Use cycle detection to bound search value

[stockfish] / src / position.h

diff --git a/src/position.h b/src/position.h
index 25e57512cd18720345b7f04fd73fe80e73a2fa8a..06000e0ff264abfa7f993ce2fc8b248f1b24e58b 100644 (file)
--- a/src/position.h
+++ b/src/position.h
@@ -2,7 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -52,11 +52,14 @@ struct StateInfo {
   Piece      capturedPiece;
   StateInfo* previous;
   Bitboard   blockersForKing[COLOR_NB];
-  Bitboard   pinnersForKing[COLOR_NB];
+  Bitboard   pinners[COLOR_NB];
   Bitboard   checkSquares[PIECE_TYPE_NB];
 };
 
-// In a std::deque references to elements are unaffected upon resizing
+/// A list to keep track of the position states along the setup moves (from the
+/// start position to the position just before the search starts). Needed by
+/// 'draw by repetition' detection. Use a std::deque because pointers to
+/// elements are not invalidated upon list resizing.
 typedef std::unique_ptr<std::deque<StateInfo>> StateListPtr;
 
 
@@ -102,8 +105,7 @@ public:
 
   // Checking
   Bitboard checkers() const;
-  Bitboard discovered_check_candidates() const;
-  Bitboard pinned_pieces(Color c) const;
+  Bitboard blockers_for_king(Color c) const;
   Bitboard check_squares(PieceType pt) const;
 
   // Attacks to/from a given square
@@ -134,11 +136,9 @@ public:
   void undo_move(Move m);
   void do_null_move(StateInfo& newSt);
   void undo_null_move();
-  void increment_nodes();
-  void increment_tbHits();
 
   // Static Exchange Evaluation
-  bool see_ge(Move m, Value value = VALUE_ZERO) const;
+  bool see_ge(Move m, Value threshold = VALUE_ZERO) const;
 
   // Accessing hash keys
   Key key() const;
@@ -148,20 +148,19 @@ public:
 
   // Other properties of the position
   Color side_to_move() const;
-  Phase game_phase() const;
   int game_ply() const;
   bool is_chess960() const;
   Thread* this_thread() const;
-  uint64_t nodes_searched() const;
-  uint64_t tb_hits() const;
   bool is_draw(int ply) const;
+  bool has_game_cycle(int ply) const;
+  bool has_repeated() const;
   int rule50_count() const;
   Score psq_score() const;
   Value non_pawn_material(Color c) const;
   Value non_pawn_material() const;
 
   // Position consistency check, for debugging
-  bool pos_is_ok(int* failedStep = nullptr) const;
+  bool pos_is_ok() const;
   void flip();
 
 private:
@@ -187,8 +186,6 @@ private:
   int castlingRightsMask[SQUARE_NB];
   Square castlingRookSquare[CASTLING_RIGHT_NB];
   Bitboard castlingPath[CASTLING_RIGHT_NB];
-  uint64_t nodes;
-  uint64_t tbHits;
   int gamePly;
   Color sideToMove;
   Thread* thisThread;
@@ -300,12 +297,8 @@ inline Bitboard Position::checkers() const {
   return st->checkersBB;
 }
 
-inline Bitboard Position::discovered_check_candidates() const {
-  return st->blockersForKing[~sideToMove] & pieces(sideToMove);
-}
-
-inline Bitboard Position::pinned_pieces(Color c) const {
-  return st->blockersForKing[c] & pieces(c);
+inline Bitboard Position::blockers_for_king(Color c) const {
+  return st->blockersForKing[c];
 }
 
 inline Bitboard Position::check_squares(PieceType pt) const {
@@ -353,22 +346,6 @@ inline int Position::rule50_count() const {
   return st->rule50;
 }
 
-inline uint64_t Position::nodes_searched() const {
-  return nodes;
-}
-
-inline void Position::increment_nodes() {
-  nodes++;
-}
-
-inline uint64_t Position::tb_hits() const {
-  return tbHits;
-}
-
-inline void Position::increment_tbHits() {
-  tbHits++;
-}
-
 inline bool Position::opposite_bishops() const {
   return   pieceCount[W_BISHOP] == 1
         && pieceCount[B_BISHOP] == 1