X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=53811de04701c4705053dc0d3ed1e52049db0aed;hp=a40187b8024bfcda6b858045a7679a755e872ee1;hb=c1ea5ed6f7204afd6cb03a80ca8d124bd82cc40d;hpb=d2c2af9e1c4f5711e320555fe31ae4ed940802c6

diff --git a/src/search.cpp b/src/search.cpp
index a40187b8..53811de0 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -109,7 +109,7 @@ namespace {
   class RootMoveList {
 
   public:
-    RootMoveList(Position &pos, Move searchMoves[]);
+    RootMoveList(Position& pos, Move searchMoves[]);
     inline Move get_move(int moveNum) const;
     inline Value get_move_score(int moveNum) const;
     inline void set_move_score(int moveNum, Value score);
@@ -142,38 +142,38 @@ namespace {
   const bool UseIIDAtPVNodes = true;
   const bool UseIIDAtNonPVNodes = false;
 
-  // Internal iterative deepening margin.  At Non-PV moves, when
-  // UseIIDAtNonPVNodes is true, we do an internal iterative deepening search
-  // when the static evaluation is at most IIDMargin below beta.
+  // Internal iterative deepening margin. At Non-PV moves, when
+  // UseIIDAtNonPVNodes is true, we do an internal iterative deepening
+  // search when the static evaluation is at most IIDMargin below beta.
   const Value IIDMargin = Value(0x100);
 
-  // Easy move margin.  An easy move candidate must be at least this much
+  // Easy move margin. An easy move candidate must be at least this much
   // better than the second best move.
   const Value EasyMoveMargin = Value(0x200);
 
-  // Problem margin.  If the score of the first move at iteration N+1 has
+  // Problem margin. If the score of the first move at iteration N+1 has
   // dropped by more than this since iteration N, the boolean variable
   // "Problem" is set to true, which will make the program spend some extra
   // time looking for a better move.
   const Value ProblemMargin = Value(0x28);
 
-  // No problem margin.  If the boolean "Problem" is true, and a new move
+  // No problem margin. If the boolean "Problem" is true, and a new move
   // is found at the root which is less than NoProblemMargin worse than the
   // best move from the previous iteration, Problem is set back to false.
   const Value NoProblemMargin = Value(0x14);
 
-  // Null move margin.  A null move search will not be done if the approximate
+  // Null move margin. A null move search will not be done if the approximate
   // evaluation of the position is more than NullMoveMargin below beta.
   const Value NullMoveMargin = Value(0x300);
 
-  // Pruning criterions.  See the code and comments in ok_to_prune() to
+  // Pruning criterions. See the code and comments in ok_to_prune() to
   // understand their precise meaning.
-  const bool PruneEscapeMoves = false;
+  const bool PruneEscapeMoves    = false;
   const bool PruneDefendingMoves = false;
-  const bool PruneBlockingMoves = false;
+  const bool PruneBlockingMoves  = false;
 
   // Margins for futility pruning in the quiescence search, and at frontier
-  // and near frontier nodes
+  // and near frontier nodes.
   const Value FutilityMarginQS = Value(0x80);
 
   // Remaining depth:                  1 ply         1.5 ply       2 ply         2.5 ply       3 ply         3.5 ply
@@ -190,7 +190,7 @@ namespace {
   const Value RazorApprMargins[6] = { Value(0x520), Value(0x300), Value(0x300), Value(0x300), Value(0x300), Value(0x300) };
 
 
-  /// Variables initialized from UCI options
+  /// Variables initialized by UCI options
 
   // Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes
   int LMRPVMoves, LMRNonPVMoves; // heavy SMP read access for the latter
@@ -199,10 +199,10 @@ namespace {
   Depth ThreatDepth; // heavy SMP read access
 
   // Last seconds noise filtering (LSN)
-  bool UseLSNFiltering;
-  bool looseOnTime = false;
-  int LSNTime; // In milliseconds
-  Value LSNValue;
+  const bool UseLSNFiltering = true;
+  const int LSNTime = 4000; // In milliseconds
+  const Value LSNValue = value_from_centipawns(200);
+  bool loseOnTime = false;
 
   // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
   // There is heavy SMP read access on these arrays
@@ -223,8 +223,7 @@ namespace {
   // Time managment variables
   int SearchStartTime;
   int MaxNodes, MaxDepth;
-  int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime;
-  Move EasyMove;
+  int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
   int RootMoveNumber;
   bool InfiniteSearch;
   bool PonderSearch;
@@ -234,8 +233,6 @@ namespace {
   bool FailHigh;
   bool FailLow;
   bool Problem;
-  bool PonderingEnabled;
-  int ExactMaxTime;
 
   // Show current line?
   bool ShowCurrentLine;
@@ -268,31 +265,31 @@ namespace {
   int NodesSincePoll;
   int NodesBetweenPolls = 30000;
 
-   // The main transposition table
-   TranspositionTable TT;
+  // History table
+  History H;
 
 
   /// Functions
 
-  Value id_loop(const Position &pos, Move searchMoves[]);
-  Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml, Value alpha, Value beta);
-  Value search_pv(Position &pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
-  Value search(Position &pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID);
-  Value qsearch(Position &pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
-  void sp_search(SplitPoint *sp, int threadID);
-  void sp_search_pv(SplitPoint *sp, int threadID);
+  Value id_loop(const Position& pos, Move searchMoves[]);
+  Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta);
+  Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
+  Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID);
+  Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
+  void sp_search(SplitPoint* sp, int threadID);
+  void sp_search_pv(SplitPoint* sp, int threadID);
   void init_node(SearchStack ss[], int ply, int threadID);
   void update_pv(SearchStack ss[], int ply);
-  void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply);
-  bool connected_moves(const Position &pos, Move m1, Move m2);
+  void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply);
+  bool connected_moves(const Position& pos, Move m1, Move m2);
   bool value_is_mate(Value value);
   bool move_is_killer(Move m, const SearchStack& ss);
-  Depth extension(const Position &pos, Move m, bool pvNode, bool capture, bool check, bool singleReply, bool mateThreat, bool* dangerous);
-  bool ok_to_do_nullmove(const Position &pos);
-  bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d, const History& H);
+  Depth extension(const Position& pos, Move m, bool pvNode, bool capture, bool check, bool singleReply, bool mateThreat, bool* dangerous);
+  bool ok_to_do_nullmove(const Position& pos);
+  bool ok_to_prune(const Position& pos, Move m, Move threat, Depth d);
   bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
-  bool ok_to_history(const Position &pos, Move m);
-  void update_history(const Position& pos, Move m, Depth depth, History& H, Move movesSearched[], int moveCount);
+  bool ok_to_history(const Position& pos, Move m);
+  void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount);
   void update_killers(Move m, SearchStack& ss);
 
   bool fail_high_ply_1();
@@ -302,14 +299,15 @@ namespace {
   void ponderhit();
   void print_current_line(SearchStack ss[], int ply, int threadID);
   void wait_for_stop_or_ponderhit();
+  void init_ss_array(SearchStack ss[]);
 
-  void idle_loop(int threadID, SplitPoint *waitSp);
+  void idle_loop(int threadID, SplitPoint* waitSp);
   void init_split_point_stack();
   void destroy_split_point_stack();
   bool thread_should_stop(int threadID);
   bool thread_is_available(int slave, int master);
   bool idle_thread_exists(int master);
-  bool split(const Position &pos, SearchStack *ss, int ply,
+  bool split(const Position& pos, SearchStack* ss, int ply,
              Value *alpha, Value *beta, Value *bestValue, Depth depth, int *moves,
              MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode);
   void wake_sleeping_threads();
@@ -332,7 +330,7 @@ namespace {
 /// search-related global variables, and calls root_search(). It returns false
 /// when a quit command is received during the search.
 
-bool think(const Position &pos, bool infinite, bool ponder, int side_to_move,
+bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
            int time[], int increment[], int movesToGo, int maxDepth,
            int maxNodes, int maxTime, Move searchMoves[]) {
 
@@ -354,7 +352,6 @@ bool think(const Position &pos, bool infinite, bool ponder, int side_to_move,
   // Initialize global search variables
   Idle = false;
   SearchStartTime = get_system_time();
-  EasyMove = MOVE_NONE;
   for (int i = 0; i < THREAD_MAX; i++)
   {
       Threads[i].nodes = 0ULL;
@@ -374,9 +371,12 @@ bool think(const Position &pos, bool infinite, bool ponder, int side_to_move,
   // Read UCI option values
   TT.set_size(get_option_value_int("Hash"));
   if (button_was_pressed("Clear Hash"))
+  {
       TT.clear();
+      loseOnTime = false; // reset at the beginning of a new game
+  }
 
-  PonderingEnabled = get_option_value_bool("Ponder");
+  bool PonderingEnabled = get_option_value_bool("Ponder");
   MultiPV = get_option_value_int("MultiPV");
 
   CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)"));
@@ -397,9 +397,9 @@ bool think(const Position &pos, bool infinite, bool ponder, int side_to_move,
   MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
   MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
 
-  LMRPVMoves     = get_option_value_int("Full Depth Moves (PV nodes)") + 1;
-  LMRNonPVMoves  = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1;
-  ThreatDepth    = get_option_value_int("Threat Depth") * OnePly;
+  LMRPVMoves    = get_option_value_int("Full Depth Moves (PV nodes)") + 1;
+  LMRNonPVMoves = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1;
+  ThreatDepth   = get_option_value_int("Threat Depth") * OnePly;
 
   Chess960 = get_option_value_bool("UCI_Chess960");
   ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
@@ -407,15 +407,12 @@ bool think(const Position &pos, bool infinite, bool ponder, int side_to_move,
   if (UseLogFile)
       LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
 
-  UseLSNFiltering = get_option_value_bool("LSN filtering");
-  LSNTime = get_option_value_int("LSN Time Margin (sec)") * 1000;
-  LSNValue = value_from_centipawns(get_option_value_int("LSN Value Margin"));
-
   MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
   MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
 
   read_weights(pos.side_to_move());
 
+  // Set the number of active threads
   int newActiveThreads = get_option_value_int("Threads");
   if (newActiveThreads != ActiveThreads)
   {
@@ -429,7 +426,7 @@ bool think(const Position &pos, bool infinite, bool ponder, int side_to_move,
   for (int i = 1; i < ActiveThreads; i++)
       assert(thread_is_available(i, 0));
 
-  // Set thinking time:
+  // Set thinking time
   int myTime = time[side_to_move];
   int myIncrement = increment[side_to_move];
 
@@ -449,7 +446,8 @@ bool think(const Position &pos, bool infinite, bool ponder, int side_to_move,
       if (movesToGo == 1)
       {
           MaxSearchTime = myTime / 2;
-          AbsoluteMaxSearchTime = Min(myTime / 2, myTime - 500);
+          AbsoluteMaxSearchTime = 
+             (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4);
       } else {
           MaxSearchTime = myTime / Min(movesToGo, 20);
           AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
@@ -473,33 +471,37 @@ bool think(const Position &pos, bool infinite, bool ponder, int side_to_move,
       NodesBetweenPolls = Min(MaxNodes, 30000);
       InfiniteSearch = true; // HACK
   }
+  else if (myTime && myTime < 1000)
+      NodesBetweenPolls = 1000;
+  else if (myTime && myTime < 5000)
+      NodesBetweenPolls = 5000;
   else
       NodesBetweenPolls = 30000;
 
-
-  // Write information to search log file:
+  // Write information to search log file
   if (UseLogFile)
       LogFile << "Searching: " << pos.to_fen() << std::endl
-              << "infinite: " << infinite
-              << " ponder: " << ponder
-              << " time: " << myTime
+              << "infinite: "  << infinite
+              << " ponder: "   << ponder
+              << " time: "     << myTime
               << " increment: " << myIncrement
               << " moves to go: " << movesToGo << std::endl;
 
 
-  // We're ready to start thinking.  Call the iterative deepening loop
-  // function:
-  if (!looseOnTime)
+  // We're ready to start thinking. Call the iterative deepening loop function
+  //
+  // FIXME we really need to cleanup all this LSN ugliness
+  if (!loseOnTime)
   {
       Value v = id_loop(pos, searchMoves);
-      looseOnTime = (   UseLSNFiltering
-                     && myTime < LSNTime
-                     && myIncrement == 0
-                     && v < -LSNValue);
+      loseOnTime = (   UseLSNFiltering
+                    && myTime < LSNTime
+                    && myIncrement == 0
+                    && v < -LSNValue);
   }
   else
   {
-      looseOnTime = false; // reset for next match
+      loseOnTime = false; // reset for next match
       while (SearchStartTime + myTime + 1000 > get_system_time())
           ; // wait here
       id_loop(pos, searchMoves); // to fail gracefully
@@ -528,7 +530,7 @@ void init_threads() {
   for (i = 0; i < THREAD_MAX; i++)
       Threads[i].activeSplitPoints = 0;
 
-  // Initialize global locks:
+  // Initialize global locks
   lock_init(&MPLock, NULL);
   lock_init(&IOLock, NULL);
 
@@ -561,7 +563,7 @@ void init_threads() {
       CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID);
 #endif
 
-      // Wait until the thread has finished launching:
+      // Wait until the thread has finished launching
       while (!Threads[i].running);
   }
 }
@@ -620,7 +622,7 @@ namespace {
   // been consumed, the user stops the search, or the maximum search depth is
   // reached.
 
-  Value id_loop(const Position &pos, Move searchMoves[]) {
+  Value id_loop(const Position& pos, Move searchMoves[]) {
 
     Position p(pos);
     SearchStack ss[PLY_MAX_PLUS_2];
@@ -628,20 +630,23 @@ namespace {
     // searchMoves are verified, copied, scored and sorted
     RootMoveList rml(p, searchMoves);
 
+    // Print RootMoveList c'tor startup scoring to the standard output,
+    // so that we print information also for iteration 1.
+    std::cout << "info depth " << 1 << "\ninfo depth " << 1
+              << " score " << value_to_string(rml.get_move_score(0))
+              << " time " << current_search_time()
+              << " nodes " << nodes_searched()
+              << " nps " << nps()
+              << " pv " << rml.get_move(0) << "\n";
+
     // Initialize
     TT.new_search();
-    for (int i = 0; i < THREAD_MAX; i++)
-        Threads[i].H.clear();
-
-    for (int i = 0; i < 3; i++)
-    {
-        ss[i].init(i);
-        ss[i].initKillers();
-    }
+    H.clear();
+    init_ss_array(ss);
     IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0));
     Iteration = 1;
 
-    EasyMove = rml.scan_for_easy_move();
+    Move EasyMove = rml.scan_for_easy_move();
 
     // Iterative deepening loop
     while (Iteration < PLY_MAX)
@@ -658,7 +663,7 @@ namespace {
         // Calculate dynamic search window based on previous iterations
         Value alpha, beta;
 
-        if (MultiPV == 1 && Iteration >= 6)
+        if (MultiPV == 1 && Iteration >= 6 && abs(IterationInfo[Iteration - 1].value) < VALUE_KNOWN_WIN)
         {
             int prevDelta1 = IterationInfo[Iteration - 1].speculatedValue - IterationInfo[Iteration - 2].speculatedValue;
             int prevDelta2 = IterationInfo[Iteration - 2].speculatedValue - IterationInfo[Iteration - 3].speculatedValue;
@@ -723,7 +728,7 @@ namespace {
             // Time to stop?
             bool stopSearch = false;
 
-            // Stop search early if there is only a single legal move:
+            // Stop search early if there is only a single legal move
             if (Iteration >= 6 && rml.move_count() == 1)
                 stopSearch = true;
 
@@ -821,7 +826,7 @@ namespace {
   // scheme (perhaps we should try to use this at internal PV nodes, too?)
   // and prints some information to the standard output.
 
-  Value root_search(Position &pos, SearchStack ss[], RootMoveList &rml, Value alpha, Value beta) {
+  Value root_search(Position& pos, SearchStack ss[], RootMoveList &rml, Value alpha, Value beta) {
 
     Value oldAlpha = alpha;
     Value value;
@@ -861,8 +866,9 @@ namespace {
                       << " currmovenumber " << i + 1 << std::endl;
 
         // Decide search depth for this move
+        bool moveIsCapture = pos.move_is_capture(move);
         bool dangerous;
-        ext = extension(pos, move, true, pos.move_is_capture(move), pos.move_is_check(move), false, false, &dangerous);
+        ext = extension(pos, move, true, moveIsCapture, pos.move_is_check(move), false, false, &dangerous);
         newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
 
         // Make the move, and search it
@@ -886,15 +892,30 @@ namespace {
         }
         else
         {
-            value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
+            if (   newDepth >= 3*OnePly
+                && i >= MultiPV + LMRPVMoves
+                && !dangerous
+                && !moveIsCapture
+                && !move_is_promotion(move)
+                && !move_is_castle(move))
+            {
+                ss[0].reduction = OnePly;
+                value = -search(pos, ss, -alpha, newDepth-OnePly, 1, true, 0);
+            } else
+                value = alpha + 1; // Just to trigger next condition
+
             if (value > alpha)
             {
-                // Fail high! Set the boolean variable FailHigh to true, and
-                // re-search the move with a big window. The variable FailHigh is
-                // used for time managment: We try to avoid aborting the search
-                // prematurely during a fail high research.
-                FailHigh = true;
-                value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
+                value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
+                if (value > alpha)
+                {
+                    // Fail high! Set the boolean variable FailHigh to true, and
+                    // re-search the move with a big window. The variable FailHigh is
+                    // used for time managment: We try to avoid aborting the search
+                    // prematurely during a fail high research.
+                    FailHigh = true;
+                    value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
+                }
             }
         }
 
@@ -928,6 +949,7 @@ namespace {
             // Update PV
             rml.set_move_score(i, value);
             update_pv(ss, 0);
+            TT.extract_pv(pos, ss[0].pv, PLY_MAX);
             rml.set_move_pv(i, ss[0].pv);
 
             if (MultiPV == 1)
@@ -938,9 +960,11 @@ namespace {
                 if (i > 0)
                     BestMoveChangesByIteration[Iteration]++;
 
-                // Print search information to the standard output:
+                // Print search information to the standard output
                 std::cout << "info depth " << Iteration
                           << " score " << value_to_string(value)
+                          << ((value >= beta)?
+                              " lowerbound" : ((value <= alpha)? " upperbound" : ""))
                           << " time " << current_search_time()
                           << " nodes " << nodes_searched()
                           << " nps " << nps()
@@ -952,7 +976,10 @@ namespace {
                 std::cout << std::endl;
 
                 if (UseLogFile)
-                    LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, ss[0].pv)
+                    LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value, 
+                                         ((value >= beta)? VALUE_TYPE_LOWER
+                                          : ((value <= alpha)? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)),
+                                         ss[0].pv)
                             << std::endl;
 
                 if (value > alpha)
@@ -996,7 +1023,7 @@ namespace {
 
   // search_pv() is the main search function for PV nodes.
 
-  Value search_pv(Position &pos, SearchStack ss[], Value alpha, Value beta,
+  Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta,
                   Depth depth, int ply, int threadID) {
 
     assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
@@ -1021,7 +1048,7 @@ namespace {
     EvalInfo ei;
 
     if (ply >= PLY_MAX - 1)
-        return evaluate(pos, ei, threadID);
+        return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
 
     // Mate distance pruning
     Value oldAlpha = alpha;
@@ -1044,16 +1071,16 @@ namespace {
 
     // Initialize a MovePicker object for the current position, and prepare
     // to search all moves
-    MovePicker mp = MovePicker(pos, ttMove, depth, Threads[threadID].H, &ss[ply]);
-
     Move move, movesSearched[256];
     int moveCount = 0;
     Value value, bestValue = -VALUE_INFINITE;
-    Bitboard dcCandidates = mp.discovered_check_candidates();
     Color us = pos.side_to_move();
     bool isCheck = pos.is_check();
     bool mateThreat = pos.has_mate_threat(opposite_color(us));
 
+    MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
+    Bitboard dcCandidates = mp.discovered_check_candidates();
+
     // Loop through all legal moves until no moves remain or a beta cutoff
     // occurs.
     while (   alpha < beta
@@ -1062,7 +1089,7 @@ namespace {
     {
       assert(move_is_ok(move));
 
-      bool singleReply = (isCheck && mp.number_of_moves() == 1);
+      bool singleReply = (isCheck && mp.number_of_evasions() == 1);
       bool moveIsCheck = pos.move_is_check(move, dcCandidates);
       bool moveIsCapture = pos.move_is_capture(move);
 
@@ -1083,11 +1110,11 @@ namespace {
       {
         // Try to reduce non-pv search depth by one ply if move seems not problematic,
         // if the move fails high will be re-searched at full depth.
-        if (    depth >= 2*OnePly
+        if (    depth >= 3*OnePly
             &&  moveCount >= LMRPVMoves
             && !dangerous
             && !moveIsCapture
-            && !move_promotion(move)
+            && !move_is_promotion(move)
             && !move_is_castle(move)
             && !move_is_killer(move, ss[ply]))
         {
@@ -1134,7 +1161,7 @@ namespace {
           }
           // If we are at ply 1, and we are searching the first root move at
           // ply 0, set the 'Problem' variable if the score has dropped a lot
-          // (from the computer's point of view) since the previous iteration:
+          // (from the computer's point of view) since the previous iteration.
           if (   ply == 1
               && Iteration >= 2
               && -value <= IterationInfo[Iteration-1].value - ProblemMargin)
@@ -1155,7 +1182,7 @@ namespace {
     }
 
     // All legal moves have been searched.  A special case: If there were
-    // no legal moves, it must be mate or stalemate:
+    // no legal moves, it must be mate or stalemate.
     if (moveCount == 0)
         return (isCheck ? value_mated_in(ply) : VALUE_DRAW);
 
@@ -1173,7 +1200,7 @@ namespace {
         Move m = ss[ply].pv[ply];
         if (ok_to_history(pos, m)) // Only non capture moves are considered
         {
-            update_history(pos, m, depth, Threads[threadID].H, movesSearched, moveCount);
+            update_history(pos, m, depth, movesSearched, moveCount);
             update_killers(m, ss[ply]);
         }
         TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, m);
@@ -1187,7 +1214,7 @@ namespace {
 
   // search() is the search function for zero-width nodes.
 
-  Value search(Position &pos, SearchStack ss[], Value beta, Depth depth,
+  Value search(Position& pos, SearchStack ss[], Value beta, Depth depth,
                int ply, bool allowNullmove, int threadID) {
 
     assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
@@ -1211,7 +1238,7 @@ namespace {
     EvalInfo ei;
 
     if (ply >= PLY_MAX - 1)
-        return evaluate(pos, ei, threadID);
+        return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
 
     // Mate distance pruning
     if (value_mated_in(ply) >= beta)
@@ -1252,11 +1279,7 @@ namespace {
 
         pos.undo_null_move();
 
-        if (value_is_mate(nullValue))
-        {
-            /* Do not return unproven mates */
-        }
-        else if (nullValue >= beta)
+        if (nullValue >= beta)
         {
             if (depth < 6 * OnePly)
                 return beta;
@@ -1304,8 +1327,8 @@ namespace {
     }
 
     // Initialize a MovePicker object for the current position, and prepare
-    // to search all moves:
-    MovePicker mp = MovePicker(pos, ttMove, depth, Threads[threadID].H, &ss[ply]);
+    // to search all moves.
+    MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
 
     Move move, movesSearched[256];
     int moveCount = 0;
@@ -1315,6 +1338,10 @@ namespace {
     bool useFutilityPruning =   depth < SelectiveDepth
                              && !isCheck;
 
+    // Avoid calling evaluate() if we already have the score in TT
+    if (tte && (tte->type() & VALUE_TYPE_EVAL))
+        futilityValue = value_from_tt(tte->value(), ply) + FutilityMargins[int(depth) - 2];
+
     // Loop through all legal moves until no moves remain or a beta cutoff
     // occurs.
     while (   bestValue < beta
@@ -1323,7 +1350,7 @@ namespace {
     {
       assert(move_is_ok(move));
 
-      bool singleReply = (isCheck && mp.number_of_moves() == 1);
+      bool singleReply = (isCheck && mp.number_of_evasions() == 1);
       bool moveIsCheck = pos.move_is_check(move, dcCandidates);
       bool moveIsCapture = pos.move_is_capture(move);
 
@@ -1338,11 +1365,12 @@ namespace {
       if (    useFutilityPruning
           && !dangerous
           && !moveIsCapture
-          && !move_promotion(move))
+          && !move_is_promotion(move))
       {
           // History pruning. See ok_to_prune() definition
           if (   moveCount >= 2 + int(depth)
-              && ok_to_prune(pos, move, ss[ply].threatMove, depth, Threads[threadID].H))
+              && ok_to_prune(pos, move, ss[ply].threatMove, depth)
+              && bestValue > value_mated_in(PLY_MAX))
               continue;
 
           // Value based pruning
@@ -1367,11 +1395,11 @@ namespace {
 
       // Try to reduce non-pv search depth by one ply if move seems not problematic,
       // if the move fails high will be re-searched at full depth.
-      if (    depth >= 2*OnePly
+      if (    depth >= 3*OnePly
           &&  moveCount >= LMRNonPVMoves
           && !dangerous
           && !moveIsCapture
-          && !move_promotion(move)
+          && !move_is_promotion(move)
           && !move_is_castle(move)
           && !move_is_killer(move, ss[ply]))
       {
@@ -1432,7 +1460,7 @@ namespace {
         Move m = ss[ply].pv[ply];
         if (ok_to_history(pos, m)) // Only non capture moves are considered
         {
-            update_history(pos, m, depth, Threads[threadID].H, movesSearched, moveCount);
+            update_history(pos, m, depth, movesSearched, moveCount);
             update_killers(m, ss[ply]);
         }
         TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, m);
@@ -1448,7 +1476,7 @@ namespace {
   // search function when the remaining depth is zero (or, to be more precise,
   // less than OnePly).
 
-  Value qsearch(Position &pos, SearchStack ss[], Value alpha, Value beta,
+  Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta,
                 Depth depth, int ply, int threadID) {
 
     assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
@@ -1492,10 +1520,9 @@ namespace {
     if (isCheck)
         staticValue = -VALUE_INFINITE;
 
-    else if (tte && tte->type() == VALUE_TYPE_EVAL)
+    else if (tte && (tte->type() & VALUE_TYPE_EVAL))
     {
         // Use the cached evaluation score if possible
-        assert(tte->value() == evaluate(pos, ei, threadID));
         assert(ei.futilityMargin == Value(0));
 
         staticValue = tte->value();
@@ -1503,8 +1530,8 @@ namespace {
     else
         staticValue = evaluate(pos, ei, threadID);
 
-    if (ply == PLY_MAX - 1)
-        return evaluate(pos, ei, threadID);
+    if (ply >= PLY_MAX - 1)
+        return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
 
     // Initialize "stand pat score", and return it immediately if it is
     // at least beta.
@@ -1514,7 +1541,7 @@ namespace {
     {
         // Store the score to avoid a future costly evaluation() call
         if (!isCheck && !tte && ei.futilityMargin == 0)
-            TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EVAL, Depth(-127*OnePly), MOVE_NONE);
+            TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EV_LO, Depth(-127*OnePly), MOVE_NONE);
 
         return bestValue;
     }
@@ -1525,7 +1552,7 @@ namespace {
     // 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 == 0) will be generated.
-    MovePicker mp = MovePicker(pos, ttMove, depth, Threads[threadID].H);
+    MovePicker mp = MovePicker(pos, ttMove, depth, H);
     Move move;
     int moveCount = 0;
     Bitboard dcCandidates = mp.discovered_check_candidates();
@@ -1546,7 +1573,7 @@ namespace {
       if (   enoughMaterial
           && !isCheck
           && !pvNode
-          && !move_promotion(move)
+          && !move_is_promotion(move)
           && !pos.move_is_check(move, dcCandidates)
           && !pos.move_is_passed_pawn_push(move))
       {
@@ -1567,10 +1594,8 @@ namespace {
 
       // Don't search captures and checks with negative SEE values
       if (   !isCheck
-          && !move_promotion(move)
-          && (pos.midgame_value_of_piece_on(move_from(move)) >
-              pos.midgame_value_of_piece_on(move_to(move)))
-          &&  pos.see(move) < 0)
+          && !move_is_promotion(move)
+          &&  pos.see_sign(move) < 0)
           continue;
 
       // Make and search the move.
@@ -1594,7 +1619,7 @@ namespace {
     }
 
     // All legal moves have been searched.  A special case: If we're in check
-    // and no legal moves were found, it is checkmate:
+    // and no legal moves were found, it is checkmate.
     if (pos.is_check() && moveCount == 0) // Mate!
         return value_mated_in(ply);
 
@@ -1604,9 +1629,13 @@ namespace {
     Move m = ss[ply].pv[ply];
     if (!pvNode)
     {
+        // If bestValue isn't changed it means it is still the static evaluation of
+        // the node, so keep this info to avoid a future costly evaluation() call.
+        ValueType type = (bestValue == staticValue && !ei.futilityMargin ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER);
         Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
+
         if (bestValue < beta)
-            TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, d, MOVE_NONE);
+            TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
         else
             TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, m);
     }
@@ -1627,13 +1656,13 @@ namespace {
   // also don't need to store anything to the hash table here:  This is taken
   // care of after we return from the split point.
 
-  void sp_search(SplitPoint *sp, int threadID) {
+  void sp_search(SplitPoint* sp, int threadID) {
 
     assert(threadID >= 0 && threadID < ActiveThreads);
     assert(ActiveThreads > 1);
 
     Position pos = Position(sp->pos);
-    SearchStack *ss = sp->sstack[threadID];
+    SearchStack* ss = sp->sstack[threadID];
     Value value;
     Move move;
     bool isCheck = pos.is_check();
@@ -1664,9 +1693,9 @@ namespace {
       if (    useFutilityPruning
           && !dangerous
           && !moveIsCapture
-          && !move_promotion(move)
+          && !move_is_promotion(move)
           &&  moveCount >= 2 + int(sp->depth)
-          &&  ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth, Threads[threadID].H))
+          &&  ok_to_prune(pos, move, ss[sp->ply].threatMove, sp->depth))
         continue;
 
       // Make and search the move.
@@ -1678,7 +1707,7 @@ namespace {
       if (   !dangerous
           &&  moveCount >= LMRNonPVMoves
           && !moveIsCapture
-          && !move_promotion(move)
+          && !move_is_promotion(move)
           && !move_is_castle(move)
           && !move_is_killer(move, ss[sp->ply]))
       {
@@ -1721,7 +1750,7 @@ namespace {
     lock_grab(&(sp->lock));
 
     // If this is the master thread and we have been asked to stop because of
-    // a beta cutoff higher up in the tree, stop all slave threads:
+    // a beta cutoff higher up in the tree, stop all slave threads.
     if (sp->master == threadID && thread_should_stop(threadID))
         for (int i = 0; i < ActiveThreads; i++)
             if (sp->slaves[i])
@@ -1739,16 +1768,16 @@ namespace {
   // the normal search_pv() function, but simpler.  Because we have already
   // probed the hash table and searched the first move before splitting, we
   // don't have to repeat all this work in sp_search_pv().  We also don't
-  // need to store anything to the hash table here:  This is taken care of
+  // need to store anything to the hash table here: This is taken care of
   // after we return from the split point.
 
-  void sp_search_pv(SplitPoint *sp, int threadID) {
+  void sp_search_pv(SplitPoint* sp, int threadID) {
 
     assert(threadID >= 0 && threadID < ActiveThreads);
     assert(ActiveThreads > 1);
 
     Position pos = Position(sp->pos);
-    SearchStack *ss = sp->sstack[threadID];
+    SearchStack* ss = sp->sstack[threadID];
     Value value;
     Move move;
 
@@ -1781,7 +1810,7 @@ namespace {
       if (   !dangerous
           &&  moveCount >= LMRPVMoves
           && !moveIsCapture
-          && !move_promotion(move)
+          && !move_is_promotion(move)
           && !move_is_castle(move)
           && !move_is_killer(move, ss[sp->ply]))
       {
@@ -1800,7 +1829,7 @@ namespace {
           {
               // When the search fails high at ply 1 while searching the first
               // move at the root, set the flag failHighPly1.  This is used for
-              // time managment:  We don't want to stop the search early in
+              // time managment: We don't want to stop the search early in
               // such cases, because resolving the fail high at ply 1 could
               // result in a big drop in score at the root.
               if (sp->ply == 1 && RootMoveNumber == 1)
@@ -1829,10 +1858,10 @@ namespace {
               if (value == value_mate_in(sp->ply + 1))
                   ss[sp->ply].mateKiller = move;
 
-              if(value >= sp->beta)
+              if (value >= sp->beta)
               {
-                  for(int i = 0; i < ActiveThreads; i++)
-                      if(i != threadID && (i == sp->master || sp->slaves[i]))
+                  for (int i = 0; i < ActiveThreads; i++)
+                      if (i != threadID && (i == sp->master || sp->slaves[i]))
                           Threads[i].stop = true;
 
                   sp->finished = true;
@@ -1922,15 +1951,15 @@ namespace {
     bool includeAllMoves = (searchMoves[0] == MOVE_NONE);
 
     // Generate all legal moves
-    int lm_count = generate_legal_moves(pos, mlist);
+    MoveStack* last = generate_moves(pos, mlist);
 
     // Add each move to the moves[] array
-    for (int i = 0; i < lm_count; i++)
+    for (MoveStack* cur = mlist; cur != last; cur++)
     {
         bool includeMove = includeAllMoves;
 
         for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++)
-            includeMove = (searchMoves[k] == mlist[i].move);
+            includeMove = (searchMoves[k] == cur->move);
 
         if (!includeMove)
             continue;
@@ -1938,8 +1967,9 @@ namespace {
         // Find a quick score for the move
         StateInfo st;
         SearchStack ss[PLY_MAX_PLUS_2];
+        init_ss_array(ss);
 
-        moves[count].move = mlist[i].move;
+        moves[count].move = cur->move;
         pos.do_move(moves[count].move, st);
         moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0);
         pos.undo_move(moves[count].move);
@@ -2050,24 +2080,26 @@ namespace {
   // for user input and checks whether it is time to stop the search.
 
   void init_node(SearchStack ss[], int ply, int threadID) {
+
     assert(ply >= 0 && ply < PLY_MAX);
     assert(threadID >= 0 && threadID < ActiveThreads);
 
     Threads[threadID].nodes++;
 
-    if(threadID == 0) {
-      NodesSincePoll++;
-      if(NodesSincePoll >= NodesBetweenPolls) {
-        poll();
-        NodesSincePoll = 0;
-      }
+    if (threadID == 0)
+    {
+        NodesSincePoll++;
+        if (NodesSincePoll >= NodesBetweenPolls)
+        {
+            poll();
+            NodesSincePoll = 0;
+        }
     }
-
     ss[ply].init(ply);
     ss[ply+2].initKillers();
 
-    if(Threads[threadID].printCurrentLine)
-      print_current_line(ss, ply, threadID);
+    if (Threads[threadID].printCurrentLine)
+        print_current_line(ss, ply, threadID);
   }
 
 
@@ -2090,7 +2122,7 @@ namespace {
   // difference between the two functions is that sp_update_pv also updates
   // the PV at the parent node.
 
-  void sp_update_pv(SearchStack *pss, SearchStack ss[], int ply) {
+  void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply) {
     assert(ply >= 0 && ply < PLY_MAX);
 
     ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove;
@@ -2107,62 +2139,65 @@ namespace {
   // assumed to be the move that was made to reach the current position, while
   // the second move is assumed to be a move from the current position.
 
-  bool connected_moves(const Position &pos, Move m1, Move m2) {
+  bool connected_moves(const Position& pos, Move m1, Move m2) {
+
     Square f1, t1, f2, t2;
+    Piece p;
 
     assert(move_is_ok(m1));
     assert(move_is_ok(m2));
 
-    if(m2 == MOVE_NONE)
-      return false;
+    if (m2 == MOVE_NONE)
+        return false;
 
-    // Case 1: The moving piece is the same in both moves.
+    // Case 1: The moving piece is the same in both moves
     f2 = move_from(m2);
     t1 = move_to(m1);
-    if(f2 == t1)
-      return true;
+    if (f2 == t1)
+        return true;
 
-    // Case 2: The destination square for m2 was vacated by m1.
+    // Case 2: The destination square for m2 was vacated by m1
     t2 = move_to(m2);
     f1 = move_from(m1);
-    if(t2 == f1)
-      return true;
+    if (t2 == f1)
+        return true;
 
-    // Case 3: Moving through the vacated square:
-    if(piece_is_slider(pos.piece_on(f2)) &&
-       bit_is_set(squares_between(f2, t2), f1))
+    // Case 3: Moving through the vacated square
+    if (   piece_is_slider(pos.piece_on(f2))
+        && bit_is_set(squares_between(f2, t2), f1))
       return true;
 
-    // Case 4: The destination square for m2 is attacked by the moving piece
-    // in m1:
-    if(pos.piece_attacks_square(pos.piece_on(t1), t1, t2))
-      return true;
+    // Case 4: The destination square for m2 is attacked by the moving piece in m1
+    p = pos.piece_on(t1);
+    if (bit_is_set(pos.attacks_from(p, t1), t2))
+        return true;
 
-    // Case 5: Discovered check, checking piece is the piece moved in m1:
-    if(piece_is_slider(pos.piece_on(t1)) &&
-       bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())),
-                  f2) &&
-       !bit_is_set(squares_between(t2, pos.king_square(pos.side_to_move())),
-                   t2)) {
-      Bitboard occ = pos.occupied_squares();
-      Color us = pos.side_to_move();
-      Square ksq = pos.king_square(us);
-      clear_bit(&occ, f2);
-      if(pos.type_of_piece_on(t1) == BISHOP) {
-        if(bit_is_set(bishop_attacks_bb(ksq, occ), t1))
-          return true;
-      }
-      else if(pos.type_of_piece_on(t1) == ROOK) {
-        if(bit_is_set(rook_attacks_bb(ksq, occ), t1))
-          return true;
-      }
-      else {
-        assert(pos.type_of_piece_on(t1) == QUEEN);
-        if(bit_is_set(queen_attacks_bb(ksq, occ), t1))
-          return true;
-      }
+    // Case 5: Discovered check, checking piece is the piece moved in m1
+    if (   piece_is_slider(p)
+        && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2)
+        && !bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), t2))
+    {
+        Bitboard occ = pos.occupied_squares();
+        Color us = pos.side_to_move();
+        Square ksq = pos.king_square(us);
+        clear_bit(&occ, f2);
+        if (type_of_piece(p) == BISHOP)
+        {
+            if (bit_is_set(bishop_attacks_bb(ksq, occ), t1))
+                return true;
+        }
+        else if (type_of_piece(p) == ROOK)
+        {
+            if (bit_is_set(rook_attacks_bb(ksq, occ), t1))
+                return true;
+        }
+        else
+        {
+            assert(type_of_piece(p) == QUEEN);
+            if (bit_is_set(queen_attacks_bb(ksq, occ), t1))
+                return true;
+        }
     }
-
     return false;
   }
 
@@ -2206,25 +2241,29 @@ namespace {
     assert(m != MOVE_NONE);
 
     Depth result = Depth(0);
-    *dangerous = check || singleReply || mateThreat;
+    *dangerous = check | singleReply | mateThreat;
 
-    if (check)
-        result += CheckExtension[pvNode];
+    if (*dangerous)
+    {
+        if (check)
+            result += CheckExtension[pvNode];
 
-    if (singleReply)
-        result += SingleReplyExtension[pvNode];
+        if (singleReply)
+            result += SingleReplyExtension[pvNode];
 
-    if (mateThreat)
-        result += MateThreatExtension[pvNode];
+        if (mateThreat)
+            result += MateThreatExtension[pvNode];
+    }
 
     if (pos.type_of_piece_on(move_from(m)) == PAWN)
     {
-        if (pos.move_is_pawn_push_to_7th(m))
+        Color c = pos.side_to_move();
+        if (relative_rank(c, move_to(m)) == RANK_7)
         {
             result += PawnPushTo7thExtension[pvNode];
             *dangerous = true;
         }
-        if (pos.move_is_passed_pawn_push(m))
+        if (pos.pawn_is_passed(c, move_to(m)))
         {
             result += PassedPawnExtension[pvNode];
             *dangerous = true;
@@ -2235,7 +2274,7 @@ namespace {
         && pos.type_of_piece_on(move_to(m)) != PAWN
         && (  pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
             - pos.midgame_value_of_piece_on(move_to(m)) == Value(0))
-        && !move_promotion(m)
+        && !move_is_promotion(m)
         && !move_is_ep(m))
     {
         result += PawnEndgameExtension[pvNode];
@@ -2245,7 +2284,7 @@ namespace {
     if (   pvNode
         && capture
         && pos.type_of_piece_on(move_to(m)) != PAWN
-        && pos.see(m) >= 0)
+        && pos.see_sign(m) >= 0)
     {
         result += OnePly/2;
         *dangerous = true;
@@ -2263,10 +2302,9 @@ namespace {
   // probably a good idea to avoid null moves in at least some more
   // complicated endgames, e.g. KQ vs KR.  FIXME
 
-  bool ok_to_do_nullmove(const Position &pos) {
-    if(pos.non_pawn_material(pos.side_to_move()) == Value(0))
-      return false;
-    return true;
+  bool ok_to_do_nullmove(const Position& pos) {
+
+    return pos.non_pawn_material(pos.side_to_move()) != Value(0);
   }
 
 
@@ -2274,23 +2312,24 @@ namespace {
   // non-tactical moves late in the move list close to the leaves are
   // candidates for pruning.
 
-  bool ok_to_prune(const Position &pos, Move m, Move threat, Depth d, const History& H) {
-    Square mfrom, mto, tfrom, tto;
+  bool ok_to_prune(const Position& pos, Move m, Move threat, Depth d) {
 
     assert(move_is_ok(m));
     assert(threat == MOVE_NONE || move_is_ok(threat));
-    assert(!move_promotion(m));
+    assert(!move_is_promotion(m));
     assert(!pos.move_is_check(m));
     assert(!pos.move_is_capture(m));
     assert(!pos.move_is_passed_pawn_push(m));
     assert(d >= OnePly);
 
+    Square mfrom, mto, tfrom, tto;
+
     mfrom = move_from(m);
     mto = move_to(m);
     tfrom = move_from(threat);
     tto = move_to(threat);
 
-    // Case 1: Castling moves are never pruned.
+    // Case 1: Castling moves are never pruned
     if (move_is_castle(m))
         return false;
 
@@ -2306,9 +2345,9 @@ namespace {
         && (   pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
             || pos.type_of_piece_on(tfrom) == KING)
         && pos.move_attacks_square(m, tto))
-      return false;
+        return false;
 
-    // Case 4: Don't prune moves with good history.
+    // Case 4: Don't prune moves with good history
     if (!H.ok_to_prune(pos.piece_on(mfrom), mto, d))
         return false;
 
@@ -2318,8 +2357,8 @@ namespace {
         && threat != MOVE_NONE
         && piece_is_slider(pos.piece_on(tfrom))
         && bit_is_set(squares_between(tfrom, tto), mto)
-        && pos.see(m) >= 0)
-            return false;
+        && pos.see_sign(m) >= 0)
+        return false;
 
     return true;
   }
@@ -2346,14 +2385,14 @@ namespace {
 
   bool ok_to_history(const Position& pos, Move m) {
 
-    return !pos.move_is_capture(m) && !move_promotion(m);
+    return !pos.move_is_capture(m) && !move_is_promotion(m);
   }
 
 
   // update_history() registers a good move that produced a beta-cutoff
   // in history and marks as failures all the other moves of that ply.
 
-  void update_history(const Position& pos, Move m, Depth depth, History& H,
+  void update_history(const Position& pos, Move m, Depth depth,
                       Move movesSearched[], int moveCount) {
 
     H.success(pos.piece_on(move_from(m)), move_to(m), depth);
@@ -2381,14 +2420,17 @@ namespace {
     ss.killers[0] = m;
   }
 
+
   // fail_high_ply_1() checks if some thread is currently resolving a fail
   // high at ply 1 at the node below the first root node.  This information
   // is used for time managment.
 
   bool fail_high_ply_1() {
+
     for(int i = 0; i < ActiveThreads; i++)
-      if(Threads[i].failHighPly1)
-        return true;
+        if (Threads[i].failHighPly1)
+            return true;
+
     return false;
   }
 
@@ -2433,12 +2475,12 @@ namespace {
             Quit = true;
             return;
         }
-        else if(command == "stop")
+        else if (command == "stop")
         {
             AbortSearch = true;
             PonderSearch = false;
         }
-        else if(command == "ponderhit")
+        else if (command == "ponderhit")
             ponderhit();
     }
     // Print search information
@@ -2487,9 +2529,10 @@ namespace {
   // it correctly predicted the opponent's move.
 
   void ponderhit() {
+
     int t = current_search_time();
     PonderSearch = false;
-    if(Iteration >= 3 &&
+    if (Iteration >= 3 &&
        (!InfiniteSearch && (StopOnPonderhit ||
                             t > AbsoluteMaxSearchTime ||
                             (RootMoveNumber == 1 &&
@@ -2504,20 +2547,35 @@ namespace {
   // thread.  Called when the UCI option UCI_ShowCurrLine is 'true'.
 
   void print_current_line(SearchStack ss[], int ply, int threadID) {
+
     assert(ply >= 0 && ply < PLY_MAX);
     assert(threadID >= 0 && threadID < ActiveThreads);
 
-    if(!Threads[threadID].idle) {
-      lock_grab(&IOLock);
-      std::cout << "info currline " << (threadID + 1);
-      for(int p = 0; p < ply; p++)
-        std::cout << " " << ss[p].currentMove;
-      std::cout << std::endl;
-      lock_release(&IOLock);
+    if (!Threads[threadID].idle)
+    {
+        lock_grab(&IOLock);
+        std::cout << "info currline " << (threadID + 1);
+        for (int p = 0; p < ply; p++)
+            std::cout << " " << ss[p].currentMove;
+
+        std::cout << std::endl;
+        lock_release(&IOLock);
     }
     Threads[threadID].printCurrentLine = false;
-    if(threadID + 1 < ActiveThreads)
-      Threads[threadID + 1].printCurrentLine = true;
+    if (threadID + 1 < ActiveThreads)
+        Threads[threadID + 1].printCurrentLine = true;
+  }
+
+
+  // init_ss_array() does a fast reset of the first entries of a SearchStack array
+
+  void init_ss_array(SearchStack ss[]) {
+
+    for (int i = 0; i < 3; i++)
+    {
+        ss[i].init(i);
+        ss[i].initKillers();
+    }
   }
 
 
@@ -2542,7 +2600,7 @@ namespace {
             Quit = true;
             break;
         }
-        else if(command == "ponderhit" || command == "stop")
+        else if (command == "ponderhit" || command == "stop")
             break;
     }
   }
@@ -2552,7 +2610,7 @@ namespace {
   // The parameter "waitSp", if non-NULL, is a pointer to an active SplitPoint
   // object for which the current thread is the master.
 
-  void idle_loop(int threadID, SplitPoint *waitSp) {
+  void idle_loop(int threadID, SplitPoint* waitSp) {
     assert(threadID >= 0 && threadID < THREAD_MAX);
 
     Threads[threadID].running = true;
@@ -2574,7 +2632,7 @@ namespace {
 #endif
       }
 
-      // If this thread has been assigned work, launch a search:
+      // If this thread has been assigned work, launch a search
       if(Threads[threadID].workIsWaiting) {
         Threads[threadID].workIsWaiting = false;
         if(Threads[threadID].splitPoint->pvNode)
@@ -2585,7 +2643,7 @@ namespace {
       }
 
       // If this thread is the master of a split point and all threads have
-      // finished their work at this split point, return from the idle loop:
+      // finished their work at this split point, return from the idle loop.
       if(waitSp != NULL && waitSp->cpus == 0)
         return;
     }
@@ -2624,7 +2682,7 @@ namespace {
   bool thread_should_stop(int threadID) {
     assert(threadID >= 0 && threadID < ActiveThreads);
 
-    SplitPoint *sp;
+    SplitPoint* sp;
 
     if(Threads[threadID].stop)
       return true;
@@ -2697,9 +2755,9 @@ namespace {
   // threads have returned from sp_search_pv (or, equivalently, when
   // splitPoint->cpus becomes 0), split() returns true.
 
-  bool split(const Position &p, SearchStack *sstck, int ply,
-             Value *alpha, Value *beta, Value *bestValue, Depth depth, int *moves,
-             MovePicker *mp, Bitboard dcCandidates, int master, bool pvNode) {
+  bool split(const Position& p, SearchStack* sstck, int ply,
+             Value* alpha, Value* beta, Value* bestValue, Depth depth, int* moves,
+             MovePicker* mp, Bitboard dcCandidates, int master, bool pvNode) {
 
     assert(p.is_ok());
     assert(sstck != NULL);
@@ -2711,24 +2769,24 @@ namespace {
     assert(master >= 0 && master < ActiveThreads);
     assert(ActiveThreads > 1);
 
-    SplitPoint *splitPoint;
+    SplitPoint* splitPoint;
     int i;
 
     lock_grab(&MPLock);
 
     // If no other thread is available to help us, or if we have too many
-    // active split points, don't split:
+    // active split points, don't split.
     if(!idle_thread_exists(master) ||
        Threads[master].activeSplitPoints >= MaxActiveSplitPoints) {
       lock_release(&MPLock);
       return false;
     }
 
-    // Pick the next available split point object from the split point stack:
+    // Pick the next available split point object from the split point stack
     splitPoint = SplitPointStack[master] + Threads[master].activeSplitPoints;
     Threads[master].activeSplitPoints++;
 
-    // Initialize the split point object:
+    // Initialize the split point object
     splitPoint->parent = Threads[master].splitPoint;
     splitPoint->finished = false;
     splitPoint->ply = ply;
@@ -2747,11 +2805,11 @@ namespace {
     for(i = 0; i < ActiveThreads; i++)
       splitPoint->slaves[i] = 0;
 
-    // Copy the current position and the search stack to the master thread:
+    // Copy the current position and the search stack to the master thread
     memcpy(splitPoint->sstack[master], sstck, (ply+1)*sizeof(SearchStack));
     Threads[master].splitPoint = splitPoint;
 
-    // Make copies of the current position and search stack for each thread:
+    // Make copies of the current position and search stack for each thread
     for(i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint;
         i++)
       if(thread_is_available(i, master)) {
@@ -2781,7 +2839,7 @@ namespace {
     idle_loop(master, splitPoint);
 
     // We have returned from the idle loop, which means that all threads are
-    // finished.  Update alpha, beta and bestvalue, and return:
+    // finished. Update alpha, beta and bestvalue, and return.
     lock_grab(&MPLock);
     if(pvNode) *alpha = splitPoint->alpha;
     *beta = splitPoint->beta;