X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.h;h=7d78886fb648cf2c7fe6eedbdaf935549bcfab86;hb=e4b7403f127a36a35bbace9f833ab43babd98a6c;hp=c9c37f93c7a7f709cbd1e190234f04dfec52d3d9;hpb=6cf28d4aa733447373430708fd2c35dee4469b10;p=stockfish
diff --git a/src/movepick.h b/src/movepick.h
index c9c37f93..7d78886f 100644
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -1,7 +1,6 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -17,96 +16,148 @@
along with this program. If not, see .
*/
-
-#if !defined MOVEPICK_H_INCLUDED
+#ifndef MOVEPICK_H_INCLUDED
#define MOVEPICK_H_INCLUDED
-////
-//// Includes
-////
+#include
+#include
+#include
-#include "depth.h"
-#include "history.h"
-#include "lock.h"
+#include "movegen.h"
#include "position.h"
+#include "types.h"
+
+namespace Stockfish {
+
+/// StatsEntry stores the stat table value. It is usually a number but could
+/// be a move or even a nested history. We use a class instead of naked value
+/// to directly call history update operator<<() on the entry so to use stats
+/// tables at caller sites as simple multi-dim arrays.
+template
+class StatsEntry {
+ T entry;
+
+public:
+ void operator=(const T& v) { entry = v; }
+ T* operator&() { return &entry; }
+ T* operator->() { return &entry; }
+ operator const T&() const { return entry; }
-////
-//// Types
-////
+ void operator<<(int bonus) {
+ assert(abs(bonus) <= D); // Ensure range is [-D, D]
+ static_assert(D <= std::numeric_limits::max(), "D overflows T");
-struct SearchStack;
+ entry += bonus - entry * abs(bonus) / D;
-enum MovegenPhase {
- PH_NULL_MOVE, // Null move
- PH_TT_MOVES, // Transposition table move and mate killer
- PH_GOOD_CAPTURES, // Queen promotions and captures with SEE values >= 0
- PH_KILLERS, // Killer moves from the current ply
- PH_NONCAPTURES, // Non-captures and underpromotions
- PH_BAD_CAPTURES, // Queen promotions and captures with SEE values < 0
- PH_EVASIONS, // Check evasions
- PH_QCAPTURES, // Captures in quiescence search
- PH_QCHECKS, // Non-capture checks in quiescence search
- PH_STOP
+ assert(abs(entry) <= D);
+ }
};
-typedef uint8_t MovegenPhaseT;
+/// Stats is a generic N-dimensional array used to store various statistics.
+/// The first template parameter T is the base type of the array, the second
+/// template parameter D limits the range of updates in [-D, D] when we update
+/// values with the << operator, while the last parameters (Size and Sizes)
+/// encode the dimensions of the array.
+template
+struct Stats : public std::array, Size>
+{
+ typedef Stats stats;
+
+ void fill(const T& v) {
+
+ // For standard-layout 'this' points to first struct member
+ assert(std::is_standard_layout::value);
+
+ typedef StatsEntry entry;
+ entry* p = reinterpret_cast(this);
+ std::fill(p, p + sizeof(*this) / sizeof(entry), v);
+ }
+};
-/// MovePicker is a class which is used to pick one legal move at a time from
-/// the current position. It is initialized with a Position object and a few
-/// moves we have reason to believe are good. The most important method is
-/// MovePicker::pick_next_move(), which returns a new legal move each time it
-/// is called, until there are no legal moves left, when MOVE_NONE is returned.
-/// In order to improve the efficiency of the alpha beta algorithm, MovePicker
-/// attempts to return the moves which are most likely to be strongest first.
+template
+struct Stats : public std::array, Size> {};
-class MovePicker {
+/// In stats table, D=0 means that the template parameter is not used
+enum StatsParams { NOT_USED = 0 };
+enum StatsType { NoCaptures, Captures };
- MovePicker& operator=(const MovePicker&); // silence a warning under MSVC
+/// ButterflyHistory records how often quiet moves have been successful or
+/// unsuccessful during the current search, and is used for reduction and move
+/// ordering decisions. It uses 2 tables (one for each color) indexed by
+/// the move's from and to squares, see www.chessprogramming.org/Butterfly_Boards
+typedef Stats ButterflyHistory;
-public:
- MovePicker(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss = NULL, bool useNullMove = false);
- Move get_next_move();
- Move get_next_move(Lock& lock);
- int number_of_moves() const;
- Bitboard discovered_check_candidates() const;
+/// At higher depths LowPlyHistory records successful quiet moves near the root
+/// and quiet moves which are/were in the PV (ttPv). LowPlyHistory is populated during
+/// iterative deepening and at each new search the data is shifted down by 2 plies
+constexpr int MAX_LPH = 4;
+typedef Stats LowPlyHistory;
-private:
- void score_captures();
- void score_noncaptures();
- void score_evasions();
- void go_next_phase();
+/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
+/// move, see www.chessprogramming.org/Countermove_Heuristic
+typedef Stats CounterMoveHistory;
- const Position& pos;
- const History& H;
- Move ttMoves[2], killers[2];
- const MovegenPhaseT* phasePtr;
- int phase, movesPicked, numOfMoves, numOfBadCaptures;
- bool finished;
- Bitboard dc, pinned;
- MoveStack moves[256], badCaptures[64];
-};
+/// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type]
+typedef Stats CapturePieceToHistory;
+
+/// PieceToHistory is like ButterflyHistory but is addressed by a move's [piece][to]
+typedef Stats PieceToHistory;
+/// ContinuationHistory is the combined history of a given pair of moves, usually
+/// the current one given a previous one. The nested history table is based on
+/// PieceToHistory instead of ButterflyBoards.
+typedef Stats ContinuationHistory;
-////
-//// Inline functions
-////
-/// MovePicker::number_of_moves() simply returns the numOfMoves member
-/// variable. It is intended to be used in positions where the side to move
-/// is in check, for detecting checkmates or situations where there is only
-/// a single reply to check.
+/// MovePicker class is used to pick one pseudo-legal move at a time from the
+/// current position. The most important method is next_move(), which returns a
+/// new pseudo-legal move each time it is called, until there are no moves left,
+/// when MOVE_NONE is returned. In order to improve the efficiency of the
+/// alpha-beta algorithm, MovePicker attempts to return the moves which are most
+/// likely to get a cut-off first.
+class MovePicker {
-inline int MovePicker::number_of_moves() const {
- return numOfMoves;
-}
+ enum PickType { Next, Best };
+
+public:
+ MovePicker(const MovePicker&) = delete;
+ MovePicker& operator=(const MovePicker&) = delete;
+ MovePicker(const Position&, Move, Value, const CapturePieceToHistory*);
+ MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
+ const CapturePieceToHistory*,
+ const PieceToHistory**,
+ Square);
+ MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
+ const LowPlyHistory*,
+ const CapturePieceToHistory*,
+ const PieceToHistory**,
+ Move,
+ const Move*,
+ int);
+ Move next_move(bool skipQuiets = false);
-/// MovePicker::discovered_check_candidates() returns a bitboard containing
-/// all pieces which can possibly give discovered check. This bitboard is
-/// computed by the constructor function.
+private:
+ template Move select(Pred);
+ template void score();
+ ExtMove* begin() { return cur; }
+ ExtMove* end() { return endMoves; }
+
+ const Position& pos;
+ const ButterflyHistory* mainHistory;
+ const LowPlyHistory* lowPlyHistory;
+ const CapturePieceToHistory* captureHistory;
+ const PieceToHistory** continuationHistory;
+ Move ttMove;
+ ExtMove refutations[3], *cur, *endMoves, *endBadCaptures;
+ int stage;
+ Square recaptureSquare;
+ Value threshold;
+ Depth depth;
+ int ply;
+ ExtMove moves[MAX_MOVES];
+};
-inline Bitboard MovePicker::discovered_check_candidates() const {
- return dc;
-}
+} // namespace Stockfish
-#endif // !defined(MOVEPICK_H_INCLUDED)
+#endif // #ifndef MOVEPICK_H_INCLUDED