/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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
const int PushClose[8] = { 0, 0, 100, 80, 60, 40, 20, 10 };
const int PushAway [8] = { 0, 5, 20, 40, 60, 80, 90, 100 };
- // Get the material key of a Position out of the given endgame key code
- // like "KBPKN". The trick here is to first forge an ad-hoc fen string
- // and then let a Position object to do the work for us. Note that the
- // fen string could correspond to an illegal position.
+ // Pawn Rank based scaling factors used in KRPPKRP endgame
+ const 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) {
+ return pos.non_pawn_material(c) == npm && pos.count<PAWN>(c) == pawnsCnt;
+ }
+#endif
+
+ // Map the square as if strongSide is white and strongSide's only pawn
+ // is on the left half of the board.
+ Square normalize(const Position& pos, Color strongSide, Square sq) {
+
+ assert(pos.count<PAWN>(strongSide) == 1);
+
+ 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;
+ }
+
+ // Get the material key of Position out of the given endgame key code
+ // like "KBPKN". The trick here is to first forge an ad-hoc FEN string
+ // and then let a Position object do the work for us.
Key key(const string& code, Color c) {
assert(code.length() > 0 && code.length() < 8);
assert(code[0] == 'K');
- string sides[] = { code.substr(code.find('K', 1)), // Weaker
- code.substr(0, code.find('K', 1)) }; // Stronger
+ string sides[] = { code.substr(code.find('K', 1)), // Weak
+ code.substr(0, code.find('K', 1)) }; // Strong
std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower);
- string fen = sides[0] + char('0' + int(8 - code.length()))
- + sides[1] + "/8/8/8/8/8/8/8 w - - 0 10";
+ string fen = sides[0] + char(8 - sides[0].length() + '0') + "/8/8/8/8/8/8/"
+ + sides[1] + char(8 - sides[1].length() + '0') + " w - - 0 10";
- return Position(fen, false, NULL).material_key();
+ return Position(fen, false, nullptr).material_key();
}
- template<typename M>
- void delete_endgame(const typename M::value_type& p) { delete p.second; }
-
} // namespace
add<KRKN>("KRKN");
add<KQKP>("KQKP");
add<KQKR>("KQKR");
- add<KBBKN>("KBBKN");
add<KNPK>("KNPK");
add<KNPKB>("KNPKB");
add<KRPKR>("KRPKR");
+ add<KRPKB>("KRPKB");
add<KBPKB>("KBPKB");
add<KBPKN>("KBPKN");
add<KBPPKB>("KBPPKB");
add<KRPPKRP>("KRPPKRP");
}
-Endgames::~Endgames() {
- for_each(m1.begin(), m1.end(), delete_endgame<M1>);
- for_each(m2.begin(), m2.end(), delete_endgame<M2>);
-}
-
-template<EndgameType E>
+template<EndgameType E, typename T>
void Endgames::add(const string& code) {
-
- map((Endgame<E>*)0)[key(code, WHITE)] = new Endgame<E>(WHITE);
- map((Endgame<E>*)0)[key(code, BLACK)] = new Endgame<E>(BLACK);
+ map<T>()[key(code, WHITE)] = std::unique_ptr<EndgameBase<T>>(new Endgame<E>(WHITE));
+ map<T>()[key(code, BLACK)] = std::unique_ptr<EndgameBase<T>>(new Endgame<E>(BLACK));
}
/// 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
+/// 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
/// of the board, and for keeping the distance between the two kings small.
template<>
Value Endgame<KXK>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
- assert(!pos.count<PAWN>(weakerSide));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
assert(!pos.checkers()); // Eval is never called when in check
// Stalemate detection with lone king
- if (pos.side_to_move() == weakerSide && !MoveList<LEGAL>(pos).size())
+ if (pos.side_to_move() == weakSide && !MoveList<LEGAL>(pos).size())
return VALUE_DRAW;
- Square winnerKSq = pos.king_square(strongerSide);
- Square loserKSq = pos.king_square(weakerSide);
+ Square winnerKSq = pos.square<KING>(strongSide);
+ Square loserKSq = pos.square<KING>(weakSide);
- Value result = pos.non_pawn_material(strongerSide)
- + pos.count<PAWN>(strongerSide) * PawnValueEg
- + PushToEdges[loserKSq]
- + PushClose[square_distance(winnerKSq, loserKSq)];
+ Value result = pos.non_pawn_material(strongSide)
+ + pos.count<PAWN>(strongSide) * PawnValueEg
+ + PushToEdges[loserKSq]
+ + PushClose[distance(winnerKSq, loserKSq)];
- if ( pos.count<QUEEN>(strongerSide)
- || pos.count<ROOK>(strongerSide)
- || pos.bishop_pair(strongerSide))
+ if ( pos.count<QUEEN>(strongSide)
+ || pos.count<ROOK>(strongSide)
+ ||(pos.count<BISHOP>(strongSide) && pos.count<KNIGHT>(strongSide))
+ ||(pos.count<BISHOP>(strongSide) > 1 && opposite_colors(pos.squares<BISHOP>(strongSide)[0],
+ pos.squares<BISHOP>(strongSide)[1])))
result += VALUE_KNOWN_WIN;
- return strongerSide == pos.side_to_move() ? result : -result;
+ return strongSide == pos.side_to_move() ? result : -result;
}
template<>
Value Endgame<KBNK>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == KnightValueMg + BishopValueMg);
- assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
- assert(pos.count<BISHOP>(strongerSide) == 1);
- assert(pos.count<KNIGHT>(strongerSide) == 1);
- assert(pos.count< PAWN>(strongerSide) == 0);
- assert(pos.count< PAWN>(weakerSide ) == 0);
+ assert(verify_material(pos, strongSide, KnightValueMg + BishopValueMg, 0));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
- Square winnerKSq = pos.king_square(strongerSide);
- Square loserKSq = pos.king_square(weakerSide);
- Square bishopSq = pos.list<BISHOP>(strongerSide)[0];
+ Square winnerKSq = pos.square<KING>(strongSide);
+ 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
- // mirror the kings so to drive enemy toward corners A8 or H1.
+ // 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 = mirror(winnerKSq);
- loserKSq = mirror(loserKSq);
+ winnerKSq = ~winnerKSq;
+ loserKSq = ~loserKSq;
}
Value result = VALUE_KNOWN_WIN
- + PushClose[square_distance(winnerKSq, loserKSq)]
+ + PushClose[distance(winnerKSq, loserKSq)]
+ PushToCorners[loserKSq];
- return strongerSide == pos.side_to_move() ? result : -result;
+ return strongSide == pos.side_to_move() ? result : -result;
}
template<>
Value Endgame<KPK>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO);
- assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
- assert(pos.count<PAWN>(strongerSide) == 1);
- assert(pos.count<PAWN>(weakerSide ) == 0);
-
- Square wksq = pos.king_square(strongerSide);
- Square bksq = pos.king_square(weakerSide);
- Square psq = pos.list<PAWN>(strongerSide)[0];
- Color us = pos.side_to_move();
+ assert(verify_material(pos, strongSide, VALUE_ZERO, 1));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
- if (strongerSide == BLACK)
- {
- wksq = ~wksq;
- bksq = ~bksq;
- psq = ~psq;
- us = ~us;
- }
+ // Assume strongSide is white and the pawn is on files A-D
+ Square wksq = normalize(pos, strongSide, pos.square<KING>(strongSide));
+ Square bksq = normalize(pos, strongSide, pos.square<KING>(weakSide));
+ Square psq = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
- if (file_of(psq) >= FILE_E)
- {
- wksq = mirror(wksq);
- bksq = mirror(bksq);
- psq = mirror(psq);
- }
+ Color us = strongSide == pos.side_to_move() ? WHITE : BLACK;
- if (!Bitbases::probe_kpk(wksq, psq, bksq, us))
+ if (!Bitbases::probe(wksq, psq, bksq, us))
return VALUE_DRAW;
Value result = VALUE_KNOWN_WIN + PawnValueEg + Value(rank_of(psq));
- return strongerSide == pos.side_to_move() ? result : -result;
+ return strongSide == pos.side_to_move() ? result : -result;
}
template<>
Value Endgame<KRKP>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMg);
- assert(pos.non_pawn_material(weakerSide) == 0);
- assert(pos.count<PAWN>(strongerSide) == 0);
- assert(pos.count<PAWN>(weakerSide ) == 1);
+ assert(verify_material(pos, strongSide, RookValueMg, 0));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
- Square wksq = pos.king_square(strongerSide);
- Square bksq = pos.king_square(weakerSide);
- Square rsq = pos.list<ROOK>(strongerSide)[0];
- Square psq = pos.list<PAWN>(weakerSide)[0];
+ Square wksq = relative_square(strongSide, pos.square<KING>(strongSide));
+ Square bksq = relative_square(strongSide, pos.square<KING>(weakSide));
+ Square rsq = relative_square(strongSide, pos.square<ROOK>(strongSide));
+ Square psq = relative_square(strongSide, pos.square<PAWN>(weakSide));
- if (strongerSide == BLACK)
- {
- wksq = ~wksq;
- bksq = ~bksq;
- rsq = ~rsq;
- psq = ~psq;
- }
-
- Square queeningSq = file_of(psq) | RANK_1;
+ Square queeningSq = make_square(file_of(psq), RANK_1);
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))
- result = RookValueEg - Value(square_distance(wksq, psq));
+ result = RookValueEg - distance(wksq, psq);
// If the weaker side's king is too far from the pawn and the rook,
// it's a win.
- else if ( square_distance(bksq, psq) >= 3 + (pos.side_to_move() == weakerSide)
- && square_distance(bksq, rsq) >= 3)
- result = RookValueEg - Value(square_distance(wksq, psq));
+ else if ( distance(bksq, psq) >= 3 + (pos.side_to_move() == weakSide)
+ && distance(bksq, rsq) >= 3)
+ result = RookValueEg - distance(wksq, psq);
// If the pawn is far advanced and supported by the defending king,
// the position is drawish
else if ( rank_of(bksq) <= RANK_3
- && square_distance(bksq, psq) == 1
+ && distance(bksq, psq) == 1
&& rank_of(wksq) >= RANK_4
- && square_distance(wksq, psq) > 2 + (pos.side_to_move() == strongerSide))
- result = Value(80 - square_distance(wksq, psq) * 8);
+ && distance(wksq, psq) > 2 + (pos.side_to_move() == strongSide))
+ result = Value(80) - 8 * distance(wksq, psq);
else
- result = Value(200)
- - Value(square_distance(wksq, psq + DELTA_S) * 8)
- + Value(square_distance(bksq, psq + DELTA_S) * 8)
- + Value(square_distance(psq, queeningSq) * 8);
+ result = Value(200) - 8 * ( distance(wksq, psq + DELTA_S)
+ - distance(bksq, psq + DELTA_S)
+ - distance(psq, queeningSq));
- return strongerSide == pos.side_to_move() ? result : -result;
+ return strongSide == pos.side_to_move() ? result : -result;
}
template<>
Value Endgame<KRKB>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMg);
- assert(pos.non_pawn_material(weakerSide ) == BishopValueMg);
- assert(pos.count<BISHOP>(weakerSide ) == 1);
- assert(pos.count< PAWN>(weakerSide ) == 0);
- assert(pos.count< PAWN>(strongerSide) == 0);
+ assert(verify_material(pos, strongSide, RookValueMg, 0));
+ assert(verify_material(pos, weakSide, BishopValueMg, 0));
- Value result = Value(PushToEdges[pos.king_square(weakerSide)]);
- return strongerSide == pos.side_to_move() ? result : -result;
+ Value result = Value(PushToEdges[pos.square<KING>(weakSide)]);
+ return strongSide == pos.side_to_move() ? result : -result;
}
-/// KR vs KN. The attacking side has slightly better winning chances than
+/// KR vs KN. The attacking side has slightly better winning chances than
/// in KR vs KB, particularly if the king and the knight are far apart.
template<>
Value Endgame<KRKN>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMg);
- assert(pos.non_pawn_material(weakerSide ) == KnightValueMg);
- assert(pos.count<KNIGHT>(weakerSide ) == 1);
- assert(pos.count< PAWN>(weakerSide ) == 0);
- assert(pos.count< PAWN>(strongerSide) == 0);
+ assert(verify_material(pos, strongSide, RookValueMg, 0));
+ assert(verify_material(pos, weakSide, KnightValueMg, 0));
- Square bksq = pos.king_square(weakerSide);
- Square bnsq = pos.list<KNIGHT>(weakerSide)[0];
- Value result = Value(PushToEdges[bksq] + PushAway[square_distance(bksq, bnsq)]);
- return strongerSide == pos.side_to_move() ? result : -result;
+ Square bksq = pos.square<KING>(weakSide);
+ Square bnsq = pos.square<KNIGHT>(weakSide);
+ Value result = Value(PushToEdges[bksq] + PushAway[distance(bksq, bnsq)]);
+ return strongSide == pos.side_to_move() ? result : -result;
}
-/// KQ vs KP. In general, a win for the stronger side, however, there are a few
-/// important exceptions. Pawn on 7th rank, A,C,F or H file, with king next can
-/// be a draw, so we scale down to distance between kings only.
+/// KQ vs KP. In general, this is a win for the stronger side, but there are a
+/// few important exceptions. A pawn on 7th rank and on the A,C,F or H files
+/// with a king positioned next to it can be a draw, so in that case, we only
+/// use the distance between the kings.
template<>
Value Endgame<KQKP>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == QueenValueMg);
- assert(pos.non_pawn_material(weakerSide ) == VALUE_ZERO);
- assert(pos.count<PAWN>(strongerSide) == 0);
- assert(pos.count<PAWN>(weakerSide ) == 1);
+ assert(verify_material(pos, strongSide, QueenValueMg, 0));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
- Square winnerKSq = pos.king_square(strongerSide);
- Square loserKSq = pos.king_square(weakerSide);
- Square pawnSq = pos.list<PAWN>(weakerSide)[0];
+ Square winnerKSq = pos.square<KING>(strongSide);
+ Square loserKSq = pos.square<KING>(weakSide);
+ Square pawnSq = pos.square<PAWN>(weakSide);
- Value result = Value(PushClose[square_distance(winnerKSq, loserKSq)]);
+ Value result = Value(PushClose[distance(winnerKSq, loserKSq)]);
- if ( relative_rank(weakerSide, pawnSq) != RANK_7
- || square_distance(loserKSq, pawnSq) != 1
+ if ( relative_rank(weakSide, pawnSq) != RANK_7
+ || distance(loserKSq, pawnSq) != 1
|| !((FileABB | FileCBB | FileFBB | FileHBB) & pawnSq))
result += QueenValueEg - PawnValueEg;
- return strongerSide == pos.side_to_move() ? result : -result;
+ return strongSide == pos.side_to_move() ? result : -result;
}
/// KQ vs KR. This is almost identical to KX vs K: We give the attacking
/// king a bonus for having the kings close together, and for forcing the
-/// defending king towards the edge. If we also take care to avoid null move
-/// for the defending side in the search, this is usually sufficient to be
-/// able to win KQ vs KR.
+/// defending king towards the edge. If we also take care to avoid null move for
+/// the defending side in the search, this is usually sufficient to win KQ vs KR.
template<>
Value Endgame<KQKR>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == QueenValueMg);
- assert(pos.non_pawn_material(weakerSide ) == RookValueMg);
- assert(pos.count<PAWN>(strongerSide) == 0);
- assert(pos.count<PAWN>(weakerSide ) == 0);
+ assert(verify_material(pos, strongSide, QueenValueMg, 0));
+ assert(verify_material(pos, weakSide, RookValueMg, 0));
- Square winnerKSq = pos.king_square(strongerSide);
- Square loserKSq = pos.king_square(weakerSide);
+ Square winnerKSq = pos.square<KING>(strongSide);
+ Square loserKSq = pos.square<KING>(weakSide);
Value result = QueenValueEg
- RookValueEg
+ PushToEdges[loserKSq]
- + PushClose[square_distance(winnerKSq, loserKSq)];
+ + PushClose[distance(winnerKSq, loserKSq)];
- return strongerSide == pos.side_to_move() ? result : -result;
-}
-
-
-/// KBB vs KN. This is almost always a win. We try to push enemy king to a corner
-/// and away from his knight. For a reference of this difficult endgame see:
-/// en.wikipedia.org/wiki/Chess_endgame#Effect_of_tablebases_on_endgame_theory
-
-template<>
-Value Endgame<KBBKN>::operator()(const Position& pos) const {
-
- assert(pos.non_pawn_material(strongerSide) == 2 * BishopValueMg);
- assert(pos.non_pawn_material(weakerSide ) == KnightValueMg);
- assert(pos.count<BISHOP>(strongerSide) == 2);
- assert(pos.count<KNIGHT>(weakerSide ) == 1);
- assert(!pos.pieces(PAWN));
-
- Square winnerKSq = pos.king_square(strongerSide);
- Square loserKSq = pos.king_square(weakerSide);
- Square knightSq = pos.list<KNIGHT>(weakerSide)[0];
-
- Value result = VALUE_KNOWN_WIN
- + PushToCorners[loserKSq]
- + PushClose[square_distance(winnerKSq, loserKSq)]
- + PushAway[square_distance(loserKSq, knightSq)];
-
- return strongerSide == pos.side_to_move() ? result : -result;
+ return strongSide == pos.side_to_move() ? result : -result;
}
/// Some cases of trivial draws
template<> Value Endgame<KNNK>::operator()(const Position&) const { return VALUE_DRAW; }
-template<> Value Endgame<KmmKm>::operator()(const Position&) const { return VALUE_DRAW; }
-/// K, bishop and one or more pawns vs K. It checks for draws with rook pawns and
+/// KB and one or more pawns vs K. It checks for draws with rook pawns and
/// a bishop of the wrong color. If such a draw is detected, SCALE_FACTOR_DRAW
/// is returned. If not, the return value is SCALE_FACTOR_NONE, i.e. no scaling
/// will be used.
template<>
ScaleFactor Endgame<KBPsK>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
- assert(pos.count<BISHOP>(strongerSide) == 1);
- assert(pos.count< PAWN>(strongerSide) >= 1);
+ assert(pos.non_pawn_material(strongSide) == BishopValueMg);
+ assert(pos.count<PAWN>(strongSide) >= 1);
- // No assertions about the material of weakerSide, because we want draws to
+ // No assertions about the material of weakSide, because we want draws to
// be detected even when the weaker side has some pawns.
- Bitboard pawns = pos.pieces(strongerSide, PAWN);
- File pawnFile = file_of(pos.list<PAWN>(strongerSide)[0]);
+ Bitboard pawns = pos.pieces(strongSide, PAWN);
+ File pawnsFile = file_of(lsb(pawns));
- // All pawns are on a single rook file ?
- if ( (pawnFile == FILE_A || pawnFile == FILE_H)
- && !(pawns & ~file_bb(pawnFile)))
+ // All pawns are on a single rook file?
+ if ( (pawnsFile == FILE_A || pawnsFile == FILE_H)
+ && !(pawns & ~file_bb(pawnsFile)))
{
- Square bishopSq = pos.list<BISHOP>(strongerSide)[0];
- Square queeningSq = relative_square(strongerSide, pawnFile | RANK_8);
- Square kingSq = pos.king_square(weakerSide);
+ Square bishopSq = pos.square<BISHOP>(strongSide);
+ Square queeningSq = relative_square(strongSide, make_square(pawnsFile, RANK_8));
+ Square kingSq = pos.square<KING>(weakSide);
if ( opposite_colors(queeningSq, bishopSq)
- && abs(file_of(kingSq) - pawnFile) <= 1)
- {
- // The bishop has the wrong color, and the defending king is on the
- // file of the pawn(s) or the adjacent file. Find the rank of the
- // frontmost pawn.
- Square pawnSq = frontmost_sq(strongerSide, pawns);
-
- // If the defending king has distance 1 to the promotion square or
- // is placed somewhere in front of the pawn, it's a draw.
- if ( square_distance(kingSq, queeningSq) <= 1
- || relative_rank(weakerSide, kingSq) <= relative_rank(weakerSide, pawnSq))
- return SCALE_FACTOR_DRAW;
- }
+ && distance(queeningSq, kingSq) <= 1)
+ return SCALE_FACTOR_DRAW;
}
- // All pawns on same B or G file? Then potential draw
- if ( (pawnFile == FILE_B || pawnFile == FILE_G)
- && !(pos.pieces(PAWN) & ~file_bb(pawnFile))
- && pos.non_pawn_material(weakerSide) == 0
- && pos.count<PAWN>(weakerSide) >= 1)
+ // If all the pawns are on the same B or G file, then it's potentially a draw
+ if ( (pawnsFile == FILE_B || pawnsFile == FILE_G)
+ && !(pos.pieces(PAWN) & ~file_bb(pawnsFile))
+ && pos.non_pawn_material(weakSide) == 0
+ && pos.count<PAWN>(weakSide) >= 1)
{
- // Get weakerSide pawn that is closest to home rank
- Square weakerPawnSq = backmost_sq(weakerSide, pos.pieces(weakerSide, PAWN));
-
- Square strongerKingSq = pos.king_square(strongerSide);
- Square weakerKingSq = pos.king_square(weakerSide);
- Square bishopSq = pos.list<BISHOP>(strongerSide)[0];
-
- // Draw if weaker pawn is on rank 7, bishop can't attack the pawn, and
- // weaker king can stop opposing opponent's king from penetrating.
- if ( relative_rank(strongerSide, weakerPawnSq) == RANK_7
- && opposite_colors(bishopSq, weakerPawnSq)
- && square_distance(weakerPawnSq, weakerKingSq) <= square_distance(weakerPawnSq, strongerKingSq))
- return SCALE_FACTOR_DRAW;
+ // Get weakSide pawn that is closest to the home rank
+ Square weakPawnSq = backmost_sq(weakSide, pos.pieces(weakSide, PAWN));
+
+ Square strongKingSq = pos.square<KING>(strongSide);
+ Square weakKingSq = pos.square<KING>(weakSide);
+ Square bishopSq = pos.square<BISHOP>(strongSide);
+
+ // There's potential for a draw if our pawn is blocked on the 7th rank,
+ // the bishop cannot attack it or they only have one pawn left
+ if ( relative_rank(strongSide, weakPawnSq) == RANK_7
+ && (pos.pieces(strongSide, PAWN) & (weakPawnSq + pawn_push(weakSide)))
+ && (opposite_colors(bishopSq, weakPawnSq) || pos.count<PAWN>(strongSide) == 1))
+ {
+ int strongKingDist = distance(weakPawnSq, strongKingSq);
+ int weakKingDist = distance(weakPawnSq, weakKingSq);
+
+ // It's a draw if the weak king is on its back two ranks, within 2
+ // squares of the blocking pawn and the strong king is not
+ // closer. (I think this rule only fails in practically
+ // unreachable positions such as 5k1K/6p1/6P1/8/8/3B4/8/8 w
+ // and positions where qsearch will immediately correct the
+ // problem such as 8/4k1p1/6P1/1K6/3B4/8/8/8 w)
+ if ( relative_rank(strongSide, weakKingSq) >= RANK_7
+ && weakKingDist <= 2
+ && weakKingDist <= strongKingDist)
+ return SCALE_FACTOR_DRAW;
+ }
}
return SCALE_FACTOR_NONE;
}
-/// K and queen vs K, rook and one or more pawns. It tests for fortress draws with
-/// a rook on the third rank defended by a pawn.
+/// KQ vs KR and one or more pawns. It tests for fortress draws with a rook on
+/// the third rank defended by a pawn.
template<>
ScaleFactor Endgame<KQKRPs>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == QueenValueMg);
- assert(pos.count<QUEEN>(strongerSide) == 1);
- assert(pos.count< PAWN>(strongerSide) == 0);
- assert(pos.count< ROOK>(weakerSide ) == 1);
- assert(pos.count< PAWN>(weakerSide ) >= 1);
-
- Square kingSq = pos.king_square(weakerSide);
- Square rsq = pos.list<ROOK>(weakerSide)[0];
-
- if ( relative_rank(weakerSide, kingSq) <= RANK_2
- && relative_rank(weakerSide, pos.king_square(strongerSide)) >= RANK_4
- && (pos.pieces(weakerSide, ROOK) & rank_bb(relative_rank(weakerSide, RANK_3)))
- && (pos.pieces(weakerSide, PAWN) & rank_bb(relative_rank(weakerSide, RANK_2)))
- && (pos.attacks_from<KING>(kingSq) & pos.pieces(weakerSide, PAWN))
- && (pos.attacks_from<PAWN>(rsq, strongerSide) & pos.pieces(weakerSide, PAWN)))
+ assert(verify_material(pos, strongSide, QueenValueMg, 0));
+ assert(pos.count<ROOK>(weakSide) == 1);
+ assert(pos.count<PAWN>(weakSide) >= 1);
+
+ Square kingSq = pos.square<KING>(weakSide);
+ Square rsq = pos.square<ROOK>(weakSide);
+
+ if ( relative_rank(weakSide, kingSq) <= RANK_2
+ && relative_rank(weakSide, pos.square<KING>(strongSide)) >= RANK_4
+ && relative_rank(weakSide, rsq) == RANK_3
+ && ( pos.pieces(weakSide, PAWN)
+ & pos.attacks_from<KING>(kingSq)
+ & pos.attacks_from<PAWN>(rsq, strongSide)))
return SCALE_FACTOR_DRAW;
return SCALE_FACTOR_NONE;
}
-/// K, rook and one pawn vs K and a rook. This function knows a handful of the
-/// most important classes of drawn positions, but is far from perfect. It would
-/// probably be a good idea to add more knowledge in the future.
+/// KRP vs KR. This function knows a handful of the most important classes of
+/// drawn positions, but is far from perfect. It would probably be a good idea
+/// to add more knowledge in the future.
///
/// It would also be nice to rewrite the actual code for this function,
-/// which is mostly copied from Glaurung 1.x, and not very pretty.
+/// which is mostly copied from Glaurung 1.x, and isn't very pretty.
template<>
ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMg);
- assert(pos.non_pawn_material(weakerSide) == RookValueMg);
- assert(pos.count<PAWN>(strongerSide) == 1);
- assert(pos.count<PAWN>(weakerSide ) == 0);
-
- Square wksq = pos.king_square(strongerSide);
- Square bksq = pos.king_square(weakerSide);
- Square wrsq = pos.list<ROOK>(strongerSide)[0];
- Square wpsq = pos.list<PAWN>(strongerSide)[0];
- Square brsq = pos.list<ROOK>(weakerSide)[0];
-
- // Orient the board in such a way that the stronger side is white, and the
- // pawn is on the left half of the board.
- if (strongerSide == BLACK)
- {
- wksq = ~wksq;
- wrsq = ~wrsq;
- wpsq = ~wpsq;
- bksq = ~bksq;
- brsq = ~brsq;
- }
+ assert(verify_material(pos, strongSide, RookValueMg, 1));
+ assert(verify_material(pos, weakSide, RookValueMg, 0));
- if (file_of(wpsq) > FILE_D)
- {
- wksq = mirror(wksq);
- wrsq = mirror(wrsq);
- wpsq = mirror(wpsq);
- bksq = mirror(bksq);
- brsq = mirror(brsq);
- }
+ // Assume strongSide is white and the pawn is on files A-D
+ Square wksq = normalize(pos, strongSide, pos.square<KING>(strongSide));
+ Square bksq = normalize(pos, strongSide, pos.square<KING>(weakSide));
+ Square wrsq = normalize(pos, strongSide, pos.square<ROOK>(strongSide));
+ Square wpsq = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
+ Square brsq = normalize(pos, strongSide, pos.square<ROOK>(weakSide));
File f = file_of(wpsq);
Rank r = rank_of(wpsq);
- Square queeningSq = f | RANK_8;
- int tempo = (pos.side_to_move() == strongerSide);
+ Square queeningSq = make_square(f, RANK_8);
+ int tempo = (pos.side_to_move() == strongSide);
// If the pawn is not too far advanced and the defending king defends the
// queening square, use the third-rank defence.
if ( r <= RANK_5
- && square_distance(bksq, queeningSq) <= 1
+ && distance(bksq, queeningSq) <= 1
&& wksq <= SQ_H5
&& (rank_of(brsq) == RANK_6 || (r <= RANK_3 && rank_of(wrsq) != RANK_6)))
return SCALE_FACTOR_DRAW;
// The defending side saves a draw by checking from behind in case the pawn
// has advanced to the 6th rank with the king behind.
if ( r == RANK_6
- && square_distance(bksq, queeningSq) <= 1
+ && distance(bksq, queeningSq) <= 1
&& rank_of(wksq) + tempo <= RANK_6
- && (rank_of(brsq) == RANK_1 || (!tempo && abs(file_of(brsq) - f) >= 3)))
+ && (rank_of(brsq) == RANK_1 || (!tempo && distance<File>(brsq, wpsq) >= 3)))
return SCALE_FACTOR_DRAW;
if ( r >= RANK_6
&& bksq == queeningSq
&& rank_of(brsq) == RANK_1
- && (!tempo || square_distance(wksq, wpsq) >= 2))
+ && (!tempo || distance(wksq, wpsq) >= 2))
return SCALE_FACTOR_DRAW;
// White pawn on a7 and rook on a8 is a draw if black's king is on g7 or h7
// away, it's a draw.
if ( r <= RANK_5
&& bksq == wpsq + DELTA_N
- && square_distance(wksq, wpsq) - tempo >= 2
- && square_distance(wksq, brsq) - tempo >= 2)
+ && distance(wksq, wpsq) - tempo >= 2
+ && distance(wksq, brsq) - tempo >= 2)
return SCALE_FACTOR_DRAW;
// Pawn on the 7th rank supported by the rook from behind usually wins if the
&& f != FILE_A
&& file_of(wrsq) == f
&& wrsq != queeningSq
- && (square_distance(wksq, queeningSq) < square_distance(bksq, queeningSq) - 2 + tempo)
- && (square_distance(wksq, queeningSq) < square_distance(bksq, wrsq) + tempo))
- return ScaleFactor(SCALE_FACTOR_MAX - 2 * square_distance(wksq, queeningSq));
+ && (distance(wksq, queeningSq) < distance(bksq, queeningSq) - 2 + tempo)
+ && (distance(wksq, queeningSq) < distance(bksq, wrsq) + tempo))
+ return ScaleFactor(SCALE_FACTOR_MAX - 2 * distance(wksq, queeningSq));
// Similar to the above, but with the pawn further back
if ( f != FILE_A
&& file_of(wrsq) == f
&& wrsq < wpsq
- && (square_distance(wksq, queeningSq) < square_distance(bksq, queeningSq) - 2 + tempo)
- && (square_distance(wksq, wpsq + DELTA_N) < square_distance(bksq, wpsq + DELTA_N) - 2 + tempo)
- && ( square_distance(bksq, wrsq) + tempo >= 3
- || ( square_distance(wksq, queeningSq) < square_distance(bksq, wrsq) + tempo
- && (square_distance(wksq, wpsq + DELTA_N) < square_distance(bksq, wrsq) + tempo))))
+ && (distance(wksq, queeningSq) < distance(bksq, queeningSq) - 2 + tempo)
+ && (distance(wksq, wpsq + DELTA_N) < distance(bksq, wpsq + DELTA_N) - 2 + tempo)
+ && ( distance(bksq, wrsq) + tempo >= 3
+ || ( distance(wksq, queeningSq) < distance(bksq, wrsq) + tempo
+ && (distance(wksq, wpsq + DELTA_N) < distance(bksq, wrsq) + tempo))))
return ScaleFactor( SCALE_FACTOR_MAX
- - 8 * square_distance(wpsq, queeningSq)
- - 2 * square_distance(wksq, queeningSq));
+ - 8 * distance(wpsq, queeningSq)
+ - 2 * distance(wksq, queeningSq));
- // If the pawn is not far advanced, and the defending king is somewhere in
+ // If the pawn is not far advanced and the defending king is somewhere in
// the pawn's path, it's probably a draw.
if (r <= RANK_4 && bksq > wpsq)
{
if (file_of(bksq) == file_of(wpsq))
return ScaleFactor(10);
- if ( abs(file_of(bksq) - file_of(wpsq)) == 1
- && square_distance(wksq, bksq) > 2)
- return ScaleFactor(24 - 2 * square_distance(wksq, bksq));
+ if ( distance<File>(bksq, wpsq) == 1
+ && distance(wksq, bksq) > 2)
+ return ScaleFactor(24 - 2 * distance(wksq, bksq));
}
return SCALE_FACTOR_NONE;
}
+template<>
+ScaleFactor Endgame<KRPKB>::operator()(const Position& pos) const {
+
+ assert(verify_material(pos, strongSide, RookValueMg, 1));
+ assert(verify_material(pos, weakSide, BishopValueMg, 0));
+
+ // Test for a rook pawn
+ if (pos.pieces(PAWN) & (FileABB | FileHBB))
+ {
+ Square ksq = pos.square<KING>(weakSide);
+ Square bsq = pos.square<BISHOP>(weakSide);
+ Square psq = pos.square<PAWN>(strongSide);
+ Rank rk = relative_rank(strongSide, psq);
+ Square push = pawn_push(strongSide);
+
+ // If the pawn is on the 5th rank and the pawn (currently) is on
+ // the same color square as the bishop then there is a chance of
+ // a fortress. Depending on the king position give a moderate
+ // reduction or a stronger one if the defending king is near the
+ // corner but not trapped there.
+ if (rk == RANK_5 && !opposite_colors(bsq, psq))
+ {
+ int d = distance(psq + 3 * push, ksq);
+
+ if (d <= 2 && !(d == 0 && ksq == pos.square<KING>(strongSide) + 2 * push))
+ return ScaleFactor(24);
+ else
+ return ScaleFactor(48);
+ }
+
+ // When the pawn has moved to the 6th rank we can be fairly sure
+ // it's drawn if the bishop attacks the square in front of the
+ // pawn from a reasonable distance and the defending king is near
+ // the corner
+ if ( rk == RANK_6
+ && distance(psq + 2 * push, ksq) <= 1
+ && (PseudoAttacks[BISHOP][bsq] & (psq + push))
+ && distance<File>(bsq, psq) >= 2)
+ return ScaleFactor(8);
+ }
-/// K, rook and two pawns vs K, rook and one pawn. There is only a single
-/// pattern: If the stronger side has no passed pawns and the defending king
-/// is actively placed, the position is drawish.
+ return SCALE_FACTOR_NONE;
+}
+
+/// KRPP vs KRP. There is just a single rule: if the stronger side has no passed
+/// pawns and the defending king is actively placed, the position is drawish.
template<>
ScaleFactor Endgame<KRPPKRP>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == RookValueMg);
- assert(pos.non_pawn_material(weakerSide) == RookValueMg);
- assert(pos.count<PAWN>(strongerSide) == 2);
- assert(pos.count<PAWN>(weakerSide ) == 1);
+ assert(verify_material(pos, strongSide, RookValueMg, 2));
+ assert(verify_material(pos, weakSide, RookValueMg, 1));
- Square wpsq1 = pos.list<PAWN>(strongerSide)[0];
- Square wpsq2 = pos.list<PAWN>(strongerSide)[1];
- Square bksq = pos.king_square(weakerSide);
+ Square wpsq1 = pos.squares<PAWN>(strongSide)[0];
+ Square wpsq2 = pos.squares<PAWN>(strongSide)[1];
+ Square bksq = pos.square<KING>(weakSide);
// Does the stronger side have a passed pawn?
- if ( pos.pawn_is_passed(strongerSide, wpsq1)
- || pos.pawn_is_passed(strongerSide, wpsq2))
+ if (pos.pawn_passed(strongSide, wpsq1) || pos.pawn_passed(strongSide, wpsq2))
return SCALE_FACTOR_NONE;
- Rank r = std::max(relative_rank(strongerSide, wpsq1), relative_rank(strongerSide, wpsq2));
+ Rank r = std::max(relative_rank(strongSide, wpsq1), relative_rank(strongSide, wpsq2));
- if ( file_distance(bksq, wpsq1) <= 1
- && file_distance(bksq, wpsq2) <= 1
- && relative_rank(strongerSide, bksq) > r)
+ if ( distance<File>(bksq, wpsq1) <= 1
+ && distance<File>(bksq, wpsq2) <= 1
+ && relative_rank(strongSide, bksq) > r)
{
- switch (r) {
- case RANK_2: return ScaleFactor(10);
- case RANK_3: return ScaleFactor(10);
- case RANK_4: return ScaleFactor(15);
- case RANK_5: return ScaleFactor(20);
- case RANK_6: return ScaleFactor(40);
- default: assert(false);
- }
+ assert(r > RANK_1 && r < RANK_7);
+ return ScaleFactor(KRPPKRPScaleFactors[r]);
}
return SCALE_FACTOR_NONE;
}
template<>
ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO);
- assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
- assert(pos.count<PAWN>(strongerSide) >= 2);
- assert(pos.count<PAWN>(weakerSide ) == 0);
+ assert(pos.non_pawn_material(strongSide) == VALUE_ZERO);
+ assert(pos.count<PAWN>(strongSide) >= 2);
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
- Square ksq = pos.king_square(weakerSide);
- Bitboard pawns = pos.pieces(strongerSide, PAWN);
+ Square ksq = pos.square<KING>(weakSide);
+ Bitboard pawns = pos.pieces(strongSide, PAWN);
+
+ // If all pawns are ahead of the king, on a single rook file and
+ // the king is within one file of the pawns, it's a draw.
+ if ( !(pawns & ~in_front_bb(weakSide, rank_of(ksq)))
+ && !((pawns & ~FileABB) && (pawns & ~FileHBB))
+ && distance<File>(ksq, lsb(pawns)) <= 1)
+ return SCALE_FACTOR_DRAW;
- // Are all pawns on the 'a' file?
- if (!(pawns & ~FileABB))
- {
- // Does the defending king block the pawns?
- if ( square_distance(ksq, relative_square(strongerSide, SQ_A8)) <= 1
- || ( file_of(ksq) == FILE_A
- && !(in_front_bb(strongerSide, rank_of(ksq)) & pawns)))
- return SCALE_FACTOR_DRAW;
- }
- // Are all pawns on the 'h' file?
- else if (!(pawns & ~FileHBB))
- {
- // Does the defending king block the pawns?
- if ( square_distance(ksq, relative_square(strongerSide, SQ_H8)) <= 1
- || ( file_of(ksq) == FILE_H
- && !(in_front_bb(strongerSide, rank_of(ksq)) & pawns)))
- return SCALE_FACTOR_DRAW;
- }
return SCALE_FACTOR_NONE;
}
-/// K, bishop and a pawn vs K and a bishop. There are two rules: If the defending
-/// king is somewhere along the path of the pawn, and the square of the king is
-/// not of the same color as the stronger side's bishop, it's a draw. If the two
-/// bishops have opposite color, it's almost always a draw.
+/// KBP vs KB. There are two rules: if the defending king is somewhere along the
+/// path of the pawn, and the square of the king is not of the same color as the
+/// stronger side's bishop, it's a draw. If the two bishops have opposite color,
+/// it's almost always a draw.
template<>
ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
- assert(pos.non_pawn_material(weakerSide ) == BishopValueMg);
- assert(pos.count<BISHOP>(strongerSide) == 1);
- assert(pos.count<BISHOP>(weakerSide ) == 1);
- assert(pos.count< PAWN>(strongerSide) == 1);
- assert(pos.count< PAWN>(weakerSide ) == 0);
+ assert(verify_material(pos, strongSide, BishopValueMg, 1));
+ assert(verify_material(pos, weakSide, BishopValueMg, 0));
- Square pawnSq = pos.list<PAWN>(strongerSide)[0];
- Square strongerBishopSq = pos.list<BISHOP>(strongerSide)[0];
- Square weakerBishopSq = pos.list<BISHOP>(weakerSide)[0];
- Square weakerKingSq = pos.king_square(weakerSide);
+ Square pawnSq = pos.square<PAWN>(strongSide);
+ Square strongBishopSq = pos.square<BISHOP>(strongSide);
+ Square weakBishopSq = pos.square<BISHOP>(weakSide);
+ Square weakKingSq = pos.square<KING>(weakSide);
// Case 1: Defending king blocks the pawn, and cannot be driven away
- if ( file_of(weakerKingSq) == file_of(pawnSq)
- && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq)
- && ( opposite_colors(weakerKingSq, strongerBishopSq)
- || relative_rank(strongerSide, weakerKingSq) <= RANK_6))
+ if ( file_of(weakKingSq) == file_of(pawnSq)
+ && relative_rank(strongSide, pawnSq) < relative_rank(strongSide, weakKingSq)
+ && ( opposite_colors(weakKingSq, strongBishopSq)
+ || relative_rank(strongSide, weakKingSq) <= RANK_6))
return SCALE_FACTOR_DRAW;
// Case 2: Opposite colored bishops
- if (opposite_colors(strongerBishopSq, weakerBishopSq))
+ if (opposite_colors(strongBishopSq, weakBishopSq))
{
// We assume that the position is drawn in the following three situations:
//
// These rules are probably not perfect, but in practice they work
// reasonably well.
- if (relative_rank(strongerSide, pawnSq) <= RANK_5)
+ if (relative_rank(strongSide, pawnSq) <= RANK_5)
return SCALE_FACTOR_DRAW;
else
{
- Bitboard path = forward_bb(strongerSide, pawnSq);
+ Bitboard path = forward_bb(strongSide, pawnSq);
- if (path & pos.pieces(weakerSide, KING))
+ if (path & pos.pieces(weakSide, KING))
return SCALE_FACTOR_DRAW;
- if ( (pos.attacks_from<BISHOP>(weakerBishopSq) & path)
- && square_distance(weakerBishopSq, pawnSq) >= 3)
+ if ( (pos.attacks_from<BISHOP>(weakBishopSq) & path)
+ && distance(weakBishopSq, pawnSq) >= 3)
return SCALE_FACTOR_DRAW;
}
}
}
-/// K, bishop and two pawns vs K and bishop. It detects a few basic draws with
-/// opposite-colored bishops.
+/// KBPP vs KB. It detects a few basic draws with opposite-colored bishops
template<>
ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
- assert(pos.non_pawn_material(weakerSide ) == BishopValueMg);
- assert(pos.count<BISHOP>(strongerSide) == 1);
- assert(pos.count<BISHOP>(weakerSide ) == 1);
- assert(pos.count< PAWN>(strongerSide) == 2);
- assert(pos.count< PAWN>(weakerSide ) == 0);
+ assert(verify_material(pos, strongSide, BishopValueMg, 2));
+ assert(verify_material(pos, weakSide, BishopValueMg, 0));
- Square wbsq = pos.list<BISHOP>(strongerSide)[0];
- Square bbsq = pos.list<BISHOP>(weakerSide)[0];
+ Square wbsq = pos.square<BISHOP>(strongSide);
+ Square bbsq = pos.square<BISHOP>(weakSide);
if (!opposite_colors(wbsq, bbsq))
return SCALE_FACTOR_NONE;
- Square ksq = pos.king_square(weakerSide);
- Square psq1 = pos.list<PAWN>(strongerSide)[0];
- Square psq2 = pos.list<PAWN>(strongerSide)[1];
+ 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(strongerSide, psq1) > relative_rank(strongerSide, psq2))
+ if (relative_rank(strongSide, psq1) > relative_rank(strongSide, psq2))
{
- blockSq1 = psq1 + pawn_push(strongerSide);
- blockSq2 = file_of(psq2) | rank_of(psq1);
+ blockSq1 = psq1 + pawn_push(strongSide);
+ blockSq2 = make_square(file_of(psq2), rank_of(psq1));
}
else
{
- blockSq1 = psq2 + pawn_push(strongerSide);
- blockSq2 = file_of(psq1) | rank_of(psq2);
+ blockSq1 = psq2 + pawn_push(strongSide);
+ blockSq2 = make_square(file_of(psq1), rank_of(psq2));
}
- switch (file_distance(psq1, psq2))
+ switch (distance<File>(psq1, psq2))
{
case 0:
- // Both pawns are on the same file. Easy draw if defender firmly controls
- // some square in the frontmost pawn's path.
+ // Both pawns are on the same file. It's an easy draw if the defender firmly
+ // controls some square in the frontmost pawn's path.
if ( file_of(ksq) == file_of(blockSq1)
- && relative_rank(strongerSide, ksq) >= relative_rank(strongerSide, blockSq1)
+ && relative_rank(strongSide, ksq) >= relative_rank(strongSide, blockSq1)
&& opposite_colors(ksq, wbsq))
return SCALE_FACTOR_DRAW;
else
return SCALE_FACTOR_NONE;
case 1:
- // Pawns on adjacent files. Draw if defender firmly controls the square
- // in front of the frontmost pawn's path, and the square diagonally behind
- // this square on the file of the other pawn.
+ // Pawns on adjacent files. It's a draw if the defender firmly controls the
+ // square in front of the frontmost pawn's path, and the square diagonally
+ // behind this square on the file of the other pawn.
if ( ksq == blockSq1
&& opposite_colors(ksq, wbsq)
&& ( bbsq == blockSq2
- || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(weakerSide, BISHOP))
- || abs(r1 - r2) >= 2))
+ || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(weakSide, BISHOP))
+ || distance(r1, r2) >= 2))
return SCALE_FACTOR_DRAW;
else if ( ksq == blockSq2
&& opposite_colors(ksq, wbsq)
&& ( bbsq == blockSq1
- || (pos.attacks_from<BISHOP>(blockSq1) & pos.pieces(weakerSide, BISHOP))))
+ || (pos.attacks_from<BISHOP>(blockSq1) & pos.pieces(weakSide, BISHOP))))
return SCALE_FACTOR_DRAW;
else
return SCALE_FACTOR_NONE;
}
-/// K, bisop and a pawn vs K and knight. There is a single rule: If the defending
-/// king is somewhere along the path of the pawn, and the square of the king is
-/// not of the same color as the stronger side's bishop, it's a draw.
+/// KBP vs KN. There is a single rule: If the defending king is somewhere along
+/// the path of the pawn, and the square of the king is not of the same color as
+/// the stronger side's bishop, it's a draw.
template<>
ScaleFactor Endgame<KBPKN>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == BishopValueMg);
- assert(pos.non_pawn_material(weakerSide ) == KnightValueMg);
- assert(pos.count<BISHOP>(strongerSide) == 1);
- assert(pos.count<KNIGHT>(weakerSide ) == 1);
- assert(pos.count< PAWN>(strongerSide) == 1);
- assert(pos.count< PAWN>(weakerSide ) == 0);
-
- Square pawnSq = pos.list<PAWN>(strongerSide)[0];
- Square strongerBishopSq = pos.list<BISHOP>(strongerSide)[0];
- Square weakerKingSq = pos.king_square(weakerSide);
-
- if ( file_of(weakerKingSq) == file_of(pawnSq)
- && relative_rank(strongerSide, pawnSq) < relative_rank(strongerSide, weakerKingSq)
- && ( opposite_colors(weakerKingSq, strongerBishopSq)
- || relative_rank(strongerSide, weakerKingSq) <= RANK_6))
+ assert(verify_material(pos, strongSide, BishopValueMg, 1));
+ assert(verify_material(pos, weakSide, KnightValueMg, 0));
+
+ Square pawnSq = pos.square<PAWN>(strongSide);
+ Square strongBishopSq = pos.square<BISHOP>(strongSide);
+ Square weakKingSq = pos.square<KING>(weakSide);
+
+ if ( file_of(weakKingSq) == file_of(pawnSq)
+ && relative_rank(strongSide, pawnSq) < relative_rank(strongSide, weakKingSq)
+ && ( opposite_colors(weakKingSq, strongBishopSq)
+ || relative_rank(strongSide, weakKingSq) <= RANK_6))
return SCALE_FACTOR_DRAW;
return SCALE_FACTOR_NONE;
}
-/// K, knight and a pawn vs K. There is a single rule: If the pawn is a rook pawn
-/// on the 7th rank and the defending king prevents the pawn from advancing, the
-/// position is drawn.
+/// KNP vs K. There is a single rule: if the pawn is a rook pawn on the 7th rank
+/// and the defending king prevents the pawn from advancing, the position is drawn.
template<>
ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == KnightValueMg);
- assert(pos.non_pawn_material(weakerSide ) == VALUE_ZERO);
- assert(pos.count<KNIGHT>(strongerSide) == 1);
- assert(pos.count< PAWN>(strongerSide) == 1);
- assert(pos.count< PAWN>(weakerSide ) == 0);
+ assert(verify_material(pos, strongSide, KnightValueMg, 1));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
- Square pawnSq = pos.list<PAWN>(strongerSide)[0];
- Square weakerKingSq = pos.king_square(weakerSide);
+ // Assume strongSide is white and the pawn is on files A-D
+ Square pawnSq = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
+ Square weakKingSq = normalize(pos, strongSide, pos.square<KING>(weakSide));
- if ( pawnSq == relative_square(strongerSide, SQ_A7)
- && square_distance(weakerKingSq, relative_square(strongerSide, SQ_A8)) <= 1)
- return SCALE_FACTOR_DRAW;
-
- if ( pawnSq == relative_square(strongerSide, SQ_H7)
- && square_distance(weakerKingSq, relative_square(strongerSide, SQ_H8)) <= 1)
+ if (pawnSq == SQ_A7 && distance(SQ_A8, weakKingSq) <= 1)
return SCALE_FACTOR_DRAW;
return SCALE_FACTOR_NONE;
}
-/// K, knight and a pawn vs K and bishop. If knight can block bishop from taking
-/// pawn, it's a win. Otherwise, drawn.
+/// KNP vs KB. If knight can block bishop from taking pawn, it's a win.
+/// Otherwise the position is drawn.
template<>
ScaleFactor Endgame<KNPKB>::operator()(const Position& pos) const {
- Square pawnSq = pos.list<PAWN>(strongerSide)[0];
- Square bishopSq = pos.list<BISHOP>(weakerSide)[0];
- Square weakerKingSq = pos.king_square(weakerSide);
+ Square pawnSq = pos.square<PAWN>(strongSide);
+ Square bishopSq = pos.square<BISHOP>(weakSide);
+ Square weakKingSq = pos.square<KING>(weakSide);
// King needs to get close to promoting pawn to prevent knight from blocking.
// Rules for this are very tricky, so just approximate.
- if (forward_bb(strongerSide, pawnSq) & pos.attacks_from<BISHOP>(bishopSq))
- return ScaleFactor(square_distance(weakerKingSq, pawnSq));
+ if (forward_bb(strongSide, pawnSq) & pos.attacks_from<BISHOP>(bishopSq))
+ return ScaleFactor(distance(weakKingSq, pawnSq));
return SCALE_FACTOR_NONE;
}
-/// K and a pawn vs K and a pawn. This is done by removing the weakest side's
-/// pawn and probing the KP vs K bitbase: If the weakest side has a draw without
-/// the pawn, she probably has at least a draw with the pawn as well. The exception
-/// is when the stronger side's pawn is far advanced and not on a rook file; in
-/// this case it is often possible to win (e.g. 8/4k3/3p4/3P4/6K1/8/8/8 w - - 0 1).
+/// KP vs KP. This is done by removing the weakest side's pawn and probing the
+/// KP vs K bitbase: If the weakest side has a draw without the pawn, it probably
+/// has at least a draw with the pawn as well. The exception is when the stronger
+/// side's pawn is far advanced and not on a rook file; in this case it is often
+/// possible to win (e.g. 8/4k3/3p4/3P4/6K1/8/8/8 w - - 0 1).
template<>
ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {
- assert(pos.non_pawn_material(strongerSide) == VALUE_ZERO);
- assert(pos.non_pawn_material(weakerSide ) == VALUE_ZERO);
- assert(pos.count<PAWN>(WHITE) == 1);
- assert(pos.count<PAWN>(BLACK) == 1);
+ assert(verify_material(pos, strongSide, VALUE_ZERO, 1));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
- Square wksq = pos.king_square(strongerSide);
- Square bksq = pos.king_square(weakerSide);
- Square psq = pos.list<PAWN>(strongerSide)[0];
- Color us = pos.side_to_move();
+ // Assume strongSide is white and the pawn is on files A-D
+ Square wksq = normalize(pos, strongSide, pos.square<KING>(strongSide));
+ Square bksq = normalize(pos, strongSide, pos.square<KING>(weakSide));
+ Square psq = normalize(pos, strongSide, pos.square<PAWN>(strongSide));
- if (strongerSide == BLACK)
- {
- wksq = ~wksq;
- bksq = ~bksq;
- psq = ~psq;
- us = ~us;
- }
-
- if (file_of(psq) >= FILE_E)
- {
- wksq = mirror(wksq);
- bksq = mirror(bksq);
- psq = mirror(psq);
- }
+ Color us = strongSide == pos.side_to_move() ? WHITE : BLACK;
// If the pawn has advanced to the fifth rank or further, and is not a
// rook pawn, it's too dangerous to assume that it's at least a draw.
// Probe the KPK bitbase with the weakest side's pawn removed. If it's a draw,
// it's probably at least a draw even with the pawn.
- return Bitbases::probe_kpk(wksq, psq, bksq, us) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
+ return Bitbases::probe(wksq, psq, bksq, us) ? SCALE_FACTOR_NONE : SCALE_FACTOR_DRAW;
}
projects / stockfish / blobdiff