/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, 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
#include <cassert>
-#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); }
-
namespace {
- enum CastlingSide {
- KING_SIDE,
- QUEEN_SIDE
- };
-
- template<CastlingSide>
- MoveStack* generate_castle_moves(const Position&, MoveStack*, Color us);
-
- template<Color, MoveType>
- MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard, Square);
-
- template<PieceType Pt>
- inline MoveStack* generate_discovered_checks(const Position& pos, MoveStack* mlist, Square from) {
+ template<GenType Type, Direction D>
+ ExtMove* make_promotions(ExtMove* moveList, Square to, Square ksq) {
- assert(Pt != QUEEN);
- assert(Pt != PAWN);
+ if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
+ *moveList++ = make<PROMOTION>(to - D, to, QUEEN);
- Bitboard b = pos.attacks_from<Pt>(from) & pos.empty_squares();
+ if (Type == QUIETS || Type == EVASIONS || Type == NON_EVASIONS)
+ {
+ *moveList++ = make<PROMOTION>(to - D, to, ROOK);
+ *moveList++ = make<PROMOTION>(to - D, to, BISHOP);
+ *moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
+ }
- if (Pt == KING)
- b &= ~QueenPseudoAttacks[pos.king_square(opposite_color(pos.side_to_move()))];
+ // Knight promotion is the only promotion that can give a direct check
+ // that's not already included in the queen promotion.
+ if (Type == QUIET_CHECKS && (PseudoAttacks[KNIGHT][to] & ksq))
+ *moveList++ = make<PROMOTION>(to - D, to, KNIGHT);
+ else
+ (void)ksq; // Silence a warning under MSVC
- SERIALIZE_MOVES(b);
- return mlist;
+ return moveList;
}
- template<PieceType Pt>
- inline MoveStack* generate_direct_checks(const Position& pos, MoveStack* mlist, Color us,
- Bitboard dc, Square ksq) {
- assert(Pt != KING);
- assert(Pt != PAWN);
-
- Bitboard checkSqs, b;
- Square from;
- const Square* pl = pos.piece_list(us, Pt);
- if ((from = *pl++) == SQ_NONE)
- return mlist;
+ template<Color Us, GenType Type>
+ ExtMove* generate_pawn_moves(const Position& pos, ExtMove* moveList, Bitboard target) {
- checkSqs = pos.attacks_from<Pt>(ksq) & pos.empty_squares();
-
- do
- {
- if ( (Pt == QUEEN && !(QueenPseudoAttacks[from] & checkSqs))
- || (Pt == ROOK && !(RookPseudoAttacks[from] & checkSqs))
- || (Pt == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
- continue;
+ constexpr Color Them = ~Us;
+ constexpr Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
+ constexpr Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
+ constexpr Direction Up = pawn_push(Us);
+ constexpr Direction UpRight = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
+ constexpr Direction UpLeft = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
- if (dc && bit_is_set(dc, from))
- continue;
+ const Square ksq = pos.square<KING>(Them);
+ Bitboard emptySquares;
- b = pos.attacks_from<Pt>(from) & checkSqs;
- SERIALIZE_MOVES(b);
+ Bitboard pawnsOn7 = pos.pieces(Us, PAWN) & TRank7BB;
+ Bitboard pawnsNotOn7 = pos.pieces(Us, PAWN) & ~TRank7BB;
- } while ((from = *pl++) != SQ_NONE);
+ Bitboard enemies = (Type == EVASIONS ? pos.pieces(Them) & target:
+ Type == CAPTURES ? target : pos.pieces(Them));
- return mlist;
- }
+ // Single and double pawn pushes, no promotions
+ if (Type != CAPTURES)
+ {
+ emptySquares = (Type == QUIETS || Type == QUIET_CHECKS ? target : ~pos.pieces());
- template<>
- FORCE_INLINE MoveStack* generate_direct_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
+ Bitboard b1 = shift<Up>(pawnsNotOn7) & emptySquares;
+ Bitboard b2 = shift<Up>(b1 & TRank3BB) & emptySquares;
- return (us == WHITE ? generate_pawn_moves<WHITE, MV_CHECK>(p, m, dc, ksq)
- : generate_pawn_moves<BLACK, MV_CHECK>(p, m, dc, ksq));
- }
+ if (Type == EVASIONS) // Consider only blocking squares
+ {
+ b1 &= target;
+ b2 &= target;
+ }
- template<PieceType Pt, MoveType Type>
- FORCE_INLINE MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us, Bitboard t) {
+ if (Type == QUIET_CHECKS)
+ {
+ b1 &= pos.attacks_from<PAWN>(ksq, Them);
+ b2 &= pos.attacks_from<PAWN>(ksq, Them);
- assert(Pt == PAWN);
- assert(Type == MV_CAPTURE || Type == MV_NON_CAPTURE || Type == MV_EVASION);
+ // 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 amongst the captures.
+ Bitboard dcCandidateQuiets = pos.blockers_for_king(Them) & pawnsNotOn7;
+ if (dcCandidateQuiets)
+ {
+ Bitboard dc1 = shift<Up>(dcCandidateQuiets) & emptySquares & ~file_bb(ksq);
+ Bitboard dc2 = shift<Up>(dc1 & TRank3BB) & emptySquares;
- return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m, t, SQ_NONE)
- : generate_pawn_moves<BLACK, Type>(p, m, t, SQ_NONE));
- }
+ b1 |= dc1;
+ b2 |= dc2;
+ }
+ }
- template<PieceType Pt>
- FORCE_INLINE MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
+ while (b1)
+ {
+ Square to = pop_lsb(&b1);
+ *moveList++ = make_move(to - Up, to);
+ }
- Bitboard b;
- Square from;
- const Square* pl = pos.piece_list(us, Pt);
+ while (b2)
+ {
+ Square to = pop_lsb(&b2);
+ *moveList++ = make_move(to - Up - Up, to);
+ }
+ }
- if (*pl != SQ_NONE)
+ // Promotions and underpromotions
+ if (pawnsOn7)
{
- do {
- from = *pl;
- b = pos.attacks_from<Pt>(from) & target;
- SERIALIZE_MOVES(b);
- } while (*++pl != SQ_NONE);
- }
- return mlist;
- }
+ if (Type == CAPTURES)
+ emptySquares = ~pos.pieces();
- template<>
- FORCE_INLINE MoveStack* generate_piece_moves<KING>(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
+ if (Type == EVASIONS)
+ emptySquares &= target;
- Bitboard b;
- Square from = pos.king_square(us);
+ Bitboard b1 = shift<UpRight>(pawnsOn7) & enemies;
+ Bitboard b2 = shift<UpLeft >(pawnsOn7) & enemies;
+ Bitboard b3 = shift<Up >(pawnsOn7) & emptySquares;
- b = pos.attacks_from<KING>(from) & target;
- SERIALIZE_MOVES(b);
- return mlist;
- }
+ while (b1)
+ moveList = make_promotions<Type, UpRight>(moveList, pop_lsb(&b1), ksq);
-}
+ while (b2)
+ moveList = make_promotions<Type, UpLeft >(moveList, pop_lsb(&b2), ksq);
+ while (b3)
+ moveList = make_promotions<Type, Up >(moveList, pop_lsb(&b3), ksq);
+ }
-/// generate<MV_CAPTURE> generates all pseudo-legal captures and queen
-/// promotions. Returns a pointer to the end of the move list.
-///
-/// generate<MV_NON_CAPTURE> generates all pseudo-legal non-captures and
-/// underpromotions. Returns a pointer to the end of the move list.
-///
-/// generate<MV_NON_EVASION> generates all pseudo-legal captures and
-/// non-captures. Returns a pointer to the end of the move list.
+ // Standard and en-passant captures
+ if (Type == CAPTURES || Type == EVASIONS || Type == NON_EVASIONS)
+ {
+ Bitboard b1 = shift<UpRight>(pawnsNotOn7) & enemies;
+ Bitboard b2 = shift<UpLeft >(pawnsNotOn7) & enemies;
-template<MoveType Type>
-MoveStack* generate(const Position& pos, MoveStack* mlist) {
+ while (b1)
+ {
+ Square to = pop_lsb(&b1);
+ *moveList++ = make_move(to - UpRight, to);
+ }
- assert(!pos.in_check());
+ while (b2)
+ {
+ Square to = pop_lsb(&b2);
+ *moveList++ = make_move(to - UpLeft, to);
+ }
- Color us = pos.side_to_move();
- Bitboard target;
+ if (pos.ep_square() != SQ_NONE)
+ {
+ assert(rank_of(pos.ep_square()) == relative_rank(Us, RANK_6));
- if (Type == MV_CAPTURE || Type == MV_NON_EVASION)
- target = pos.pieces(opposite_color(us));
- else if (Type == MV_NON_CAPTURE)
- target = pos.empty_squares();
- else
- assert(false);
+ // 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 moveList;
- if (Type == MV_NON_EVASION)
- {
- mlist = generate_piece_moves<PAWN, MV_CAPTURE>(pos, mlist, us, target);
- mlist = generate_piece_moves<PAWN, MV_NON_CAPTURE>(pos, mlist, us, pos.empty_squares());
- target |= pos.empty_squares();
- }
- else
- mlist = generate_piece_moves<PAWN, Type>(pos, mlist, us, target);
+ b1 = pawnsNotOn7 & pos.attacks_from<PAWN>(pos.ep_square(), Them);
- 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);
+ assert(b1);
- if (Type != MV_CAPTURE && pos.can_castle(us))
- {
- if (pos.can_castle(us == WHITE ? WHITE_OO : BLACK_OO))
- mlist = generate_castle_moves<KING_SIDE>(pos, mlist, us);
+ while (b1)
+ *moveList++ = make<ENPASSANT>(pop_lsb(&b1), pos.ep_square());
+ }
+ }
- if (pos.can_castle(us == WHITE ? WHITE_OOO : BLACK_OOO))
- mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist, us);
+ return moveList;
}
- return mlist;
-}
-// Explicit template instantiations
-template MoveStack* generate<MV_CAPTURE>(const Position& pos, MoveStack* mlist);
-template MoveStack* generate<MV_NON_CAPTURE>(const Position& pos, MoveStack* mlist);
-template MoveStack* generate<MV_NON_EVASION>(const Position& pos, MoveStack* mlist);
+ template<PieceType Pt, bool Checks>
+ ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Color us,
+ Bitboard target) {
+ static_assert(Pt != KING && Pt != PAWN, "Unsupported piece type in generate_moves()");
-/// 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.
-template<>
-MoveStack* generate<MV_NON_CAPTURE_CHECK>(const Position& pos, MoveStack* mlist) {
+ const Square* pl = pos.squares<Pt>(us);
- assert(!pos.in_check());
+ for (Square from = *pl; from != SQ_NONE; from = *++pl)
+ {
+ if (Checks)
+ {
+ if ( (Pt == BISHOP || Pt == ROOK || Pt == QUEEN)
+ && !(PseudoAttacks[Pt][from] & target & pos.check_squares(Pt)))
+ continue;
- Bitboard b, dc;
- Square from;
- Color us = pos.side_to_move();
- Square ksq = pos.king_square(opposite_color(us));
+ if (pos.blockers_for_king(~us) & from)
+ continue;
+ }
- assert(pos.piece_on(ksq) == make_piece(opposite_color(us), KING));
+ Bitboard b = pos.attacks_from<Pt>(from) & target;
- // Discovered non-capture checks
- b = dc = pos.discovered_check_candidates();
+ if (Checks)
+ b &= pos.check_squares(Pt);
- while (b)
- {
- from = pop_1st_bit(&b);
- switch (piece_type(pos.piece_on(from)))
- {
- case PAWN: /* Will be generated togheter with pawns direct checks */ 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;
- }
+ while (b)
+ *moveList++ = make_move(from, pop_lsb(&b));
+ }
+
+ return moveList;
}
- // Direct non-capture checks
- mlist = generate_direct_checks<PAWN>(pos, mlist, us, dc, ksq);
- mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, dc, ksq);
- mlist = generate_direct_checks<BISHOP>(pos, mlist, us, dc, ksq);
- mlist = generate_direct_checks<ROOK>(pos, mlist, us, dc, ksq);
- return generate_direct_checks<QUEEN>(pos, mlist, us, dc, ksq);
-}
+ template<Color Us, GenType Type>
+ ExtMove* generate_all(const Position& pos, ExtMove* moveList, Bitboard target) {
+ constexpr bool Checks = Type == QUIET_CHECKS; // Reduce template instantations
-/// generate_evasions() generates all pseudo-legal check evasions when
-/// the side to move is in check. Returns a pointer to the end of the move list.
-template<>
-MoveStack* generate<MV_EVASION>(const Position& pos, MoveStack* mlist) {
+ moveList = generate_pawn_moves<Us, Type>(pos, moveList, target);
+ moveList = generate_moves<KNIGHT, Checks>(pos, moveList, Us, target);
+ moveList = generate_moves<BISHOP, Checks>(pos, moveList, Us, target);
+ moveList = generate_moves< ROOK, Checks>(pos, moveList, Us, target);
+ moveList = generate_moves< QUEEN, Checks>(pos, moveList, Us, target);
- assert(pos.in_check());
+ if (Type != QUIET_CHECKS && Type != EVASIONS)
+ {
+ Square ksq = pos.square<KING>(Us);
+ Bitboard b = pos.attacks_from<KING>(ksq) & target;
+ while (b)
+ *moveList++ = make_move(ksq, pop_lsb(&b));
+
+ if ((Type != CAPTURES) && pos.can_castle(Us & ANY_CASTLING))
+ for(CastlingRights cr : { Us & KING_SIDE, Us & QUEEN_SIDE } )
+ if (!pos.castling_impeded(cr) && pos.can_castle(cr))
+ *moveList++ = make<CASTLING>(ksq, pos.castling_rook_square(cr));
+ }
- Bitboard b, target;
- Square from, checksq;
- int checkersCnt = 0;
- Color us = pos.side_to_move();
- Square ksq = pos.king_square(us);
- Bitboard checkers = pos.checkers();
- Bitboard sliderAttacks = EmptyBoardBB;
-
- assert(pos.piece_on(ksq) == make_piece(us, KING));
- assert(checkers);
-
- // Find squares attacked by slider checkers, we will remove
- // them from the king evasions set so to early skip known
- // illegal moves and avoid an useless legality check later.
- b = checkers;
- do
- {
- checkersCnt++;
- checksq = pop_1st_bit(&b);
-
- assert(piece_color(pos.piece_on(checksq)) == opposite_color(us));
-
- switch (piece_type(pos.piece_on(checksq)))
- {
- case BISHOP: sliderAttacks |= BishopPseudoAttacks[checksq]; break;
- case ROOK: sliderAttacks |= RookPseudoAttacks[checksq]; break;
- case QUEEN:
- // If queen and king are far 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) || (RookPseudoAttacks[checksq] & (1ULL << ksq)))
- sliderAttacks |= QueenPseudoAttacks[checksq];
-
- // Otherwise, if king and queen are adjacent and on a diagonal line, 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 |= BishopPseudoAttacks[checksq] | pos.attacks_from<ROOK>(checksq);
-
- default:
- break;
- }
- } while (b);
+ return moveList;
+ }
- // Generate evasions for king, capture and non capture moves
- b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
- from = ksq;
- SERIALIZE_MOVES(b);
-
- // Generate evasions for other pieces only if not double check
- if (checkersCnt > 1)
- return mlist;
-
- // Find squares where a blocking evasion or a capture of the
- // checker piece is possible.
- target = squares_between(checksq, ksq) | checkers;
-
- mlist = generate_piece_moves<PAWN, MV_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);
-}
+} // namespace
-/// generate<MV_LEGAL> computes a complete list of legal moves in the current position
+/// <CAPTURES> Generates all pseudo-legal captures and queen promotions
+/// <QUIETS> Generates all pseudo-legal non-captures and underpromotions
+/// <NON_EVASIONS> Generates all pseudo-legal captures and non-captures
+///
+/// Returns a pointer to the end of the move list.
-template<>
-MoveStack* generate<MV_LEGAL>(const Position& pos, MoveStack* mlist) {
+template<GenType Type>
+ExtMove* generate(const Position& pos, ExtMove* moveList) {
- MoveStack *last, *cur = mlist;
- Bitboard pinned = pos.pinned_pieces();
+ static_assert(Type == CAPTURES || Type == QUIETS || Type == NON_EVASIONS, "Unsupported type in generate()");
+ assert(!pos.checkers());
- last = pos.in_check() ? generate<MV_EVASION>(pos, mlist)
- : generate<MV_NON_EVASION>(pos, mlist);
+ Color us = pos.side_to_move();
- // Remove illegal moves from the list
- while (cur != last)
- if (!pos.pl_move_is_legal(cur->move, pinned))
- cur->move = (--last)->move;
- else
- cur++;
+ Bitboard target = Type == CAPTURES ? pos.pieces(~us)
+ : Type == QUIETS ? ~pos.pieces()
+ : Type == NON_EVASIONS ? ~pos.pieces(us) : 0;
- return last;
+ return us == WHITE ? generate_all<WHITE, Type>(pos, moveList, target)
+ : generate_all<BLACK, Type>(pos, moveList, target);
}
+// Explicit template instantiations
+template ExtMove* generate<CAPTURES>(const Position&, ExtMove*);
+template ExtMove* generate<QUIETS>(const Position&, ExtMove*);
+template ExtMove* generate<NON_EVASIONS>(const Position&, ExtMove*);
-namespace {
-
- template<Square Delta>
- inline Bitboard move_pawns(Bitboard p) {
-
- return Delta == DELTA_N ? p << 8 : Delta == DELTA_S ? p >> 8 :
- Delta == DELTA_NE ? p << 9 : Delta == DELTA_SE ? p >> 7 :
- Delta == DELTA_NW ? p << 7 : Delta == DELTA_SW ? p >> 9 : p;
- }
-
- template<MoveType Type, Square Delta>
- inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard target) {
-
- const Bitboard TFileABB = (Delta == DELTA_NE || Delta == DELTA_SE ? FileABB : FileHBB);
-
- Bitboard b;
- Square to;
-
- // Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
- b = move_pawns<Delta>(pawns) & target & ~TFileABB;
- SERIALIZE_MOVES_D(b, -Delta);
- return mlist;
- }
-
- template<MoveType Type, Square Delta>
- inline MoveStack* generate_promotions(const Position& pos, MoveStack* mlist, Bitboard pawnsOn7, Bitboard target) {
- const Bitboard TFileABB = (Delta == DELTA_NE || Delta == DELTA_SE ? FileABB : FileHBB);
+/// generate<QUIET_CHECKS> generates all pseudo-legal non-captures and knight
+/// underpromotions that give check. Returns a pointer to the end of the move list.
+template<>
+ExtMove* generate<QUIET_CHECKS>(const Position& pos, ExtMove* moveList) {
- Bitboard b;
- Square to;
+ assert(!pos.checkers());
- // Promotions and under-promotions, both captures and non-captures
- b = move_pawns<Delta>(pawnsOn7) & target;
+ Color us = pos.side_to_move();
+ Bitboard dc = pos.blockers_for_king(~us) & pos.pieces(us);
- if (Delta != DELTA_N && Delta != DELTA_S)
- b &= ~TFileABB;
+ while (dc)
+ {
+ Square from = pop_lsb(&dc);
+ PieceType pt = type_of(pos.piece_on(from));
- while (b)
- {
- to = pop_1st_bit(&b);
+ if (pt == PAWN)
+ continue; // Will be generated together with direct checks
- if (Type == MV_CAPTURE || Type == MV_EVASION)
- (*mlist++).move = make_promotion_move(to - Delta, to, QUEEN);
+ Bitboard b = pos.attacks_from(pt, from) & ~pos.pieces();
- if (Type == MV_NON_CAPTURE || Type == MV_EVASION)
- {
- (*mlist++).move = make_promotion_move(to - Delta, to, ROOK);
- (*mlist++).move = make_promotion_move(to - Delta, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - Delta, to, KNIGHT);
- }
+ if (pt == KING)
+ b &= ~PseudoAttacks[QUEEN][pos.square<KING>(~us)];
- // This is the only possible under promotion that can give a check
- // not already included in the queen-promotion.
- if ( Type == MV_CHECK
- && bit_is_set(pos.attacks_from<KNIGHT>(to), pos.king_square(Delta > 0 ? BLACK : WHITE)))
- (*mlist++).move = make_promotion_move(to - Delta, to, KNIGHT);
- else (void)pos; // Silence a warning under MSVC
- }
- return mlist;
+ while (b)
+ *moveList++ = make_move(from, pop_lsb(&b));
}
- template<Color Us, MoveType Type>
- MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {
-
- // Calculate 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 TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
- const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
- const Square UP = (Us == WHITE ? DELTA_N : DELTA_S);
- const Square RIGHT_UP = (Us == WHITE ? DELTA_NE : DELTA_SW);
- const Square LEFT_UP = (Us == WHITE ? DELTA_NW : DELTA_SE);
-
- Square to;
- Bitboard b1, b2, dc1, dc2, pawnPushes, emptySquares;
- Bitboard pawns = pos.pieces(PAWN, Us);
- Bitboard pawnsOn7 = pawns & TRank7BB;
- Bitboard enemyPieces = (Type == MV_CAPTURE ? target : pos.pieces(Them));
-
- // Pre-calculate pawn pushes before changing emptySquares definition
- if (Type != MV_CAPTURE)
- {
- emptySquares = (Type == MV_NON_CAPTURE ? target : pos.empty_squares());
- pawnPushes = move_pawns<UP>(pawns & ~TRank7BB) & emptySquares;
- }
-
- if (Type == MV_EVASION)
- {
- emptySquares &= target; // Only blocking squares
- enemyPieces &= target; // Capture only the checker piece
- }
-
- // Promotions and underpromotions
- if (pawnsOn7)
- {
- if (Type == MV_CAPTURE)
- emptySquares = pos.empty_squares();
-
- pawns &= ~TRank7BB;
- mlist = generate_promotions<Type, RIGHT_UP>(pos, mlist, pawnsOn7, enemyPieces);
- mlist = generate_promotions<Type, LEFT_UP>(pos, mlist, pawnsOn7, enemyPieces);
- mlist = generate_promotions<Type, UP>(pos, mlist, pawnsOn7, emptySquares);
- }
-
- // Standard captures
- if (Type == MV_CAPTURE || Type == MV_EVASION)
- {
- mlist = generate_pawn_captures<Type, RIGHT_UP>(mlist, pawns, enemyPieces);
- mlist = generate_pawn_captures<Type, LEFT_UP>(mlist, pawns, enemyPieces);
- }
+ return us == WHITE ? generate_all<WHITE, QUIET_CHECKS>(pos, moveList, ~pos.pieces())
+ : generate_all<BLACK, QUIET_CHECKS>(pos, moveList, ~pos.pieces());
+}
- // Single and double pawn pushes
- if (Type != MV_CAPTURE)
- {
- b1 = (Type != MV_EVASION ? pawnPushes : pawnPushes & emptySquares);
- b2 = move_pawns<UP>(pawnPushes & TRank3BB) & emptySquares;
- if (Type == MV_CHECK)
- {
- // Consider only pawn moves which give direct checks
- b1 &= pos.attacks_from<PAWN>(ksq, Them);
- b2 &= pos.attacks_from<PAWN>(ksq, Them);
+/// generate<EVASIONS> generates all pseudo-legal check evasions when the side
+/// to move is in check. Returns a pointer to the end of the move list.
+template<>
+ExtMove* generate<EVASIONS>(const Position& pos, ExtMove* moveList) {
- // Add 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
- {
- dc1 = move_pawns<UP>(pawns & target & ~file_bb(ksq)) & emptySquares;
- dc2 = move_pawns<UP>(dc1 & TRank3BB) & emptySquares;
+ assert(pos.checkers());
- b1 |= dc1;
- b2 |= dc2;
- }
- }
- SERIALIZE_MOVES_D(b1, -UP);
- SERIALIZE_MOVES_D(b2, -UP -UP);
- }
+ Color us = pos.side_to_move();
+ Square ksq = pos.square<KING>(us);
+ Bitboard sliderAttacks = 0;
+ Bitboard sliders = pos.checkers() & ~pos.pieces(KNIGHT, PAWN);
+
+ // Find all the squares attacked by slider checkers. We will remove them from
+ // the king evasions in order to skip known illegal moves, which avoids any
+ // useless legality checks later on.
+ while (sliders)
+ {
+ Square checksq = pop_lsb(&sliders);
+ sliderAttacks |= LineBB[ksq][checksq] ^ checksq;
+ }
- // En passant captures
- if ((Type == MV_CAPTURE || Type == MV_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);
+ // Generate evasions for king, capture and non capture moves
+ Bitboard b = pos.attacks_from<KING>(ksq) & ~pos.pieces(us) & ~sliderAttacks;
+ while (b)
+ *moveList++ = make_move(ksq, pop_lsb(&b));
- // 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 && !bit_is_set(target, pos.ep_square() - UP))
- return mlist;
+ if (more_than_one(pos.checkers()))
+ return moveList; // Double check, only a king move can save the day
- b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);
+ // Generate blocking evasions or captures of the checking piece
+ Square checksq = lsb(pos.checkers());
+ Bitboard target = between_bb(checksq, ksq) | checksq;
- assert(b1 != EmptyBoardBB);
+ return us == WHITE ? generate_all<WHITE, EVASIONS>(pos, moveList, target)
+ : generate_all<BLACK, EVASIONS>(pos, moveList, target);
+}
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_ep_move(to, pos.ep_square());
- }
- }
- return mlist;
- }
- template<CastlingSide Side>
- MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist, Color us) {
-
- CastleRight f = CastleRight((Side == KING_SIDE ? WHITE_OO : WHITE_OOO) << us);
- Color them = opposite_color(us);
-
- // After castling, the rook and king's final positions are exactly the same
- // in Chess960 as they would be in standard chess.
- Square kfrom = pos.king_square(us);
- Square rfrom = pos.castle_rook_square(f);
- Square kto = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
- Square rto = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1);
-
- assert(!pos.in_check());
- assert(pos.piece_on(kfrom) == make_piece(us, KING));
- assert(pos.piece_on(rfrom) == make_piece(us, ROOK));
-
- // Unimpeded rule: All the squares between the king's initial and final squares
- // (including the final square), and all the squares between the rook's initial
- // and final squares (including the final square), must be vacant except for
- // the king and castling rook.
- for (Square s = Min(kfrom, kto); s <= Max(kfrom, kto); s++)
- if ( (s != kfrom && s != rfrom && !pos.square_is_empty(s))
- ||(pos.attackers_to(s) & pos.pieces(them)))
- return mlist;
-
- for (Square s = Min(rfrom, rto); s <= Max(rfrom, rto); s++)
- if (s != kfrom && s != rfrom && !pos.square_is_empty(s))
- return 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())
- {
- Bitboard occ = pos.occupied_squares();
- clear_bit(&occ, rfrom);
- if (pos.attackers_to(kto, occ) & pos.pieces(them))
- return mlist;
- }
+/// generate<LEGAL> generates all the legal moves in the given position
- (*mlist++).move = make_castle_move(kfrom, rfrom);
+template<>
+ExtMove* generate<LEGAL>(const Position& pos, ExtMove* moveList) {
- return mlist;
- }
+ Color us = pos.side_to_move();
+ Bitboard pinned = pos.blockers_for_king(us) & pos.pieces(us);
+ Square ksq = pos.square<KING>(us);
+ ExtMove* cur = moveList;
+
+ moveList = pos.checkers() ? generate<EVASIONS >(pos, moveList)
+ : generate<NON_EVASIONS>(pos, moveList);
+ while (cur != moveList)
+ if ( (pinned || from_sq(*cur) == ksq || type_of(*cur) == ENPASSANT)
+ && !pos.legal(*cur))
+ *cur = (--moveList)->move;
+ else
+ ++cur;
-} // namespace
+ return moveList;
+}