue = std::max(bestValue, futilityValue);
+                  && !pos.see_ge(move, Value(-35 * lmrDepth * lmrDepth)))
                   continue;
-              }
+          }
-          // Prune moves with negative SEE at low depths
+          else if (   depth < 7 * ONE_PLY
+                   && !extension
-          if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO)
+                   && !pos.see_ge(move, Value(-35 * depth / ONE_PLY * depth / ONE_PLY)))
-              continue;
+                  continue;
+      }
       // Speculative prefetch as early as possible
       prefetch(TT.first_entry(pos.key_after(move)));
       // Check for legality just before making the move
-      if (!rootNode && !pos.legal(move, ci.pinned))
+      if (!rootNode && !pos.legal(move))
+      {
           ss->moveCount = --moveCount;
           continue;
+      }
       ss->currentMove = move;
+      ss->counterMoves = &thisThread->counterMoveHistory[moved_piece][to_sq(move)];
       // Step 14. Make the move
       pos.do_move(move, st, givesCheck);
       // Step 15. Reduced depth search (LMR). If the move fails high it will be
       // re-searched at full depth.
       if (    depth >= 3 * ONE_PLY
           &&  moveCount > 1
-          && !captureOrPromotion)
+          && (!captureOrPromotion || moveCountPruning))
+      {
           Depth r = reduction<PvNode>(improving, depth, moveCount);
-          // Increase reduction for cut nodes and moves with a bad history
+          if (captureOrPromotion)
-          if (   (!PvNode && cutNode)
+              r -= r ? ONE_PLY : DEPTH_ZERO;
+          else
+          {
-              || (   thisThread->history[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO
+              // Increase reduction for cut nodes
-                  && cmh[pos.piece_on(to_sq(move))][to_sq(move)] <= VALUE_ZERO))
+              if (cutNode)
-              r += ONE_PLY;
+                  r += 2 * ONE_PLY;
-          // Decrease/increase reduction for moves with a good/bad history
+              // Decrease reduction for moves that escape a capture. Filter out
+              // castling moves, because they are coded as "king captures rook" and
+              // hence break make_move(). Also use see() instead of see_sign(),
+              // because the destination square is empty.
+              else if (   type_of(move) == NORMAL
-          int rHist = (  thisThread->history[pos.piece_on(to_sq(move))][to_sq(move)]
+                       && type_of(pos.piece_on(to_sq(move))) != PAWN
-                       + cmh[pos.piece_on(to_sq(move))][to_sq(move)]) / 14980;
+                       && !pos.see_ge(make_move(to_sq(move), from_sq(move)),  VALUE_ZERO))
-          r = std::max(DEPTH_ZERO, r - rHist * ONE_PLY);
+                  r -= 2 * ONE_PLY;
-          // Decrease reduction for moves that escape a capture. Filter out
+              ss->history = thisThread->history[moved_piece][to_sq(move)]
-          // castling moves, because they are coded as "king captures rook" and
+                           +    (cmh  ? (*cmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
-          // hence break make_move(). Also use see() instead of see_sign(),
+                           +    (fmh  ? (*fmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
+                           +    (fmh2 ? (*fmh2)[moved_piece][to_sq(move)] : VALUE_ZERO)
+                           +    thisThread->fromTo.get(~pos.side_to_move(), move)
-          // because the destination square is empty.
+                           -    8000; // Correction factor
+              // Decrease/increase reduction by comparing opponent's stat score
+              if (ss->history > VALUE_ZERO && (ss-1)->history < VALUE_ZERO)
-          if (   r
+                  r -= ONE_PLY;
-              && type_of(move) == NORMAL
+              else if (ss->history < VALUE_ZERO && (ss-1)->history > VALUE_ZERO)
-              && type_of(pos.piece_on(to_sq(move))) != PAWN
+                  r += ONE_PLY;
-              && pos.see(make_move(to_sq(move), from_sq(move))) < VALUE_ZERO)
+              // Decrease/increase reduction for moves with a good/bad history
-              r = std::max(DEPTH_ZERO, r - ONE_PLY);
+              r = std::max(DEPTH_ZERO, (r / ONE_PLY - ss->history / 20000) * ONE_PLY);
+          }
           Depth d = std::max(newDepth - r, ONE_PLY);
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
-          doFullDepthSearch = (value > alpha && r != DEPTH_ZERO);
+          doFullDepthSearch = (value > alpha && d != newDepth);
+      }
       else
           doFullDepthSearch = !PvNode || moveCount > 1;
       // Step 16. Full depth search when LMR is skipped or fails high
     // Step 20. Check for mate and stalemate
     // All legal moves have been searched and if there are no legal moves, it
     // must be a mate or a stalemate. If we are in a singular extension search then
     // return a fail low score.
+    assert(moveCount || !inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
     if (!moveCount)
         bestValue = excludedMove ? alpha
                    :     inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
+    else if (bestMove)
+    {
+        int d = depth / ONE_PLY;
-    // Quiet best move: update killers, history and countermoves
+        // Quiet best move: update killers, history and countermoves
-    else if (bestMove && !pos.capture_or_promotion(bestMove))
+        if (!pos.capture_or_promotion(bestMove))
+        {
+            Value bonus = Value(d * d + 2 * d - 2);
-        update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount);
+            update_stats(pos, ss, bestMove, quietsSearched, quietCount, bonus);
+        }
+        // Extra penalty for a quiet TT move in previous ply when it gets refuted
+        if ((ss-1)->moveCount == 1 && !pos.captured_piece())
+        {
+            Value penalty = Value(d * d + 4 * d + 1);
+            Square prevSq = to_sq((ss-1)->currentMove);
+            update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -penalty);
+        }
+    }
     // Bonus for prior countermove that caused the fail low
     else if (    depth >= 3 * ONE_PLY
-             && !bestMove
-             && !inCheck
-             && !pos.captured_piece_type()
+             && !pos.captured_piece()
-             && is_ok((ss - 1)->currentMove)
-             && is_ok((ss - 2)->currentMove))
+             && is_ok((ss-1)->currentMove))
+    {
+        int d = depth / ONE_PLY;
-        Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1);
+        Value bonus = Value(d * d + 2 * d - 2);
-        Square prevPrevSq = to_sq((ss - 2)->currentMove);
+        Square prevSq = to_sq((ss-1)->currentMove);
-        CounterMoveStats& prevCmh = CounterMoveHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
-        prevCmh.update(pos.piece_on(prevSq), prevSq, bonus);
+        update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, bonus);
+    }
     tte->save(posKey, value_to_tt(bestValue, ss->ply),
               bestValue >= beta ? BOUND_LOWER :
               PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
     assert(InCheck == !!pos.checkers());
     assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
     assert(PvNode || (alpha == beta - 1));
     assert(depth <= DEPTH_ZERO);
+    assert(depth / ONE_PLY * ONE_PLY == depth);
     Move pv[MAX_PLY+1];
     StateInfo st;
     TTEntry* tte;
     Key posKey;
         && ttHit
         && tte->depth() >= ttDepth
         && ttValue != VALUE_NONE // Only in case of TT access race
         && (ttValue >= beta ? (tte->bound() &  BOUND_LOWER)
                             : (tte->bound() &  BOUND_UPPER)))
-    {
-        ss->currentMove = ttMove; // Can be MOVE_NONE
         return ttValue;
-    }
     // Evaluate the position statically
     if (InCheck)
+    {
         ss->staticEval = VALUE_NONE;
     // Initialize a MovePicker object for the current position, and prepare
     // to search the moves. Because the depth is <= 0 here, only captures,
     // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
     // be generated.
-    MovePicker mp(pos, ttMove, depth, pos.this_thread()->history, to_sq((ss-1)->currentMove));
+    MovePicker mp(pos, ttMove, depth, to_sq((ss-1)->currentMove));
-    CheckInfo ci(pos);
     // Loop through the moves until no moves remain or a beta cutoff occurs
     while ((move = mp.next_move()) != MOVE_NONE)
+    {
       assert(is_ok(move));
-      givesCheck =  type_of(move) == NORMAL && !ci.dcCandidates
+      givesCheck =  type_of(move) == NORMAL && !pos.discovered_check_candidates()
-                  ? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
+                  ? pos.check_squares(type_of(pos.piece_on(from_sq(move)))) & to_sq(move)
-                  : pos.gives_check(move, ci);
+                  : pos.gives_check(move);
       // Futility pruning
       if (   !InCheck
           && !givesCheck
           &&  futilityBase > -VALUE_KNOWN_WIN
+          {
               bestValue = std::max(bestValue, futilityValue);
               continue;
+          }
-          if (futilityBase <= alpha && pos.see(move) <= VALUE_ZERO)
+          if (futilityBase <= alpha && !pos.see_ge(move, VALUE_ZERO + 1))
+          {
               bestValue = std::max(bestValue, futilityBase);
               continue;
+          }
+      }
                        && !pos.capture(move);
       // Don't search moves with negative SEE values
       if (  (!InCheck || evasionPrunable)
           &&  type_of(move) != PROMOTION
-          &&  pos.see_sign(move) < VALUE_ZERO)
+          &&  !pos.see_ge(move, VALUE_ZERO))
           continue;
       // Speculative prefetch as early as possible
       prefetch(TT.first_entry(pos.key_after(move)));
       // Check for legality just before making the move
-      if (!pos.legal(move, ci.pinned))
+      if (!pos.legal(move))
           continue;
       ss->currentMove = move;
       // Make and search the move
         *pv++ = *childPv++;
     *pv = MOVE_NONE;
+  }
+  // update_cm_stats() updates countermove and follow-up move history
+  void update_cm_stats(Stack* ss, Piece pc, Square s, Value bonus) {
+    CounterMoveStats* cmh  = (ss-1)->counterMoves;
+    CounterMoveStats* fmh1 = (ss-2)->counterMoves;
+    CounterMoveStats* fmh2 = (ss-4)->counterMoves;
+    if (cmh)
+        cmh->update(pc, s, bonus);
+    if (fmh1)
+        fmh1->update(pc, s, bonus);
+    if (fmh2)
+        fmh2->update(pc, s, bonus);
+  }
-  // update_stats() updates killers, history, countermove and countermove
+  // update_stats() updates killers, history, countermove and countermove plus
-  // history when a new quiet best move is found.
+  // follow-up move history when a new quiet best move is found.
   void update_stats(const Position& pos, Stack* ss, Move move,
-                    Depth depth, Move* quiets, int quietsCnt) {
+                    Move* quiets, int quietsCnt, Value bonus) {
     if (ss->killers[0] != move)
+    {
         ss->killers[1] = ss->killers[0];
         ss->killers[0] = move;
+    }
-    Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1);
-    Square prevSq = to_sq((ss-1)->currentMove);
+    Color c = pos.side_to_move();
-    CounterMoveStats& cmh = CounterMoveHistory[pos.piece_on(prevSq)][prevSq];
     Thread* thisThread = pos.this_thread();
+    thisThread->fromTo.update(c, move, bonus);
     thisThread->history.update(pos.moved_piece(move), to_sq(move), bonus);
+    update_cm_stats(ss, pos.moved_piece(move), to_sq(move), bonus);
-    if (is_ok((ss-1)->currentMove))
+    if ((ss-1)->counterMoves)
+    {
+        Square prevSq = to_sq((ss-1)->currentMove);
         thisThread->counterMoves.update(pos.piece_on(prevSq), prevSq, move);
-        cmh.update(pos.moved_piece(move), to_sq(move), bonus);
+    }
     // Decrease all the other played quiet moves
     for (int i = 0; i < quietsCnt; ++i)
+    {
+        thisThread->fromTo.update(c, quiets[i], -bonus);
         thisThread->history.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
-        if (is_ok((ss-1)->currentMove))
-            cmh.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
+        update_cm_stats(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
-    }
-    // Extra penalty for a quiet TT move in previous ply when it gets refuted
-    if (   (ss-1)->moveCount == 1
-        && !pos.captured_piece_type()
-        && is_ok((ss-2)->currentMove))
-    {
-        Square prevPrevSq = to_sq((ss-2)->currentMove);
-        CounterMoveStats& prevCmh = CounterMoveHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
-        prevCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * (depth + 1) / ONE_PLY);
+    }
+  }
   // When playing with strength handicap, choose best move among a set of RootMoves
   // using a statistical rule dependent on 'level'. Idea by Heinz van Saanen.
   Move Skill::pick_best(size_t multiPV) {
-    const Search::RootMoveVector& rootMoves = Threads.main()->rootMoves;
+    const RootMoves& rootMoves = Threads.main()->rootMoves;
     static PRNG rng(now()); // PRNG sequence should be non-deterministic
     // RootMoves are already sorted by score in descending order
     Value topScore = rootMoves[0].score;
     int delta = std::min(topScore - rootMoves[multiPV - 1].score, PawnValueMg);
     if (Limits.ponder)
         return;
     if (   (Limits.use_time_management() && elapsed > Time.maximum() - 10)
         || (Limits.movetime && elapsed >= Limits.movetime)
-        || (Limits.nodes && Threads.nodes_searched() >= Limits.nodes))
+        || (Limits.nodes && Threads.nodes_searched() >= (uint64_t)Limits.nodes))
             Signals.stop = true;
+  }
 } // namespace
 string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
   std::stringstream ss;
   int elapsed = Time.elapsed() + 1;
-  const Search::RootMoveVector& rootMoves = pos.this_thread()->rootMoves;
+  const RootMoves& rootMoves = pos.this_thread()->rootMoves;
   size_t PVIdx = pos.this_thread()->PVIdx;
   size_t multiPV = std::min((size_t)Options["MultiPV"], rootMoves.size());
-  uint64_t nodes_searched = Threads.nodes_searched();
+  uint64_t nodesSearched = Threads.nodes_searched();
+  uint64_t tbHits = Threads.tb_hits() + (TB::RootInTB ? rootMoves.size() : 0);
   for (size_t i = 0; i < multiPV; ++i)
+  {
       bool updated = (i <= PVIdx);
          << " score "    << UCI::value(v);
       if (!tb && i == PVIdx)
           ss << (v >= beta ? " lowerbound" : v <= alpha ? " upperbound" : "");
-      ss << " nodes "    << nodes_searched
+      ss << " nodes "    << nodesSearched
-         << " nps "      << nodes_searched * 1000 / elapsed;
+         << " nps "      << nodesSearched * 1000 / elapsed;
       if (elapsed > 1000) // Earlier makes little sense
           ss << " hashfull " << TT.hashfull();
-      ss << " tbhits "   << TB::Hits
+      ss << " tbhits "   << tbHits
          << " time "     << elapsed
          << " pv";
       for (Move m : rootMoves[i].pv)
           ss << " " << UCI::move(m, pos.is_chess960());
+  }
   return ss.str();
-}
-/// RootMove::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.
-void RootMove::insert_pv_in_tt(Position& pos) {
-  StateInfo state[MAX_PLY], *st = state;
-  bool ttHit;
-  for (Move m : pv)
-  {
-      assert(MoveList<LEGAL>(pos).contains(m));
-      TTEntry* tte = TT.probe(pos.key(), ttHit);
-      if (!ttHit || tte->move() != m) // Don't overwrite correct entries
-          tte->save(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE,
-                    m, VALUE_NONE, TT.generation());
-      pos.do_move(m, *st++, pos.gives_check(m, CheckInfo(pos)));
-  }
-  for (size_t i = pv.size(); i > 0; )
-      pos.undo_move(pv[--i]);
+}
 /// RootMove::extract_ponder_from_tt() is called in case we have no ponder move
 /// before exiting the search, for instance, in case we stop the search during a
 /// fail high at root. We try hard to have a ponder move to return to the GUI,
 /// otherwise in case of 'ponder on' we have nothing to think on.
-bool RootMove::extract_ponder_from_tt(Position& pos)
+bool RootMove::extract_ponder_from_tt(Position& pos) {
-{
     StateInfo st;
     bool ttHit;
     assert(pv.size() == 1);
+    if (!pv[0])
+        return false;
-    pos.do_move(pv[0], st, pos.gives_check(pv[0], CheckInfo(pos)));
+    pos.do_move(pv[0], st, pos.gives_check(pv[0]));
     TTEntry* tte = TT.probe(pos.key(), ttHit);
-    pos.undo_move(pv[0]);
     if (ttHit)
+    {
         Move m = tte->move(); // Local copy to be SMP safe
         if (MoveList<LEGAL>(pos).contains(m))
-           return pv.push_back(m), true;
+            pv.push_back(m);
+    }
+    pos.undo_move(pv[0]);
+    return pv.size() > 1;
+}
+void Tablebases::filter_root_moves(Position& pos, Search::RootMoves& rootMoves) {
+    RootInTB = false;
+    UseRule50 = Options["Syzygy50MoveRule"];
+    ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
+    Cardinality = Options["SyzygyProbeLimit"];
+    // Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality
+    if (Cardinality > MaxCardinality)
+    {
+        Cardinality = MaxCardinality;
+        ProbeDepth = DEPTH_ZERO;
+    }
+    if (Cardinality < popcount(pos.pieces()) || pos.can_castle(ANY_CASTLING))
+        return;
+    // If the current root position is in the tablebases, then RootMoves
+    // contains only moves that preserve the draw or the win.
+    RootInTB = root_probe(pos, rootMoves, TB::Score);
+    if (RootInTB)
+        Cardinality = 0; // Do not probe tablebases during the search
+    else // If DTZ tables are missing, use WDL tables as a fallback
+    {
+        // Filter out moves that do not preserve the draw or the win.
+        RootInTB = root_probe_wdl(pos, rootMoves, TB::Score);
+        // Only probe during search if winning
+        if (RootInTB && TB::Score <= VALUE_DRAW)
+            Cardinality = 0;
+    }
-    return false;
+    if (RootInTB && !UseRule50)
+        TB::Score =  TB::Score > VALUE_DRAW ?  VALUE_MATE - MAX_PLY - 1
+                   : TB::Score < VALUE_DRAW ? -VALUE_MATE + MAX_PLY + 1
+                                            :  VALUE_DRAW;
+}

Subversion Repositories Games.Chess Giants

Games.Chess Giants//engine-stockfish/search.cpp – Rev 96 → 154