X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=d145ddfa0def3ae65959b0593667a6ad2e34e466;hp=ad699cc0e93423ef4112093b442da41c0466cb72;hb=7e95495b35ef84a87fa6be34639a5f96e67972b0;hpb=d5e49a3ad44bde500102090e7fe2c19027a73b14

diff --git a/src/position.cpp b/src/position.cpp
index ad699cc0..d145ddfa 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -105,9 +105,9 @@ void init() {
 
 namespace {
 
-/// next_attacker() is an helper function used by see() to locate the least
-/// valuable attacker for the side to move, remove the attacker we just found
-/// from the 'occupied' bitboard and scan for new X-ray attacks behind it.
+// next_attacker() is an helper function used by see() to locate the least
+// valuable attacker for the side to move, remove the attacker we just found
+// from the 'occupied' bitboard and scan for new X-ray attacks behind it.
 
 template<int Pt> FORCE_INLINE
 PieceType next_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers,
@@ -408,8 +408,8 @@ const string Position::pretty(Move move) const {
       ss << square_to_string(pop_lsb(&b)) << " ";
 
   ss << "\nLegal moves: ";
-  for (MoveList<LEGAL> ml(*this); !ml.end(); ++ml)
-      ss << move_to_san(*const_cast<Position*>(this), ml.move()) << " ";
+  for (MoveList<LEGAL> it(*this); *it; ++it)
+      ss << move_to_san(*const_cast<Position*>(this), *it) << " ";
 
   return ss.str();
 }
@@ -767,8 +767,9 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
 
       do_castle(from, to, rfrom, rto);
 
-      st->psqScore += psq_delta(make_piece(us, ROOK), rfrom, rto);
       k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
+      st->psqScore += pieceSquareTable[make_piece(us, ROOK)][rto]
+                    - pieceSquareTable[make_piece(us, ROOK)][rfrom];
   }
 
   if (capture)
@@ -919,7 +920,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
   }
 
   // Update incremental scores
-  st->psqScore += psq_delta(piece, from, to);
+  st->psqScore += pieceSquareTable[piece][to] - pieceSquareTable[piece][from];
 
   // Set capture piece
   st->capturedType = capture;
@@ -1129,10 +1130,10 @@ void Position::undo_null_move() {
 
 
 /// Position::see() is a static exchange evaluator: It tries to estimate the
-/// material gain or loss resulting from a move. There are three versions of
-/// this function: One which takes a destination square as input, one takes a
-/// move, and one which takes a 'from' and a 'to' square. The function does
-/// not yet understand promotions captures.
+/// material gain or loss resulting from a move. Parameter 'asymmThreshold' takes
+/// tempi into account. If the side who initiated the capturing sequence does the
+/// last capture, he loses a tempo and if the result is below 'asymmThreshold'
+/// the capturing sequence is considered bad.
 
 int Position::see_sign(Move m) const {
 
@@ -1147,7 +1148,7 @@ int Position::see_sign(Move m) const {
   return see(m);
 }
 
-int Position::see(Move m) const {
+int Position::see(Move m, int asymmThreshold) const {
 
   Square from, to;
   Bitboard occupied, attackers, stmAttackers;
@@ -1224,6 +1225,15 @@ int Position::see(Move m) const {
 
   } while (stmAttackers);
 
+  // If we are doing asymmetric SEE evaluation and the same side does the first
+  // and the last capture, he loses a tempo and gain must be at least worth
+  // 'asymmThreshold', otherwise we replace the score with a very low value,
+  // before negamaxing.
+  if (asymmThreshold)
+      for (int i = 0; i < slIndex; i += 2)
+          if (swapList[i] < asymmThreshold)
+              swapList[i] = - QueenValueMg * 16;
+
   // Having built the swap list, we negamax through it to find the best
   // achievable score from the point of view of the side to move.
   while (--slIndex)
@@ -1367,7 +1377,6 @@ Value Position::compute_non_pawn_material(Color c) const {
 /// Position::is_draw() tests whether the position is drawn by material,
 /// repetition, or the 50 moves rule. It does not detect stalemates, this
 /// must be done by the search.
-template<bool SkipRepetition>
 bool Position::is_draw() const {
 
   // Draw by material?
@@ -1380,33 +1389,26 @@ bool Position::is_draw() const {
       return true;
 
   // Draw by repetition?
-  if (!SkipRepetition)
-  {
-      int i = 4, e = std::min(st->rule50, st->pliesFromNull);
+  int i = 4, e = std::min(st->rule50, st->pliesFromNull);
 
-      if (i <= e)
-      {
-          StateInfo* stp = st->previous->previous;
+  if (i <= e)
+  {
+      StateInfo* stp = st->previous->previous;
 
-          do {
-              stp = stp->previous->previous;
+      do {
+          stp = stp->previous->previous;
 
-              if (stp->key == st->key)
-                  return true;
+          if (stp->key == st->key)
+              return true;
 
-              i += 2;
+          i += 2;
 
-          } while (i <= e);
-      }
+      } while (i <= e);
   }
 
   return false;
 }
 
-// Explicit template instantiations
-template bool Position::is_draw<false>() const;
-template bool Position::is_draw<true>() const;
-
 
 /// Position::flip() flips position with the white and black sides reversed. This
 /// is only useful for debugging especially for finding evaluation symmetry bugs.