X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovegen.cpp;h=83f844484720169118763e9ffe7f056fa4707de1;hp=56caa9a4e583112cb304e6c543e7a39ca6044aa6;hb=6dddcecb09df268d93810a1a38deb116f97672af;hpb=5e2fc2aa165b3c0406bcf98c773b952e20f50325
diff --git a/src/movegen.cpp b/src/movegen.cpp
index 56caa9a4..88c31cfa 100644
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -1,6 +1,6 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -16,932 +16,349 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
#include
#include "movegen.h"
-
-// Simple macro to wrap a very common while loop, no facny, no flexibility,
-// hardcoded list name 'mlist' and from square 'from'.
-#define SERIALIZE_MOVES(b) while (b) (*mlist++).move = make_move(from, pop_1st_bit(&b))
-
-////
-//// Local definitions
-////
+#include "position.h"
namespace {
- // Function
- MoveStack* generate_castle_moves(const Position&, MoveStack*);
-
- // Template generate_pawn_captures() with specializations
- template
- MoveStack* do_generate_pawn_captures(const Position& pos, MoveStack* mlist);
-
- template
- inline MoveStack* generate_pawn_captures(const Position& p, MoveStack* m) {
- return do_generate_pawn_captures(p, m);
- }
- template<>
- inline MoveStack* generate_pawn_captures(const Position& p, MoveStack* m) {
- return do_generate_pawn_captures(p, m);
- }
-
- // Template generate_pawn_noncaptures() with specializations
- template
- MoveStack* do_generate_pawn_noncaptures(const Position& pos, MoveStack* mlist);
-
- template
- inline MoveStack* generate_pawn_noncaptures(const Position& p, MoveStack* m) {
- return do_generate_pawn_noncaptures(p, m);
- }
- template<>
- inline MoveStack* generate_pawn_noncaptures(const Position& p, MoveStack* m) {
- return do_generate_pawn_noncaptures(p, m);
- }
+ template
+ ExtMove* make_promotions(ExtMove* moveList, Square to, Square ksq) {
- // Template generate_pawn_blocking_evasions() with specializations
- template
- MoveStack* do_generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned,
- Bitboard blockSquares, MoveStack* mlist);
- template
- inline MoveStack* generate_pawn_blocking_evasions(const Position& p, Bitboard np, Bitboard bs, MoveStack* m) {
- return do_generate_pawn_blocking_evasions(p, np, bs, m);
- }
- template<>
- inline MoveStack* generate_pawn_blocking_evasions(const Position& p, Bitboard np, Bitboard bs, MoveStack* m) {
- return do_generate_pawn_blocking_evasions(p, np, bs, m);
- }
+ if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
+ {
+ *moveList++ = make(to - D, to, QUEEN);
+ if (attacks_bb(to) & ksq)
+ *moveList++ = make(to - D, to, KNIGHT);
+ }
- // Template generate_pawn_checks() with specializations
- template
- MoveStack* do_generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*);
+ if (Type == QUIETS || Type == EVASIONS || Type == NON_EVASIONS)
+ {
+ *moveList++ = make(to - D, to, ROOK);
+ *moveList++ = make(to - D, to, BISHOP);
+ if (!(attacks_bb(to) & ksq))
+ *moveList++ = make(to - D, to, KNIGHT);
+ }
- template
- inline MoveStack* generate_pawn_checks(const Position& p, Bitboard dc, Square ksq, MoveStack* m) {
- return do_generate_pawn_checks(p, dc, ksq, m);
+ return moveList;
}
- template<>
- inline MoveStack* generate_pawn_checks(const Position& p, Bitboard dc, Square ksq, MoveStack* m) {
- return do_generate_pawn_checks(p, dc, ksq, m);
- }
-
- // non-pawn templates
- template
- MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard);
- template<>
- MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target);
-
- template
- MoveStack* generate_piece_checks(const Position&, Bitboard, Bitboard, Square, MoveStack*);
- MoveStack* generate_piece_checks_king(const Position&, Square, Bitboard, Square, MoveStack*);
-
- template
- MoveStack* generate_piece_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*);
-}
-
-
-////
-//// 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));
- MoveStack* mlist_start = mlist;
-
- if (us == WHITE)
- mlist = generate_pawn_captures(pos, mlist);
- else
- mlist = generate_pawn_captures(pos, mlist);
-
- mlist = generate_piece_moves(pos, mlist, us, target);
- mlist = generate_piece_moves(pos, mlist, us, target);
- mlist = generate_piece_moves(pos, mlist, us, target);
- mlist = generate_piece_moves(pos, mlist, us, target);
- mlist = generate_piece_moves(pos, mlist, us, target);
- return int(mlist - mlist_start);
-}
-
-
-/// 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();
- MoveStack* mlist_start = mlist;
-
- if (us == WHITE)
- mlist = generate_pawn_noncaptures(pos, mlist);
- else
- mlist = generate_pawn_noncaptures(pos, mlist);
-
- mlist = generate_piece_moves(pos, mlist, us, target);
- mlist = generate_piece_moves(pos, mlist, us, target);
- mlist = generate_piece_moves(pos, mlist, us, target);
- mlist = generate_piece_moves(pos, mlist, us, target);
- mlist = generate_piece_moves(pos, mlist, us, target);
- mlist = generate_castle_moves(pos, mlist);
- return int(mlist - mlist_start);
-}
-
-
-/// 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.
-
-int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
-
- assert(pos.is_ok());
- assert(!pos.is_check());
-
- Color us = pos.side_to_move();
- Square ksq = pos.king_square(opposite_color(us));
- MoveStack* mlist_start = mlist;
- assert(pos.piece_on(ksq) == king_of_color(opposite_color(us)));
- dc = pos.discovered_check_candidates(us);
+ template
+ ExtMove* generate_pawn_moves(const Position& pos, ExtMove* moveList, Bitboard target) {
- // Pawn moves
- if (us == WHITE)
- mlist = generate_pawn_checks(pos, dc, ksq, mlist);
- else
- mlist = generate_pawn_checks(pos, dc, ksq, mlist);
+ 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);
- // Pieces moves
- Bitboard b = pos.knights(us);
- if (b)
- mlist = generate_piece_checks(pos, b, dc, ksq, mlist);
+ const Square ksq = pos.square(Them);
+ Bitboard emptySquares;
- b = pos.bishops(us);
- if (b)
- mlist = generate_piece_checks(pos, b, dc, ksq, mlist);
+ Bitboard pawnsOn7 = pos.pieces(Us, PAWN) & TRank7BB;
+ Bitboard pawnsNotOn7 = pos.pieces(Us, PAWN) & ~TRank7BB;
- b = pos.rooks(us);
- if (b)
- mlist = generate_piece_checks(pos, b, dc, ksq, mlist);
+ Bitboard enemies = (Type == EVASIONS ? pos.pieces(Them) & target:
+ Type == CAPTURES ? target : pos.pieces(Them));
- b = pos.queens(us);
- if (b)
- mlist = generate_piece_checks(pos, b, dc, ksq, mlist);
-
- // Hopefully we always have a king ;-)
- mlist = generate_piece_checks_king(pos, pos.king_square(us), dc, ksq, mlist);
-
- // TODO: Castling moves!
+ // Single and double pawn pushes, no promotions
+ if (Type != CAPTURES)
+ {
+ emptySquares = (Type == QUIETS || Type == QUIET_CHECKS ? target : ~pos.pieces());
- return int(mlist - mlist_start);
-}
+ Bitboard b1 = shift(pawnsNotOn7) & emptySquares;
+ Bitboard b2 = shift(b1 & TRank3BB) & emptySquares;
+ if (Type == EVASIONS) // Consider only blocking squares
+ {
+ b1 &= target;
+ b2 &= target;
+ }
-/// 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
+ 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(dcCandidateQuiets) & emptySquares & ~file_bb(ksq);
+ Bitboard dc2 = shift(dc1 & TRank3BB) & emptySquares;
+
+ b1 |= dc1;
+ b2 |= dc2;
+ }
+ }
-int generate_evasions(const Position& pos, MoveStack* mlist) {
+ while (b1)
+ {
+ Square to = pop_lsb(&b1);
+ *moveList++ = make_move(to - Up, to);
+ }
- assert(pos.is_ok());
- assert(pos.is_check());
+ while (b2)
+ {
+ Square to = pop_lsb(&b2);
+ *moveList++ = make_move(to - Up - Up, to);
+ }
+ }
- Square from, to;
- Color us = pos.side_to_move();
- Color them = opposite_color(us);
- Square ksq = pos.king_square(us);
- MoveStack* mlist_start = mlist;
+ // Promotions and underpromotions
+ if (pawnsOn7)
+ {
+ if (Type == CAPTURES)
+ emptySquares = ~pos.pieces();
- assert(pos.piece_on(ksq) == king_of_color(us));
+ if (Type == EVASIONS)
+ emptySquares &= target;
- // Generate evasions for king
- Bitboard b1 = pos.piece_attacks(ksq) & ~pos.pieces_of_color(us);
- Bitboard b2 = pos.occupied_squares();
- clear_bit(&b2, ksq);
+ Bitboard b1 = shift(pawnsOn7) & enemies;
+ Bitboard b2 = shift(pawnsOn7) & enemies;
+ Bitboard b3 = shift(pawnsOn7) & emptySquares;
- while (b1)
- {
- 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 (!( (pos.piece_attacks(to) & pos.knights(them))
- || (pos.pawn_attacks(us, to) & pos.pawns(them))
- || (bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them))
- || (rook_attacks_bb(to, b2) & pos.rooks_and_queens(them))
- || (pos.piece_attacks(to) & pos.kings(them))))
-
- (*mlist++).move = make_move(ksq, to);
- }
+ while (b1)
+ moveList = make_promotions(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(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++).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);
- }
-
- // Pieces captures
- b1 = ( (pos.piece_attacks(checksq) & pos.knights(us))
- | (pos.piece_attacks(checksq) & pos.bishops_and_queens(us))
- | (pos.piece_attacks(checksq) & pos.rooks_and_queens(us)) ) & not_pinned;
-
- while (b1)
- {
- from = pop_1st_bit(&b1);
- (*mlist++).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)
- mlist = generate_pawn_blocking_evasions(pos, not_pinned, blockSquares, mlist);
- else
- mlist = generate_pawn_blocking_evasions(pos, not_pinned, blockSquares, mlist);
-
- // Pieces moves
- b1 = pos.knights(us) & not_pinned;
- if (b1)
- mlist = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist);
-
- b1 = pos.bishops(us) & not_pinned;
- if (b1)
- mlist = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist);
-
- b1 = pos.rooks(us) & not_pinned;
- if (b1)
- mlist = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist);
-
- b1 = pos.queens(us) & not_pinned;
- if (b1)
- mlist = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist);
+ while (b3)
+ moveList = make_promotions(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(pawnsNotOn7) & enemies;
+ Bitboard b2 = shift(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++).move = make_ep_move(from, to);
+ Square to = pop_lsb(&b1);
+ *moveList++ = make_move(to - UpRight, to);
}
- }
- }
- return int(mlist - mlist_start);
-}
-
-
-/// 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.pl_move_is_legal(mlist[i].move, pinned))
- mlist[i--].move = mlist[--n].move;
-
- return n;
-}
-
-
-/// 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();
- Color them = opposite_color(us);
- Square from = move_from(m);
- Piece pc = pos.piece_on(from);
+ while (b2)
+ {
+ Square to = pop_lsb(&b2);
+ *moveList++ = make_move(to - UpLeft, to);
+ }
- // 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 (pos.ep_square() != SQ_NONE)
+ {
+ assert(rank_of(pos.ep_square()) == relative_rank(Us, RANK_6));
- Square to = move_to(m);
+ // An en passant capture cannot resolve a discovered check.
+ if (Type == EVASIONS && (target & (pos.ep_square() + Up)))
+ return moveList;
- // 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;
+ b1 = pawnsNotOn7 & pawn_attacks_bb(Them, pos.ep_square());
- assert(pos.square_is_empty(to));
- assert(pos.piece_on(to - pawn_push(us)) == pawn_of_color(them));
+ assert(b1);
- // The move is pseudo-legal, check if it is also legal
- return pos.pl_move_is_legal(m, pinned);
- }
+ while (b1)
+ *moveList++ = make(pop_lsb(&b1), pos.ep_square());
+ }
+ }
- // 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) == 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;
+ return moveList;
}
- 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) == 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;
- }
- // Normal moves
+ template
+ ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Bitboard piecesToMove, Bitboard target) {
- // The destination square cannot be occupied by a friendly piece
- if (pos.color_of_piece_on(to) == us)
- return false;
+ static_assert(Pt != KING && Pt != PAWN, "Unsupported piece type in generate_moves()");
- // 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 false;
-
- // 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 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;
-
- default:
- return false;
- }
- // The move is pseudo-legal, check if it is also legal
- return pos.pl_move_is_legal(m, pinned);
- }
+ Bitboard bb = piecesToMove & pos.pieces(Pt);
- // Luckly we can handle all the other pieces in one go
- return ( pos.piece_attacks_square(from, to)
- && pos.pl_move_is_legal(m, pinned)
- && !move_promotion(m));
-}
+ if (!bb)
+ return moveList;
+ [[maybe_unused]] const Bitboard checkSquares = pos.check_squares(Pt);
-namespace {
+ while (bb) {
+ Square from = pop_lsb(&bb);
- template
- MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
+ Bitboard b = attacks_bb(from, pos.pieces()) & target;
+ if constexpr (Checks)
+ b &= checkSquares;
- 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(from) & target;
- SERIALIZE_MOVES(b);
+ while (b)
+ *moveList++ = make_move(from, pop_lsb(&b));
}
- return mlist;
- }
-
- template<>
- MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
-
- Bitboard b;
- Square from = pos.king_square(us);
- b = pos.piece_attacks(from) & target;
- SERIALIZE_MOVES(b);
- return mlist;
+ return moveList;
}
- template
- MoveStack* generate_piece_blocking_evasions(const Position& pos, Bitboard b,
- Bitboard blockSquares, MoveStack* mlist) {
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks(from) & blockSquares;
- SERIALIZE_MOVES(bb);
- }
- return mlist;
- }
-
-
- template
- MoveStack* do_generate_pawn_captures(const Position& pos, MoveStack* mlist) {
-
- Square to;
- Bitboard pawns = pos.pawns(Us);
- Bitboard enemyPieces = pos.pieces_of_color(Them);
-
- // Captures in the a1-h8 (a8-h1 for black) direction
- Bitboard b1 = (Us == WHITE ? pawns << 9 : pawns >> 7) & ~FileABB & enemyPieces;
-
- // Capturing promotions
- Bitboard b2 = b1 & TRank8BB;
- while (b2)
- {
- to = pop_1st_bit(&b2);
- (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, QUEEN);
- }
- // Capturing non-promotions
- b2 = b1 & ~TRank8BB;
- while (b2)
- {
- to = pop_1st_bit(&b2);
- (*mlist++).move = make_move(to - TDELTA_NE, to);
- }
+ template
+ ExtMove* generate_all(const Position& pos, ExtMove* moveList) {
- // Captures in the h1-a8 (h8-a1 for black) direction
- b1 = (Us == WHITE ? pawns << 7 : pawns >> 9) & ~FileHBB & enemyPieces;
+ static_assert(Type != LEGAL, "Unsupported type in generate_all()");
- // Capturing promotions
- b2 = b1 & TRank8BB;
- while (b2)
- {
- to = pop_1st_bit(&b2);
- (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, QUEEN);
- }
+ constexpr bool Checks = Type == QUIET_CHECKS; // Reduce template instantations
+ Bitboard target, piecesToMove = pos.pieces(Us);
- // Capturing non-promotions
- b2 = b1 & ~TRank8BB;
- while (b2)
- {
- to = pop_1st_bit(&b2);
- (*mlist++).move = make_move(to - TDELTA_NW, to);
- }
-
- // Non-capturing promotions
- b1 = (Us == WHITE ? pawns << 8 : pawns >> 8) & pos.empty_squares() & TRank8BB;
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
- }
+ if(Type == QUIET_CHECKS)
+ piecesToMove &= ~pos.blockers_for_king(~Us);
- // En passant captures
- if (pos.ep_square() != SQ_NONE)
+ switch (Type)
{
- assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6);
- assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3);
-
- b1 = pawns & pos.pawn_attacks(Them, pos.ep_square());
- assert(b1 != EmptyBoardBB);
-
- while (b1)
+ case CAPTURES:
+ target = pos.pieces(~Us);
+ break;
+ case QUIETS:
+ case QUIET_CHECKS:
+ target = ~pos.pieces();
+ break;
+ case EVASIONS:
{
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_ep_move(to, pos.ep_square());
+ Square checksq = lsb(pos.checkers());
+ target = between_bb(pos.square(Us), checksq) | checksq;
+ break;
}
+ case NON_EVASIONS:
+ target = ~pos.pieces(Us);
+ break;
}
- return mlist;
- }
-
- template
- MoveStack* do_generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) {
-
- Bitboard pawns = pos.pawns(Us);
- Bitboard enemyPieces = pos.pieces_of_color(Them);
- Bitboard emptySquares = pos.empty_squares();
- Bitboard b1, b2;
- Square to;
- // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
- b1 = (Us == WHITE ? pawns << 9 : pawns >> 7) & ~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);
- }
-
- // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
- b1 = (Us == WHITE ? pawns << 7 : pawns >> 9) & ~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);
- }
+ moveList = generate_pawn_moves(pos, moveList, target);
+ moveList = generate_moves(pos, moveList, piecesToMove, target);
+ moveList = generate_moves(pos, moveList, piecesToMove, target);
+ moveList = generate_moves< ROOK, Checks>(pos, moveList, piecesToMove, target);
+ moveList = generate_moves< QUEEN, Checks>(pos, moveList, piecesToMove, target);
- // Single pawn pushes
- b1 = (Us == WHITE ? pawns << 8 : pawns >> 8) & emptySquares;
- b2 = b1 & TRank8BB;
- while (b2)
+ if (Type != QUIET_CHECKS && Type != EVASIONS)
{
- to = pop_1st_bit(&b2);
- (*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);
- }
- b2 = b1 & ~TRank8BB;
- while (b2)
- {
- to = pop_1st_bit(&b2);
- (*mlist++).move = make_move(to - TDELTA_N, to);
+ Square ksq = pos.square(Us);
+ Bitboard b = attacks_bb(ksq) & target;
+ while (b)
+ *moveList++ = make_move(ksq, pop_lsb(&b));
+
+ 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(ksq, pos.castling_rook_square(cr));
}
- // Double pawn pushes
- b2 = (Us == WHITE ? (b1 & TRank3BB) << 8 : (b1 & TRank3BB) >> 8) & emptySquares;
- while (b2)
- {
- to = pop_1st_bit(&b2);
- (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to);
- }
- return mlist;
+ return moveList;
}
+} // namespace
- template
- MoveStack* do_generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist)
- {
- // 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(Us) & ~file_bb(ksq), b2, b3;
-
- // Discovered checks, single pawn pushes
- b2 = b3 = (Us == WHITE ? (b1 & dc) << 8 : (b1 & dc) >> 8) & ~TRank8BB & empty;
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- (*mlist++).move = make_move(to - TDELTA_N, to);
- }
-
- // Discovered checks, double pawn pushes
- b3 = (Us == WHITE ? (b2 & TRank3BB) << 8 : (b2 & TRank3BB) >> 8) & empty;
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to);
- }
- // Direct checks. These are possible only for pawns on neighboring files
- // of the enemy king
+/// Generates all pseudo-legal captures plus queen and checking knight promotions
+/// Generates all pseudo-legal non-captures and underpromotions(except checking knight)
+/// Generates all pseudo-legal captures and non-captures
+///
+/// Returns a pointer to the end of the move list.
- b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
+template
+ExtMove* generate(const Position& pos, ExtMove* moveList) {
- // Direct checks, single pawn pushes
- b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & empty;
- b3 = b2 & pos.pawn_attacks(Them, ksq);
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- (*mlist++).move = make_move(to - TDELTA_N, to);
- }
+ static_assert(Type == CAPTURES || Type == QUIETS || Type == NON_EVASIONS, "Unsupported type in generate()");
+ assert(!pos.checkers());
- // Direct checks, double pawn pushes
- b3 = (Us == WHITE ? (b2 & TRank3BB) << 8 : (b2 & TRank3BB) >> 8)
- & empty
- & pos.pawn_attacks(Them, ksq);
+ Color us = pos.side_to_move();
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to);
- }
- return mlist;
- }
+ return us == WHITE ? generate_all(pos, moveList)
+ : generate_all(pos, moveList);
+}
- template
- MoveStack* generate_piece_checks(const Position& pos, Bitboard target, Bitboard dc,
- Square ksq, MoveStack* mlist) {
- // Discovered checks
- Bitboard b = target & dc;
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks(from) & pos.empty_squares();
- SERIALIZE_MOVES(bb);
- }
- // Direct checks
- b = target & ~dc;
- Bitboard checkSqs = pos.piece_attacks(ksq) & pos.empty_squares();
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks(from) & checkSqs;
- SERIALIZE_MOVES(bb);
- }
- return mlist;
- }
+// Explicit template instantiations
+template ExtMove* generate(const Position&, ExtMove*);
+template ExtMove* generate(const Position&, ExtMove*);
+template ExtMove* generate(const Position&, ExtMove*);
- MoveStack* generate_piece_checks_king(const Position& pos, Square from, Bitboard dc,
- Square ksq, MoveStack* mlist) {
- if (bit_is_set(dc, from))
- {
- Bitboard b = pos.piece_attacks(from)
- & pos.empty_squares()
- & ~QueenPseudoAttacks[ksq];
- SERIALIZE_MOVES(b);
- }
- return mlist;
- }
+/// generate generates all pseudo-legal non-captures.
+/// Returns a pointer to the end of the move list.
+template<>
+ExtMove* generate(const Position& pos, ExtMove* moveList) {
- template
- MoveStack* do_generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned,
- Bitboard blockSquares, MoveStack* mlist) {
- Square to;
+ assert(!pos.checkers());
- // Find non-pinned pawns
- Bitboard b1 = pos.pawns(Us) & not_pinned;
+ Color us = pos.side_to_move();
+ Bitboard dc = pos.blockers_for_king(~us) & pos.pieces(us) & ~pos.pieces(PAWN);
- // Single pawn pushes. We don't have to AND with empty squares here,
- // because the blocking squares will always be empty.
- Bitboard b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & blockSquares;
- while (b2)
- {
- to = pop_1st_bit(&b2);
+ while (dc)
+ {
+ Square from = pop_lsb(&dc);
+ PieceType pt = type_of(pos.piece_on(from));
- assert(pos.piece_on(to) == EMPTY);
+ Bitboard b = attacks_bb(pt, from, pos.pieces()) & ~pos.pieces();
- 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);
- }
+ if (pt == KING)
+ b &= ~attacks_bb(pos.square(~us));
- // Double pawn pushes
- b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & pos.empty_squares() & TRank3BB;
- b2 = (Us == WHITE ? b2 << 8 : b2 >> 8) & blockSquares;;
- while (b2)
- {
- to = pop_1st_bit(&b2);
+ while (b)
+ *moveList++ = make_move(from, pop_lsb(&b));
+ }
- assert(pos.piece_on(to) == EMPTY);
- assert(Us != WHITE || square_rank(to) == RANK_4);
- assert(Us != BLACK || square_rank(to) == RANK_5);
+ return us == WHITE ? generate_all(pos, moveList)
+ : generate_all(pos, moveList);
+}
- (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to);
- }
- return mlist;
- }
+/// generate 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(const Position& pos, ExtMove* moveList) {
- MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist) {
+ assert(pos.checkers());
- Color us = pos.side_to_move();
+ Color us = pos.side_to_move();
+ Square ksq = pos.square(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(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(pos, moveList)
+ : generate_all(pos, moveList);
+}
- if (pos.can_castle(us))
- {
- Color them = opposite_color(us);
- Square ksq = pos.king_square(us);
- assert(pos.piece_on(ksq) == king_of_color(us));
+/// generate generates all the legal moves in the given position
- 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++).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++).move = make_castle_move(ksq, rsq);
- }
- }
- return mlist;
- }
+template<>
+ExtMove* generate(const Position& pos, ExtMove* moveList) {
+ Color us = pos.side_to_move();
+ Bitboard pinned = pos.blockers_for_king(us) & pos.pieces(us);
+ Square ksq = pos.square(us);
+ ExtMove* cur = moveList;
+
+ moveList = pos.checkers() ? generate(pos, moveList)
+ : generate(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;
}