X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fendgame.cpp;h=efc41a98844799be346293c83e103da236b32a48;hb=a2cdb6e5d2b33deedfe09baa43708151c45c802a;hp=39db219ed85a2c26f3f61f38f5999c51e5339bee;hpb=9afa1d73306cb98e95acec5daf4efd65e592ceff;p=stockfish
diff --git a/src/endgame.cpp b/src/endgame.cpp
index 39db219e..efc41a98 100644
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -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) 2015-2018 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
@@ -18,7 +18,6 @@
along with this program. If not, see .
*/
-#include
#include
#include "bitboard.h"
@@ -31,7 +30,7 @@ namespace {
// Table used to drive the king towards the edge of the board
// in KX vs K and KQ vs KR endgames.
- const int PushToEdges[SQUARE_NB] = {
+ constexpr int PushToEdges[SQUARE_NB] = {
100, 90, 80, 70, 70, 80, 90, 100,
90, 70, 60, 50, 50, 60, 70, 90,
80, 60, 40, 30, 30, 40, 60, 80,
@@ -44,23 +43,23 @@ namespace {
// Table used to drive the king towards a corner square of the
// right color in KBN vs K endgames.
- const 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
+ constexpr int PushToCorners[SQUARE_NB] = {
+ 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
- const int PushClose[8] = { 0, 0, 100, 80, 60, 40, 20, 10 };
- const int PushAway [8] = { 0, 5, 20, 40, 60, 80, 90, 100 };
+ constexpr int PushClose[8] = { 0, 0, 100, 80, 60, 40, 20, 10 };
+ constexpr int PushAway [8] = { 0, 5, 20, 40, 60, 80, 90, 100 };
// Pawn Rank based scaling factors used in KRPPKRP endgame
- const int KRPPKRPScaleFactors[RANK_NB] = { 0, 9, 10, 14, 21, 44, 0, 0 };
+ constexpr int KRPPKRPScaleFactors[RANK_NB] = { 0, 9, 10, 14, 21, 44, 0, 0 };
#ifndef NDEBUG
bool verify_material(const Position& pos, Color c, Value npm, int pawnsCnt) {
@@ -77,39 +76,12 @@ namespace {
if (file_of(pos.square(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
-
-Endgames::Endgames() {
-
- add("KPK");
- add("KNNK");
- add("KBNK");
- add("KRKP");
- add("KRKB");
- add("KRKN");
- add("KQKP");
- add("KQKR");
-
- add("KNPK");
- add("KNPKB");
- add("KRPKR");
- add("KRPKB");
- add("KBPKB");
- add("KBPKN");
- add("KBPPKB");
- add("KRPPKRP");
-}
-
-
/// Mate with KX vs K. This function is used to evaluate positions with
/// king and plenty of material vs a lone king. It simply gives the
/// attacking side a bonus for driving the defending king towards the edge
@@ -144,7 +116,7 @@ Value Endgame::operator()(const Position& pos) const {
/// 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::operator()(const Position& pos) const {
@@ -155,19 +127,14 @@ Value Endgame::operator()(const Position& pos) const {
Square loserKSq = pos.square(weakSide);
Square bishopSq = pos.square(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;
}
@@ -214,7 +181,7 @@ Value Endgame::operator()(const Position& pos) const {
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,
@@ -240,7 +207,7 @@ Value Endgame::operator()(const Position& pos) const {
}
-/// 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::operator()(const Position& pos) const {
@@ -315,6 +282,21 @@ Value Endgame::operator()(const Position& pos) const {
}
+/// KNN vs KP. Simply push the opposing king to the corner
+template<>
+Value Endgame::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(weakSide)];
+
+ return strongSide == pos.side_to_move() ? result : -result;
+}
+
+
/// Some cases of trivial draws
template<> Value Endgame::operator()(const Position&) const { return VALUE_DRAW; }
@@ -631,29 +613,8 @@ ScaleFactor Endgame::operator()(const Position& pos) const {
// 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(weakBishopSq) & path)
- && distance(weakBishopSq, pawnSq) >= 3)
- return SCALE_FACTOR_DRAW;
- }
return SCALE_FACTOR_NONE;
}
@@ -774,6 +735,9 @@ ScaleFactor Endgame::operator()(const Position& pos) const {
template<>
ScaleFactor Endgame::operator()(const Position& pos) const {
+ assert(verify_material(pos, strongSide, KnightValueMg, 1));
+ assert(verify_material(pos, weakSide, BishopValueMg, 0));
+
Square pawnSq = pos.square(strongSide);
Square bishopSq = pos.square(weakSide);
Square weakKingSq = pos.square(weakSide);