/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
- Glaurung is free software: you can redistribute it and/or modify
+ Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
- Glaurung is distributed in the hope that it will be useful,
+
+ Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
-
+
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
#include <cassert>
#include "movegen.h"
-
-
-////
-//// Local definitions
-////
+#include "position.h"
namespace {
- inline Bitboard forward_white(Bitboard b) { return b << 8; }
- inline Bitboard forward_right_white(Bitboard b) { return b << 9; }
- inline Bitboard forward_left_white(Bitboard b) { return b << 7; }
-
- inline Bitboard forward_black(Bitboard b) { return b >> 8; }
- inline Bitboard forward_right_black(Bitboard b) { return b >> 7; }
- inline Bitboard forward_left_black(Bitboard b) { return b >> 9; }
-
- struct PawnOffsets {
-
- Bitboard Rank3BB, Rank8BB;
- Rank RANK_8;
- SquareDelta DELTA_N, DELTA_NE, DELTA_NW;
- Color us, them;
- typedef Bitboard (*Shift_fn)(Bitboard b);
- Shift_fn forward, forward_left, forward_right;
- };
-
- const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, RANK_8, DELTA_N, DELTA_NE, DELTA_NW, WHITE, BLACK,
- &forward_white, forward_left_white, forward_right_white };
-
- const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, RANK_1, DELTA_S, DELTA_SE, DELTA_SW, BLACK, WHITE,
- &forward_black, &forward_left_black, &forward_right_black };
-
- int generate_pawn_captures(const PawnOffsets&, const Position&, MoveStack*);
- int generate_pawn_noncaptures(const PawnOffsets&, const Position&, MoveStack*);
- int generate_pawn_checks(const PawnOffsets&, const Position&, Bitboard, Square, MoveStack*, int);
- int generate_castle_moves(const Position&, MoveStack*, Color);
- int generate_pawn_blocking_evasions(const PawnOffsets&, const Position&, Bitboard, Bitboard, MoveStack*, int);
-
- template<PieceType>
- int generate_piece_moves(const Position&, MoveStack*, Color, Bitboard);
-
- template<PieceType>
- int generate_piece_checks(const Position&, Bitboard, Bitboard, Square, MoveStack*, int);
-
- template<PieceType>
- int generate_piece_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*, int);
-}
-
-
-////
-//// Functions
-////
-
-
-/// generate_captures generates() all pseudo-legal captures and queen
-/// promotions. The return value is the number of moves generated.
-
-int 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));
- int n;
-
- if (us == WHITE)
- n = generate_pawn_captures(WhitePawnOffsets, pos, mlist);
- else
- n = generate_pawn_captures(BlackPawnOffsets, pos, mlist);
-
- n += generate_piece_moves<KNIGHT>(pos, mlist+n, us, target);
- n += generate_piece_moves<BISHOP>(pos, mlist+n, us, target);
- n += generate_piece_moves<ROOK>(pos, mlist+n, us, target);
- n += generate_piece_moves<QUEEN>(pos, mlist+n, us, target);
- n += generate_piece_moves<KING>(pos, mlist+n, us, target);
- return n;
-}
-
-
-/// generate_noncaptures() generates all pseudo-legal non-captures and
-/// underpromotions. The return value is the number of moves generated.
-
-int 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();
- int n;
-
- if (us == WHITE)
- n = generate_pawn_noncaptures(WhitePawnOffsets, pos, mlist);
- else
- n = generate_pawn_noncaptures(BlackPawnOffsets, pos, mlist);
-
- n += generate_piece_moves<KNIGHT>(pos, mlist+n, us, target);
- n += generate_piece_moves<BISHOP>(pos, mlist+n, us, target);
- n += generate_piece_moves<ROOK>(pos, mlist+n, us, target);
- n += generate_piece_moves<QUEEN>(pos, mlist+n, us, target);
- n += generate_piece_moves<KING>(pos, mlist+n, us, target);
-
- n += generate_castle_moves(pos, mlist+n, us);
- return n;
-}
+ template<GenType Type, Direction D>
+ ExtMove* make_promotions(ExtMove* moveList, Square to, Square ksq) {
+ if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
+ {
+ *moveList++ = make<PROMOTION>(to - D, to, QUEEN);
+ if (attacks_bb<KNIGHT>(to) & ksq)
+ *moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
+ }
-/// generate_checks() generates all pseudo-legal non-capturing, non-promoting
-/// checks, except castling moves (will add this later). It returns the
-/// number of generated moves.
+ if (Type == QUIETS || Type == EVASIONS || Type == NON_EVASIONS)
+ {
+ *moveList++ = make<PROMOTION>(to - D, to, ROOK);
+ *moveList++ = make<PROMOTION>(to - D, to, BISHOP);
+ if (!(attacks_bb<KNIGHT>(to) & ksq))
+ *moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
+ }
-int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
+ return moveList;
+ }
- assert(pos.is_ok());
- assert(!pos.is_check());
- int n;
- Color us = pos.side_to_move();
- Square ksq = pos.king_square(opposite_color(us));
+ template<Color Us, GenType Type>
+ ExtMove* generate_pawn_moves(const Position& pos, ExtMove* moveList, Bitboard target) {
- assert(pos.piece_on(ksq) == king_of_color(opposite_color(us)));
+ constexpr Color Them = ~Us;
+ constexpr Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
+ constexpr Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
+ constexpr Direction Up = pawn_push(Us);
+ constexpr Direction UpRight = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
+ constexpr Direction UpLeft = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
- dc = pos.discovered_check_candidates(us);
+ const Square ksq = pos.square<KING>(Them);
+ Bitboard emptySquares;
- // Pawn moves
- if (us == WHITE)
- n = generate_pawn_checks(WhitePawnOffsets, pos, dc, ksq, mlist, 0);
- else
- n = generate_pawn_checks(BlackPawnOffsets, pos, dc, ksq, mlist, 0);
+ Bitboard pawnsOn7 = pos.pieces(Us, PAWN) & TRank7BB;
+ Bitboard pawnsNotOn7 = pos.pieces(Us, PAWN) & ~TRank7BB;
- // Pieces moves
- Bitboard b = pos.knights(us);
- if (b)
- n = generate_piece_checks<KNIGHT>(pos, b, dc, ksq, mlist, n);
+ Bitboard enemies = (Type == EVASIONS ? pos.pieces(Them) & target:
+ Type == CAPTURES ? target : pos.pieces(Them));
- b = pos.bishops(us);
- if (b)
- n = generate_piece_checks<BISHOP>(pos, b, dc, ksq, mlist, n);
+ // Single and double pawn pushes, no promotions
+ if (Type != CAPTURES)
+ {
+ emptySquares = (Type == QUIETS || Type == QUIET_CHECKS ? target : ~pos.pieces());
- b = pos.rooks(us);
- if (b)
- n = generate_piece_checks<ROOK>(pos, b, dc, ksq, mlist, n);
+ Bitboard b1 = shift<Up>(pawnsNotOn7) & emptySquares;
+ Bitboard b2 = shift<Up>(b1 & TRank3BB) & emptySquares;
- b = pos.queens(us);
- if (b)
- n = generate_piece_checks<QUEEN>(pos, b, dc, ksq, mlist, n);
+ if (Type == EVASIONS) // Consider only blocking squares
+ {
+ b1 &= target;
+ b2 &= target;
+ }
- // King moves
- Square from = pos.king_square(us);
- if (bit_is_set(dc, from))
- {
- b = pos.piece_attacks<KING>(from) & pos.empty_squares() & ~QueenPseudoAttacks[ksq];
- while (b)
- {
- Square to = pop_1st_bit(&b);
- mlist[n++].move = make_move(from, to);
- }
- }
+ if (Type == QUIET_CHECKS)
+ {
+ b1 &= pawn_attacks_bb(Them, ksq);
+ b2 &= pawn_attacks_bb(Them, ksq);
+
+ // 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 discovered check
+ // promotion has been already generated amongst the captures.
+ Bitboard dcCandidateQuiets = pos.blockers_for_king(Them) & pawnsNotOn7;
+ if (dcCandidateQuiets)
+ {
+ Bitboard dc1 = shift<Up>(dcCandidateQuiets) & emptySquares & ~file_bb(ksq);
+ Bitboard dc2 = shift<Up>(dc1 & TRank3BB) & emptySquares;
+
+ b1 |= dc1;
+ b2 |= dc2;
+ }
+ }
- // TODO: Castling moves!
-
- return n;
-}
+ while (b1)
+ {
+ Square to = pop_lsb(&b1);
+ *moveList++ = make_move(to - Up, to);
+ }
+ while (b2)
+ {
+ Square to = pop_lsb(&b2);
+ *moveList++ = make_move(to - Up - Up, to);
+ }
+ }
-/// 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. This
-/// function is very ugly, and needs cleaning up some time later. FIXME
+ // Promotions and underpromotions
+ if (pawnsOn7)
+ {
+ if (Type == CAPTURES)
+ emptySquares = ~pos.pieces();
-int generate_evasions(const Position& pos, MoveStack* mlist) {
+ if (Type == EVASIONS)
+ emptySquares &= target;
- assert(pos.is_ok());
- assert(pos.is_check());
+ Bitboard b1 = shift<UpRight>(pawnsOn7) & enemies;
+ Bitboard b2 = shift<UpLeft >(pawnsOn7) & enemies;
+ Bitboard b3 = shift<Up >(pawnsOn7) & emptySquares;
- Color us = pos.side_to_move();
- Color them = opposite_color(us);
- Square ksq = pos.king_square(us);
- Square from, to;
- int n = 0;
-
- assert(pos.piece_on(ksq) == king_of_color(us));
-
- // Generate evasions for king
- Bitboard b1 = pos.piece_attacks<KING>(ksq) & ~pos.pieces_of_color(us);
- Bitboard b2 = pos.occupied_squares();
- clear_bit(&b2, ksq);
-
- while (b1)
- {
- Square to = pop_1st_bit(&b1);
-
- // Make sure to is not attacked by the other side. This is a bit ugly,
- // because we can't use Position::square_is_attacked. Instead we use
- // the low-level bishop_attacks_bb and rook_attacks_bb with the bitboard
- // b2 (the occupied squares with the king removed) in order to test whether
- // the king will remain in check on the destination square.
- if (!( (bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them))
- || (rook_attacks_bb(to, b2) & pos.rooks_and_queens(them))
- || (pos.piece_attacks<KNIGHT>(to) & pos.knights(them))
- || (pos.pawn_attacks(us, to) & pos.pawns(them))
- || (pos.piece_attacks<KING>(to) & pos.kings(them))))
-
- mlist[n++].move = make_move(ksq, to);
- }
+ while (b1)
+ moveList = make_promotions<Type, UpRight>(moveList, pop_lsb(&b1), ksq);
- // 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).
- Bitboard checkers = pos.checkers();
+ while (b2)
+ moveList = make_promotions<Type, UpLeft >(moveList, pop_lsb(&b2), ksq);
- if (!(checkers & (checkers - 1))) // Only one bit set?
- {
- Square checksq = first_1(checkers);
-
- assert(pos.color_of_piece_on(checksq) == them);
-
- // Find pinned pieces
- Bitboard not_pinned = ~pos.pinned_pieces(us);
-
- // Generate captures of the checking piece
-
- // Pawn captures
- b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & not_pinned;
- while (b1)
- {
- from = pop_1st_bit(&b1);
- if (relative_rank(us, checksq) == RANK_8)
- {
- mlist[n++].move = make_promotion_move(from, checksq, QUEEN);
- mlist[n++].move = make_promotion_move(from, checksq, ROOK);
- mlist[n++].move = make_promotion_move(from, checksq, BISHOP);
- mlist[n++].move = make_promotion_move(from, checksq, KNIGHT);
- } else
- mlist[n++].move = make_move(from, checksq);
- }
-
- // 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)) ) & not_pinned;
-
- while (b1)
- {
- from = pop_1st_bit(&b1);
- mlist[n++].move = make_move(from, checksq);
- }
-
- // 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);
-
- // Pawn moves. Because a blocking evasion can never be a capture, we
- // only generate pawn pushes.
- if (us == WHITE)
- n = generate_pawn_blocking_evasions(WhitePawnOffsets, pos, not_pinned, blockSquares, mlist, n);
- else
- n = generate_pawn_blocking_evasions(BlackPawnOffsets, pos, not_pinned, blockSquares, mlist, n);
-
- // Pieces moves
- b1 = pos.knights(us) & not_pinned;
- if (b1)
- n = generate_piece_blocking_evasions<KNIGHT>(pos, b1, blockSquares, mlist, n);
-
- b1 = pos.bishops(us) & not_pinned;
- if (b1)
- n = generate_piece_blocking_evasions<BISHOP>(pos, b1, blockSquares, mlist, n);
-
- b1 = pos.rooks(us) & not_pinned;
- if (b1)
- n = generate_piece_blocking_evasions<ROOK>(pos, b1, blockSquares, mlist, n);
-
- b1 = pos.queens(us) & not_pinned;
- if (b1)
- n = generate_piece_blocking_evasions<QUEEN>(pos, b1, blockSquares, mlist, n);
+ while (b3)
+ moveList = make_promotions<Type, Up >(moveList, pop_lsb(&b3), ksq);
}
- // Finally, the ugly 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)))
+ // Standard and en passant captures
+ if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
{
- to = pos.ep_square();
- b1 = pos.pawn_attacks(them, to) & pos.pawns(us);
+ Bitboard b1 = shift<UpRight>(pawnsNotOn7) & enemies;
+ Bitboard b2 = shift<UpLeft >(pawnsNotOn7) & enemies;
- assert(b1 != EmptyBoardBB);
-
- b1 &= not_pinned;
while (b1)
{
- from = pop_1st_bit(&b1);
-
- // Before generating the move, we have to make sure it is legal.
- // This is somewhat tricky, because the two disappearing pawns may
- // cause new "discovered checks". We test this by removing the
- // two relevant bits from the occupied squares bitboard, and using
- // the low-level bitboard functions for bishop and rook attacks.
- b2 = pos.occupied_squares();
- clear_bit(&b2, from);
- clear_bit(&b2, checksq);
- if (!( (bishop_attacks_bb(ksq, b2) & pos.bishops_and_queens(them))
- ||(rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them))))
-
- mlist[n++].move = make_ep_move(from, to);
+ Square to = pop_lsb(&b1);
+ *moveList++ = make_move(to - UpRight, to);
}
- }
- }
- return n;
-}
-
-
-/// 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.
-
-int generate_legal_moves(const Position& pos, MoveStack* mlist) {
- assert(pos.is_ok());
-
- if (pos.is_check())
- return generate_evasions(pos, mlist);
-
- // Generate pseudo-legal moves:
- int n = generate_captures(pos, mlist);
- n += generate_noncaptures(pos, mlist + n);
-
- Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
-
- // Remove illegal moves from the list:
- for (int i = 0; i < n; i++)
- if (!pos.move_is_legal(mlist[i].move, pinned))
- mlist[i--].move = mlist[--n].move;
-
- return n;
-}
-
-
-/// generate_move_if_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 MOVE_NONE. This function must
-/// only be used when the side to move is not in check.
-
-Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) {
-
- assert(pos.is_ok());
- assert(!pos.is_check());
- assert(move_is_ok(m));
-
- Color us = pos.side_to_move();
- Color them = opposite_color(us);
- Square from = move_from(m);
- Piece pc = pos.piece_on(from);
-
- // 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 MOVE_NONE;
+ while (b2)
+ {
+ Square to = pop_lsb(&b2);
+ *moveList++ = make_move(to - UpLeft, to);
+ }
- Square to = move_to(m);
+ if (pos.ep_square() != SQ_NONE)
+ {
+ assert(rank_of(pos.ep_square()) == relative_rank(Us, RANK_6));
- // 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 MOVE_NONE;
+ // An en passant capture cannot resolve a discovered check.
+ if (Type == EVASIONS && (target & (pos.ep_square() + Up)))
+ return moveList;
- assert(pos.square_is_empty(to));
- assert(pos.piece_on(to - pawn_push(us)) == pawn_of_color(them));
+ b1 = pawnsNotOn7 & pawn_attacks_bb(Them, pos.ep_square());
- // The move is pseudo-legal. If it is legal, return it.
- return (pos.move_is_legal(m) ? m : MOVE_NONE);
- }
+ assert(b1);
- // 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 MOVE_NONE;
-
- assert(from == pos.king_square(us));
- assert(to == pos.initial_kr_square(us));
- assert(pos.piece_on(to) == rook_of_color(us));
-
- 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 ? m : MOVE_NONE);
- }
+ while (b1)
+ *moveList++ = make<EN_PASSANT>(pop_lsb(&b1), pos.ep_square());
+ }
+ }
- 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 MOVE_NONE;
-
- assert(from == pos.king_square(us));
- assert(to == pos.initial_qr_square(us));
- assert(pos.piece_on(to) == rook_of_color(us));
-
- 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) == rook_of_color(them)
- || pos.piece_on(to + DELTA_W) == queen_of_color(them)))
- illegal = true;
-
- return (!illegal ? m : MOVE_NONE);
+ return moveList;
}
- // Normal moves
-
- // The destination square cannot be occupied by a friendly piece
- if (pos.color_of_piece_on(to) == us)
- return MOVE_NONE;
-
- // Proceed according to the type of the moving piece.
- if (type_of_piece(pc) == PAWN)
- {
- // 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_promotion(m))
- return MOVE_NONE;
-
- // Proceed according to the square delta between the source and
- // destionation squares.
- switch (to - from)
- {
- 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 MOVE_NONE;
- break;
-
- case DELTA_N:
- case DELTA_S:
- // Pawn push. The destination square must be empty.
- if (!pos.square_is_empty(to))
- return MOVE_NONE;
- 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 MOVE_NONE;
- 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 MOVE_NONE;
- break;
-
- default:
- return MOVE_NONE;
- }
- // The move is pseudo-legal. Return it if it is legal.
- return (pos.move_is_legal(m) ? m : MOVE_NONE);
- }
- // Luckly we can handle all the other pieces in one go
- return ( pos.piece_attacks_square(from, to)
- && pos.move_is_legal(m)
- && !move_promotion(m) ? m : MOVE_NONE);
-}
+ template<PieceType Pt, bool Checks>
+ ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Bitboard piecesToMove, Bitboard target) {
+ static_assert(Pt != KING && Pt != PAWN, "Unsupported piece type in generate_moves()");
-namespace {
+ Bitboard bb = piecesToMove & pos.pieces(Pt);
- int generate_pawn_captures(const PawnOffsets& ofs, const Position& pos, MoveStack* mlist) {
+ if (!bb)
+ return moveList;
- Bitboard pawns = pos.pawns(ofs.us);
- Bitboard enemyPieces = pos.pieces_of_color(ofs.them);
- Square sq;
- int n = 0;
+ [[maybe_unused]] const Bitboard checkSquares = pos.check_squares(Pt);
- // Captures in the a1-h8 (a8-h1 for black) direction
- Bitboard b1 = (ofs.forward_right)(pawns) & ~FileABB & enemyPieces;
+ while (bb) {
+ Square from = pop_lsb(&bb);
- // Capturing promotions
- Bitboard b2 = b1 & ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, QUEEN);
- }
+ Bitboard b = attacks_bb<Pt>(from, pos.pieces()) & target;
+ if constexpr (Checks)
+ b &= checkSquares;
- // Capturing non-promotions
- b2 = b1 & ~ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_move(sq - ofs.DELTA_NE, sq);
+ while (b)
+ *moveList++ = make_move(from, pop_lsb(&b));
}
- // Captures in the h1-a8 (h8-a1 for black) direction
- b1 = (ofs.forward_left)(pawns) & ~FileHBB & enemyPieces;
+ return moveList;
+ }
- // Capturing promotions
- b2 = b1 & ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, QUEEN);
- }
- // Capturing non-promotions
- b2 = b1 & ~ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_move(sq - ofs.DELTA_NW, sq);
- }
+ template<Color Us, GenType Type>
+ ExtMove* generate_all(const Position& pos, ExtMove* moveList) {
- // Non-capturing promotions
- b1 = (ofs.forward)(pawns) & pos.empty_squares() & Rank8BB;
- while (b1)
- {
- sq = pop_1st_bit(&b1);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, QUEEN);
- }
+ static_assert(Type != LEGAL, "Unsupported type in generate_all()");
- // En passant captures
- if (pos.ep_square() != SQ_NONE)
- {
- assert(ofs.us != WHITE || square_rank(pos.ep_square()) == RANK_6);
- assert(ofs.us != BLACK || square_rank(pos.ep_square()) == RANK_3);
+ constexpr bool Checks = Type == QUIET_CHECKS; // Reduce template instantations
+ Bitboard target, piecesToMove = pos.pieces(Us);
- b1 = pawns & pos.pawn_attacks(ofs.them, pos.ep_square());
- assert(b1 != EmptyBoardBB);
+ if(Type == QUIET_CHECKS)
+ piecesToMove &= ~pos.blockers_for_king(~Us);
- while (b1)
+ switch (Type)
+ {
+ case CAPTURES:
+ target = pos.pieces(~Us);
+ break;
+ case QUIETS:
+ case QUIET_CHECKS:
+ target = ~pos.pieces();
+ break;
+ case EVASIONS:
{
- sq = pop_1st_bit(&b1);
- mlist[n++].move = make_ep_move(sq, pos.ep_square());
+ Square checksq = lsb(pos.checkers());
+ target = between_bb(pos.square<KING>(Us), checksq) | checksq;
+ break;
}
+ case NON_EVASIONS:
+ target = ~pos.pieces(Us);
+ break;
}
- return n;
- }
-
- int generate_pawn_noncaptures(const PawnOffsets& ofs, const Position& pos, MoveStack* mlist) {
+ moveList = generate_pawn_moves<Us, Type>(pos, moveList, target);
+ moveList = generate_moves<KNIGHT, Checks>(pos, moveList, piecesToMove, target);
+ moveList = generate_moves<BISHOP, Checks>(pos, moveList, piecesToMove, target);
+ moveList = generate_moves< ROOK, Checks>(pos, moveList, piecesToMove, target);
+ moveList = generate_moves< QUEEN, Checks>(pos, moveList, piecesToMove, target);
- Bitboard pawns = pos.pawns(ofs.us);
- Bitboard enemyPieces = pos.pieces_of_color(ofs.them);
- Bitboard emptySquares = pos.empty_squares();
- Bitboard b1, b2;
- Square sq;
- int n = 0;
-
- // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
- b1 = ofs.forward_right(pawns) & ~FileABB & enemyPieces & ofs.Rank8BB;
- while (b1)
+ if (Type != QUIET_CHECKS && Type != EVASIONS)
{
- sq = pop_1st_bit(&b1);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, ROOK);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, BISHOP);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, KNIGHT);
- }
+ Square ksq = pos.square<KING>(Us);
+ Bitboard b = attacks_bb<KING>(ksq) & target;
+ while (b)
+ *moveList++ = make_move(ksq, pop_lsb(&b));
- // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
- b1 = ofs.forward_left(pawns) & ~FileHBB & enemyPieces & ofs.Rank8BB;
- while (b1)
- {
- sq = pop_1st_bit(&b1);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, ROOK);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, BISHOP);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, KNIGHT);
+ if ((Type != CAPTURES) && pos.can_castle(Us & ANY_CASTLING))
+ for (CastlingRights cr : { Us & KING_SIDE, Us & QUEEN_SIDE } )
+ if (!pos.castling_impeded(cr) && pos.can_castle(cr))
+ *moveList++ = make<CASTLING>(ksq, pos.castling_rook_square(cr));
}
- // Single pawn pushes
- b1 = ofs.forward(pawns) & emptySquares;
- b2 = b1 & ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, ROOK);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, BISHOP);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, KNIGHT);
- }
- b2 = b1 & ~ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_move(sq - ofs.DELTA_N, sq);
- }
-
- // Double pawn pushes
- b2 = (ofs.forward(b1 & ofs.Rank3BB)) & emptySquares;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_move(sq - ofs.DELTA_N - ofs.DELTA_N, sq);
- }
- return n;
+ return moveList;
}
+} // namespace
- template<PieceType Piece>
- int generate_piece_moves(const Position &pos, MoveStack *mlist,
- Color side, Bitboard target) {
- Square from, to;
- Bitboard b;
- int n = 0;
+/// <CAPTURES> Generates all pseudo-legal captures plus queen and checking knight promotions
+/// <QUIETS> Generates all pseudo-legal non-captures and underpromotions(except checking knight)
+/// <NON_EVASIONS> Generates all pseudo-legal captures and non-captures
+///
+/// Returns a pointer to the end of the move list.
- for (int i = 0; i < pos.piece_count(side, Piece); i++)
- {
- from = pos.piece_list(side, Piece, i);
- b = pos.piece_attacks<Piece>(from) & target;
- while (b)
- {
- to = pop_1st_bit(&b);
- mlist[n++].move = make_move(from, to);
- }
- }
- return n;
- }
+template<GenType Type>
+ExtMove* generate(const Position& pos, ExtMove* moveList) {
+ static_assert(Type == CAPTURES || Type == QUIETS || Type == NON_EVASIONS, "Unsupported type in generate()");
+ assert(!pos.checkers());
- int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) {
+ Color us = pos.side_to_move();
- int n = 0;
+ return us == WHITE ? generate_all<WHITE, Type>(pos, moveList)
+ : generate_all<BLACK, Type>(pos, moveList);
+}
- if (pos.can_castle(us))
- {
- Color them = opposite_color(us);
- Square ksq = pos.king_square(us);
+// Explicit template instantiations
+template ExtMove* generate<CAPTURES>(const Position&, ExtMove*);
+template ExtMove* generate<QUIETS>(const Position&, ExtMove*);
+template ExtMove* generate<NON_EVASIONS>(const Position&, ExtMove*);
- assert(pos.piece_on(ksq) == king_of_color(us));
- if (pos.can_castle_kingside(us))
- {
- Square rsq = pos.initial_kr_square(us);
- Square g1 = relative_square(us, SQ_G1);
- Square f1 = relative_square(us, SQ_F1);
- Square s;
- bool illegal = false;
-
- assert(pos.piece_on(rsq) == rook_of_color(us));
-
- for (s = Min(ksq, g1); s <= Max(ksq, g1); s++)
- if ( (s != ksq && s != rsq && pos.square_is_occupied(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- for (s = Min(rsq, f1); s <= Max(rsq, f1); s++)
- if (s != ksq && s != rsq && pos.square_is_occupied(s))
- illegal = true;
-
- if (!illegal)
- mlist[n++].move = make_castle_move(ksq, rsq);
- }
-
- if (pos.can_castle_queenside(us))
- {
- Square rsq = pos.initial_qr_square(us);
- Square c1 = relative_square(us, SQ_C1);
- Square d1 = relative_square(us, SQ_D1);
- Square s;
- bool illegal = false;
-
- assert(pos.piece_on(rsq) == rook_of_color(us));
-
- for (s = Min(ksq, c1); s <= Max(ksq, c1); s++)
- if ( (s != ksq && s != rsq && pos.square_is_occupied(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- for (s = Min(rsq, d1); s <= Max(rsq, d1); s++)
- if (s != ksq && s != rsq && pos.square_is_occupied(s))
- illegal = true;
-
- if ( square_file(rsq) == FILE_B
- && ( pos.piece_on(relative_square(us, SQ_A1)) == rook_of_color(them)
- || pos.piece_on(relative_square(us, SQ_A1)) == queen_of_color(them)))
- illegal = true;
-
- if (!illegal)
- mlist[n++].move = make_castle_move(ksq, rsq);
- }
- }
- return n;
- }
+/// generate<QUIET_CHECKS> generates all pseudo-legal non-captures.
+/// Returns a pointer to the end of the move list.
+template<>
+ExtMove* generate<QUIET_CHECKS>(const Position& pos, ExtMove* moveList) {
- template<PieceType Piece>
- int generate_piece_checks(const Position& pos, Bitboard target, Bitboard dc,
- Square ksq, MoveStack* mlist, int n) {
+ assert(!pos.checkers());
- // Discovered checks
- Bitboard b = target & dc;
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks<Piece>(from) & pos.empty_squares();
- while (bb)
- {
- Square to = pop_1st_bit(&bb);
- mlist[n++].move = make_move(from, to);
- }
- }
-
- // Direct checks
- b = target & ~dc;
- Bitboard checkSqs = pos.piece_attacks<Piece>(ksq) & pos.empty_squares();
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks<Piece>(from) & checkSqs;
- while (bb)
- {
- Square to = pop_1st_bit(&bb);
- mlist[n++].move = make_move(from, to);
- }
- }
- return n;
- }
+ Color us = pos.side_to_move();
+ Bitboard dc = pos.blockers_for_king(~us) & pos.pieces(us) & ~pos.pieces(PAWN);
- int generate_pawn_checks(const PawnOffsets& ofs, const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist, int n)
+ while (dc)
{
- // Pawn moves 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.
- Bitboard empty = pos.empty_squares();
-
- // Find all friendly pawns not on the enemy king's file
- Bitboard b1 = pos.pawns(pos.side_to_move()) & ~file_bb(ksq), b2, b3;
-
- // Discovered checks, single pawn pushes
- b2 = b3 = (ofs.forward)(b1 & dc) & ~ofs.Rank8BB & empty;
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - ofs.DELTA_N, to);
- }
+ Square from = pop_lsb(&dc);
+ PieceType pt = type_of(pos.piece_on(from));
- // Discovered checks, double pawn pushes
- b3 = (ofs.forward)(b2 & ofs.Rank3BB) & empty;
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
- }
+ Bitboard b = attacks_bb(pt, from, pos.pieces()) & ~pos.pieces();
- // Direct checks. These are possible only for pawns on neighboring files
- // of the enemy king
+ if (pt == KING)
+ b &= ~attacks_bb<QUEEN>(pos.square<KING>(~us));
- b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
-
- // Direct checks, single pawn pushes
- b2 = (ofs.forward)(b1) & empty;
- b3 = b2 & pos.pawn_attacks(ofs.them, ksq);
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - ofs.DELTA_N, to);
- }
-
- // Direct checks, double pawn pushes
- b3 = (ofs.forward)(b2 & ofs.Rank3BB) & empty & pos.pawn_attacks(ofs.them, ksq);
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
- }
- return n;
+ while (b)
+ *moveList++ = make_move(from, pop_lsb(&b));
}
-
- template<PieceType Piece>
- int generate_piece_blocking_evasions(const Position& pos, Bitboard b,
- Bitboard blockSquares, MoveStack* mlist, int n) {
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks<Piece>(from) & blockSquares;
- while (bb)
- {
- Square to = pop_1st_bit(&bb);
- mlist[n++].move = make_move(from, to);
- }
- }
- return n;
- }
+ return us == WHITE ? generate_all<WHITE, QUIET_CHECKS>(pos, moveList)
+ : generate_all<BLACK, QUIET_CHECKS>(pos, moveList);
+}
- int generate_pawn_blocking_evasions(const PawnOffsets& ofs, const Position& pos, Bitboard not_pinned,
- Bitboard blockSquares, MoveStack* mlist, int n) {
- // Find non-pinned pawns
- Bitboard b1 = pos.pawns(ofs.us) & not_pinned;
+/// generate<EVASIONS> 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<>
+ExtMove* generate<EVASIONS>(const Position& pos, ExtMove* moveList) {
- // Single pawn pushes. We don't have to AND with empty squares here,
- // because the blocking squares will always be empty.
- Bitboard b2 = (ofs.forward)(b1) & blockSquares;
- while (b2)
- {
- Square to = pop_1st_bit(&b2);
+ assert(pos.checkers());
- assert(pos.piece_on(to) == EMPTY);
+ Color us = pos.side_to_move();
+ Square ksq = pos.square<KING>(us);
+ Bitboard sliderAttacks = 0;
+ Bitboard sliders = pos.checkers() & ~pos.pieces(KNIGHT, PAWN);
+
+ // Find all the squares attacked by slider checkers. We will remove them from
+ // the king evasions in order to skip known illegal moves, which avoids any
+ // useless legality checks later on.
+ while (sliders)
+ sliderAttacks |= line_bb(ksq, pop_lsb(&sliders)) & ~pos.checkers();
+
+ // Generate evasions for king, capture and non capture moves
+ Bitboard b = attacks_bb<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
+ while (b)
+ *moveList++ = make_move(ksq, pop_lsb(&b));
+
+ if (more_than_one(pos.checkers()))
+ return moveList; // Double check, only a king move can save the day
+
+ // Generate blocking evasions or captures of the checking piece
+ return us == WHITE ? generate_all<WHITE, EVASIONS>(pos, moveList)
+ : generate_all<BLACK, EVASIONS>(pos, moveList);
+}
- if (square_rank(to) == ofs.RANK_8)
- {
- mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, QUEEN);
- mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, ROOK);
- mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, BISHOP);
- mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, KNIGHT);
- } else
- mlist[n++].move = make_move(to - ofs.DELTA_N, to);
- }
- // Double pawn pushes
- b2 = (ofs.forward)((ofs.forward)(b1) & pos.empty_squares() & ofs.Rank3BB) & blockSquares;
- while (b2)
- {
- Square to = pop_1st_bit(&b2);
+/// generate<LEGAL> generates all the legal moves in the given position
- assert(pos.piece_on(to) == EMPTY);
- assert(ofs.us != WHITE || square_rank(to) == RANK_4);
- assert(ofs.us != BLACK || square_rank(to) == RANK_5);
+template<>
+ExtMove* generate<LEGAL>(const Position& pos, ExtMove* moveList) {
- mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
- }
- return n;
- }
+ Color us = pos.side_to_move();
+ Bitboard pinned = pos.blockers_for_king(us) & pos.pieces(us);
+ Square ksq = pos.square<KING>(us);
+ ExtMove* cur = moveList;
+
+ moveList = pos.checkers() ? generate<EVASIONS >(pos, moveList)
+ : generate<NON_EVASIONS>(pos, moveList);
+ while (cur != moveList)
+ if ( (pinned || from_sq(*cur) == ksq || type_of(*cur) == EN_PASSANT)
+ && !pos.legal(*cur))
+ *cur = (--moveList)->move;
+ else
+ ++cur;
+
+ return moveList;
}
projects / stockfish / blobdiff