Extract only exact scores to get the PV

[stockfish] / src / position.cpp

diff --git a/src/position.cpp b/src/position.cpp
index 646b61ea154153b26eaf4cb97f30bce408b885b0..5026ed761f02a96ba9b564b0ee15d814e879cef2 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -74,23 +74,23 @@ CheckInfo::CheckInfo(const Position& pos) {
 }
 
 
-/// Position c'tors. Here we always create a slower but safer copy of
-/// the original position or the FEN string, we want the new born Position
-/// object do not depend on any external data. Instead if we know what we
-/// are doing and we need speed we can create a position with default
-/// c'tor Position() and then use just fast_copy().
+/// Position c'tors. Here we always create a copy of the original position
+/// or the FEN string, we want the new born Position object do not depend
+/// on any external data so we detach state pointer from the source one.
 
-Position::Position() {}
+Position::Position(int th) : threadID(th) {}
 
-Position::Position(const Position& pos) {
+Position::Position(const Position& pos, int th) {
 
   memcpy(this, &pos, sizeof(Position));
   detach(); // Always detach() in copy c'tor to avoid surprises
+  threadID = th;
 }
 
-Position::Position(const string& fen) {
+Position::Position(const string& fen, int th) {
 
   from_fen(fen);
+  threadID = th;
 }
 
 
@@ -340,7 +340,7 @@ void Position::print(Move m) const {
   std::cout << std::endl;
   if (m != MOVE_NONE)
   {
-      Position p(*this);
+      Position p(*this, thread());
       string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : "");
       std::cout << "Move is: " << col << move_to_san(p, m) << std::endl;
   }
@@ -772,7 +772,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
   }
 
   // Prefetch TT access as soon as we know key is updated
-  TT.prefetch(key);
+  prefetch((char*)TT.first_entry(key));
 
   // Move the piece
   Bitboard move_bb = make_move_bb(from, to);
@@ -819,7 +819,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
           set_bit(&(byTypeBB[promotion]), to);
           board[to] = piece_of_color_and_type(us, promotion);
 
-          // Update piece counts      
+          // Update piece counts
           pieceCount[us][promotion]++;
           pieceCount[us][PAWN]--;
 
@@ -1250,7 +1250,7 @@ void Position::do_null_move(StateInfo& backupSt) {
       st->key ^= zobEp[st->epSquare];
 
   st->key ^= zobSideToMove;
-  TT.prefetch(st->key);
+  prefetch((char*)TT.first_entry(st->key));
 
   sideToMove = opposite_color(sideToMove);
   st->epSquare = SQ_NONE;
@@ -1307,11 +1307,11 @@ int Position::see_sign(Move m) const {
   Square from = move_from(m);
   Square to = move_to(m);
 
-  // Early return if SEE cannot be negative because capturing piece value
-  // is not bigger then captured one.
-  if (   midgame_value_of_piece_on(from) <= midgame_value_of_piece_on(to)
-      && type_of_piece_on(from) != KING)
-         return 1;
+  // Early return if SEE cannot be negative because captured piece value
+  // is not less then capturing one. Note that king moves always return
+  // here because king midgame value is set to 0.
+  if (midgame_value_of_piece_on(to) >= midgame_value_of_piece_on(from))
+      return 1;
 
   return see(from, to);
 }
@@ -1783,6 +1783,7 @@ void Position::flipped_copy(const Position& pos) {
   assert(pos.is_ok());
 
   clear();
+  threadID = pos.thread();
 
   // Board
   for (Square s = SQ_A1; s <= SQ_H8; s++)