((1ULL << SQ_A8) | (1ULL << SQ_H8))
};
- // The SpaceMask[color] contains the area of the board which is consdered
+ // The SpaceMask[color] contains the area of the board which is considered
// by the space evaluation. In the middle game, each side is given a bonus
// based on how many squares inside this area are safe and available for
// friendly minor pieces.
// Evaluate passed pawns. We evaluate passed pawns for both sides at once,
// because we need to know which side promotes first in positions where
- // both sides have an unstoppable passed pawn.
+ // both sides have an unstoppable passed pawn. To be called after all attacks
+ // are computed, included king.
if (ei.pi->passed_pawns())
evaluate_passed_pawns(pos, ei);
ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
}
- // The squares occupied by enemy pieces will be counted two times instead
- // of one. The shift (almost) guarantees that intersection with b is zero
- // so when we 'or' the two bitboards togheter and count we get the correct
- // sum of '1' in b and attacked bitboards.
- Bitboard attacked = Us == WHITE ? ((b & pos.pieces_of_color(Them)) >> 1)
- : ((b & pos.pieces_of_color(Them)) << 1);
-
// Remove squares protected by enemy pawns or occupied by our pieces
b &= ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
+ // The squares occupied by enemy pieces (not defended by pawns) will be
+ // counted two times instead of one. The shift (almost) guarantees that
+ // intersection of the shifted value with b is zero so that after or-ing
+ // the count of 1s bits is increased by the number of affected squares.
+ b |= Us == WHITE ? ((b & pos.pieces_of_color(Them)) >> 1)
+ : ((b & pos.pieces_of_color(Them)) << 1);
+
// Mobility
- int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b | attacked)
- : count_1s<HasPopCnt>(b | attacked));
+ int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b)
+ : count_1s<HasPopCnt>(b));
if (mob > lastIndex[Piece])
mob = lastIndex[Piece];
}
- // evaluate_passed_pawns() evaluates the passed pawns for both sides
+ // evaluate_passed_pawns() evaluates the passed pawns of the given color
- void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
+ template<Color Us>
+ void evaluate_passed_pawns_of_color(const Position& pos, int movesToGo[], Square pawnToGo[], EvalInfo& ei) {
+
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
- bool hasUnstoppable[2] = {false, false};
- int movesToGo[2] = {100, 100};
+ Bitboard b2, b3, b4;
+ Square ourKingSq = pos.king_square(Us);
+ Square theirKingSq = pos.king_square(Them);
+ Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, Us);
- for (Color us = WHITE; us <= BLACK; us++)
+ while (b)
{
- Color them = opposite_color(us);
- Square ourKingSq = pos.king_square(us);
- Square theirKingSq = pos.king_square(them);
- Bitboard b = ei.pi->passed_pawns() & pos.pieces(PAWN, us), b2, b3, b4;
+ Square s = pop_1st_bit(&b);
- while (b)
- {
- Square s = pop_1st_bit(&b);
+ assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
+ assert(pos.pawn_is_passed(Us, s));
+
+ int r = int(relative_rank(Us, s) - RANK_2);
+ int tr = Max(0, r * (r - 1));
- assert(pos.piece_on(s) == piece_of_color_and_type(us, PAWN));
- assert(pos.pawn_is_passed(us, s));
+ // Base bonus based on rank
+ Value mbonus = Value(20 * tr);
+ Value ebonus = Value(10 + r * r * 10);
- int r = int(relative_rank(us, s) - RANK_2);
- int tr = Max(0, r * (r - 1));
- Square blockSq = s + pawn_push(us);
+ // Adjust bonus based on king proximity
+ if (tr)
+ {
+ Square blockSq = s + pawn_push(Us);
- // Base bonus based on rank
- Value mbonus = Value(20 * tr);
- Value ebonus = Value(10 + r * r * 10);
+ ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
+ ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(Us)) * 1 * tr);
+ ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
- // Adjust bonus based on king proximity
- if (tr != 0)
+ // If the pawn is free to advance, increase bonus
+ if (pos.square_is_empty(blockSq))
{
- ebonus -= Value(square_distance(ourKingSq, blockSq) * 3 * tr);
- ebonus -= Value(square_distance(ourKingSq, blockSq + pawn_push(us)) * 1 * tr);
- ebonus += Value(square_distance(theirKingSq, blockSq) * 6 * tr);
+ // There are no enemy pawns in the pawn's path
+ b2 = squares_in_front_of(Us, s);
- // If the pawn is free to advance, increase bonus
- if (pos.square_is_empty(blockSq))
- {
- b2 = squares_in_front_of(us, s);
- b3 = b2 & ei.attacked_by(them);
- b4 = b2 & ei.attacked_by(us);
-
- // If there is an enemy rook or queen attacking the pawn from behind,
- // add all X-ray attacks by the rook or queen.
- if ( bit_is_set(ei.attacked_by(them,ROOK) | ei.attacked_by(them,QUEEN),s)
- && (squares_behind(us, s) & pos.pieces(ROOK, QUEEN, them)))
- b3 = b2;
-
- // Squares attacked or occupied by enemy pieces
- b3 |= (b2 & pos.pieces_of_color(them));
-
- // There are no enemy pawns in the pawn's path
- assert((b2 & pos.pieces(PAWN, them)) == EmptyBoardBB);
-
- // Are any of the squares in the pawn's path attacked or occupied by the enemy?
- if (b3 == EmptyBoardBB)
- // No enemy attacks or pieces, huge bonus!
- ebonus += Value(tr * (b2 == b4 ? 17 : 15));
- else
- // OK, there are enemy attacks or pieces (but not pawns). Are those
- // squares which are attacked by the enemy also attacked by us?
- // If yes, big bonus (but smaller than when there are no enemy attacks),
- // if no, somewhat smaller bonus.
- ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
-
- // At last, add a small bonus when there are no *friendly* pieces
- // in the pawn's path.
- if ((b2 & pos.pieces_of_color(us)) == EmptyBoardBB)
- ebonus += Value(tr);
- }
- }
+ assert((b2 & pos.pieces(PAWN, Them)) == EmptyBoardBB);
- // If the pawn is supported by a friendly pawn, increase bonus
- b2 = pos.pieces(PAWN, us) & neighboring_files_bb(s);
- if (b2 & rank_bb(s))
- ebonus += Value(r * 20);
- else if (pos.attacks_from<PAWN>(s, them) & b2)
- ebonus += Value(r * 12);
+ // Squares attacked by us
+ b4 = b2 & ei.attacked_by(Us);
- // If the other side has only a king, check whether the pawn is
- // unstoppable
- if (pos.non_pawn_material(them) == Value(0))
- {
- Square qsq;
- int d;
+ // Squares attacked or occupied by enemy pieces
+ b3 = b2 & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
- qsq = relative_square(us, make_square(square_file(s), RANK_8));
- d = square_distance(s, qsq)
- - square_distance(theirKingSq, qsq)
- + (us != pos.side_to_move());
+ // If there is an enemy rook or queen attacking the pawn from behind,
+ // add all X-ray attacks by the rook or queen.
+ if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
+ && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<QUEEN>(s)))
+ b3 = b2;
- if (d < 0)
- {
- int mtg = RANK_8 - relative_rank(us, s);
- int blockerCount = count_1s_max_15(squares_in_front_of(us,s) & pos.occupied_squares());
- mtg += blockerCount;
- d += blockerCount;
- if (d < 0)
- {
- hasUnstoppable[us] = true;
- movesToGo[us] = Min(movesToGo[us], mtg);
- }
- }
+ // Are any of the squares in the pawn's path attacked or occupied by the enemy?
+ if (b3 == EmptyBoardBB)
+ // No enemy attacks or pieces, huge bonus!
+ // Even bigger if we protect the pawn's path
+ ebonus += Value(tr * (b2 == b4 ? 17 : 15));
+ else
+ // OK, there are enemy attacks or pieces (but not pawns). Are those
+ // squares which are attacked by the enemy also attacked by us ?
+ // If yes, big bonus (but smaller than when there are no enemy attacks),
+ // if no, somewhat smaller bonus.
+ ebonus += Value(tr * ((b3 & b4) == b3 ? 13 : 8));
+
+ // At last, add a small bonus when there are no *friendly* pieces
+ // in the pawn's path.
+ if ((b2 & pos.pieces_of_color(Us)) == EmptyBoardBB)
+ ebonus += Value(tr);
}
- // Rook pawns are a special case: They are sometimes worse, and
- // sometimes better than other passed pawns. It is difficult to find
- // good rules for determining whether they are good or bad. For now,
- // we try the following: Increase the value for rook pawns if the
- // other side has no pieces apart from a knight, and decrease the
- // value if the other side has a rook or queen.
- if (square_file(s) == FILE_A || square_file(s) == FILE_H)
+ } // tr != 0
+
+ // If the pawn is supported by a friendly pawn, increase bonus
+ b2 = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
+ if (b2 & rank_bb(s))
+ ebonus += Value(r * 20);
+ else if (pos.attacks_from<PAWN>(s, Them) & b2)
+ ebonus += Value(r * 12);
+
+ // If the other side has only a king, check whether the pawn is
+ // unstoppable
+ if (pos.non_pawn_material(Them) == Value(0))
+ {
+ Square qsq;
+ int d;
+
+ qsq = relative_square(Us, make_square(square_file(s), RANK_8));
+ d = square_distance(s, qsq)
+ - square_distance(theirKingSq, qsq)
+ + (Us != pos.side_to_move());
+
+ if (d < 0)
{
- if ( pos.non_pawn_material(them) <= KnightValueMidgame
- && pos.piece_count(them, KNIGHT) <= 1)
- ebonus += ebonus / 4;
- else if (pos.pieces(ROOK, QUEEN, them))
- ebonus -= ebonus / 4;
+ int mtg = RANK_8 - relative_rank(Us, s);
+ int blockerCount = count_1s_max_15(squares_in_front_of(Us,s) & pos.occupied_squares());
+ mtg += blockerCount;
+ d += blockerCount;
+ if (d < 0 && (!movesToGo[Us] || movesToGo[Us] > mtg))
+ {
+ movesToGo[Us] = mtg;
+ pawnToGo[Us] = s;
+ }
}
+ }
- // Add the scores for this pawn to the middle game and endgame eval.
- ei.mgValue += apply_weight(Sign[us] * mbonus, WeightPassedPawnsMidgame);
- ei.egValue += apply_weight(Sign[us] * ebonus, WeightPassedPawnsEndgame);
+ // Rook pawns are a special case: They are sometimes worse, and
+ // sometimes better than other passed pawns. It is difficult to find
+ // good rules for determining whether they are good or bad. For now,
+ // we try the following: Increase the value for rook pawns if the
+ // other side has no pieces apart from a knight, and decrease the
+ // value if the other side has a rook or queen.
+ if (square_file(s) == FILE_A || square_file(s) == FILE_H)
+ {
+ if ( pos.non_pawn_material(Them) <= KnightValueMidgame
+ && pos.piece_count(Them, KNIGHT) <= 1)
+ ebonus += ebonus / 4;
+ else if (pos.pieces(ROOK, QUEEN, Them))
+ ebonus -= ebonus / 4;
}
- }
- // Does either side have an unstoppable passed pawn?
- if (hasUnstoppable[WHITE] && !hasUnstoppable[BLACK])
- ei.egValue += UnstoppablePawnValue - Value(0x40 * movesToGo[WHITE]);
- else if (hasUnstoppable[BLACK] && !hasUnstoppable[WHITE])
- ei.egValue -= UnstoppablePawnValue - Value(0x40 * movesToGo[BLACK]);
- else if (hasUnstoppable[BLACK] && hasUnstoppable[WHITE])
+ // Add the scores for this pawn to the middle game and endgame eval.
+ ei.mgValue += apply_weight(Sign[Us] * mbonus, WeightPassedPawnsMidgame);
+ ei.egValue += apply_weight(Sign[Us] * ebonus, WeightPassedPawnsEndgame);
+
+ } // while
+ }
+
+
+ // evaluate_passed_pawns() evaluates the passed pawns for both sides
+
+ void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
+
+ int movesToGo[2] = {0, 0};
+ Square pawnToGo[2] = {SQ_NONE, SQ_NONE};
+
+ // Evaluate pawns for each color
+ evaluate_passed_pawns_of_color<WHITE>(pos, movesToGo, pawnToGo, ei);
+ evaluate_passed_pawns_of_color<BLACK>(pos, movesToGo, pawnToGo, ei);
+
+ // Neither side has an unstoppable passed pawn?
+ if (!(movesToGo[WHITE] | movesToGo[BLACK]))
+ return;
+
+ // Does only one side have an unstoppable passed pawn?
+ if (!movesToGo[WHITE] || !movesToGo[BLACK])
{
- // Both sides have unstoppable pawns! Try to find out who queens
+ Color winnerSide = movesToGo[WHITE] ? WHITE : BLACK;
+ ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * movesToGo[winnerSide]));
+ }
+ else
+ { // Both sides have unstoppable pawns! Try to find out who queens
// first. We begin by transforming 'movesToGo' to the number of
// plies until the pawn queens for both sides.
movesToGo[WHITE] *= 2;
movesToGo[BLACK] *= 2;
movesToGo[pos.side_to_move()]--;
- // If one side queens at least three plies before the other, that
- // side wins.
- if (movesToGo[WHITE] <= movesToGo[BLACK] - 3)
- ei.egValue += UnstoppablePawnValue - Value(0x40 * (movesToGo[WHITE]/2));
- else if (movesToGo[BLACK] <= movesToGo[WHITE] - 3)
- ei.egValue -= UnstoppablePawnValue - Value(0x40 * (movesToGo[BLACK]/2));
-
- // We could also add some rules about the situation when one side
- // queens exactly one ply before the other: Does the first queen
- // check the opponent's king, or attack the opponent's queening square?
- // This is slightly tricky to get right, because it is possible that
- // the opponent's king has moved somewhere before the first pawn queens.
+ Color winnerSide = movesToGo[WHITE] < movesToGo[BLACK] ? WHITE : BLACK;
+ Color loserSide = opposite_color(winnerSide);
+
+ // If one side queens at least three plies before the other, that side wins
+ if (movesToGo[winnerSide] <= movesToGo[loserSide] - 3)
+ ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
+
+ // If one side queens one ply before the other and checks the king or attacks
+ // the undefended opponent's queening square, that side wins. To avoid cases
+ // where the opponent's king could move somewhere before first pawn queens we
+ // consider only free paths to queen for both pawns.
+ else if ( !(squares_in_front_of(WHITE, pawnToGo[WHITE]) & pos.occupied_squares())
+ && !(squares_in_front_of(BLACK, pawnToGo[BLACK]) & pos.occupied_squares()))
+ {
+ assert(movesToGo[loserSide] - movesToGo[winnerSide] == 1);
+
+ Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8));
+ Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8));
+
+ Bitboard b = pos.attacks_from<QUEEN>(winnerQSq);
+
+ if ( (b & pos.pieces(KING, loserSide))
+ ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq)))
+ ei.egValue += Sign[winnerSide] * (UnstoppablePawnValue - Value(0x40 * (movesToGo[winnerSide]/2)));
+ }
}
}
projects / stockfish / blobdiff