const int PushClose[8] = { 0, 0, 100, 80, 60, 40, 20, 10 };
const int PushAway [8] = { 0, 5, 20, 40, 60, 80, 90, 100 };
+#ifndef NDEBUG
+ bool verify_material(const Position& pos, Color c, Value npm, int num_pawns) {
+ return pos.non_pawn_material(c) == npm && pos.count<PAWN>(c) == num_pawns;
+ }
+#endif
+
// 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
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);
add<KNPK>("KNPK");
add<KNPKB>("KNPKB");
add<KRPKR>("KRPKR");
+ add<KRPKB>("KRPKB");
add<KBPKB>("KBPKB");
add<KBPKN>("KBPKN");
add<KBPPKB>("KBPPKB");
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.king_square(strongSide);
+ Square loserKSq = pos.king_square(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[square_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.bishop_pair(strongSide))
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.king_square(strongSide);
+ Square loserKSq = pos.king_square(weakSide);
+ Square bishopSq = pos.list<BISHOP>(strongSide)[0];
// 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.
+ // flip the kings so to drive 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)]
+ PushToCorners[loserKSq];
- return strongerSide == pos.side_to_move() ? result : -result;
+ return strongSide == pos.side_to_move() ? result : -result;
}
+// Returns a square that will allow us to orient the board so that
+// strongSide is white and strongSide's only pawn is on the left
+// half of the board
+Square get_flip_sq(const Position& pos, Color strongSide) {
+
+ assert(pos.count<PAWN>(strongSide) == 1);
+
+ Square psq = pos.list<PAWN>(strongSide)[0];
+
+ return (FILE_H * (file_of(psq) >= FILE_E)) | (RANK_8 * int(strongSide));
+}
+
+Square operator^(Square s, Square flip_sq) {
+ assert(flip_sq == SQ_A1 || flip_sq == SQ_H1 || flip_sq == SQ_A8 || flip_sq == SQ_H8);
+ return Square(int(s) ^ int(flip_sq));
+}
/// KP vs K. This endgame is evaluated with the help of a bitbase.
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);
+ assert(verify_material(pos, strongSide, VALUE_ZERO, 1));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 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();
+ // Assume strongSide is white and the pawn is on files A-D
+ Square flip_sq = get_flip_sq(pos, strongSide);
- if (strongerSide == BLACK)
- {
- wksq = ~wksq;
- bksq = ~bksq;
- psq = ~psq;
- us = ~us;
- }
+ Square wksq = pos.king_square(strongSide) ^ flip_sq;
+ Square bksq = pos.king_square(weakSide) ^ flip_sq;
+ Square psq = pos.list<PAWN>(strongSide)[0] ^ flip_sq;
- 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))
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);
-
- 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];
+ assert(verify_material(pos, strongSide, RookValueMg, 0));
+ assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
- if (strongerSide == BLACK)
- {
- wksq = ~wksq;
- bksq = ~bksq;
- rsq = ~rsq;
- psq = ~psq;
- }
+ Square wksq = relative_square(strongSide, pos.king_square(strongSide));
+ Square bksq = relative_square(strongSide, pos.king_square(weakSide));
+ Square rsq = relative_square(strongSide, pos.list<ROOK>(strongSide)[0]);
+ Square psq = relative_square(strongSide, pos.list<PAWN>(weakSide)[0]);
Square queeningSq = file_of(psq) | RANK_1;
Value result;
// 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)
+ else if ( square_distance(bksq, psq) >= 3 + (pos.side_to_move() == weakSide)
&& square_distance(bksq, rsq) >= 3)
result = RookValueEg - Value(square_distance(wksq, psq));
else if ( rank_of(bksq) <= RANK_3
&& square_distance(bksq, psq) == 1
&& rank_of(wksq) >= RANK_4
- && square_distance(wksq, psq) > 2 + (pos.side_to_move() == strongerSide))
+ && square_distance(wksq, psq) > 2 + (pos.side_to_move() == strongSide))
result = Value(80 - square_distance(wksq, psq) * 8);
else
+ Value(square_distance(bksq, psq + DELTA_S) * 8)
+ Value(square_distance(psq, queeningSq) * 8);
- 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.king_square(weakSide)]);
+ return strongSide == pos.side_to_move() ? result : -result;
}
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];
+ Square bksq = pos.king_square(weakSide);
+ Square bnsq = pos.list<KNIGHT>(weakSide)[0];
Value result = Value(PushToEdges[bksq] + PushAway[square_distance(bksq, bnsq)]);
- return strongerSide == pos.side_to_move() ? result : -result;
+ return strongSide == pos.side_to_move() ? result : -result;
}
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.king_square(strongSide);
+ Square loserKSq = pos.king_square(weakSide);
+ Square pawnSq = pos.list<PAWN>(weakSide)[0];
Value result = Value(PushClose[square_distance(winnerKSq, loserKSq)]);
- if ( relative_rank(weakerSide, pawnSq) != RANK_7
+ if ( relative_rank(weakSide, pawnSq) != RANK_7
|| square_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;
}
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.king_square(strongSide);
+ Square loserKSq = pos.king_square(weakSide);
Value result = QueenValueEg
- RookValueEg
+ PushToEdges[loserKSq]
+ PushClose[square_distance(winnerKSq, loserKSq)];
- return strongerSide == pos.side_to_move() ? result : -result;
+ return strongSide == pos.side_to_move() ? result : -result;
}
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));
+ assert(verify_material(pos, strongSide, 2 * BishopValueMg, 0));
+ assert(verify_material(pos, weakSide, KnightValueMg, 0));
- Square winnerKSq = pos.king_square(strongerSide);
- Square loserKSq = pos.king_square(weakerSide);
- Square knightSq = pos.list<KNIGHT>(weakerSide)[0];
+ Square winnerKSq = pos.king_square(strongSide);
+ Square loserKSq = pos.king_square(weakSide);
+ Square knightSq = pos.list<KNIGHT>(weakSide)[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;
}
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 pawnFile = file_of(pos.list<PAWN>(strongSide)[0]);
// All pawns are on a single rook file ?
if ( (pawnFile == FILE_A || pawnFile == FILE_H)
&& !(pawns & ~file_bb(pawnFile)))
{
- Square bishopSq = pos.list<BISHOP>(strongerSide)[0];
- Square queeningSq = relative_square(strongerSide, pawnFile | RANK_8);
- Square kingSq = pos.king_square(weakerSide);
+ Square bishopSq = pos.list<BISHOP>(strongSide)[0];
+ Square queeningSq = relative_square(strongSide, pawnFile | RANK_8);
+ Square kingSq = pos.king_square(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;
- }
+ && square_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)
+ && 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 home rank
+ Square weakPawnSq = backmost_sq(weakSide, pos.pieces(weakSide, PAWN));
+
+ Square strongKingSq = pos.king_square(strongSide);
+ Square weakKingSq = pos.king_square(weakSide);
+ Square bishopSq = pos.list<BISHOP>(strongSide)[0];
+
+ // 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 = square_distance(weakPawnSq, strongKingSq);
+ int weakKingDist = square_distance(weakPawnSq, weakKingSq);
+
+ // Draw if the weak king is on it's 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;
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.king_square(weakSide);
+ Square rsq = pos.list<ROOK>(weakSide)[0];
+
+ if ( relative_rank(weakSide, kingSq) <= RANK_2
+ && relative_rank(weakSide, pos.king_square(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;
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);
+ assert(verify_material(pos, strongSide, RookValueMg, 1));
+ assert(verify_material(pos, weakSide, RookValueMg, 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];
+ // Assume strongSide is white and the pawn is on files A-D
+ Square flip_sq = get_flip_sq(pos, strongSide);
- // 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;
- }
-
- if (file_of(wpsq) > FILE_D)
- {
- wksq = mirror(wksq);
- wrsq = mirror(wrsq);
- wpsq = mirror(wpsq);
- bksq = mirror(bksq);
- brsq = mirror(brsq);
- }
+ Square wksq = pos.king_square(strongSide) ^ flip_sq;
+ Square bksq = pos.king_square(weakSide) ^ flip_sq;
+ Square wrsq = pos.list<ROOK>(strongSide)[0] ^ flip_sq;
+ Square wpsq = pos.list<PAWN>(strongSide)[0] ^ flip_sq;
+ Square brsq = pos.list<ROOK>(weakSide)[0] ^ flip_sq;
File f = file_of(wpsq);
Rank r = rank_of(wpsq);
Square queeningSq = f | RANK_8;
- int tempo = (pos.side_to_move() == strongerSide);
+ 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.
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.king_square(weakSide);
+ Square bsq = pos.list<BISHOP>(weakSide)[0];
+ Square psq = pos.list<PAWN>(strongSide)[0];
+ 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 = square_distance(psq + 3 * push, ksq);
+
+ if (d <= 2 && !(d == 0 && ksq == pos.king_square(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
+ && square_distance(psq + 2 * push, ksq) <= 1
+ && (PseudoAttacks[BISHOP][bsq] & (psq + push))
+ && file_distance(bsq, psq) >= 2)
+ return ScaleFactor(8);
+ }
+
+ return SCALE_FACTOR_NONE;
+}
/// 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
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.list<PAWN>(strongSide)[0];
+ Square wpsq2 = pos.list<PAWN>(strongSide)[1];
+ Square bksq = pos.king_square(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)
+ && relative_rank(strongSide, bksq) > r)
{
switch (r) {
case RANK_2: return ScaleFactor(10);
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.king_square(weakSide);
+ Bitboard pawns = pos.pieces(strongSide, PAWN);
+ Square psq = pos.list<PAWN>(strongSide)[0];
+
+ // If all pawns are ahead of the king, all pawns are on a single
+ // rook file and the king is within one file of the pawns then draw.
+ if ( !(pawns & ~in_front_bb(weakSide, rank_of(ksq)))
+ && !((pawns & ~FileABB) && (pawns & ~FileHBB))
+ && file_distance(ksq, psq) <= 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;
}
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.list<PAWN>(strongSide)[0];
+ Square strongBishopSq = pos.list<BISHOP>(strongSide)[0];
+ Square weakBishopSq = pos.list<BISHOP>(weakSide)[0];
+ Square weakKingSq = pos.king_square(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)
+ && square_distance(weakBishopSq, pawnSq) >= 3)
return SCALE_FACTOR_DRAW;
}
}
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.list<BISHOP>(strongSide)[0];
+ Square bbsq = pos.list<BISHOP>(weakSide)[0];
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.king_square(weakSide);
+ Square psq1 = pos.list<PAWN>(strongSide)[0];
+ Square psq2 = pos.list<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);
+ blockSq1 = psq1 + pawn_push(strongSide);
blockSq2 = file_of(psq2) | rank_of(psq1);
}
else
{
- blockSq1 = psq2 + pawn_push(strongerSide);
+ blockSq1 = psq2 + pawn_push(strongSide);
blockSq2 = file_of(psq1) | rank_of(psq2);
}
// Both pawns are on the same file. Easy draw if 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
if ( ksq == blockSq1
&& opposite_colors(ksq, wbsq)
&& ( bbsq == blockSq2
- || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(weakerSide, BISHOP))
+ || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(weakSide, BISHOP))
|| abs(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;
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.list<PAWN>(strongSide)[0];
+ Square strongBishopSq = pos.list<BISHOP>(strongSide)[0];
+ Square weakKingSq = pos.king_square(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;
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 flip_sq = get_flip_sq(pos, strongSide);
- if ( pawnSq == relative_square(strongerSide, SQ_A7)
- && square_distance(weakerKingSq, relative_square(strongerSide, SQ_A8)) <= 1)
- return SCALE_FACTOR_DRAW;
+ Square pawnSq = pos.list<PAWN>(strongSide)[0] ^ flip_sq;
+ Square weakKingSq = pos.king_square(weakSide) ^ flip_sq;
- if ( pawnSq == relative_square(strongerSide, SQ_H7)
- && square_distance(weakerKingSq, relative_square(strongerSide, SQ_H8)) <= 1)
+ if (pawnSq == SQ_A7 && square_distance(SQ_A8, weakKingSq) <= 1)
return SCALE_FACTOR_DRAW;
return SCALE_FACTOR_NONE;
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.list<PAWN>(strongSide)[0];
+ Square bishopSq = pos.list<BISHOP>(weakSide)[0];
+ Square weakKingSq = pos.king_square(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(square_distance(weakKingSq, pawnSq));
return SCALE_FACTOR_NONE;
}
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 flip_sq = get_flip_sq(pos, strongSide);
- if (strongerSide == BLACK)
- {
- wksq = ~wksq;
- bksq = ~bksq;
- psq = ~psq;
- us = ~us;
- }
+ Square wksq = pos.king_square(strongSide) ^ flip_sq;
+ Square bksq = pos.king_square(weakSide) ^ flip_sq;
+ Square psq = pos.list<PAWN>(strongSide)[0] ^ flip_sq;
- 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.
projects / stockfish / blobdiff