-
-
-namespace {
-
- template<Square Delta>
- inline Bitboard move_pawns(Bitboard p) {
-
- return Delta == DELTA_N ? p << 8 : Delta == DELTA_S ? p >> 8 :
- Delta == DELTA_NE ? p << 9 : Delta == DELTA_SE ? p >> 7 :
- Delta == DELTA_NW ? p << 7 : Delta == DELTA_SW ? p >> 9 : p;
- }
-
- template<MoveType Type, Square Delta>
- inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard target) {
-
- const Bitboard TFileABB = (Delta == DELTA_NE || Delta == DELTA_SE ? FileABB : FileHBB);
-
- Bitboard b;
- Square to;
-
- // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
- b = move_pawns<Delta>(pawns) & target & ~TFileABB;
- SERIALIZE_MOVES_D(b, -Delta);
- return mlist;
- }
-
- template<MoveType Type, Square Delta>
- inline MoveStack* generate_promotions(const Position& pos, MoveStack* mlist, Bitboard pawnsOn7, Bitboard target) {
-
- const Bitboard TFileABB = (Delta == DELTA_NE || Delta == DELTA_SE ? FileABB : FileHBB);
-
- Bitboard b;
- Square to;
-
- // Promotions and under-promotions, both captures and non-captures
- b = move_pawns<Delta>(pawnsOn7) & target;
-
- if (Delta != DELTA_N && Delta != DELTA_S)
- b &= ~TFileABB;
-
- while (b)
- {
- to = pop_1st_bit(&b);
-
- if (Type == MV_CAPTURE || Type == MV_EVASION)
- (*mlist++).move = make_promotion_move(to - Delta, to, QUEEN);
-
- if (Type == MV_NON_CAPTURE || Type == MV_EVASION)
- {
- (*mlist++).move = make_promotion_move(to - Delta, to, ROOK);
- (*mlist++).move = make_promotion_move(to - Delta, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - Delta, to, KNIGHT);
- }
-
- // This is the only possible under promotion that can give a check
- // not already included in the queen-promotion.
- if ( Type == MV_CHECK
- && bit_is_set(pos.attacks_from<KNIGHT>(to), pos.king_square(Delta > 0 ? BLACK : WHITE)))
- (*mlist++).move = make_promotion_move(to - Delta, to, KNIGHT);
- else (void)pos; // Silence a warning under MSVC
- }
- return mlist;
- }
-
- template<Color Us, MoveType Type>
- MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {
-
- // Calculate our parametrized parameters at compile time, named
- // according to the point of view of white side.
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
- const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
- const Square UP = (Us == WHITE ? DELTA_N : DELTA_S);
- const Square RIGHT_UP = (Us == WHITE ? DELTA_NE : DELTA_SW);
- const Square LEFT_UP = (Us == WHITE ? DELTA_NW : DELTA_SE);
-
- Square to;
- Bitboard b1, b2, dc1, dc2, pawnPushes, emptySquares;
- Bitboard pawns = pos.pieces(PAWN, Us);
- Bitboard pawnsOn7 = pawns & TRank7BB;
- Bitboard enemyPieces = (Type == MV_CAPTURE ? target : pos.pieces(Them));
-
- // Pre-calculate pawn pushes before changing emptySquares definition
- if (Type != MV_CAPTURE)
- {
- emptySquares = (Type == MV_NON_CAPTURE ? target : pos.empty_squares());
- pawnPushes = move_pawns<UP>(pawns & ~TRank7BB) & emptySquares;
- }
-
- if (Type == MV_EVASION)
- {
- emptySquares &= target; // Only blocking squares
- enemyPieces &= target; // Capture only the checker piece
- }
-
- // Promotions and underpromotions
- if (pawnsOn7)
- {
- if (Type == MV_CAPTURE)
- emptySquares = pos.empty_squares();
-
- pawns &= ~TRank7BB;
- mlist = generate_promotions<Type, RIGHT_UP>(pos, mlist, pawnsOn7, enemyPieces);
- mlist = generate_promotions<Type, LEFT_UP>(pos, mlist, pawnsOn7, enemyPieces);
- mlist = generate_promotions<Type, UP>(pos, mlist, pawnsOn7, emptySquares);
- }
-
- // Standard captures
- if (Type == MV_CAPTURE || Type == MV_EVASION)
- {
- mlist = generate_pawn_captures<Type, RIGHT_UP>(mlist, pawns, enemyPieces);
- mlist = generate_pawn_captures<Type, LEFT_UP>(mlist, pawns, enemyPieces);
- }
-
- // Single and double pawn pushes
- if (Type != MV_CAPTURE)
- {
- b1 = (Type != MV_EVASION ? pawnPushes : pawnPushes & emptySquares);
- b2 = move_pawns<UP>(pawnPushes & TRank3BB) & emptySquares;
-
- if (Type == MV_CHECK)
- {
- // Consider only pawn moves which give direct checks
- b1 &= pos.attacks_from<PAWN>(ksq, Them);
- b2 &= pos.attacks_from<PAWN>(ksq, Them);
-
- // Add pawn moves which gives discovered check. This is possible only
- // if the pawn is not on the same file as the enemy king, because we
- // don't generate captures.
- if (pawns & target) // For CHECK type target is dc bitboard
- {
- dc1 = move_pawns<UP>(pawns & target & ~file_bb(ksq)) & emptySquares;
- dc2 = move_pawns<UP>(dc1 & TRank3BB) & emptySquares;
-
- b1 |= dc1;
- b2 |= dc2;
- }
- }
- SERIALIZE_MOVES_D(b1, -UP);
- SERIALIZE_MOVES_D(b2, -UP -UP);
- }
-
- // En passant captures
- if ((Type == MV_CAPTURE || Type == MV_EVASION) && pos.ep_square() != SQ_NONE)
- {
- assert(Us != WHITE || rank_of(pos.ep_square()) == RANK_6);
- assert(Us != BLACK || rank_of(pos.ep_square()) == RANK_3);
-
- // An en passant capture can be an evasion only if the checking piece
- // is the double pushed pawn and so is in the target. Otherwise this
- // is a discovery check and we are forced to do otherwise.
- if (Type == MV_EVASION && !bit_is_set(target, pos.ep_square() - UP))
- return mlist;
-
- b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);
-
- assert(b1 != EmptyBoardBB);
-
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_enpassant_move(to, pos.ep_square());
- }
- }
- return mlist;
- }
-
- template<CastlingSide Side>
- MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist, Color us) {
-
- CastleRight f = CastleRight((Side == KING_SIDE ? WHITE_OO : WHITE_OOO) << us);
- Color them = flip(us);
-
- // After castling, the rook and king's final positions are exactly the same
- // in Chess960 as they would be in standard chess.
- Square kfrom = pos.king_square(us);
- Square rfrom = pos.castle_rook_square(f);
- Square kto = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
- Square rto = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1);
-
- assert(!pos.in_check());
- assert(pos.piece_on(kfrom) == make_piece(us, KING));
- assert(pos.piece_on(rfrom) == make_piece(us, ROOK));
-
- // Unimpeded rule: All the squares between the king's initial and final squares
- // (including the final square), and all the squares between the rook's initial
- // and final squares (including the final square), must be vacant except for
- // the king and castling rook.
- for (Square s = Min(kfrom, kto); s <= Max(kfrom, kto); s++)
- if ( (s != kfrom && s != rfrom && !pos.square_is_empty(s))
- ||(pos.attackers_to(s) & pos.pieces(them)))
- return mlist;
-
- for (Square s = Min(rfrom, rto); s <= Max(rfrom, rto); s++)
- if (s != kfrom && s != rfrom && !pos.square_is_empty(s))
- return mlist;
-
- // Because we generate only legal castling moves we need to verify that
- // when moving the castling rook we do not discover some hidden checker.
- // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
- if (pos.is_chess960())
- {
- Bitboard occ = pos.occupied_squares();
- clear_bit(&occ, rfrom);
- if (pos.attackers_to(kto, occ) & pos.pieces(them))
- return mlist;
- }
-
- (*mlist++).move = make_castle_move(kfrom, rfrom);
-
- return mlist;
- }
-
-} // namespace