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) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2019 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#include <algorithm>
#include <cassert>
#include "bitboard.h"
// Table used to drive the king towards a corner square of the
// right color in KBN vs K endgames.
constexpr int PushToCorners[SQUARE_NB] = {
- 200, 190, 180, 170, 160, 150, 140, 130,
- 190, 180, 170, 160, 150, 140, 130, 140,
- 180, 170, 155, 140, 140, 125, 140, 150,
- 170, 160, 140, 120, 110, 140, 150, 160,
- 160, 150, 140, 110, 120, 140, 160, 170,
- 150, 140, 125, 140, 140, 155, 170, 180,
- 140, 130, 140, 150, 160, 170, 180, 190,
- 130, 140, 150, 160, 170, 180, 190, 200
+ 6400, 6080, 5760, 5440, 5120, 4800, 4480, 4160,
+ 6080, 5760, 5440, 5120, 4800, 4480, 4160, 4480,
+ 5760, 5440, 4960, 4480, 4480, 4000, 4480, 4800,
+ 5440, 5120, 4480, 3840, 3520, 4480, 4800, 5120,
+ 5120, 4800, 4480, 3520, 3840, 4480, 5120, 5440,
+ 4800, 4480, 4000, 4480, 4480, 4960, 5440, 5760,
+ 4480, 4160, 4480, 4800, 5120, 5440, 5760, 6080,
+ 4160, 4480, 4800, 5120, 5440, 5760, 6080, 6400
};
// Tables used to drive a piece towards or away from another piece
if (file_of(pos.square<PAWN>(strongSide)) >= FILE_E)
sq = Square(sq ^ 7); // Mirror SQ_H1 -> SQ_A1
- if (strongSide == BLACK)
- sq = ~sq;
-
- return sq;
+ return strongSide == WHITE ? sq : ~sq;
}
} // namespace
-/// Endgames members definitions
+namespace Endgames {
+
+ std::pair<Map<Value>, Map<ScaleFactor>> maps;
-Endgames::Endgames() {
+ void init() {
- add<KPK>("KPK");
- add<KNNK>("KNNK");
- add<KBNK>("KBNK");
- add<KRKP>("KRKP");
- add<KRKB>("KRKB");
- add<KRKN>("KRKN");
- add<KQKP>("KQKP");
- add<KQKR>("KQKR");
+ add<KPK>("KPK");
+ add<KNNK>("KNNK");
+ add<KBNK>("KBNK");
+ add<KRKP>("KRKP");
+ add<KRKB>("KRKB");
+ add<KRKN>("KRKN");
+ add<KQKP>("KQKP");
+ add<KQKR>("KQKR");
+ add<KNNKP>("KNNKP");
- add<KNPK>("KNPK");
- add<KNPKB>("KNPKB");
- add<KRPKR>("KRPKR");
- add<KRPKB>("KRPKB");
- add<KBPKB>("KBPKB");
- add<KBPKN>("KBPKN");
- add<KBPPKB>("KBPPKB");
- add<KRPPKRP>("KRPPKRP");
+ add<KNPK>("KNPK");
+ add<KNPKB>("KNPKB");
+ add<KRPKR>("KRPKR");
+ add<KRPKB>("KRPKB");
+ add<KBPKB>("KBPKB");
+ add<KBPKN>("KBPKN");
+ add<KBPPKB>("KBPPKB");
+ add<KRPPKRP>("KRPPKRP");
+ }
}
/// Mate with KBN vs K. This is similar to KX vs K, but we have to drive the
-/// defending king towards a corner square of the right color.
+/// defending king towards a corner square that our bishop attacks.
template<>
Value Endgame<KBNK>::operator()(const Position& pos) const {
Square loserKSq = pos.square<KING>(weakSide);
Square bishopSq = pos.square<BISHOP>(strongSide);
- // kbnk_mate_table() tries to drive toward corners A1 or H8. If we have a
- // bishop that cannot reach the above squares, we flip the kings in order
- // to drive the enemy toward corners A8 or H1.
- if (opposite_colors(bishopSq, SQ_A1))
- {
- winnerKSq = ~winnerKSq;
- loserKSq = ~loserKSq;
- }
+ // If our Bishop does not attack A1/H8, we flip the enemy king square
+ // to drive to opposite corners (A8/H1).
Value result = VALUE_KNOWN_WIN
+ PushClose[distance(winnerKSq, loserKSq)]
- + PushToCorners[loserKSq];
+ + PushToCorners[opposite_colors(bishopSq, SQ_A1) ? ~loserKSq : loserKSq];
+ assert(abs(result) < VALUE_MATE_IN_MAX_PLY);
return strongSide == pos.side_to_move() ? result : -result;
}
Value result;
// If the stronger side's king is in front of the pawn, it's a win
- if (wksq < psq && file_of(wksq) == file_of(psq))
+ if (forward_file_bb(WHITE, wksq) & psq)
result = RookValueEg - distance(wksq, psq);
// If the weaker side's king is too far from the pawn and the rook,
}
-/// KR vs KB. This is very simple, and always returns drawish scores. The
+/// KR vs KB. This is very simple, and always returns drawish scores. The
/// score is slightly bigger when the defending king is close to the edge.
template<>
Value Endgame<KRKB>::operator()(const Position& pos) const {
}
+/// KNN vs KP. Simply push the opposing king to the corner
+template<>
+Value Endgame<KNNKP>::operator()(const Position& pos) const {
+
+ assert(verify_material(pos, strongSide, 2 * KnightValueMg, 0));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
+
+ Value result = 2 * KnightValueEg
+ - PawnValueEg
+ + PushToEdges[pos.square<KING>(weakSide)];
+
+ return strongSide == pos.side_to_move() ? result : -result;
+}
+
+
/// Some cases of trivial draws
template<> Value Endgame<KNNK>::operator()(const Position&) const { return VALUE_DRAW; }
&& pos.count<PAWN>(weakSide) >= 1)
{
// Get weakSide pawn that is closest to the home rank
- Square weakPawnSq = backmost_sq(weakSide, pos.pieces(weakSide, PAWN));
+ Square weakPawnSq = frontmost_sq(strongSide, pos.pieces(weakSide, PAWN));
Square strongKingSq = pos.square<KING>(strongSide);
Square weakKingSq = pos.square<KING>(weakSide);
// Case 2: Opposite colored bishops
if (opposite_colors(strongBishopSq, weakBishopSq))
- {
- // We assume that the position is drawn in the following three situations:
- //
- // a. The pawn is on rank 5 or further back.
- // b. The defending king is somewhere in the pawn's path.
- // c. The defending bishop attacks some square along the pawn's path,
- // and is at least three squares away from the pawn.
- //
- // These rules are probably not perfect, but in practice they work
- // reasonably well.
-
- if (relative_rank(strongSide, pawnSq) <= RANK_5)
- return SCALE_FACTOR_DRAW;
-
- Bitboard path = forward_file_bb(strongSide, pawnSq);
-
- if (path & pos.pieces(weakSide, KING))
- return SCALE_FACTOR_DRAW;
+ return SCALE_FACTOR_DRAW;
- if ( (pos.attacks_from<BISHOP>(weakBishopSq) & path)
- && distance(weakBishopSq, pawnSq) >= 3)
- return SCALE_FACTOR_DRAW;
- }
return SCALE_FACTOR_NONE;
}
Square ksq = pos.square<KING>(weakSide);
Square psq1 = pos.squares<PAWN>(strongSide)[0];
Square psq2 = pos.squares<PAWN>(strongSide)[1];
- Rank r1 = rank_of(psq1);
- Rank r2 = rank_of(psq2);
Square blockSq1, blockSq2;
if (relative_rank(strongSide, psq1) > relative_rank(strongSide, psq2))
&& opposite_colors(ksq, wbsq)
&& ( bbsq == blockSq2
|| (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(weakSide, BISHOP))
- || distance(r1, r2) >= 2))
+ || distance<Rank>(psq1, psq2) >= 2))
return SCALE_FACTOR_DRAW;
else if ( ksq == blockSq2
template<>
ScaleFactor Endgame<KNPKB>::operator()(const Position& pos) const {
+ assert(verify_material(pos, strongSide, KnightValueMg, 1));
+ assert(verify_material(pos, weakSide, BishopValueMg, 0));
+
Square pawnSq = pos.square<PAWN>(strongSide);
Square bishopSq = pos.square<BISHOP>(weakSide);
Square weakKingSq = pos.square<KING>(weakSide);
projects / stockfish / blobdiff