/*
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) 2008-2010 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
MoveStack* generate_castle_moves(const Position&, MoveStack*);
template<Color Us, MoveType Type>
- MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard = EmptyBoardBB,
- Square = SQ_NONE, Bitboard = EmptyBoardBB);
+ MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard, Square);
// Template generate_piece_moves (captures and non-captures) with specializations and overloads
template<PieceType>
MoveStack* generate_piece_moves<KING>(const Position&, MoveStack*, Color, Bitboard);
template<PieceType Piece, MoveType Type>
- inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us) {
+ inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us, Bitboard t) {
assert(Piece == PAWN);
- assert(Type == CAPTURE || Type == NON_CAPTURE);
+ assert(Type == CAPTURE || Type == NON_CAPTURE || Type == EVASION);
- return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m)
- : generate_pawn_moves<BLACK, Type>(p, m));
+ return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m, t, SQ_NONE)
+ : generate_pawn_moves<BLACK, Type>(p, m, t, SQ_NONE));
}
// Templates for non-capture checks generation
template<PieceType Piece>
- MoveStack* generate_discovered_checks(const Position& pos, Square from, MoveStack* mlist);
+ MoveStack* generate_discovered_checks(const Position&, MoveStack*, Square);
template<PieceType>
MoveStack* generate_direct_checks(const Position&, MoveStack*, Color, Bitboard, Square);
return (us == WHITE ? generate_pawn_moves<WHITE, CHECK>(p, m, dc, ksq)
: generate_pawn_moves<BLACK, CHECK>(p, m, dc, ksq));
}
-
- // Template generate_piece_evasions with specializations
- template<PieceType>
- MoveStack* generate_piece_evasions(const Position&, MoveStack*, Color, Bitboard, Bitboard);
-
- template<>
- inline MoveStack* generate_piece_evasions<PAWN>(const Position& p, MoveStack* m,
- Color us, Bitboard t, Bitboard pnd) {
-
- return (us == WHITE ? generate_pawn_moves<WHITE, EVASION>(p, m, pnd, SQ_NONE, t)
- : generate_pawn_moves<BLACK, EVASION>(p, m, pnd, SQ_NONE, t));
- }
}
mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
- mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us);
+ mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us, target);
return generate_piece_moves<KING>(pos, mlist, us, target);
}
Color us = pos.side_to_move();
Bitboard target = pos.empty_squares();
- mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us);
+ mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us, target);
mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
}
-/// generate_non_capture_checks() generates all pseudo-legal non-captures and
+/// generate_non_evasions() generates all pseudo-legal captures and
+/// non-captures. Returns a pointer to the end of the move list.
+
+MoveStack* generate_non_evasions(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<PAWN, CAPTURE>(pos, mlist, us, target);
+ mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us, pos.empty_squares());
+
+ target |= pos.empty_squares();
+
+ mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
+ mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
+ mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
+ mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
+ mlist = generate_piece_moves<KING>(pos, mlist, us, target);
+ mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
+ return generate_castle_moves<QUEEN_SIDE>(pos, mlist);
+}
+
+
+/// generate_non_capture_checks() generates all pseudo-legal non-captures and knight
/// 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) {
+MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist) {
assert(pos.is_ok());
assert(!pos.is_check());
+ Bitboard b, dc;
+ Square from;
Color us = pos.side_to_move();
Square ksq = pos.king_square(opposite_color(us));
assert(pos.piece_on(ksq) == piece_of_color_and_type(opposite_color(us), KING));
// Discovered non-capture checks
- Bitboard b = dc;
+ b = dc = pos.discovered_check_candidates(us);
+
while (b)
{
- Square from = pop_1st_bit(&b);
+ 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<KNIGHT>(pos, from, mlist); break;
- case BISHOP: mlist = generate_discovered_checks<BISHOP>(pos, from, mlist); break;
- case ROOK: mlist = generate_discovered_checks<ROOK>(pos, from, mlist); break;
- case KING: mlist = generate_discovered_checks<KING>(pos, from, mlist); break;
+ case KNIGHT: mlist = generate_discovered_checks<KNIGHT>(pos, mlist, from); break;
+ case BISHOP: mlist = generate_discovered_checks<BISHOP>(pos, mlist, from); break;
+ case ROOK: mlist = generate_discovered_checks<ROOK>(pos, mlist, from); break;
+ case KING: mlist = generate_discovered_checks<KING>(pos, mlist, from); break;
default: assert(false); break;
}
}
}
-/// 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.
+/// 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.
-MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
+MoveStack* generate_evasions(const Position& pos, MoveStack* mlist) {
assert(pos.is_ok());
assert(pos.is_check());
- Square from, to;
+ Bitboard b, target;
+ Square from, checksq;
+ int checkersCnt = 0;
Color us = pos.side_to_move();
- Color them = opposite_color(us);
Square ksq = pos.king_square(us);
- Bitboard sliderAttacks = EmptyBoardBB;
Bitboard checkers = pos.checkers();
+ Bitboard sliderAttacks = EmptyBoardBB;
assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING));
-
- // The bitboard of occupied pieces without our king
- Bitboard b_noKing = pos.occupied_squares();
- clear_bit(&b_noKing, ksq);
+ assert(checkers);
// 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)
+ // them from the king evasions set so to early skip known
+ // illegal moves and avoid an useless legality check later.
+ b = checkers;
+ do
{
- from = pop_1st_bit(&b);
- sliderAttacks |= bishop_attacks_bb(from, b_noKing);
- }
+ checkersCnt++;
+ checksq = pop_1st_bit(&b);
- b = checkers & pos.pieces(ROOK, QUEEN);
- while (b)
- {
- from = pop_1st_bit(&b);
- sliderAttacks |= rook_attacks_bb(from, b_noKing);
- }
+ assert(pos.color_of_piece_on(checksq) == opposite_color(us));
+
+ switch (pos.type_of_piece_on(checksq))
+ {
+ case BISHOP: sliderAttacks |= BishopPseudoAttacks[checksq]; break;
+ case ROOK: sliderAttacks |= RookPseudoAttacks[checksq]; break;
+ case QUEEN:
+ // In case of a queen remove also squares attacked in the other direction to
+ // avoid possible illegal moves when queen and king are on adjacent squares.
+ if (direction_is_straight(checksq, ksq))
+ sliderAttacks |= RookPseudoAttacks[checksq] | pos.attacks_from<BISHOP>(checksq);
+ else
+ sliderAttacks |= BishopPseudoAttacks[checksq] | pos.attacks_from<ROOK>(checksq);
+ default:
+ break;
+ }
+ } while (b);
// Generate evasions for king, capture and non capture moves
- Bitboard enemy = pos.pieces_of_color(them);
- Bitboard b1 = pos.attacks_from<KING>(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);
- }
+ b = pos.attacks_from<KING>(ksq) & ~pos.pieces_of_color(us) & ~sliderAttacks;
+ from = ksq;
+ SERIALIZE_MOVES(b);
- // 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?
+ // Generate evasions for other pieces only if not double check
+ if (checkersCnt > 1)
return mlist;
- Square checksq = first_1(checkers);
- Bitboard target = squares_between(checksq, ksq);
+ // Find squares where a blocking evasion or a capture of the
+ // checker piece is possible.
+ target = squares_between(checksq, ksq) | checkers;
- assert(pos.color_of_piece_on(checksq) == them);
-
- // Pawn captures
- b1 = pos.attacks_from<PAWN>(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);
- }
-
- // Pawn blocking evasions (possible only if the checking piece is a slider)
- if (sliderAttacks)
- mlist = generate_piece_evasions<PAWN>(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<KNIGHT>(pos, mlist, us, target, pinned);
- mlist = generate_piece_evasions<BISHOP>(pos, mlist, us, target, pinned);
- mlist = generate_piece_evasions<ROOK>(pos, mlist, us, target, pinned);
- mlist = generate_piece_evasions<QUEEN>(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<PAWN>(to, them) & pos.pieces(PAWN, us);
-
- // The checking pawn cannot be a discovered (bishop) check candidate
- // otherwise we were in check also before last double push move.
- assert(!bit_is_set(pos.discovered_check_candidates(them), checksq));
- assert(count_1s(b1) == 1 || count_1s(b1) == 2);
-
- b1 &= ~pinned;
- while (b1)
- {
- from = pop_1st_bit(&b1);
- // Move is always legal because checking pawn is not a discovered
- // check candidate and our capturing pawn has been already tested
- // against pinned pieces.
- (*mlist++).move = make_ep_move(from, to);
- }
- }
- return mlist;
+ mlist = generate_piece_moves<PAWN, EVASION>(pos, mlist, us, target);
+ mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
+ mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
+ mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
+ return generate_piece_moves<QUEEN>(pos, mlist, us, target);
}
assert(pos.is_ok());
+ MoveStack *last, *cur = mlist;
Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
- if (pos.is_check())
- return generate_evasions(pos, mlist, pinned);
-
// Generate pseudo-legal moves
- MoveStack* last = generate_captures(pos, mlist);
- last = generate_noncaptures(pos, last);
+ last = pos.is_check() ? generate_evasions(pos, mlist)
+ : generate_non_evasions(pos, mlist);
if (pseudoLegal)
return last;
// Remove illegal moves from the list
- for (MoveStack* cur = mlist; cur != last; cur++)
- if (!pos.pl_move_is_legal(cur->move, pinned))
- {
+ while (cur != last)
+ if (pos.pl_move_is_legal(cur->move, pinned))
+ cur++;
+ else
cur->move = (--last)->move;
- cur--;
- }
+
return last;
}
bool move_is_legal(const Position& pos, const Move m) {
MoveStack mlist[256];
- MoveStack* last = generate_moves(pos, mlist, true);
- for (MoveStack* cur = mlist; cur != last; cur++)
+ MoveStack *cur, *last = generate_moves(pos, mlist, true);
+
+ for (cur = mlist; cur != last; cur++)
if (cur->move == m)
- return pos.pl_move_is_legal(m);
+ return pos.pl_move_is_legal(m, pos.pinned_pieces(pos.side_to_move()));
return false;
}
/// 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.
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()));
- // Use a slower but simpler function for uncommon cases
- if (move_is_ep(m) || move_is_castle(m))
- return move_is_legal(pos, m);
-
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);
+ // 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 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)
||(square_rank(to) == RANK_1 && us != WHITE)) != bool(move_is_promotion(m)))
return false;
+ // The promotion piece, if any, must be valid
+ if (move_promotion_piece(m) > QUEEN || move_promotion_piece(m) == PAWN)
+ return false;
+
// Proceed according to the square delta between the origin and
// destination squares.
switch (direction)
return false;
}
// The move is pseudo-legal, check if it is also legal
- return pos.pl_move_is_legal(m, pinned);
+ return pos.is_check() ? pos.pl_move_is_evasion(m, pinned) : pos.pl_move_is_legal(m, pinned);
}
// 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));
+ return bit_is_set(pos.attacks_from(pc, from), to)
+ && (pos.is_check() ? pos.pl_move_is_evasion(m, pinned) : pos.pl_move_is_legal(m, pinned))
+ && !move_is_promotion(m);
}
template<PieceType Piece>
MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
- Square from;
Bitboard b;
+ Square from;
const Square* ptr = pos.piece_list_begin(us, Piece);
while ((from = *ptr++) != SQ_NONE)
return mlist;
}
- template<PieceType Piece>
- 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);
-
- while ((from = *ptr++) != SQ_NONE)
- {
- if (pinned && bit_is_set(pinned, from))
- continue;
-
- b = pos.attacks_from<Piece>(from) & target;
- SERIALIZE_MOVES(b);
- }
- return mlist;
- }
-
template<Color Us, SquareDelta Direction>
inline Bitboard move_pawns(Bitboard p) {
return p;
}
- template<Color Us, SquareDelta Diagonal>
- MoveStack* generate_pawn_diagonal_captures(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion) {
+ template<Color Us, MoveType Type, SquareDelta Diagonal>
+ inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces) {
// Calculate our parametrized parameters at compile time
const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
const SquareDelta TTDELTA_NE = (Diagonal == DELTA_NE ? TDELTA_NE : TDELTA_NW);
+ Bitboard b1, b2;
Square to;
// Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
- Bitboard b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
+ b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
- // Capturing promotions
- if (promotion)
+ // Capturing promotions and under-promotions
+ if (b1 & TRank8BB)
{
- Bitboard b2 = b1 & TRank8BB;
+ b2 = b1 & TRank8BB;
b1 &= ~TRank8BB;
while (b2)
{
to = pop_1st_bit(&b2);
- (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
+
+ if (Type == CAPTURE || Type == EVASION)
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
+
+ if (Type == NON_CAPTURE || Type == EVASION)
+ {
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, ROOK);
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, BISHOP);
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, KNIGHT);
+ }
+
+ // This is the only possible under promotion that can give a check
+ // not already included in the queen-promotion. It is not sure that
+ // the promoted knight will give check, but it doesn't worth to verify.
+ if (Type == CHECK)
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, KNIGHT);
}
}
- // Capturing non-promotions
- SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
+ // Serialize standard captures
+ if (Type == CAPTURE || Type == EVASION)
+ SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
+
return mlist;
}
template<Color Us, MoveType Type>
- MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard dcp,
- Square ksq, Bitboard blockSquares) {
+ MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {
// 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<Us, DELTA_NE>(mlist, pawns, enemyPieces, possiblePromotion);
- mlist = generate_pawn_diagonal_captures<Us, DELTA_NW>(mlist, pawns, enemyPieces, possiblePromotion);
- }
+ Bitboard b1, b2, enemyPieces, emptySquares;
+ Bitboard pawns = pos.pieces(PAWN, Us);
- if (possiblePromotion)
+ // Standard captures and capturing promotions and underpromotions
+ if (Type == CAPTURE || Type == EVASION || (pawns & TRank7BB))
{
- // 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);
+ enemyPieces = (Type == CAPTURE ? target : pos.pieces_of_color(opposite_color(Us)));
- if (Type != EVASION && Type != CAPTURE)
- {
- Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
+ if (Type == EVASION)
+ enemyPieces &= target; // Capture only the checker piece
- // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
- b1 = move_pawns<Us, DELTA_NE>(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);
- }
+ mlist = generate_pawn_captures<Us, Type, DELTA_NE>(mlist, pawns, enemyPieces);
+ mlist = generate_pawn_captures<Us, Type, DELTA_NW>(mlist, pawns, enemyPieces);
+ }
- // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
- b1 = move_pawns<Us, DELTA_NW>(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);
- }
- }
+ // Non-capturing promotions and underpromotions
+ if (pawns & TRank7BB)
+ {
+ b1 = move_pawns<Us, DELTA_N>(pawns) & TRank8BB & pos.empty_squares();
- // Underpromotion pawn pushes. Also queen promotions for evasions and captures.
- b1 = move_pawns<Us, DELTA_N>(pp) & TRank8BB;
- b1 &= (Type == EVASION ? blockSquares : pos.empty_squares());
+ if (Type == EVASION)
+ b1 &= target; // Only blocking promotion pushes
while (b1)
{
to = pop_1st_bit(&b1);
- if (Type == EVASION || Type == CAPTURE)
+
+ if (Type == CAPTURE || Type == EVASION)
(*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
- if (Type != CAPTURE)
+ if (Type == NON_CAPTURE || Type == EVASION)
{
(*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);
}
+
+ // This is the only possible under promotion that can give a check
+ // not already included in the queen-promotion.
+ if (Type == CHECK && bit_is_set(pos.attacks_from<KNIGHT>(to), pos.king_square(Them)))
+ (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
}
}
+ // Standard pawn pushes and double pushes
if (Type != CAPTURE)
{
- Bitboard emptySquares = pos.empty_squares();
- dcPawns1 = dcPawns2 = EmptyBoardBB;
- if (Type == CHECK && (pawns & dcp))
+ emptySquares = (Type == NON_CAPTURE ? target : pos.empty_squares());
+
+ // Single and double pawn pushes
+ b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
+ b2 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
+
+ // Filter out unwanted pushes according to the move type
+ if (Type == EVASION)
{
- // 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<Us, DELTA_N>(pawns & dcp & ~file_bb(ksq)) & emptySquares & ~TRank8BB;
- dcPawns2 = move_pawns<Us, DELTA_N>(dcPawns1 & TRank3BB) & emptySquares;
+ b1 &= target;
+ b2 &= target;
}
+ else if (Type == CHECK)
+ {
+ // Pawn moves which give direct cheks
+ b1 &= pos.attacks_from<PAWN>(ksq, Them);
+ b2 &= pos.attacks_from<PAWN>(ksq, Them);
+
+ // Pawn moves which gives discovered check. This is possible only if
+ // the pawn is not on the same file as the enemy king, because we
+ // don't generate captures.
+ if (pawns & target) // For CHECK type target is dc bitboard
+ {
+ Bitboard dc1 = move_pawns<Us, DELTA_N>(pawns & target & ~file_bb(ksq)) & emptySquares & ~TRank8BB;
+ Bitboard dc2 = move_pawns<Us, DELTA_N>(dc1 & TRank3BB) & emptySquares;
- // Single pawn pushes
- b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
- b2 = (Type == CHECK ? (b1 & pos.attacks_from<PAWN>(ksq, Them)) | dcPawns1 :
- (Type == EVASION ? b1 & blockSquares : b1));
- SERIALIZE_MOVES_D(b2, -TDELTA_N);
-
- // Double pawn pushes
- b1 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
- b2 = (Type == CHECK ? (b1 & pos.attacks_from<PAWN>(ksq, Them)) | dcPawns2 :
- (Type == EVASION ? b1 & blockSquares : b1));
+ b1 |= dc1;
+ b2 |= dc2;
+ }
+ }
+ SERIALIZE_MOVES_D(b1, -TDELTA_N);
SERIALIZE_MOVES_D(b2, -TDELTA_N -TDELTA_N);
}
- else if (pos.ep_square() != SQ_NONE) // En passant captures
+
+ // En passant captures
+ if ((Type == CAPTURE || Type == EVASION) && pos.ep_square() != SQ_NONE)
{
assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6);
assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3);
+ // 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 == EVASION && !bit_is_set(target, pos.ep_square() - TDELTA_N))
+ return mlist;
+
b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);
+
assert(b1 != EmptyBoardBB);
while (b1)
}
template<PieceType Piece>
- MoveStack* generate_discovered_checks(const Position& pos, Square from, MoveStack* mlist) {
+ MoveStack* generate_discovered_checks(const Position& pos, MoveStack* mlist, Square from) {
assert(Piece != QUEEN);
Bitboard dc, Square ksq) {
assert(Piece != KING);
+ Bitboard checkSqs, b;
Square from;
- Bitboard checkSqs;
const Square* ptr = pos.piece_list_begin(us, Piece);
if ((from = *ptr++) == SQ_NONE)
if (dc && bit_is_set(dc, from))
continue;
- Bitboard bb = pos.attacks_from<Piece>(from) & checkSqs;
- SERIALIZE_MOVES(bb);
+ b = pos.attacks_from<Piece>(from) & checkSqs;
+ SERIALIZE_MOVES(b);
} while ((from = *ptr++) != SQ_NONE);