X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovegen.cpp;h=be848cf1a6acb370e1ddf262b4f79762ba187f56;hp=3dfd8f6a488bd2348ec6d0486d5801f57ee99a69;hb=55df3fa2d7631ed67e46f9433aa7f3a71c18e5e7;hpb=ad1bb084ddde99261bcc20261a5ccee3bfb2abc7
diff --git a/src/movegen.cpp b/src/movegen.cpp
index 3dfd8f6a..be848cf1 100644
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -1,936 +1,445 @@
/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+ Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
- Glaurung is free software: you can redistribute it and/or modify
+ Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
- Glaurung is distributed in the hope that it will be useful,
+
+ Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
-
+
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
#include
#include "movegen.h"
+#include "position.h"
+/// 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_lsb(&b))
-////
-//// Local definitions
-////
-
+/// 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_lsb(&b); \
+ (*mlist++).move = make_move(to - (d), to); }
namespace {
- inline Bitboard forward_white(Bitboard b) { return b << 8; }
- inline Bitboard forward_right_white(Bitboard b) { return b << 9; }
- inline Bitboard forward_left_white(Bitboard b) { return b << 7; }
+ template
+ MoveStack* generate_castle(const Position& pos, MoveStack* mlist, Color us) {
- inline Bitboard forward_black(Bitboard b) { return b >> 8; }
- inline Bitboard forward_right_black(Bitboard b) { return b >> 7; }
- inline Bitboard forward_left_black(Bitboard b) { return b >> 9; }
+ if (pos.castle_impeded(us, Side) || !pos.can_castle(make_castle_right(us, Side)))
+ return mlist;
- struct PawnOffsets {
+ // 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);
- Bitboard Rank3BB, Rank8BB;
- Rank RANK_8;
- SquareDelta DELTA_N, DELTA_NE, DELTA_NW;
- Color us, them;
- typedef Bitboard (*Shift_fn)(Bitboard b);
- Shift_fn forward, forward_left, forward_right;
- };
+ assert(!pos.in_check());
- const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, RANK_8, DELTA_N, DELTA_NE, DELTA_NW, WHITE, BLACK,
- &forward_white, forward_left_white, forward_right_white };
+ const int K = Chess960 ? kto > kfrom ? -1 : 1
+ : Side == KING_SIDE ? -1 : 1;
- const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, RANK_1, DELTA_S, DELTA_SE, DELTA_SW, BLACK, WHITE,
- &forward_black, &forward_left_black, &forward_right_black };
-
- int generate_castle_moves(const Position&, MoveStack*, Color);
+ for (Square s = kto; s != kfrom; s += (Square)K)
+ if (pos.attackers_to(s) & enemies)
+ return mlist;
- template
- int generate_pawn_captures(const Position&, MoveStack*);
+ // Because we generate only legal castling moves we need to verify that
+ // when moving the castling rook we do not discover some hidden checker.
+ // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
+ if (Chess960 && (pos.attackers_to(kto, pos.pieces() ^ rfrom) & enemies))
+ return mlist;
- template
- int generate_pawn_noncaptures(const Position&, MoveStack*);
-
- template
- int generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*, int);
+ (*mlist++).move = make(kfrom, rfrom);
- template
- int generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*, int);
+ if (Checks && !pos.move_gives_check((mlist - 1)->move, CheckInfo(pos)))
+ mlist--;
- template
- int generate_piece_moves(const Position&, MoveStack*, Color, Bitboard);
+ return mlist;
+ }
- template
- int generate_piece_checks(const Position&, Bitboard, Bitboard, Square, MoveStack*, int);
- template
- int generate_piece_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*, int);
+ template
+ inline Bitboard move_pawns(Bitboard p) {
+ 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;
+ }
- /// Templates are defined here to avoid lookup issues with specializations
- template
- int generate_piece_moves(const Position &pos, MoveStack *mlist,
- Color side, Bitboard target) {
- int n = 0;
- for (int i = 0; i < pos.piece_count(side, Piece); i++)
- {
- Square from = pos.piece_list(side, Piece, i);
- Bitboard b = pos.piece_attacks(from) & target;
- while (b)
- {
- Square to = pop_1st_bit(&b);
- mlist[n++].move = make_move(from, to);
- }
- }
- return n;
- }
+ template
+ inline MoveStack* generate_promotions(MoveStack* mlist, Bitboard pawnsOn7,
+ Bitboard target, const CheckInfo* ci) {
+ Bitboard b = move_pawns(pawnsOn7) & target;
- template
- int generate_piece_checks(const Position& pos, Bitboard target, Bitboard dc,
- Square ksq, MoveStack* mlist, int n) {
- // Discovered checks
- Bitboard b = target & dc;
while (b)
{
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks(from) & pos.empty_squares();
- while (bb)
- {
- Square to = pop_1st_bit(&bb);
- mlist[n++].move = make_move(from, to);
- }
- }
- // Direct checks
- b = target & ~dc;
- Bitboard checkSqs = pos.piece_attacks(ksq) & pos.empty_squares();
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks(from) & checkSqs;
- while (bb)
- {
- Square to = pop_1st_bit(&bb);
- mlist[n++].move = make_move(from, to);
- }
- }
- return n;
- }
+ Square to = pop_lsb(&b);
+ if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
+ (*mlist++).move = make(to - Delta, to, QUEEN);
- template<> // Special case the King
- int generate_piece_checks(const Position& pos, Bitboard, Bitboard dc,
- Square ksq, MoveStack* mlist, int n) {
- if (bit_is_set(dc, ksq))
- {
- Bitboard bb = pos.piece_attacks(ksq)
- & pos.empty_squares()
- & ~QueenPseudoAttacks[ksq];
- while (bb)
+ if (Type == QUIETS || Type == EVASIONS || Type == NON_EVASIONS)
{
- Square to = pop_1st_bit(&bb);
- mlist[n++].move = make_move(ksq, to);
+ (*mlist++).move = make(to - Delta, to, ROOK);
+ (*mlist++).move = make(to - Delta, to, BISHOP);
+ (*mlist++).move = make(to - Delta, to, KNIGHT);
}
- }
- return n;
- }
-
- template
- int generate_piece_blocking_evasions(const Position& pos, Bitboard b,
- Bitboard blockSquares, MoveStack* mlist, int n) {
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks(from) & blockSquares;
- while (bb)
- {
- Square to = pop_1st_bit(&bb);
- mlist[n++].move = make_move(from, to);
- }
+ // Knight-promotion is the only one that can give a direct check not
+ // already included in the queen-promotion.
+ if (Type == QUIET_CHECKS && (StepAttacksBB[W_KNIGHT][to] & ci->ksq))
+ (*mlist++).move = make(to - Delta, to, KNIGHT);
+ else
+ (void)ci; // Silence a warning under MSVC
}
- return n;
- }
-}
+ return mlist;
+ }
-////
-//// Functions
-////
+ template
+ MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist,
+ Bitboard target, const CheckInfo* ci) {
-/// generate_captures generates() all pseudo-legal captures and queen
-/// promotions. The return value is the number of moves generated.
+ // 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);
-int generate_captures(const Position& pos, MoveStack* mlist) {
+ Bitboard b1, b2, dc1, dc2, emptySquares;
- assert(pos.is_ok());
- assert(!pos.is_check());
+ Bitboard pawnsOn7 = pos.pieces(Us, PAWN) & TRank7BB;
+ Bitboard pawnsNotOn7 = pos.pieces(Us, PAWN) & ~TRank7BB;
- Color us = pos.side_to_move();
- Bitboard target = pos.pieces_of_color(opposite_color(us));
- int n;
-
- if (us == WHITE)
- n = generate_pawn_captures(pos, mlist);
- else
- n = generate_pawn_captures(pos, mlist);
-
- n += generate_piece_moves(pos, mlist+n, us, target);
- n += generate_piece_moves(pos, mlist+n, us, target);
- n += generate_piece_moves(pos, mlist+n, us, target);
- n += generate_piece_moves(pos, mlist+n, us, target);
- n += generate_piece_moves(pos, mlist+n, us, target);
- return n;
-}
+ Bitboard enemies = (Type == EVASIONS ? pos.pieces(Them) & target:
+ Type == CAPTURES ? target : pos.pieces(Them));
+ // Single and double pawn pushes, no promotions
+ if (Type != CAPTURES)
+ {
+ emptySquares = (Type == QUIETS || Type == QUIET_CHECKS ? target : ~pos.pieces());
-/// generate_noncaptures() generates all pseudo-legal non-captures and
-/// underpromotions. The return value is the number of moves generated.
+ b1 = move_pawns(pawnsNotOn7) & emptySquares;
+ b2 = move_pawns(b1 & TRank3BB) & emptySquares;
-int generate_noncaptures(const Position& pos, MoveStack *mlist) {
+ if (Type == EVASIONS) // Consider only blocking squares
+ {
+ b1 &= target;
+ b2 &= target;
+ }
- assert(pos.is_ok());
- assert(!pos.is_check());
+ if (Type == QUIET_CHECKS)
+ {
+ b1 &= pos.attacks_from(ci->ksq, Them);
+ b2 &= pos.attacks_from(ci->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 & ci->dcCandidates)
+ {
+ dc1 = move_pawns(pawnsNotOn7 & ci->dcCandidates) & emptySquares & ~file_bb(ci->ksq);
+ dc2 = move_pawns(dc1 & TRank3BB) & emptySquares;
+
+ b1 |= dc1;
+ b2 |= dc2;
+ }
+ }
- Color us = pos.side_to_move();
- Bitboard target = pos.empty_squares();
- int n;
-
- if (us == WHITE)
- n = generate_pawn_noncaptures(pos, mlist);
- else
- n = generate_pawn_noncaptures(pos, mlist);
-
- n += generate_piece_moves(pos, mlist+n, us, target);
- n += generate_piece_moves(pos, mlist+n, us, target);
- n += generate_piece_moves(pos, mlist+n, us, target);
- n += generate_piece_moves(pos, mlist+n, us, target);
- n += generate_piece_moves(pos, mlist+n, us, target);
-
- n += generate_castle_moves(pos, mlist+n, us);
- return n;
-}
+ SERIALIZE_PAWNS(b1, UP);
+ SERIALIZE_PAWNS(b2, UP + UP);
+ }
+ // Promotions and underpromotions
+ if (pawnsOn7 && (Type != EVASIONS || (target & TRank8BB)))
+ {
+ if (Type == CAPTURES)
+ emptySquares = ~pos.pieces();
-/// generate_checks() generates all pseudo-legal non-capturing, non-promoting
-/// checks, except castling moves (will add this later). It returns the
-/// number of generated moves.
+ if (Type == EVASIONS)
+ emptySquares &= target;
-int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
+ mlist = generate_promotions(mlist, pawnsOn7, enemies, ci);
+ mlist = generate_promotions(mlist, pawnsOn7, enemies, ci);
+ mlist = generate_promotions(mlist, pawnsOn7, emptySquares, ci);
+ }
- assert(pos.is_ok());
- assert(!pos.is_check());
+ // Standard and en-passant captures
+ if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
+ {
+ b1 = move_pawns(pawnsNotOn7) & enemies;
+ b2 = move_pawns(pawnsNotOn7) & enemies;
- int n;
- Color us = pos.side_to_move();
- Square ksq = pos.king_square(opposite_color(us));
+ SERIALIZE_PAWNS(b1, RIGHT);
+ SERIALIZE_PAWNS(b2, LEFT);
- assert(pos.piece_on(ksq) == king_of_color(opposite_color(us)));
+ if (pos.ep_square() != SQ_NONE)
+ {
+ assert(rank_of(pos.ep_square()) == relative_rank(Us, RANK_6));
- dc = pos.discovered_check_candidates(us);
+ // 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 == EVASIONS && !(target & (pos.ep_square() - UP)))
+ return mlist;
- // Pawn moves
- if (us == WHITE)
- n = generate_pawn_checks(pos, dc, ksq, mlist, 0);
- else
- n = generate_pawn_checks(pos, dc, ksq, mlist, 0);
+ b1 = pawnsNotOn7 & pos.attacks_from(pos.ep_square(), Them);
- // Pieces moves
- Bitboard b = pos.knights(us);
- if (b)
- n = generate_piece_checks(pos, b, dc, ksq, mlist, n);
+ assert(b1);
- b = pos.bishops(us);
- if (b)
- n = generate_piece_checks(pos, b, dc, ksq, mlist, n);
+ while (b1)
+ (*mlist++).move = make(pop_lsb(&b1), pos.ep_square());
+ }
+ }
- b = pos.rooks(us);
- if (b)
- n = generate_piece_checks(pos, b, dc, ksq, mlist, n);
+ return mlist;
+ }
- b = pos.queens(us);
- if (b)
- n = generate_piece_checks(pos, b, dc, ksq, mlist, n);
- // Hopefully we always have a king ;-)
- n = generate_piece_checks(pos, b, dc, pos.king_square(us), mlist, n);
+ template FORCE_INLINE
+ MoveStack* generate_moves(const Position& pos, MoveStack* mlist, Color us,
+ Bitboard target, const CheckInfo* ci) {
- // TODO: Castling moves!
-
- return n;
-}
+ assert(Pt != KING && Pt != PAWN);
+ const Square* pl = pos.piece_list(us, Pt);
-/// 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
+ for (Square from = *pl; from != SQ_NONE; from = *++pl)
+ {
+ if (Checks)
+ {
+ if ( (Pt == BISHOP || Pt == ROOK || Pt == QUEEN)
+ && !(PseudoAttacks[Pt][from] & target & ci->checkSq[Pt]))
+ continue;
-int generate_evasions(const Position& pos, MoveStack* mlist) {
+ if (ci->dcCandidates && (ci->dcCandidates & from))
+ continue;
+ }
- assert(pos.is_ok());
- assert(pos.is_check());
+ Bitboard b = pos.attacks_from(from) & target;
- Color us = pos.side_to_move();
- Color them = opposite_color(us);
- Square ksq = pos.king_square(us);
- Square from, to;
- int n = 0;
+ if (Checks)
+ b &= ci->checkSq[Pt];
- assert(pos.piece_on(ksq) == king_of_color(us));
-
- // Generate evasions for king
- Bitboard b1 = pos.piece_attacks(ksq) & ~pos.pieces_of_color(us);
- Bitboard b2 = pos.occupied_squares();
- clear_bit(&b2, ksq);
+ SERIALIZE(b);
+ }
- while (b1)
- {
- Square to = pop_1st_bit(&b1);
-
- // Make sure to is not attacked by the other side. This is a bit ugly,
- // because we can't use Position::square_is_attacked. Instead we use
- // the low-level bishop_attacks_bb and rook_attacks_bb with the bitboard
- // b2 (the occupied squares with the king removed) in order to test whether
- // the king will remain in check on the destination square.
- if (!( (bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them))
- || (rook_attacks_bb(to, b2) & pos.rooks_and_queens(them))
- || (pos.piece_attacks(to) & pos.knights(them))
- || (pos.pawn_attacks(us, to) & pos.pawns(them))
- || (pos.piece_attacks(to) & pos.kings(them))))
-
- mlist[n++].move = make_move(ksq, to);
+ return mlist;
}
- // 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();
-
- if (!(checkers & (checkers - 1))) // Only one bit set?
- {
- Square checksq = first_1(checkers);
-
- assert(pos.color_of_piece_on(checksq) == them);
- // Find pinned pieces
- Bitboard not_pinned = ~pos.pinned_pieces(us);
-
- // Generate captures of the checking piece
-
- // Pawn captures
- b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & not_pinned;
- while (b1)
- {
- from = pop_1st_bit(&b1);
- if (relative_rank(us, checksq) == RANK_8)
- {
- mlist[n++].move = make_promotion_move(from, checksq, QUEEN);
- mlist[n++].move = make_promotion_move(from, checksq, ROOK);
- mlist[n++].move = make_promotion_move(from, checksq, BISHOP);
- mlist[n++].move = make_promotion_move(from, checksq, KNIGHT);
- } else
- mlist[n++].move = make_move(from, checksq);
- }
-
- // Pieces captures
- b1 = ( (pos.piece_attacks(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[n++].move = make_move(from, checksq);
- }
-
- // Blocking check evasions are possible only if the checking piece is
- // a slider
- if (checkers & pos.sliders())
- {
- Bitboard blockSquares = squares_between(checksq, ksq);
-
- assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
+ FORCE_INLINE MoveStack* generate_king_moves(const Position& pos, MoveStack* mlist,
+ Color us, Bitboard target) {
+ Square from = pos.king_square(us);
+ Bitboard b = pos.attacks_from(from) & target;
+ SERIALIZE(b);
+ return mlist;
+ }
- // Pawn moves. Because a blocking evasion can never be a capture, we
- // only generate pawn pushes.
- if (us == WHITE)
- n = generate_pawn_blocking_evasions(pos, not_pinned, blockSquares, mlist, n);
- else
- n = generate_pawn_blocking_evasions(pos, not_pinned, blockSquares, mlist, n);
- // Pieces moves
- b1 = pos.knights(us) & not_pinned;
- if (b1)
- n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n);
+ template FORCE_INLINE
+ MoveStack* generate_all_moves(const Position& pos, MoveStack* mlist, Color us,
+ Bitboard target, const CheckInfo* ci = NULL) {
- b1 = pos.bishops(us) & not_pinned;
- if (b1)
- n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n);
+ mlist = (us == WHITE ? generate_pawn_moves(pos, mlist, target, ci)
+ : generate_pawn_moves(pos, mlist, target, ci));
- b1 = pos.rooks(us) & not_pinned;
- if (b1)
- n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n);
+ mlist = generate_moves(pos, mlist, us, target, ci);
+ mlist = generate_moves(pos, mlist, us, target, ci);
+ mlist = generate_moves(pos, mlist, us, target, ci);
+ mlist = generate_moves(pos, mlist, us, target, ci);
- b1 = pos.queens(us) & not_pinned;
- if (b1)
- n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n);
- }
+ if (Type != QUIET_CHECKS && Type != EVASIONS)
+ mlist = generate_king_moves(pos, mlist, us, target);
- // 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)))
+ if (Type != CAPTURES && Type != EVASIONS && pos.can_castle(us))
{
- to = pos.ep_square();
- b1 = pos.pawn_attacks(them, to) & pos.pawns(us);
-
- assert(b1 != EmptyBoardBB);
-
- b1 &= not_pinned;
- while (b1)
+ if (pos.is_chess960())
{
- from = pop_1st_bit(&b1);
-
- // Before generating the move, we have to make sure it is legal.
- // This is somewhat tricky, because the two disappearing pawns may
- // cause new "discovered checks". We test this by removing the
- // two relevant bits from the occupied squares bitboard, and using
- // the low-level bitboard functions for bishop and rook attacks.
- b2 = pos.occupied_squares();
- clear_bit(&b2, from);
- clear_bit(&b2, checksq);
- if (!( (bishop_attacks_bb(ksq, b2) & pos.bishops_and_queens(them))
- ||(rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them))))
-
- mlist[n++].move = make_ep_move(from, to);
+ mlist = generate_castle(pos, mlist, us);
+ mlist = generate_castle(pos, mlist, us);
+ }
+ else
+ {
+ mlist = generate_castle(pos, mlist, us);
+ mlist = generate_castle(pos, mlist, us);
}
}
- }
- return n;
-}
-
-
-/// generate_legal_moves() computes a complete list of legal moves in the
-/// current position. This function is not very fast, and should be used
-/// only in situations where performance is unimportant. It wouldn't be
-/// very hard to write an efficient legal move generator, but for the moment
-/// we don't need it.
-
-int generate_legal_moves(const Position& pos, MoveStack* mlist) {
-
- assert(pos.is_ok());
-
- if (pos.is_check())
- return generate_evasions(pos, mlist);
- // Generate pseudo-legal moves:
- int n = generate_captures(pos, mlist);
- n += generate_noncaptures(pos, mlist + n);
-
- Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
+ return mlist;
+ }
- // Remove illegal moves from the list:
- for (int i = 0; i < n; i++)
- if (!pos.move_is_legal(mlist[i].move, pinned))
- mlist[i--].move = mlist[--n].move;
- return n;
-}
+} // namespace
-/// generate_move_if_legal() takes a position and a (not necessarily
-/// pseudo-legal) move and a pinned pieces bitboard as input, and tests
-/// whether the move is legal. If the move is legal, the move itself is
-/// returned. If not, the function returns MOVE_NONE. This function must
-/// only be used when the side to move is not in check.
+/// 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.
-Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) {
+template
+MoveStack* generate(const Position& pos, MoveStack* mlist) {
- assert(pos.is_ok());
- assert(!pos.is_check());
- assert(move_is_ok(m));
+ assert(Type == CAPTURES || Type == QUIETS || Type == NON_EVASIONS);
+ assert(!pos.in_check());
Color us = pos.side_to_move();
- Color them = opposite_color(us);
- Square from = move_from(m);
- Piece pc = pos.piece_on(from);
-
- // If the from square is not occupied by a piece belonging to the side to
- // move, the move is obviously not legal.
- if (color_of_piece(pc) != us)
- return MOVE_NONE;
-
- Square to = move_to(m);
-
- // En passant moves
- if (move_is_ep(m))
- {
- // The piece must be a pawn and destination square must be the
- // en passant square.
- if ( type_of_piece(pc) != PAWN
- || to != pos.ep_square())
- return MOVE_NONE;
-
- assert(pos.square_is_empty(to));
- assert(pos.piece_on(to - pawn_push(us)) == pawn_of_color(them));
-
- // The move is pseudo-legal. If it is legal, return it.
- return (pos.move_is_legal(m) ? m : MOVE_NONE);
- }
-
- // Castling moves
- if (move_is_short_castle(m))
- {
- // The piece must be a king and side to move must still have
- // the right to castle kingside.
- if ( type_of_piece(pc) != KING
- ||!pos.can_castle_kingside(us))
- return MOVE_NONE;
-
- assert(from == pos.king_square(us));
- assert(to == pos.initial_kr_square(us));
- assert(pos.piece_on(to) == rook_of_color(us));
-
- Square g1 = relative_square(us, SQ_G1);
- Square f1 = relative_square(us, SQ_F1);
- Square s;
- bool illegal = false;
-
- // Check if any of the squares between king and rook
- // is occupied or under attack.
- for (s = Min(from, g1); s <= Max(from, g1); s++)
- if ( (s != from && s != to && !pos.square_is_empty(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- // Check if any of the squares between king and rook
- // is occupied.
- for (s = Min(to, f1); s <= Max(to, f1); s++)
- if (s != from && s != to && !pos.square_is_empty(s))
- illegal = true;
-
- return (!illegal ? m : MOVE_NONE);
- }
-
- if (move_is_long_castle(m))
- {
- // The piece must be a king and side to move must still have
- // the right to castle kingside.
- if ( type_of_piece(pc) != KING
- ||!pos.can_castle_queenside(us))
- return MOVE_NONE;
-
- assert(from == pos.king_square(us));
- assert(to == pos.initial_qr_square(us));
- assert(pos.piece_on(to) == rook_of_color(us));
-
- Square c1 = relative_square(us, SQ_C1);
- Square d1 = relative_square(us, SQ_D1);
- Square s;
- bool illegal = false;
-
- for (s = Min(from, c1); s <= Max(from, c1); s++)
- if( (s != from && s != to && !pos.square_is_empty(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- for (s = Min(to, d1); s <= Max(to, d1); s++)
- if(s != from && s != to && !pos.square_is_empty(s))
- illegal = true;
-
- if ( square_file(to) == FILE_B
- && ( pos.piece_on(to + DELTA_W) == rook_of_color(them)
- || pos.piece_on(to + DELTA_W) == queen_of_color(them)))
- illegal = true;
-
- return (!illegal ? m : MOVE_NONE);
- }
-
- // Normal moves
-
- // The destination square cannot be occupied by a friendly piece
- if (pos.color_of_piece_on(to) == us)
- return MOVE_NONE;
-
- // Proceed according to the type of the moving piece.
- if (type_of_piece(pc) == PAWN)
- {
- // If the destination square is on the 8/1th rank, the move must
- // be a promotion.
- if ( ( (square_rank(to) == RANK_8 && us == WHITE)
- ||(square_rank(to) == RANK_1 && us != WHITE))
- && !move_promotion(m))
- return MOVE_NONE;
-
- // Proceed according to the square delta between the source and
- // destionation squares.
- switch (to - from)
- {
- case DELTA_NW:
- case DELTA_NE:
- case DELTA_SW:
- case DELTA_SE:
- // Capture. The destination square must be occupied by an enemy
- // piece (en passant captures was handled earlier).
- if (pos.color_of_piece_on(to) != them)
- return MOVE_NONE;
- break;
-
- case DELTA_N:
- case DELTA_S:
- // Pawn push. The destination square must be empty.
- if (!pos.square_is_empty(to))
- return MOVE_NONE;
- break;
+ Bitboard target;
- case DELTA_NN:
- // Double white pawn push. The destination square must be on the fourth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( square_rank(to) != RANK_4
- || !pos.square_is_empty(to)
- || !pos.square_is_empty(from + DELTA_N))
- return MOVE_NONE;
- break;
+ if (Type == CAPTURES)
+ target = pos.pieces(~us);
- case DELTA_SS:
- // Double black pawn push. The destination square must be on the fifth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( square_rank(to) != RANK_5
- || !pos.square_is_empty(to)
- || !pos.square_is_empty(from + DELTA_S))
- return MOVE_NONE;
- break;
+ else if (Type == QUIETS)
+ target = ~pos.pieces();
- default:
- return MOVE_NONE;
- }
- // The move is pseudo-legal. Return it if it is legal.
- return (pos.move_is_legal(m) ? m : MOVE_NONE);
- }
+ else if (Type == NON_EVASIONS)
+ target = ~pos.pieces(us);
- // Luckly we can handle all the other pieces in one go
- return ( pos.piece_attacks_square(from, to)
- && pos.move_is_legal(m)
- && !move_promotion(m) ? m : MOVE_NONE);
+ return generate_all_moves(pos, mlist, us, target);
}
+// Explicit template instantiations
+template MoveStack* generate(const Position&, MoveStack*);
+template MoveStack* generate(const Position&, MoveStack*);
+template MoveStack* generate(const Position&, MoveStack*);
-namespace {
-
- template
- int generate_pawn_captures(const Position& pos, MoveStack* mlist) {
-
- static const PawnOffsets ofs = (C == WHITE ? WhitePawnOffsets : BlackPawnOffsets);
-
- Bitboard pawns = pos.pawns(ofs.us);
- Bitboard enemyPieces = pos.pieces_of_color(ofs.them);
- Square sq;
- int n = 0;
-
- // Captures in the a1-h8 (a8-h1 for black) direction
- Bitboard b1 = (ofs.forward_right)(pawns) & ~FileABB & enemyPieces;
-
- // Capturing promotions
- Bitboard b2 = b1 & ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, QUEEN);
- }
-
- // Capturing non-promotions
- b2 = b1 & ~ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_move(sq - ofs.DELTA_NE, sq);
- }
-
- // Captures in the h1-a8 (h8-a1 for black) direction
- b1 = (ofs.forward_left)(pawns) & ~FileHBB & enemyPieces;
-
- // Capturing promotions
- b2 = b1 & ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, QUEEN);
- }
-
- // Capturing non-promotions
- b2 = b1 & ~ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_move(sq - ofs.DELTA_NW, sq);
- }
-
- // Non-capturing promotions
- b1 = (ofs.forward)(pawns) & pos.empty_squares() & Rank8BB;
- while (b1)
- {
- sq = pop_1st_bit(&b1);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, QUEEN);
- }
-
- // En passant captures
- if (pos.ep_square() != SQ_NONE)
- {
- assert(ofs.us != WHITE || square_rank(pos.ep_square()) == RANK_6);
- assert(ofs.us != BLACK || square_rank(pos.ep_square()) == RANK_3);
-
- b1 = pawns & pos.pawn_attacks(ofs.them, pos.ep_square());
- assert(b1 != EmptyBoardBB);
-
- while (b1)
- {
- sq = pop_1st_bit(&b1);
- mlist[n++].move = make_ep_move(sq, pos.ep_square());
- }
- }
- return n;
- }
+/// 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) {
- template
- int generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) {
+ assert(!pos.in_check());
- static const PawnOffsets ofs = (C == WHITE ? WhitePawnOffsets : BlackPawnOffsets);
+ Color us = pos.side_to_move();
+ CheckInfo ci(pos);
+ Bitboard dc = ci.dcCandidates;
- Bitboard pawns = pos.pawns(ofs.us);
- Bitboard enemyPieces = pos.pieces_of_color(ofs.them);
- Bitboard emptySquares = pos.empty_squares();
- Bitboard b1, b2;
- Square sq;
- int n = 0;
+ while (dc)
+ {
+ Square from = pop_lsb(&dc);
+ PieceType pt = type_of(pos.piece_on(from));
- // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
- b1 = ofs.forward_right(pawns) & ~FileABB & enemyPieces & ofs.Rank8BB;
- while (b1)
- {
- sq = pop_1st_bit(&b1);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, ROOK);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, BISHOP);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, KNIGHT);
- }
+ if (pt == PAWN)
+ continue; // Will be generated togheter with direct checks
- // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
- b1 = ofs.forward_left(pawns) & ~FileHBB & enemyPieces & ofs.Rank8BB;
- while (b1)
- {
- sq = pop_1st_bit(&b1);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, ROOK);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, BISHOP);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, KNIGHT);
- }
+ Bitboard b = pos.attacks_from(Piece(pt), from) & ~pos.pieces();
- // Single pawn pushes
- b1 = ofs.forward(pawns) & emptySquares;
- b2 = b1 & ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, ROOK);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, BISHOP);
- mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, KNIGHT);
- }
- b2 = b1 & ~ofs.Rank8BB;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_move(sq - ofs.DELTA_N, sq);
- }
+ if (pt == KING)
+ b &= ~PseudoAttacks[QUEEN][ci.ksq];
- // Double pawn pushes
- b2 = (ofs.forward(b1 & ofs.Rank3BB)) & emptySquares;
- while (b2)
- {
- sq = pop_1st_bit(&b2);
- mlist[n++].move = make_move(sq - ofs.DELTA_N - ofs.DELTA_N, sq);
- }
- return n;
+ SERIALIZE(b);
}
+ return generate_all_moves(pos, mlist, us, ~pos.pieces(), &ci);
+}
- int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) {
-
- int n = 0;
-
- 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));
-
- 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;
+/// 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) {
- if (!illegal)
- mlist[n++].move = make_castle_move(ksq, rsq);
- }
+ assert(pos.in_check());
- if (pos.can_castle_queenside(us))
- {
- Square rsq = pos.initial_qr_square(us);
- Square c1 = relative_square(us, SQ_C1);
- Square d1 = relative_square(us, SQ_D1);
- Square s;
- bool illegal = false;
-
- assert(pos.piece_on(rsq) == rook_of_color(us));
-
- for (s = Min(ksq, c1); s <= Max(ksq, c1); s++)
- if ( (s != ksq && s != rsq && pos.square_is_occupied(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- for (s = Min(rsq, d1); s <= Max(rsq, d1); s++)
- if (s != ksq && s != rsq && pos.square_is_occupied(s))
- illegal = true;
-
- if ( square_file(rsq) == FILE_B
- && ( pos.piece_on(relative_square(us, SQ_A1)) == rook_of_color(them)
- || pos.piece_on(relative_square(us, SQ_A1)) == queen_of_color(them)))
- illegal = true;
-
- if (!illegal)
- mlist[n++].move = make_castle_move(ksq, rsq);
- }
- }
- return n;
- }
+ Square from, checksq;
+ int checkersCnt = 0;
+ Color us = pos.side_to_move();
+ Square ksq = pos.king_square(us);
+ Bitboard sliderAttacks = 0;
+ Bitboard b = pos.checkers();
+ assert(pos.checkers());
- template
- int generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist, int n)
+ // 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.
+ do
{
- static const PawnOffsets ofs = (C == WHITE ? WhitePawnOffsets : BlackPawnOffsets);
-
- // 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();
+ checkersCnt++;
+ checksq = pop_lsb(&b);
- // Find all friendly pawns not on the enemy king's file
- Bitboard b1 = pos.pawns(pos.side_to_move()) & ~file_bb(ksq), b2, b3;
+ assert(color_of(pos.piece_on(checksq)) == ~us);
- // Discovered checks, single pawn pushes
- b2 = b3 = (ofs.forward)(b1 & dc) & ~ofs.Rank8BB & empty;
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - ofs.DELTA_N, to);
- }
-
- // Discovered checks, double pawn pushes
- b3 = (ofs.forward)(b2 & ofs.Rank3BB) & empty;
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
- }
-
- // Direct checks. These are possible only for pawns on neighboring files
- // of the enemy king
-
- b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
+ 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 (between_bb(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);
- // Direct checks, single pawn pushes
- b2 = (ofs.forward)(b1) & empty;
- b3 = b2 & pos.pawn_attacks(ofs.them, ksq);
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - ofs.DELTA_N, to);
- }
+ default:
+ break;
+ }
+ } while (b);
- // Direct checks, double pawn pushes
- b3 = (ofs.forward)(b2 & ofs.Rank3BB) & empty & pos.pawn_attacks(ofs.them, ksq);
- while (b3)
- {
- Square to = pop_1st_bit(&b3);
- mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
- }
- return n;
- }
+ // Generate evasions for king, capture and non capture moves
+ b = pos.attacks_from(ksq) & ~pos.pieces(us) & ~sliderAttacks;
+ from = ksq;
+ SERIALIZE(b);
- template
- int generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned,
- Bitboard blockSquares, MoveStack* mlist, int n) {
+ if (checkersCnt > 1)
+ return mlist; // Double check, only a king move can save the day
- static const PawnOffsets ofs = (C == WHITE ? WhitePawnOffsets : BlackPawnOffsets);
+ // Generate blocking evasions or captures of the checking piece
+ Bitboard target = between_bb(checksq, ksq) | pos.checkers();
- // Find non-pinned pawns
- Bitboard b1 = pos.pawns(ofs.us) & not_pinned;
+ return generate_all_moves(pos, mlist, us, target);
+}
- // Single pawn pushes. We don't have to AND with empty squares here,
- // because the blocking squares will always be empty.
- Bitboard b2 = (ofs.forward)(b1) & blockSquares;
- while (b2)
- {
- Square to = pop_1st_bit(&b2);
- assert(pos.piece_on(to) == EMPTY);
+/// generate generates all the legal moves in the given position
- if (square_rank(to) == ofs.RANK_8)
- {
- mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, QUEEN);
- mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, ROOK);
- mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, BISHOP);
- mlist[n++].move = make_promotion_move(to - ofs.DELTA_N, to, KNIGHT);
- } else
- mlist[n++].move = make_move(to - ofs.DELTA_N, to);
- }
+template<>
+MoveStack* generate(const Position& pos, MoveStack* mlist) {
- // Double pawn pushes
- b2 = (ofs.forward)((ofs.forward)(b1) & pos.empty_squares() & ofs.Rank3BB) & blockSquares;
- while (b2)
- {
- Square to = pop_1st_bit(&b2);
+ MoveStack *end, *cur = mlist;
+ Bitboard pinned = pos.pinned_pieces();
+ Square ksq = pos.king_square(pos.side_to_move());
- assert(pos.piece_on(to) == EMPTY);
- assert(ofs.us != WHITE || square_rank(to) == RANK_4);
- assert(ofs.us != BLACK || square_rank(to) == RANK_5);
+ end = pos.in_check() ? generate(pos, mlist)
+ : generate(pos, mlist);
+ while (cur != end)
+ if ( (pinned || from_sq(cur->move) == ksq || type_of(cur->move) == ENPASSANT)
+ && !pos.pl_move_is_legal(cur->move, pinned))
+ cur->move = (--end)->move;
+ else
+ cur++;
- mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
- }
- return n;
- }
+ return end;
}