// 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. Note that the
- // FEN string could correspond to an illegal position.
+ // 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);
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();
}
if ( pos.count<QUEEN>(strongSide)
|| pos.count<ROOK>(strongSide)
+ ||(pos.count<BISHOP>(strongSide) && pos.count<KNIGHT>(strongSide))
|| pos.bishop_pair(strongSide))
result += VALUE_KNOWN_WIN;
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;
+ 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 - square_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() == weakSide)
&& square_distance(bksq, rsq) >= 3)
- result = RookValueEg - Value(square_distance(wksq, psq));
+ result = RookValueEg - square_distance(wksq, psq);
// If the pawn is far advanced and supported by the defending king,
// the position is drawish
&& square_distance(bksq, psq) == 1
&& rank_of(wksq) >= RANK_4
&& square_distance(wksq, psq) > 2 + (pos.side_to_move() == strongSide))
- result = Value(80 - square_distance(wksq, psq) * 8);
+ result = Value(80) - 8 * square_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 * ( square_distance(wksq, psq + DELTA_S)
+ - square_distance(bksq, psq + DELTA_S)
+ - square_distance(psq, queeningSq));
return strongSide == pos.side_to_move() ? result : -result;
}
// be detected even when the weaker side has some pawns.
Bitboard pawns = pos.pieces(strongSide, PAWN);
- File pawnFile = file_of(pos.list<PAWN>(strongSide)[0]);
+ 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)))
+ if ( (pawnsFile == FILE_A || pawnsFile == FILE_H)
+ && !(pawns & ~file_bb(pawnsFile)))
{
Square bishopSq = pos.list<BISHOP>(strongSide)[0];
- Square queeningSq = relative_square(strongSide, pawnFile | RANK_8);
+ Square queeningSq = relative_square(strongSide, make_square(pawnsFile, RANK_8));
Square kingSq = pos.king_square(weakSide);
+ // If the bishop has the wrong color, and the defending king is on the file
+ // of the pawn(s) or the neighboring file, then it's potentially a draw.
if ( opposite_colors(queeningSq, bishopSq)
- && square_distance(queeningSq, kingSq) <= 1)
- return SCALE_FACTOR_DRAW;
- }
-
- // If all the pawns are on the same B or G file, then it's potentially a draw
- if ( (pawnFile == FILE_B || pawnFile == FILE_G)
- && !(pos.pieces(PAWN) & ~file_bb(pawnFile))
- && pos.non_pawn_material(weakSide) == 0
- && 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 strongKingSq = pos.king_square(strongSide);
- Square weakKingSq = pos.king_square(weakSide);
- Square bishopSq = pos.list<BISHOP>(strongSide)[0];
-
- // 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))
+ && file_distance(kingSq, lsb(pawns)) <= 1)
{
- int strongKingDist = square_distance(weakPawnSq, strongKingSq);
- int weakKingDist = square_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)
+ // If the defending king has distance <= 1 to the promotion square or
+ // is placed somewhere in front of the frontmost pawn, it's a draw.
+ Rank rank = relative_rank(strongSide, (frontmost_sq(strongSide, pawns)));
+
+ if ( square_distance(kingSq, queeningSq) <= 1
+ || relative_rank(strongSide, kingSq) >= rank)
return SCALE_FACTOR_DRAW;
}
}
File f = file_of(wpsq);
Rank r = rank_of(wpsq);
- Square queeningSq = f | RANK_8;
+ 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
if (relative_rank(strongSide, psq1) > relative_rank(strongSide, psq2))
{
blockSq1 = psq1 + pawn_push(strongSide);
- blockSq2 = file_of(psq2) | rank_of(psq1);
+ blockSq2 = make_square(file_of(psq2), rank_of(psq1));
}
else
{
blockSq1 = psq2 + pawn_push(strongSide);
- blockSq2 = file_of(psq1) | rank_of(psq2);
+ blockSq2 = make_square(file_of(psq1), rank_of(psq2));
}
switch (file_distance(psq1, psq2))
projects / stockfish / blobdiff