/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
#include <cassert>
+#include <algorithm>
#include "bitcount.h"
#include "movegen.h"
+#include "position.h"
+#include "misc.h"
// Simple macro to wrap a very common while loop, no facny, no flexibility,
// hardcoded list name 'mlist' and from square 'from'.
// Version used for pawns, where the 'from' square is given as a delta from the 'to' square
#define SERIALIZE_MOVES_D(b, d) while (b) { to = pop_1st_bit(&b); (*mlist++).move = make_move(to + (d), to); }
-////
-//// Local definitions
-////
-
namespace {
- enum CastlingSide {
- KING_SIDE,
- QUEEN_SIDE
- };
-
- enum MoveType {
- CAPTURE,
- NON_CAPTURE
- };
-
- // Functions
- bool castling_is_check(const Position&, CastlingSide);
+ enum CastlingSide { KING_SIDE, QUEEN_SIDE };
- // Helper templates
template<CastlingSide Side>
- MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist);
+ MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist, Color us) {
- template<Color Us>
- MoveStack* generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*);
+ const CastleRight CR[] = { Side ? WHITE_OOO : WHITE_OO,
+ Side ? BLACK_OOO : BLACK_OO };
- template<Color Us>
- MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist);
+ if (!pos.can_castle(CR[us]))
+ return mlist;
- template<Color Us, SquareDelta Diagonal>
- MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion);
+ // After castling, the rook and king final positions are the same in Chess960
+ // as they would be in standard chess.
+ Square kfrom = pos.king_square(us);
+ Square rfrom = pos.castle_rook_square(CR[us]);
+ Square kto = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1);
+ Bitboard enemies = pos.pieces(flip(us));
+
+ 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 = std::min(rfrom, rto), e = std::max(rfrom, rto); s <= e; s++)
+ if (s != kfrom && s != rfrom && !pos.square_is_empty(s))
+ return mlist;
- template<Color Us>
- MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist);
+ for (Square s = std::min(kfrom, kto), e = std::max(kfrom, kto); s <= e; s++)
+ if ( (s != kfrom && s != rfrom && !pos.square_is_empty(s))
+ ||(pos.attackers_to(s) & enemies))
+ return mlist;
- template<Color Us>
- MoveStack* generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*);
+ // 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) & enemies)
+ return mlist;
+ }
- template<Color Us, SquareDelta Direction>
- inline Bitboard move_pawns(Bitboard p) {
+ (*mlist++).move = make_castle(kfrom, rfrom);
- if (Direction == DELTA_N)
- return Us == WHITE ? p << 8 : p >> 8;
- else if (Direction == DELTA_NE)
- return Us == WHITE ? p << 9 : p >> 7;
- else if (Direction == DELTA_NW)
- return Us == WHITE ? p << 7 : p >> 9;
- else
- return p;
+ return mlist;
}
- // Template generate_piece_checks() with specializations
- template<PieceType>
- MoveStack* generate_piece_checks(const Position&, MoveStack*, Color, Bitboard, Square);
- template<>
- inline MoveStack* generate_piece_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
+ template<Square Delta>
+ inline Bitboard move_pawns(Bitboard p) {
- return (us == WHITE ? generate_pawn_checks<WHITE>(p, dc, ksq, m)
- : generate_pawn_checks<BLACK>(p, dc, ksq, m));
+ 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 generate_piece_moves() with specializations and overloads
- template<PieceType>
- MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard);
-
- template<>
- MoveStack* generate_piece_moves<KING>(const Position&, MoveStack*, Color, Bitboard);
-
- template<PieceType Piece, MoveType Type>
- inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us) {
-
- assert(Piece == PAWN);
-
- if (Type == CAPTURE)
- return (us == WHITE ? generate_pawn_captures<WHITE>(p, m)
- : generate_pawn_captures<BLACK>(p, m));
- else
- return (us == WHITE ? generate_pawn_noncaptures<WHITE>(p, m)
- : generate_pawn_noncaptures<BLACK>(p, m));
- }
- template<PieceType>
- MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard, Bitboard);
+ template<Square Delta>
+ inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard target) {
- template<>
- inline MoveStack* generate_piece_moves<PAWN>(const Position& p, MoveStack* m,
- Color us, Bitboard t, Bitboard pnd) {
+ const Bitboard TFileABB = ( Delta == DELTA_NE
+ || Delta == DELTA_SE ? FileABB : FileHBB);
+ Bitboard b;
+ Square to;
- return (us == WHITE ? generate_pawn_blocking_evasions<WHITE>(p, pnd, t, m)
- : generate_pawn_blocking_evasions<BLACK>(p, pnd, t, m));
+ b = move_pawns<Delta>(pawns) & target & ~TFileABB;
+ SERIALIZE_MOVES_D(b, -Delta);
+ return mlist;
}
-}
-
-
-////
-//// Functions
-////
-
-/// generate_captures generates() all pseudo-legal captures and queen
-/// promotions. The return value is the number of moves generated.
-MoveStack* generate_captures(const Position& pos, MoveStack* mlist) {
-
- assert(pos.is_ok());
- assert(!pos.is_check());
-
- Color us = pos.side_to_move();
- Bitboard target = pos.pieces_of_color(opposite_color(us));
-
- mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
- mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
- mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
- mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
- mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us);
- return generate_piece_moves<KING>(pos, mlist, us, target);
-}
-
-
-/// generate_noncaptures() generates all pseudo-legal non-captures and
-/// underpromotions. The return value is the number of moves generated.
-
-MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist) {
-
- assert(pos.is_ok());
- assert(!pos.is_check());
-
- Color us = pos.side_to_move();
- Bitboard target = pos.empty_squares();
-
- mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us);
- mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
- mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
- mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
- mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
- mlist = generate_piece_moves<KING>(pos, mlist, us, target);
- mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
- return generate_castle_moves<QUEEN_SIDE>(pos, mlist);
-}
+ template<MoveType Type, Square Delta>
+ inline MoveStack* generate_promotions(MoveStack* mlist, Bitboard pawnsOn7, Bitboard target, Square ksq) {
+ const Bitboard TFileABB = ( Delta == DELTA_NE
+ || Delta == DELTA_SE ? FileABB : FileHBB);
+ Bitboard b;
+ Square to;
-/// generate_non_capture_checks() generates all pseudo-legal non-capturing,
-/// non-promoting checks. It returns the number of generated moves.
+ b = move_pawns<Delta>(pawnsOn7) & target;
-MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
+ if (Delta != DELTA_N && Delta != DELTA_S)
+ b &= ~TFileABB;
- assert(pos.is_ok());
- assert(!pos.is_check());
+ while (b)
+ {
+ to = pop_1st_bit(&b);
- Color us = pos.side_to_move();
- Square ksq = pos.king_square(opposite_color(us));
+ if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
+ (*mlist++).move = make_promotion(to - Delta, to, QUEEN);
- assert(pos.piece_on(ksq) == piece_of_color_and_type(opposite_color(us), KING));
+ if (Type == MV_NON_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
+ {
+ (*mlist++).move = make_promotion(to - Delta, to, ROOK);
+ (*mlist++).move = make_promotion(to - Delta, to, BISHOP);
+ (*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
+ }
- // Pieces moves
- mlist = generate_piece_checks<PAWN>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<KNIGHT>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<BISHOP>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<ROOK>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<QUEEN>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<KING>(pos, mlist, us, dc, ksq);
+ // Knight-promotion is the only one that can give a check (direct or
+ // discovered) not already included in the queen-promotion.
+ if ( Type == MV_CHECK
+ && bit_is_set(StepAttacksBB[W_KNIGHT][to], ksq))
+ (*mlist++).move = make_promotion(to - Delta, to, KNIGHT);
+ else
+ (void)ksq; // Silence a warning under MSVC
+ }
+ return mlist;
+ }
- // Castling moves that give check. Very rare but nice to have!
- if ( pos.can_castle_queenside(us)
- && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_D)
- && castling_is_check(pos, QUEEN_SIDE))
- mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist);
- if ( pos.can_castle_kingside(us)
- && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_F)
- && castling_is_check(pos, KING_SIDE))
- mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
+ template<Color Us, MoveType Type>
+ MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {
- return mlist;
-}
+ // 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 = (Us == WHITE ? DELTA_NE : DELTA_SW);
+ const Square LEFT = (Us == WHITE ? DELTA_NW : DELTA_SE);
+ Square to;
+ Bitboard b1, b2, dc1, dc2, emptySquares;
-/// generate_evasions() generates all check evasions when the side to move is
-/// in check. Unlike the other move generation functions, this one generates
-/// only legal moves. It returns the number of generated moves.
+ Bitboard pawns = pos.pieces(PAWN, Us);
+ Bitboard pawnsOn7 = pawns & TRank7BB;
+ Bitboard pawnsNotOn7 = pawns & ~TRank7BB;
-MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
+ Bitboard enemies = (Type == MV_EVASION ? pos.pieces(Them) & target:
+ Type == MV_CAPTURE ? target : pos.pieces(Them));
- assert(pos.is_ok());
- assert(pos.is_check());
+ // Single and double pawn pushes, no promotions
+ if (Type != MV_CAPTURE)
+ {
+ emptySquares = (Type == MV_NON_CAPTURE ? target : pos.empty_squares());
- Square from, to;
- Color us = pos.side_to_move();
- Color them = opposite_color(us);
- Square ksq = pos.king_square(us);
+ b1 = move_pawns<UP>(pawnsNotOn7) & emptySquares;
+ b2 = move_pawns<UP>(b1 & TRank3BB) & emptySquares;
- assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING));
+ if (Type == MV_EVASION)
+ {
+ b1 &= target; // Consider only blocking squares
+ b2 &= target;
+ }
- // The bitboard of occupied pieces without our king
- Bitboard b_noKing = pos.occupied_squares();
- clear_bit(&b_noKing, ksq);
+ if (Type == MV_CHECK)
+ {
+ // Consider only direct checks
+ b1 &= pos.attacks_from<PAWN>(ksq, Them);
+ b2 &= pos.attacks_from<PAWN>(ksq, Them);
+
+ // Add pawn pushes which give 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. Note that a possible discovery check
+ // promotion has been already generated among captures.
+ if (pawnsNotOn7 & target) // For CHECK type target is dc bitboard
+ {
+ dc1 = move_pawns<UP>(pawnsNotOn7 & target) & emptySquares & ~file_bb(ksq);
+ dc2 = move_pawns<UP>(dc1 & TRank3BB) & emptySquares;
+
+ b1 |= dc1;
+ b2 |= dc2;
+ }
+ }
- // Find squares attacked by slider checkers, we will
- // remove them from king evasions set so to avoid a couple
- // of cycles in the slow king evasions legality check loop
- // and to be able to use square_is_attacked().
- Bitboard checkers = pos.checkers();
- Bitboard checkersAttacks = EmptyBoardBB;
- Bitboard b = checkers & (pos.queens() | pos.bishops());
- while (b)
- {
- from = pop_1st_bit(&b);
- checkersAttacks |= bishop_attacks_bb(from, b_noKing);
- }
+ SERIALIZE_MOVES_D(b1, -UP);
+ SERIALIZE_MOVES_D(b2, -UP -UP);
+ }
- b = checkers & (pos.queens() | pos.rooks());
- while (b)
- {
- from = pop_1st_bit(&b);
- checkersAttacks |= rook_attacks_bb(from, b_noKing);
- }
+ // Promotions and underpromotions
+ if (pawnsOn7)
+ {
+ if (Type == MV_CAPTURE)
+ emptySquares = pos.empty_squares();
- // Generate evasions for king
- Bitboard b1 = pos.piece_attacks<KING>(ksq) & ~pos.pieces_of_color(us) & ~checkersAttacks;
- while (b1)
- {
- to = pop_1st_bit(&b1);
- // Note that we can use square_is_attacked() only because we
- // have already removed slider checkers.
- if (!pos.square_is_attacked(to, them))
- (*mlist++).move = make_move(ksq, to);
- }
+ if (Type == MV_EVASION)
+ emptySquares &= target;
- // Generate evasions for other pieces only if not double check. We use a
- // simple bit twiddling hack here rather than calling count_1s in order to
- // save some time (we know that pos.checkers() has at most two nonzero bits).
- if (!(checkers & (checkers - 1))) // Only one bit set?
- {
- Square checksq = first_1(checkers);
+ mlist = generate_promotions<Type, RIGHT>(mlist, pawnsOn7, enemies, ksq);
+ mlist = generate_promotions<Type, LEFT>(mlist, pawnsOn7, enemies, ksq);
+ mlist = generate_promotions<Type, UP>(mlist, pawnsOn7, emptySquares, ksq);
+ }
- assert(pos.color_of_piece_on(checksq) == them);
+ // Standard and en-passant captures
+ if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION)
+ {
+ mlist = generate_pawn_captures<RIGHT>(mlist, pawnsNotOn7, enemies);
+ mlist = generate_pawn_captures<LEFT >(mlist, pawnsNotOn7, enemies);
- // Generate captures of the checking piece
+ if (pos.ep_square() != SQ_NONE)
+ {
+ assert(rank_of(pos.ep_square()) == (Us == WHITE ? RANK_6 : RANK_3));
- // Pawn captures
- b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & ~pinned;
- while (b1)
- {
- from = pop_1st_bit(&b1);
- if (relative_rank(us, checksq) == RANK_8)
- {
- (*mlist++).move = make_promotion_move(from, checksq, QUEEN);
- (*mlist++).move = make_promotion_move(from, checksq, ROOK);
- (*mlist++).move = make_promotion_move(from, checksq, BISHOP);
- (*mlist++).move = make_promotion_move(from, checksq, KNIGHT);
- } else
- (*mlist++).move = make_move(from, checksq);
- }
+ // 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;
- // Pieces captures
- b1 = ( (pos.piece_attacks<KNIGHT>(checksq) & pos.knights(us))
- | (pos.piece_attacks<BISHOP>(checksq) & pos.bishops_and_queens(us))
- | (pos.piece_attacks<ROOK>(checksq) & pos.rooks_and_queens(us)) ) & ~pinned;
+ b1 = pawnsNotOn7 & pos.attacks_from<PAWN>(pos.ep_square(), Them);
- while (b1)
- {
- from = pop_1st_bit(&b1);
- (*mlist++).move = make_move(from, checksq);
- }
+ assert(b1);
- // Blocking check evasions are possible only if the checking piece is
- // a slider.
- if (checkers & pos.sliders())
- {
- Bitboard blockSquares = squares_between(checksq, ksq);
-
- assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
-
- if (blockSquares != EmptyBoardBB)
- {
- mlist = generate_piece_moves<PAWN>(pos, mlist, us, blockSquares, pinned);
- mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, blockSquares, pinned);
- mlist = generate_piece_moves<BISHOP>(pos, mlist, us, blockSquares, pinned);
- mlist = generate_piece_moves<ROOK>(pos, mlist, us, blockSquares, pinned);
- mlist = generate_piece_moves<QUEEN>(pos, mlist, us, blockSquares, pinned);
- }
- }
+ while (b1)
+ (*mlist++).move = make_enpassant(pop_1st_bit(&b1), pos.ep_square());
+ }
+ }
- // Finally, the special case of en passant captures. An en passant
- // capture can only be a check evasion if the check is not a discovered
- // check. If pos.ep_square() is set, the last move made must have been
- // a double pawn push. If, furthermore, the checking piece is a pawn,
- // an en passant check evasion may be possible.
- if (pos.ep_square() != SQ_NONE && (checkers & pos.pawns(them)))
- {
- to = pos.ep_square();
- b1 = pos.pawn_attacks(them, to) & pos.pawns(us);
-
- // The checking pawn cannot be a discovered (bishop) check candidate
- // otherwise we were in check also before last double push move.
- assert(!bit_is_set(pos.discovered_check_candidates(them), checksq));
- assert(count_1s(b1) == 1 || count_1s(b1) == 2);
-
- b1 &= ~pinned;
- while (b1)
- {
- from = pop_1st_bit(&b1);
- // Move is always legal because checking pawn is not a discovered
- // check candidate and our capturing pawn has been already tested
- // against pinned pieces.
- (*mlist++).move = make_ep_move(from, to);
- }
- }
+ return mlist;
}
- return mlist;
-}
-
-/// generate_legal_moves() computes a complete list of legal moves in the
-/// current position. This function is not very fast, and should be used
-/// only in situations where performance is unimportant. It wouldn't be
-/// very hard to write an efficient legal move generator, but for the moment
-/// we don't need it.
-MoveStack* generate_legal_moves(const Position& pos, MoveStack* mlist) {
+ template<PieceType Pt>
+ inline MoveStack* generate_direct_checks(const Position& pos, MoveStack* mlist, Color us,
+ Bitboard dc, Square ksq) {
+ assert(Pt != KING && Pt != PAWN);
- assert(pos.is_ok());
-
- Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
-
- if (pos.is_check())
- return generate_evasions(pos, mlist, pinned);
-
- // Generate pseudo-legal moves
- MoveStack* last = generate_captures(pos, mlist);
- last = generate_noncaptures(pos, last);
-
- // Remove illegal moves from the list
- for (MoveStack* cur = mlist; cur != last; cur++)
- if (!pos.pl_move_is_legal(cur->move, pinned))
- {
- cur->move = (--last)->move;
- cur--;
- }
- return last;
-}
-
-
-/// move_is_legal() takes a position and a (not necessarily pseudo-legal)
-/// move and a pinned pieces bitboard as input, and tests whether
-/// the move is legal. If the move is legal, the move itself is
-/// returned. If not, the function returns false. This function must
-/// only be used when the side to move is not in check.
-
-bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) {
-
- assert(pos.is_ok());
- assert(!pos.is_check());
- assert(move_is_ok(m));
- assert(pinned == pos.pinned_pieces(pos.side_to_move()));
-
- Color us = pos.side_to_move();
- Square from = move_from(m);
- Piece pc = pos.piece_on(from);
+ Bitboard checkSqs, b;
+ Square from;
+ const Square* pl = pos.piece_list(us, Pt);
- // If the from square is not occupied by a piece belonging to the side to
- // move, the move is obviously not legal.
- if (color_of_piece(pc) != us)
- return false;
+ if ((from = *pl++) == SQ_NONE)
+ return mlist;
- Color them = opposite_color(us);
- Square to = move_to(m);
+ checkSqs = pos.attacks_from<Pt>(ksq) & pos.empty_squares();
- // En passant moves
- if (move_is_ep(m))
- {
- // The piece must be a pawn and destination square must be the
- // en passant square.
- if ( type_of_piece(pc) != PAWN
- || to != pos.ep_square())
- return false;
+ do
+ {
+ if ( (Pt == QUEEN && !(QueenPseudoAttacks[from] & checkSqs))
+ || (Pt == ROOK && !(RookPseudoAttacks[from] & checkSqs))
+ || (Pt == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
+ continue;
- assert(pos.square_is_empty(to));
- assert(pos.piece_on(to - pawn_push(us)) == piece_of_color_and_type(them, PAWN));
+ if (dc && bit_is_set(dc, from))
+ continue;
- // The move is pseudo-legal, check if it is also legal
- return pos.pl_move_is_legal(m, pinned);
- }
+ b = pos.attacks_from<Pt>(from) & checkSqs;
+ SERIALIZE_MOVES(b);
- // Castling moves
- if (move_is_short_castle(m))
- {
- // The piece must be a king and side to move must still have
- // the right to castle kingside.
- if ( type_of_piece(pc) != KING
- ||!pos.can_castle_kingside(us))
- return false;
-
- assert(from == pos.king_square(us));
- assert(to == pos.initial_kr_square(us));
- assert(pos.piece_on(to) == piece_of_color_and_type(us, ROOK));
-
- Square g1 = relative_square(us, SQ_G1);
- Square f1 = relative_square(us, SQ_F1);
- Square s;
- bool illegal = false;
-
- // Check if any of the squares between king and rook
- // is occupied or under attack.
- for (s = Min(from, g1); s <= Max(from, g1); s++)
- if ( (s != from && s != to && !pos.square_is_empty(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- // Check if any of the squares between king and rook
- // is occupied.
- for (s = Min(to, f1); s <= Max(to, f1); s++)
- if (s != from && s != to && !pos.square_is_empty(s))
- illegal = true;
-
- return !illegal;
- }
+ } while ((from = *pl++) != SQ_NONE);
- if (move_is_long_castle(m))
- {
- // The piece must be a king and side to move must still have
- // the right to castle kingside.
- if ( type_of_piece(pc) != KING
- ||!pos.can_castle_queenside(us))
- return false;
-
- assert(from == pos.king_square(us));
- assert(to == pos.initial_qr_square(us));
- assert(pos.piece_on(to) == piece_of_color_and_type(us, ROOK));
-
- Square c1 = relative_square(us, SQ_C1);
- Square d1 = relative_square(us, SQ_D1);
- Square s;
- bool illegal = false;
-
- for (s = Min(from, c1); s <= Max(from, c1); s++)
- if( (s != from && s != to && !pos.square_is_empty(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- for (s = Min(to, d1); s <= Max(to, d1); s++)
- if(s != from && s != to && !pos.square_is_empty(s))
- illegal = true;
-
- if ( square_file(to) == FILE_B
- && ( pos.piece_on(to + DELTA_W) == piece_of_color_and_type(them, ROOK)
- || pos.piece_on(to + DELTA_W) == piece_of_color_and_type(them, QUEEN)))
- illegal = true;
-
- return !illegal;
+ return mlist;
}
- // Normal moves
- // The destination square cannot be occupied by a friendly piece
- if (pos.color_of_piece_on(to) == us)
- return false;
-
- // Proceed according to the type of the moving piece.
- if (type_of_piece(pc) == PAWN)
- {
- // Move direction must be compatible with pawn color
- int direction = to - from;
- if ((us == WHITE) != (direction > 0))
- return false;
-
- // If the destination square is on the 8/1th rank, the move must
- // be a promotion.
- if ( ( (square_rank(to) == RANK_8 && us == WHITE)
- ||(square_rank(to) == RANK_1 && us != WHITE))
- && !move_is_promotion(m))
- return false;
-
- // Proceed according to the square delta between the source and
- // destionation squares.
- switch (direction)
- {
- case DELTA_NW:
- case DELTA_NE:
- case DELTA_SW:
- case DELTA_SE:
- // Capture. The destination square must be occupied by an enemy
- // piece (en passant captures was handled earlier).
- if (pos.color_of_piece_on(to) != them)
- return false;
- break;
-
- case DELTA_N:
- case DELTA_S:
- // Pawn push. The destination square must be empty.
- if (!pos.square_is_empty(to))
- return false;
- break;
-
- case DELTA_NN:
- // Double white pawn push. The destination square must be on the fourth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( square_rank(to) != RANK_4
- || !pos.square_is_empty(to)
- || !pos.square_is_empty(from + DELTA_N))
- return false;
- break;
-
- case DELTA_SS:
- // Double black pawn push. The destination square must be on the fifth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( square_rank(to) != RANK_5
- || !pos.square_is_empty(to)
- || !pos.square_is_empty(from + DELTA_S))
- return false;
- break;
+ template<>
+ FORCE_INLINE MoveStack* generate_direct_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
- default:
- return false;
- }
- // The move is pseudo-legal, check if it is also legal
- return pos.pl_move_is_legal(m, pinned);
+ return (us == WHITE ? generate_pawn_moves<WHITE, MV_CHECK>(p, m, dc, ksq)
+ : generate_pawn_moves<BLACK, MV_CHECK>(p, m, dc, ksq));
}
- // Luckly we can handle all the other pieces in one go
- return ( pos.piece_attacks_square(pos.piece_on(from), from, to)
- && pos.pl_move_is_legal(m, pinned)
- && !move_is_promotion(m));
-}
-
-/// Another version of move_is_legal(), which takes only a position and a move
-/// as input. This function does not require that the side to move is not in
-/// check. It is not optimized for speed, and is only used for verifying move
-/// legality when building a PV from the transposition table.
+ template<PieceType Pt, MoveType Type>
+ FORCE_INLINE MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us, Bitboard t) {
-bool move_is_legal(const Position& pos, const Move m) {
-
- Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
- if (!pos.is_check())
- return move_is_legal(pos, m, pinned);
- else
- {
- Position p(pos);
- MoveStack mlist[64];
- MoveStack* last = generate_evasions(p, mlist, pinned);
- for (MoveStack* cur = mlist; cur != last; cur++)
- if (cur->move == m)
- return true;
-
- return false;
+ assert(Pt == PAWN);
+ return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m, t, SQ_NONE)
+ : generate_pawn_moves<BLACK, Type>(p, m, t, SQ_NONE));
}
-}
-
-namespace {
- template<PieceType Piece>
- MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
+ template<PieceType Pt>
+ FORCE_INLINE MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
- Square from;
Bitboard b;
-
- for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
- {
- from = pos.piece_list(us, Piece, i);
- b = pos.piece_attacks<Piece>(from) & target;
- SERIALIZE_MOVES(b);
- }
- return mlist;
- }
-
- template<PieceType Piece>
- MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist,
- Color us, Bitboard target, Bitboard pinned) {
Square from;
- Bitboard b;
+ const Square* pl = pos.piece_list(us, Pt);
- for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
+ if (*pl != SQ_NONE)
{
- from = pos.piece_list(us, Piece, i);
- if (pinned && bit_is_set(pinned, from))
- continue;
-
- b = pos.piece_attacks<Piece>(from) & target;
- SERIALIZE_MOVES(b);
+ do {
+ from = *pl;
+ b = pos.attacks_from<Pt>(from) & target;
+ SERIALIZE_MOVES(b);
+ } while (*++pl != SQ_NONE);
}
return mlist;
}
+
template<>
- MoveStack* generate_piece_moves<KING>(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
+ FORCE_INLINE MoveStack* generate_piece_moves<KING>(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
Bitboard b;
Square from = pos.king_square(us);
- b = pos.piece_attacks<KING>(from) & target;
+ b = pos.attacks_from<KING>(from) & target;
SERIALIZE_MOVES(b);
return mlist;
}
- template<Color Us, SquareDelta Diagonal>
- MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion) {
+} // namespace
- // Calculate our parametrized parameters at compile time
- const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
- const Bitboard TFileABB = (Diagonal == DELTA_NE ? FileABB : FileHBB);
- const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
- const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
- const SquareDelta TTDELTA_NE = (Diagonal == DELTA_NE ? TDELTA_NE : TDELTA_NW);
- Square to;
+/// generate<MV_CAPTURE> generates all pseudo-legal captures and queen
+/// promotions. Returns a pointer to the end of the move list.
+///
+/// generate<MV_NON_CAPTURE> generates all pseudo-legal non-captures and
+/// underpromotions. Returns a pointer to the end of the move list.
+///
+/// generate<MV_NON_EVASION> generates all pseudo-legal captures and
+/// non-captures. Returns a pointer to the end of the move list.
- // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
- Bitboard b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
+template<MoveType Type>
+MoveStack* generate(const Position& pos, MoveStack* mlist) {
- // Capturing promotions
- if (promotion)
- {
- Bitboard b2 = b1 & TRank8BB;
- b1 &= ~TRank8BB;
- while (b2)
- {
- to = pop_1st_bit(&b2);
- (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
- }
- }
+ assert(Type == MV_CAPTURE || Type == MV_NON_CAPTURE || Type == MV_NON_EVASION);
+ assert(!pos.in_check());
- // Capturing non-promotions
- SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
- return mlist;
- }
-
- template<Color Us>
- MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist) {
+ Color us = pos.side_to_move();
+ Bitboard target;
- // Calculate our parametrized parameters at compile time
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
- const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
- const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+ if (Type == MV_CAPTURE)
+ target = pos.pieces(flip(us));
- Square to;
- Bitboard pawns = pos.pawns(Us);
- Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
- bool possiblePromotion = (pawns & TRank7BB);
+ else if (Type == MV_NON_CAPTURE)
+ target = pos.empty_squares();
- // Standard captures and capturing promotions in both directions
- mlist = generate_pawn_captures_diagonal<Us, DELTA_NE>(mlist, pawns, enemyPieces, possiblePromotion);
- mlist = generate_pawn_captures_diagonal<Us, DELTA_NW>(mlist, pawns, enemyPieces, possiblePromotion);
+ else if (Type == MV_NON_EVASION)
+ target = pos.pieces(flip(us)) | pos.empty_squares();
- // Non-capturing promotions
- if (possiblePromotion)
- {
- Bitboard b1 = move_pawns<Us, DELTA_N>(pawns) & pos.empty_squares() & TRank8BB;
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
- }
- }
-
- // En passant captures
- if (pos.ep_square() != SQ_NONE)
- {
- assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6);
- assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3);
-
- Bitboard b1 = pawns & pos.pawn_attacks(Them, pos.ep_square());
- assert(b1 != EmptyBoardBB);
+ mlist = generate_piece_moves<PAWN, Type>(pos, mlist, us, target);
+ mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
+ mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
+ mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
+ mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
+ mlist = generate_piece_moves<KING>(pos, mlist, us, target);
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_ep_move(to, pos.ep_square());
- }
- }
- return mlist;
+ if (Type != MV_CAPTURE && pos.can_castle(us))
+ {
+ mlist = generate_castle_moves<KING_SIDE>(pos, mlist, us);
+ mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist, us);
}
- template<Color Us>
- MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) {
-
- // Calculate our parametrized parameters at compile time
- const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
- const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
- const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
- const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
- const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
- const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+ return mlist;
+}
- Bitboard b1, b2;
- Square to;
- Bitboard pawns = pos.pawns(Us);
- Bitboard emptySquares = pos.empty_squares();
+// Explicit template instantiations
+template MoveStack* generate<MV_CAPTURE>(const Position& pos, MoveStack* mlist);
+template MoveStack* generate<MV_NON_CAPTURE>(const Position& pos, MoveStack* mlist);
+template MoveStack* generate<MV_NON_EVASION>(const Position& pos, MoveStack* mlist);
- if (pawns & TRank7BB) // There is some promotion candidate ?
- {
- Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
- // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
- b1 = move_pawns<Us, DELTA_NE>(pawns) & ~FileABB & enemyPieces & TRank8BB;
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, ROOK);
- (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, KNIGHT);
- }
+/// generate<MV_NON_CAPTURE_CHECK> generates all pseudo-legal non-captures and knight
+/// underpromotions that give check. Returns a pointer to the end of the move list.
+template<>
+MoveStack* generate<MV_NON_CAPTURE_CHECK>(const Position& pos, MoveStack* mlist) {
- // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
- b1 = move_pawns<Us, DELTA_NW>(pawns) & ~FileHBB & enemyPieces & TRank8BB;
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, ROOK);
- (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, KNIGHT);
- }
+ assert(!pos.in_check());
- // Underpromotion pawn pushes
- b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & TRank8BB;
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
- }
- }
-
- // Single pawn pushes
- b2 = b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
- SERIALIZE_MOVES_D(b2, -TDELTA_N);
+ Bitboard b, dc;
+ Square from;
+ PieceType pt;
+ Color us = pos.side_to_move();
+ Square ksq = pos.king_square(flip(us));
- // Double pawn pushes
- b2 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
- SERIALIZE_MOVES_D(b2, -TDELTA_N -TDELTA_N);
- return mlist;
- }
+ assert(pos.piece_on(ksq) == make_piece(flip(us), KING));
+ // Discovered non-capture checks
+ b = dc = pos.discovered_check_candidates();
- template<Color Us>
- MoveStack* generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist)
+ while (b)
{
- // Calculate our parametrized parameters at compile time
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
- const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
- const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
- const SquareDelta TDELTA_S = (Us == WHITE ? DELTA_S : DELTA_N);
-
- Square to;
- Bitboard b1, b2, b3;
- Bitboard pawns = pos.pawns(Us);
+ from = pop_1st_bit(&b);
+ pt = type_of(pos.piece_on(from));
- if (dc & pawns)
- {
- Bitboard empty = pos.empty_squares();
+ if (pt == PAWN)
+ continue; // Will be generated togheter with direct checks
- // 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.
- b1 = pawns & ~file_bb(ksq);
+ b = pos.attacks_from(Piece(pt), from) & pos.empty_squares();
- // Discovered checks, single pawn pushes, no promotions
- b2 = b3 = move_pawns<Us, DELTA_N>(b1 & dc) & empty & ~TRank8BB;
- SERIALIZE_MOVES_D(b3, -TDELTA_N);
+ if (pt == KING)
+ b &= ~QueenPseudoAttacks[ksq];
- // Discovered checks, double pawn pushes
- b3 = move_pawns<Us, DELTA_N>(b2 & TRank3BB) & empty;
- SERIALIZE_MOVES_D(b3, -TDELTA_N -TDELTA_N);
- }
-
- // Direct checks. These are possible only for pawns on neighboring files
- // and in the two ranks that, after the push, are in front of the enemy king.
- b1 = pawns & neighboring_files_bb(ksq) & ~dc;
-
- // We can get false positives if (ksq + x) is not in [0,63] range but
- // is not a problem, they will be filtered out later.
- b2 = b1 & (rank_bb(ksq + 2 * TDELTA_S) | rank_bb(ksq + 3 * TDELTA_S));
- if (!b2)
- return mlist;
-
- // Direct checks, single pawn pushes
- Bitboard empty = pos.empty_squares();
- b2 = move_pawns<Us, DELTA_N>(b1) & empty;
- b3 = b2 & pos.pawn_attacks(Them, ksq);
- SERIALIZE_MOVES_D(b3, -TDELTA_N);
-
- // Direct checks, double pawn pushes
- b3 = move_pawns<Us, DELTA_N>(b2 & TRank3BB) & empty & pos.pawn_attacks(Them, ksq);
- SERIALIZE_MOVES_D(b3, -TDELTA_N -TDELTA_N);
- return mlist;
+ SERIALIZE_MOVES(b);
}
- template<PieceType Piece>
- MoveStack* generate_piece_checks(const Position& pos, MoveStack* mlist, Color us,
- Bitboard dc, Square ksq) {
-
- Bitboard target = pos.pieces_of_color(us) & pos.pieces_of_type(Piece);
-
- // Discovered checks
- Bitboard b = target & dc;
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks<Piece>(from) & pos.empty_squares();
- if (Piece == KING)
- bb &= ~QueenPseudoAttacks[ksq];
-
- SERIALIZE_MOVES(bb);
- }
-
- // Direct checks
- b = target & ~dc;
- if (Piece != KING || b)
- {
- Bitboard checkSqs = pos.piece_attacks<Piece>(ksq) & pos.empty_squares();
- if (!checkSqs)
- return mlist;
-
- while (b)
- {
- Square from = pop_1st_bit(&b);
- if ( (Piece == QUEEN && !(QueenPseudoAttacks[from] & checkSqs))
- || (Piece == ROOK && !(RookPseudoAttacks[from] & checkSqs))
- || (Piece == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
- continue;
-
- Bitboard bb = pos.piece_attacks<Piece>(from) & checkSqs;
- SERIALIZE_MOVES(bb);
- }
- }
- return mlist;
- }
-
- template<Color Us>
- MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard pinned,
- Bitboard blockSquares, MoveStack* mlist) {
-
- // Calculate our parametrized parameters at compile time
- const Rank TRANK_8 = (Us == WHITE ? RANK_8 : RANK_1);
- const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
- const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+ // Direct non-capture checks
+ mlist = generate_direct_checks<PAWN>(pos, mlist, us, dc, ksq);
+ mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, dc, ksq);
+ mlist = generate_direct_checks<BISHOP>(pos, mlist, us, dc, ksq);
+ mlist = generate_direct_checks<ROOK>(pos, mlist, us, dc, ksq);
+ return generate_direct_checks<QUEEN>(pos, mlist, us, dc, ksq);
+}
- Square to;
- // Find non-pinned pawns and push them one square
- Bitboard b1 = move_pawns<Us, DELTA_N>(pos.pawns(Us) & ~pinned);
+/// generate<MV_EVASION> generates all pseudo-legal check evasions when the side
+/// to move is in check. Returns a pointer to the end of the move list.
+template<>
+MoveStack* generate<MV_EVASION>(const Position& pos, MoveStack* mlist) {
- // We don't have to AND with empty squares here,
- // because the blocking squares will always be empty.
- Bitboard b2 = b1 & blockSquares;
- while (b2)
- {
- to = pop_1st_bit(&b2);
+ assert(pos.in_check());
- assert(pos.piece_on(to) == EMPTY);
+ Bitboard b, target;
+ Square from, checksq;
+ int checkersCnt = 0;
+ Color us = pos.side_to_move();
+ Square ksq = pos.king_square(us);
+ Bitboard checkers = pos.checkers();
+ Bitboard sliderAttacks = 0;
- if (square_rank(to) == TRANK_8)
- {
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
- } else
- (*mlist++).move = make_move(to - TDELTA_N, to);
- }
+ assert(pos.piece_on(ksq) == make_piece(us, KING));
+ assert(checkers);
- // Double pawn pushes
- b2 = b1 & pos.empty_squares() & TRank3BB;
- b2 = move_pawns<Us, DELTA_N>(b2) & blockSquares;
- while (b2)
- {
- to = pop_1st_bit(&b2);
-
- assert(pos.piece_on(to) == EMPTY);
- assert(Us != WHITE || square_rank(to) == RANK_4);
- assert(Us != BLACK || square_rank(to) == RANK_5);
+ // Find squares attacked by slider checkers, we will remove
+ // them from the king evasions set so to early skip known
+ // illegal moves and avoid an useless legality check later.
+ b = checkers;
+ do
+ {
+ checkersCnt++;
+ checksq = pop_1st_bit(&b);
- (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to);
- }
- return mlist;
- }
+ assert(color_of(pos.piece_on(checksq)) == flip(us));
- template<CastlingSide Side>
- MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist) {
+ switch (type_of(pos.piece_on(checksq)))
+ {
+ case BISHOP: sliderAttacks |= BishopPseudoAttacks[checksq]; break;
+ case ROOK: sliderAttacks |= RookPseudoAttacks[checksq]; break;
+ case QUEEN:
+ // If queen and king are far we can safely remove all the squares attacked
+ // in the other direction becuase are not reachable by the king anyway.
+ if (squares_between(ksq, checksq) || (RookPseudoAttacks[checksq] & (1ULL << ksq)))
+ sliderAttacks |= QueenPseudoAttacks[checksq];
+
+ // Otherwise, if king and queen are adjacent and on a diagonal line, we need to
+ // use real rook attacks to check if king is safe to move in the other direction.
+ // For example: king in B2, queen in A1 a knight in B1, and we can safely move to C1.
+ else
+ sliderAttacks |= BishopPseudoAttacks[checksq] | pos.attacks_from<ROOK>(checksq);
- Color us = pos.side_to_move();
+ default:
+ break;
+ }
+ } while (b);
- if ( (Side == KING_SIDE && pos.can_castle_kingside(us))
- ||(Side == QUEEN_SIDE && pos.can_castle_queenside(us)))
- {
- Color them = opposite_color(us);
- Square ksq = pos.king_square(us);
+ // Generate evasions for king, capture and non capture moves
+ b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
+ from = ksq;
+ SERIALIZE_MOVES(b);
- assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING));
+ // Generate evasions for other pieces only if not double check
+ if (checkersCnt > 1)
+ return mlist;
- Square rsq = (Side == KING_SIDE ? pos.initial_kr_square(us) : pos.initial_qr_square(us));
- Square s1 = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
- Square s2 = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1);
- Square s;
- bool illegal = false;
+ // Find squares where a blocking evasion or a capture of the
+ // checker piece is possible.
+ target = squares_between(checksq, ksq) | checkers;
- assert(pos.piece_on(rsq) == piece_of_color_and_type(us, ROOK));
+ mlist = generate_piece_moves<PAWN, MV_EVASION>(pos, mlist, us, target);
+ mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
+ mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
+ mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
+ return generate_piece_moves<QUEEN>(pos, mlist, us, target);
+}
- // It is a bit complicated to correctly handle Chess960
- for (s = Min(ksq, s1); s <= Max(ksq, s1); s++)
- if ( (s != ksq && s != rsq && pos.square_is_occupied(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
- for (s = Min(rsq, s2); s <= Max(rsq, s2); s++)
- if (s != ksq && s != rsq && pos.square_is_occupied(s))
- illegal = true;
+/// generate<MV_LEGAL> computes a complete list of legal moves in the current position
- if ( Side == QUEEN_SIDE
- && square_file(rsq) == FILE_B
- && ( pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, ROOK)
- || pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, QUEEN)))
- illegal = true;
+template<>
+MoveStack* generate<MV_LEGAL>(const Position& pos, MoveStack* mlist) {
- if (!illegal)
- (*mlist++).move = make_castle_move(ksq, rsq);
- }
- return mlist;
- }
+ MoveStack *last, *cur = mlist;
+ Bitboard pinned = pos.pinned_pieces();
- bool castling_is_check(const Position& pos, CastlingSide side) {
+ last = pos.in_check() ? generate<MV_EVASION>(pos, mlist)
+ : generate<MV_NON_EVASION>(pos, mlist);
- // After castling opponent king is attacked by the castled rook?
- File rookFile = (side == QUEEN_SIDE ? FILE_D : FILE_F);
- Color us = pos.side_to_move();
- Square ksq = pos.king_square(us);
- Bitboard occ = pos.occupied_squares();
+ // Remove illegal moves from the list
+ while (cur != last)
+ if (!pos.pl_move_is_legal(cur->move, pinned))
+ cur->move = (--last)->move;
+ else
+ cur++;
- clear_bit(&occ, ksq); // Remove our king from the board
- Square rsq = make_square(rookFile, square_rank(ksq));
- return bit_is_set(rook_attacks_bb(rsq, occ), pos.king_square(opposite_color(us)));
- }
+ return last;
}
projects / stockfish / blobdiff