X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovegen.cpp;h=154e69e2207dc504c718050d310254cd9f880da0;hp=23f6c1bc90f9abd9ec6512890946f0ac1651dfda;hb=d549497144ee2a704057e005d2bbe1fbc666ca7e;hpb=53c2bf069752d9d15d1678d79b0490b33ef240b4 diff --git a/src/movegen.cpp b/src/movegen.cpp index 23f6c1bc..154e69e2 100644 --- a/src/movegen.cpp +++ b/src/movegen.cpp @@ -1,7 +1,7 @@ /* 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 @@ -17,742 +17,450 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - +#include #include -#include "bitcount.h" #include "movegen.h" +#include "position.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)) - -// 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 -//// +/// Simple macro to wrap a very common while loop, no facny, no flexibility, +/// hardcoded names 'mlist' and 'from'. +#define SERIALIZE(b) while (b) (*mlist++).move = make_move(from, pop_1st_bit(&b)) +/// Version used for pawns, where the 'from' square is given as a delta from the 'to' square +#define SERIALIZE_PAWNS(b, d) while (b) { Square to = pop_1st_bit(&b); \ + (*mlist++).move = make_move(to - (d), to); } namespace { - enum CastlingSide { - KING_SIDE, - QUEEN_SIDE - }; + template + MoveStack* generate_castle(const Position& pos, MoveStack* mlist, Color us) { - enum MoveType { - CAPTURE, - NON_CAPTURE, - CHECK, - EVASION - }; - - // Helper templates - template - MoveStack* generate_castle_moves(const Position&, MoveStack*); - - template - MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard = EmptyBoardBB, - Square = SQ_NONE, Bitboard = EmptyBoardBB); - - // Template generate_piece_moves (captures and non-captures) with specializations and overloads - template - MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard); - - template<> - MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard); - - template - inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us) { + if (pos.castle_impeded(us, Side) || !pos.can_castle(make_castle_right(us, Side))) + return mlist; - assert(Piece == PAWN); - assert(Type == CAPTURE || Type == NON_CAPTURE); + // 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(us, Side); + Square kto = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1); + Bitboard enemies = pos.pieces(~us); - return (us == WHITE ? generate_pawn_moves(p, m) - : generate_pawn_moves(p, m)); - } + assert(!pos.in_check()); - // Templates for non-capture checks generation + for (Square s = std::min(kfrom, kto), e = std::max(kfrom, kto); s <= e; s++) + if ( s != kfrom // We are not in check + && (pos.attackers_to(s) & enemies)) + return mlist; - template - MoveStack* generate_discovered_checks(const Position& pos, Square from, MoveStack* mlist); + // Because we generate only legal castling moves we need to verify that + // when moving the castling rook we do not discover some hidden checker. + // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1. + if ( pos.is_chess960() + && (pos.attackers_to(kto, pos.pieces() ^ rfrom) & enemies)) + return mlist; - template - MoveStack* generate_direct_checks(const Position&, MoveStack*, Color, Bitboard, Square); + (*mlist++).move = make_castle(kfrom, rfrom); - template<> - inline MoveStack* generate_direct_checks(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) { + if (OnlyChecks && !pos.move_gives_check((mlist - 1)->move, CheckInfo(pos))) + mlist--; - return (us == WHITE ? generate_pawn_moves(p, m, dc, ksq) - : generate_pawn_moves(p, m, dc, ksq)); + return mlist; } - // Template generate_piece_evasions with specializations - template - MoveStack* generate_piece_evasions(const Position&, MoveStack*, Color, Bitboard, Bitboard); - template<> - inline MoveStack* generate_piece_evasions(const Position& p, MoveStack* m, - Color us, Bitboard t, Bitboard pnd) { + template + inline Bitboard move_pawns(Bitboard p) { - return (us == WHITE ? generate_pawn_moves(p, m, pnd, SQ_NONE, t) - : generate_pawn_moves(p, m, pnd, SQ_NONE, t)); + return Delta == DELTA_N ? p << 8 + : Delta == DELTA_S ? p >> 8 + : Delta == DELTA_NE ? (p & ~FileHBB) << 9 + : Delta == DELTA_SE ? (p & ~FileHBB) >> 7 + : Delta == DELTA_NW ? (p & ~FileABB) << 7 + : Delta == DELTA_SW ? (p & ~FileABB) >> 9 : 0; } -} - - -//// -//// Functions -//// - - -/// generate_captures() generates all pseudo-legal captures and queen -/// promotions. Returns a pointer to the end of the move list. - -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(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); - return generate_piece_moves(pos, mlist, us, target); -} -/// generate_noncaptures() generates all pseudo-legal non-captures and -/// underpromotions. Returns a pointer to the end of the move list. - -MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist) { + template + inline MoveStack* generate_promotions(MoveStack* mlist, Bitboard pawnsOn7, Bitboard target, Square ksq) { - assert(pos.is_ok()); - assert(!pos.is_check()); - - Color us = pos.side_to_move(); - Bitboard target = pos.empty_squares(); - - mlist = generate_piece_moves(pos, mlist, us); - 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 generate_castle_moves(pos, mlist); -} + Bitboard b = move_pawns(pawnsOn7) & target; + while (b) + { + Square to = pop_1st_bit(&b); -/// generate_non_capture_checks() generates all pseudo-legal non-captures and -/// underpromotions that give check. Returns a pointer to the end of the move list. - -MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc) { - - assert(pos.is_ok()); - assert(!pos.is_check()); + if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION) + (*mlist++).move = make_promotion(to - Delta, to, QUEEN); - Color us = pos.side_to_move(); - Square ksq = pos.king_square(opposite_color(us)); + if (Type == MV_QUIET || 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); + } - assert(pos.piece_on(ksq) == piece_of_color_and_type(opposite_color(us), KING)); + // Knight-promotion is the only one that can give a direct check not + // already included in the queen-promotion. + if (Type == MV_QUIET_CHECK && (StepAttacksBB[W_KNIGHT][to] & ksq)) + (*mlist++).move = make_promotion(to - Delta, to, KNIGHT); + else + (void)ksq; // Silence a warning under MSVC + } - // Discovered non-capture checks - Bitboard b = dc; - while (b) - { - Square from = pop_1st_bit(&b); - switch (pos.type_of_piece_on(from)) - { - case PAWN: /* Will be generated togheter with pawns direct checks */ break; - case KNIGHT: mlist = generate_discovered_checks(pos, from, mlist); break; - case BISHOP: mlist = generate_discovered_checks(pos, from, mlist); break; - case ROOK: mlist = generate_discovered_checks(pos, from, mlist); break; - case KING: mlist = generate_discovered_checks(pos, from, mlist); break; - default: assert(false); break; - } + return mlist; } - // Direct non-capture checks - mlist = generate_direct_checks(pos, mlist, us, dc, ksq); - mlist = generate_direct_checks(pos, mlist, us, dc, ksq); - mlist = generate_direct_checks(pos, mlist, us, dc, ksq); - mlist = generate_direct_checks(pos, mlist, us, dc, ksq); - return generate_direct_checks(pos, mlist, us, dc, ksq); -} - - -/// 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. Returns a pointer to the end of the move list. - -MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) { - - assert(pos.is_ok()); - assert(pos.is_check()); - - Square from, to; - Color us = pos.side_to_move(); - Color them = opposite_color(us); - Square ksq = pos.king_square(us); - Bitboard sliderAttacks = EmptyBoardBB; - Bitboard checkers = pos.checkers(); - assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING)); + template + MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq = SQ_NONE) { - // The bitboard of occupied pieces without our king - Bitboard b_noKing = pos.occupied_squares(); - clear_bit(&b_noKing, ksq); + // Compute 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 TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB); + 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); - // Find squares attacked by slider checkers, we will remove - // them from the king evasions set so to avoid a couple - // of cycles in the slow king evasions legality check loop - // and to be able to use attackers_to(). - Bitboard b = checkers & pos.pieces(BISHOP, QUEEN); - while (b) - { - from = pop_1st_bit(&b); - sliderAttacks |= bishop_attacks_bb(from, b_noKing); - } + Bitboard b1, b2, dc1, dc2, emptySquares; - b = checkers & pos.pieces(ROOK, QUEEN); - while (b) - { - from = pop_1st_bit(&b); - sliderAttacks |= rook_attacks_bb(from, b_noKing); - } + Bitboard pawnsOn7 = pos.pieces(PAWN, Us) & TRank7BB; + Bitboard pawnsNotOn7 = pos.pieces(PAWN, Us) & ~TRank7BB; - // Generate evasions for king, capture and non capture moves - Bitboard enemy = pos.pieces_of_color(them); - Bitboard b1 = pos.attacks_from(ksq) & ~pos.pieces_of_color(us) & ~sliderAttacks; - while (b1) - { - // Note that we can use attackers_to() only because we have already - // removed from b1 the squares attacked by slider checkers. - to = pop_1st_bit(&b1); - if (!(pos.attackers_to(to) & enemy)) - (*mlist++).move = make_move(ksq, to); - } - - // 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)) // Two bits set? - return mlist; + Bitboard enemies = (Type == MV_EVASION ? pos.pieces(Them) & target: + Type == MV_CAPTURE ? target : pos.pieces(Them)); - Square checksq = first_1(checkers); - Bitboard target = squares_between(checksq, ksq); - - assert(pos.color_of_piece_on(checksq) == them); + // Single and double pawn pushes, no promotions + if (Type != MV_CAPTURE) + { + emptySquares = (Type == MV_QUIET ? target : ~pos.pieces()); - // Pawn captures - b1 = pos.attacks_from(checksq, them) & pos.pieces(PAWN, 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); - } + b1 = move_pawns(pawnsNotOn7) & emptySquares; + b2 = move_pawns(b1 & TRank3BB) & emptySquares; - // Pawn blocking evasions (possible only if the checking piece is a slider) - if (sliderAttacks) - mlist = generate_piece_evasions(pos, mlist, us, target, pinned); - - // Add the checking piece to the target squares - target |= checkers; - - // Captures and blocking evasions for the other pieces - mlist = generate_piece_evasions(pos, mlist, us, target, pinned); - mlist = generate_piece_evasions(pos, mlist, us, target, pinned); - mlist = generate_piece_evasions(pos, mlist, us, target, pinned); - mlist = generate_piece_evasions(pos, mlist, us, target, pinned); - - // 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.pieces(PAWN, them))) - { - to = pos.ep_square(); - b1 = pos.attacks_from(to, them) & pos.pieces(PAWN, us); + if (Type == MV_EVASION) // Consider only blocking squares + { + b1 &= target; + b2 &= target; + } - // 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); + if (Type == MV_QUIET_CHECK) + { + b1 &= pos.attacks_from(ksq, Them); + b2 &= pos.attacks_from(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) // Target is dc bitboard + { + dc1 = move_pawns(pawnsNotOn7 & target) & emptySquares & ~file_bb(ksq); + dc2 = move_pawns(dc1 & TRank3BB) & emptySquares; - 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; -} + b1 |= dc1; + b2 |= dc2; + } + } + SERIALIZE_PAWNS(b1, UP); + SERIALIZE_PAWNS(b2, UP + UP); + } -/// generate_moves() computes a complete list of legal or pseudo-legal moves in -/// the current position. This function is not very fast, and should be used -/// only in non time-critical paths. + // Promotions and underpromotions + if (pawnsOn7 && (Type != MV_EVASION || (target & TRank8BB))) + { + if (Type == MV_CAPTURE) + emptySquares = ~pos.pieces(); -MoveStack* generate_moves(const Position& pos, MoveStack* mlist, bool pseudoLegal) { + if (Type == MV_EVASION) + emptySquares &= target; - assert(pos.is_ok()); + mlist = generate_promotions(mlist, pawnsOn7, enemies, ksq); + mlist = generate_promotions(mlist, pawnsOn7, enemies, ksq); + mlist = generate_promotions(mlist, pawnsOn7, emptySquares, ksq); + } - Bitboard pinned = pos.pinned_pieces(pos.side_to_move()); + // Standard and en-passant captures + if (Type == MV_CAPTURE || Type == MV_EVASION || Type == MV_NON_EVASION) + { + b1 = move_pawns(pawnsNotOn7) & enemies; + b2 = move_pawns(pawnsNotOn7) & enemies; - if (pos.is_check()) - return generate_evasions(pos, mlist, pinned); + SERIALIZE_PAWNS(b1, RIGHT); + SERIALIZE_PAWNS(b2, LEFT); - // Generate pseudo-legal moves - MoveStack* last = generate_captures(pos, mlist); - last = generate_noncaptures(pos, last); - if (pseudoLegal) - return last; + if (pos.ep_square() != SQ_NONE) + { + assert(rank_of(pos.ep_square()) == relative_rank(Us, RANK_6)); - // 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; -} + // 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 && !(target & (pos.ep_square() - UP))) + return mlist; + b1 = pawnsNotOn7 & pos.attacks_from(pos.ep_square(), Them); -/// move_is_legal() takes a position and a (not necessarily pseudo-legal) -/// move and tests whether the move is legal. This version is not very fast -/// and should be used only in non time-critical paths. + assert(b1); -bool move_is_legal(const Position& pos, const Move m) { + while (b1) + (*mlist++).move = make_enpassant(pop_1st_bit(&b1), pos.ep_square()); + } + } - MoveStack mlist[256]; - MoveStack* last = generate_moves(pos, mlist, true); - for (MoveStack* cur = mlist; cur != last; cur++) - if (cur->move == m) - return pos.pl_move_is_legal(m); + return mlist; + } - return false; -} + template + inline MoveStack* generate_direct_checks(const Position& pos, MoveStack* mlist, + Color us, const CheckInfo& ci) { + assert(Pt != KING && Pt != PAWN); -/// Fast version of move_is_legal() that takes a position a move and a -/// bitboard of pinned pieces as input, and tests whether the move is legal. -/// This version must only be used when the side to move is not in check. + Bitboard b, target; + Square from; + const Square* pl = pos.piece_list(us, Pt); -bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) { + if (*pl != SQ_NONE) + { + target = ci.checkSq[Pt] & ~pos.pieces(); // Non capture checks only - assert(pos.is_ok()); - assert(!pos.is_check()); - assert(move_is_ok(m)); - assert(pinned == pos.pinned_pieces(pos.side_to_move())); + do { + from = *pl; - // Use a slower but simpler function for uncommon cases - if (move_is_ep(m) || move_is_castle(m)) - return move_is_legal(pos, m); + if ( (Pt == BISHOP || Pt == ROOK || Pt == QUEEN) + && !(PseudoAttacks[Pt][from] & target)) + continue; - Color us = pos.side_to_move(); - Color them = opposite_color(us); - Square from = move_from(m); - Square to = move_to(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 false; - - // The destination square cannot be occupied by a friendly piece - if (pos.color_of_piece_on(to) == us) - return false; - - // Handle the special case of a pawn move - 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; - - // A pawn move is a promotion iff the destination square is - // on the 8/1th rank. - if (( (square_rank(to) == RANK_8 && us == WHITE) - ||(square_rank(to) == RANK_1 && us != WHITE)) != bool(move_is_promotion(m))) - return false; - - // Proceed according to the square delta between the origin and - // destination 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; + if (ci.dcCandidates && (ci.dcCandidates & from)) + continue; - 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; + b = pos.attacks_from(from) & target; + SERIALIZE(b); + } while (*++pl != SQ_NONE); + } - default: - return false; - } - // The move is pseudo-legal, check if it is also legal - return pos.pl_move_is_legal(m, pinned); + return mlist; } - // Luckly we can handle all the other pieces in one go - return ( bit_is_set(pos.attacks_from(pc, from), to) - && pos.pl_move_is_legal(m, pinned) - && !move_is_promotion(m)); -} - -namespace { - - template - MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) { + template + FORCE_INLINE MoveStack* generate_moves(const Position& pos, MoveStack* mlist, + Color us, Bitboard target) { + assert(Pt != KING && Pt != PAWN); - Square from; Bitboard b; - const Square* ptr = pos.piece_list_begin(us, Piece); + Square from; + const Square* pl = pos.piece_list(us, Pt); + + if (*pl != SQ_NONE) + do { + from = *pl; + b = pos.attacks_from(from) & target; + SERIALIZE(b); + } while (*++pl != SQ_NONE); - while ((from = *ptr++) != SQ_NONE) - { - b = pos.attacks_from(from) & target; - SERIALIZE_MOVES(b); - } return mlist; } - template<> - MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) { - Bitboard b; + template<> + FORCE_INLINE MoveStack* generate_moves(const Position& pos, MoveStack* mlist, + Color us, Bitboard target) { Square from = pos.king_square(us); - - b = pos.attacks_from(from) & target; - SERIALIZE_MOVES(b); + Bitboard b = pos.attacks_from(from) & target; + SERIALIZE(b); return mlist; } - template - MoveStack* generate_piece_evasions(const Position& pos, MoveStack* mlist, - Color us, Bitboard target, Bitboard pinned) { - Square from; - Bitboard b; - const Square* ptr = pos.piece_list_begin(us, Piece); +} // namespace - while ((from = *ptr++) != SQ_NONE) - { - if (pinned && bit_is_set(pinned, from)) - continue; - b = pos.attacks_from(from) & target; - SERIALIZE_MOVES(b); - } - return mlist; - } +/// generate generates all pseudo-legal captures and queen +/// promotions. Returns a pointer to the end of the move list. +/// +/// generate generates all pseudo-legal non-captures and +/// underpromotions. Returns a pointer to the end of the move list. +/// +/// generate generates all pseudo-legal captures and +/// non-captures. Returns a pointer to the end of the move list. - template - inline Bitboard move_pawns(Bitboard p) { +template +MoveStack* generate(const Position& pos, MoveStack* mlist) { - 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; - } + assert(Type == MV_CAPTURE || Type == MV_QUIET || Type == MV_NON_EVASION); + assert(!pos.in_check()); - template - MoveStack* generate_pawn_diagonal_captures(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion) { + Color us = pos.side_to_move(); + Bitboard target; - // 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); + if (Type == MV_CAPTURE) + target = pos.pieces(~us); - Square to; + else if (Type == MV_QUIET) + target = ~pos.pieces(); - // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black) - Bitboard b1 = move_pawns(pawns) & ~TFileABB & enemyPieces; + else if (Type == MV_NON_EVASION) + target = ~pos.pieces(us); - // 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); - } - } + mlist = (us == WHITE ? generate_pawn_moves(pos, mlist, target) + : generate_pawn_moves(pos, mlist, target)); - // Capturing non-promotions - SERIALIZE_MOVES_D(b1, -TTDELTA_NE); - return mlist; - } + mlist = generate_moves(pos, mlist, us, target); + mlist = generate_moves(pos, mlist, us, target); + mlist = generate_moves(pos, mlist, us, target); + mlist = generate_moves(pos, mlist, us, target); + mlist = generate_moves(pos, mlist, us, target); - template - MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard dcp, - Square ksq, Bitboard blockSquares) { - - // 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 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); - - Bitboard b1, b2, dcPawns1, dcPawns2; - Square to; - Bitboard pawns = (Type == EVASION ? pos.pieces(PAWN, Us) & ~dcp : pos.pieces(PAWN, Us)); - bool possiblePromotion = pawns & TRank7BB; - - if (Type == CAPTURE) - { - // Standard captures and capturing promotions in both directions - Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us)); - mlist = generate_pawn_diagonal_captures(mlist, pawns, enemyPieces, possiblePromotion); - mlist = generate_pawn_diagonal_captures(mlist, pawns, enemyPieces, possiblePromotion); - } + if (Type != MV_CAPTURE && pos.can_castle(us)) + { + mlist = generate_castle(pos, mlist, us); + mlist = generate_castle(pos, mlist, us); + } - if (possiblePromotion) - { - // When generating checks consider under-promotion moves (both captures - // and non captures) only if can give a discovery check. Note that dcp - // is dc bitboard or pinned bitboard when Type == EVASION. - Bitboard pp = (Type == CHECK ? pawns & dcp : pawns); + return mlist; +} - if (Type != EVASION && Type != CAPTURE) - { - Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us)); +// Explicit template instantiations +template MoveStack* generate(const Position& pos, MoveStack* mlist); +template MoveStack* generate(const Position& pos, MoveStack* mlist); +template MoveStack* generate(const Position& pos, MoveStack* mlist); - // Underpromotion captures in the a1-h8 (a8-h1 for black) direction - b1 = move_pawns(pp) & ~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 = move_pawns(pp) & ~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); - } - } +/// generate 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(const Position& pos, MoveStack* mlist) { - // Underpromotion pawn pushes. Also queen promotions for evasions and captures. - b1 = move_pawns(pp) & TRank8BB; - b1 &= (Type == EVASION ? blockSquares : pos.empty_squares()); + assert(!pos.in_check()); - while (b1) - { - to = pop_1st_bit(&b1); - if (Type == EVASION || Type == CAPTURE) - (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN); + Color us = pos.side_to_move(); + CheckInfo ci(pos); + Bitboard dc = ci.dcCandidates; - if (Type != CAPTURE) - { - (*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); - } - } - } + while (dc) + { + Square from = pop_1st_bit(&dc); + PieceType pt = type_of(pos.piece_on(from)); - if (Type != CAPTURE) - { - Bitboard emptySquares = pos.empty_squares(); - dcPawns1 = dcPawns2 = EmptyBoardBB; - if (Type == CHECK && (pawns & dcp)) - { - // 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. - dcPawns1 = move_pawns(pawns & dcp & ~file_bb(ksq)) & emptySquares & ~TRank8BB; - dcPawns2 = move_pawns(dcPawns1 & TRank3BB) & emptySquares; - } + if (pt == PAWN) + continue; // Will be generated togheter with direct checks - // Single pawn pushes - b1 = move_pawns(pawns) & emptySquares & ~TRank8BB; - b2 = (Type == CHECK ? (b1 & pos.attacks_from(ksq, Them)) | dcPawns1 : - (Type == EVASION ? b1 & blockSquares : b1)); - SERIALIZE_MOVES_D(b2, -TDELTA_N); - - // Double pawn pushes - b1 = move_pawns(b1 & TRank3BB) & emptySquares; - b2 = (Type == CHECK ? (b1 & pos.attacks_from(ksq, Them)) | dcPawns2 : - (Type == EVASION ? b1 & blockSquares : b1)); - SERIALIZE_MOVES_D(b2, -TDELTA_N -TDELTA_N); - } - else if (pos.ep_square() != SQ_NONE) // En passant captures - { - assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6); - assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3); + Bitboard b = pos.attacks_from(Piece(pt), from) & ~pos.pieces(); - b1 = pawns & pos.attacks_from(pos.ep_square(), Them); - assert(b1 != EmptyBoardBB); + if (pt == KING) + b &= ~PseudoAttacks[QUEEN][ci.ksq]; - while (b1) - { - to = pop_1st_bit(&b1); - (*mlist++).move = make_ep_move(to, pos.ep_square()); - } - } - return mlist; + SERIALIZE(b); } - template - MoveStack* generate_discovered_checks(const Position& pos, Square from, MoveStack* mlist) { + mlist = (us == WHITE ? generate_pawn_moves(pos, mlist, ci.dcCandidates, ci.ksq) + : generate_pawn_moves(pos, mlist, ci.dcCandidates, ci.ksq)); - assert(Piece != QUEEN); + mlist = generate_direct_checks(pos, mlist, us, ci); + mlist = generate_direct_checks(pos, mlist, us, ci); + mlist = generate_direct_checks(pos, mlist, us, ci); + mlist = generate_direct_checks(pos, mlist, us, ci); - Bitboard b = pos.attacks_from(from) & pos.empty_squares(); - if (Piece == KING) - { - Square ksq = pos.king_square(opposite_color(pos.side_to_move())); - b &= ~QueenPseudoAttacks[ksq]; - } - SERIALIZE_MOVES(b); - return mlist; + if (pos.can_castle(us)) + { + mlist = generate_castle(pos, mlist, us); + mlist = generate_castle(pos, mlist, us); } - template - MoveStack* generate_direct_checks(const Position& pos, MoveStack* mlist, Color us, - Bitboard dc, Square ksq) { - assert(Piece != KING); + return mlist; +} - Square from; - Bitboard checkSqs; - const Square* ptr = pos.piece_list_begin(us, Piece); - if ((from = *ptr++) == SQ_NONE) - 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<> +MoveStack* generate(const Position& pos, MoveStack* mlist) { - checkSqs = pos.attacks_from(ksq) & pos.empty_squares(); + assert(pos.in_check()); - do - { - if ( (Piece == QUEEN && !(QueenPseudoAttacks[from] & checkSqs)) - || (Piece == ROOK && !(RookPseudoAttacks[from] & checkSqs)) - || (Piece == BISHOP && !(BishopPseudoAttacks[from] & checkSqs))) - continue; + Bitboard b, target; + Square from, checksq; + int checkersCnt = 0; + Color us = pos.side_to_move(); + Square ksq = pos.king_square(us); + Bitboard sliderAttacks = 0; + Bitboard checkers = pos.checkers(); - if (dc && bit_is_set(dc, from)) - continue; + assert(checkers); - Bitboard bb = pos.attacks_from(from) & checkSqs; - SERIALIZE_MOVES(bb); + // Find squares attacked by slider checkers, we will remove them from the king + // evasions so to skip known illegal moves avoiding useless legality check later. + b = checkers; + do + { + checkersCnt++; + checksq = pop_1st_bit(&b); - } while ((from = *ptr++) != SQ_NONE); + assert(color_of(pos.piece_on(checksq)) == ~us); - return mlist; - } + switch (type_of(pos.piece_on(checksq))) + { + case BISHOP: sliderAttacks |= PseudoAttacks[BISHOP][checksq]; break; + case ROOK: sliderAttacks |= PseudoAttacks[ROOK][checksq]; break; + case QUEEN: + // If queen and king are far or not on a diagonal line 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) || !(PseudoAttacks[BISHOP][checksq] & ksq)) + sliderAttacks |= PseudoAttacks[QUEEN][checksq]; + + // Otherwise 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 |= PseudoAttacks[BISHOP][checksq] | pos.attacks_from(checksq); - template - MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist) { + default: + break; + } + } while (b); - Color us = pos.side_to_move(); + // Generate evasions for king, capture and non capture moves + b = pos.attacks_from(ksq) & ~pos.pieces(us) & ~sliderAttacks; + from = ksq; + SERIALIZE(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 other pieces only if not under a double check + if (checkersCnt > 1) + return mlist; - assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING)); + // Blocking evasions or captures of the checking piece + target = squares_between(checksq, ksq) | checkers; - 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; + mlist = (us == WHITE ? generate_pawn_moves(pos, mlist, target) + : generate_pawn_moves(pos, mlist, target)); - assert(pos.piece_on(rsq) == piece_of_color_and_type(us, ROOK)); + mlist = generate_moves(pos, mlist, us, target); + mlist = generate_moves(pos, mlist, us, target); + mlist = generate_moves(pos, mlist, us, target); + return generate_moves(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.attackers_to(s) & pos.pieces_of_color(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 generates all the legal moves in the given 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(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(); + + last = pos.in_check() ? generate(pos, mlist) + : generate(pos, mlist); + while (cur != last) + if (!pos.pl_move_is_legal(cur->move, pinned)) + cur->move = (--last)->move; + else + cur++; + + return last; }