// right to castle.
const Value TrappedRookPenalty = Value(180);
- // Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
- // enemy pawns.
- const Score TrappedBishopA7H7Penalty = make_score(300, 300);
-
- // Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
- const Bitboard MaskA7H7[2] = {
- ((1ULL << SQ_A7) | (1ULL << SQ_H7)),
- ((1ULL << SQ_A2) | (1ULL << SQ_H2))
- };
-
- // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
- // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
- // happen in Chess960 games.
- const Score TrappedBishopA1H1Penalty = make_score(100, 100);
-
- // Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
- const Bitboard MaskA1H1[2] = {
- ((1ULL << SQ_A1) | (1ULL << SQ_H1)),
- ((1ULL << SQ_A8) | (1ULL << SQ_H8))
- };
-
// 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
template<Color Us>
void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
- void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
- void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
inline Score apply_weight(Score v, Score weight);
Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Us))
evaluate_outposts<Piece, Us>(pos, ei, s);
- // Special patterns: trapped bishops on a7/h7/a2/h2
- // and trapped bishops on a1/h1/a8/h8 in Chess960.
- if (Piece == BISHOP)
- {
- if (bit_is_set(MaskA7H7[Us], s))
- evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
-
- if (Chess960 && bit_is_set(MaskA1H1[Us], s))
- evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
- }
-
// Queen or rook on 7th rank
if ( (Piece == ROOK || Piece == QUEEN)
&& relative_rank(Us, s) == RANK_7
}
- // evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
- // (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
- // if it is.
-
- void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
-
- assert(square_is_ok(s));
- assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
-
- Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
- Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
-
- if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
- && pos.see(s, b6) < 0
- && pos.see(s, b8) < 0)
- {
- ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
- }
- }
-
-
- // evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
- // (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
- // black), and assigns a penalty if it is. This pattern can obviously
- // only occur in Chess960 games.
-
- void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
-
- Piece pawn = piece_of_color_and_type(us, PAWN);
- Square b2, b3, c3;
-
- assert(Chess960);
- assert(square_is_ok(s));
- assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
-
- if (square_file(s) == FILE_A)
- {
- b2 = relative_square(us, SQ_B2);
- b3 = relative_square(us, SQ_B3);
- c3 = relative_square(us, SQ_C3);
- }
- else
- {
- b2 = relative_square(us, SQ_G2);
- b3 = relative_square(us, SQ_G3);
- c3 = relative_square(us, SQ_F3);
- }
-
- if (pos.piece_on(b2) == pawn)
- {
- Score penalty;
-
- if (!pos.square_is_empty(b3))
- penalty = 2 * TrappedBishopA1H1Penalty;
- else if (pos.piece_on(c3) == pawn)
- penalty = TrappedBishopA1H1Penalty;
- else
- penalty = TrappedBishopA1H1Penalty / 2;
-
- ei.value -= Sign[us] * penalty;
- }
- }
-
-
// evaluate_space() computes the space evaluation for a given side. The
// space evaluation is a simple bonus based on the number of safe squares
// available for minor pieces on the central four files on ranks 2--4. Safe