constexpr Direction UpLeft = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
const Square ksq = pos.square<KING>(Them);
- Bitboard emptySquares;
+ const Bitboard emptySquares = Type == QUIETS || Type == QUIET_CHECKS ? target : ~pos.pieces();
+ const Bitboard enemies = Type == EVASIONS ? pos.checkers()
+ : Type == CAPTURES ? target : pos.pieces(Them);
Bitboard pawnsOn7 = pos.pieces(Us, PAWN) & TRank7BB;
Bitboard pawnsNotOn7 = pos.pieces(Us, PAWN) & ~TRank7BB;
- Bitboard enemies = (Type == EVASIONS ? pos.checkers():
- 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());
-
Bitboard b1 = shift<Up>(pawnsNotOn7) & emptySquares;
Bitboard b2 = shift<Up>(b1 & TRank3BB) & emptySquares;
if (Type == QUIET_CHECKS)
{
- b1 &= pawn_attacks_bb(Them, ksq);
- b2 &= pawn_attacks_bb(Them, ksq);
-
- // Add pawn pushes which give discovered check. This is possible only
- // if the pawn is not on the same file as the enemy king, because we
- // don't generate captures. Note that a possible discovered check
- // promotion has been already generated amongst the captures.
- Bitboard dcCandidateQuiets = pos.blockers_for_king(Them) & pawnsNotOn7;
- if (dcCandidateQuiets)
- {
- Bitboard dc1 = shift<Up>(dcCandidateQuiets) & emptySquares & ~file_bb(ksq);
- Bitboard dc2 = shift<Up>(dc1 & TRank3BB) & emptySquares;
-
- b1 |= dc1;
- b2 |= dc2;
- }
+ // To make a quiet check, you either make a direct check by pushing a pawn
+ // or push a blocker pawn that is not on the same file as the enemy king.
+ // Discovered check promotion has been already generated amongst the captures.
+ Bitboard dcCandidatePawns = pos.blockers_for_king(Them) & ~file_bb(ksq);
+ b1 &= pawn_attacks_bb(Them, ksq) | shift< Up>(dcCandidatePawns);
+ b2 &= pawn_attacks_bb(Them, ksq) | shift<Up+Up>(dcCandidatePawns);
}
while (b1)
// Promotions and underpromotions
if (pawnsOn7)
{
- if (Type == CAPTURES)
- emptySquares = ~pos.pieces();
-
- if (Type == EVASIONS)
- emptySquares &= target;
-
Bitboard b1 = shift<UpRight>(pawnsOn7) & enemies;
Bitboard b2 = shift<UpLeft >(pawnsOn7) & enemies;
Bitboard b3 = shift<Up >(pawnsOn7) & emptySquares;
+ if (Type == EVASIONS)
+ b3 &= target;
+
while (b1)
moveList = make_promotions<Type, UpRight>(moveList, pop_lsb(b1), ksq);
}
- template<PieceType Pt, bool Checks>
- ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Bitboard piecesToMove, Bitboard target) {
+ template<Color Us, PieceType Pt, bool Checks>
+ ExtMove* generate_moves(const Position& pos, ExtMove* moveList, Bitboard target) {
static_assert(Pt != KING && Pt != PAWN, "Unsupported piece type in generate_moves()");
- Bitboard bb = piecesToMove & pos.pieces(Pt);
+ Bitboard bb = pos.pieces(Us, Pt);
while (bb)
{
Square from = pop_lsb(bb);
-
Bitboard b = attacks_bb<Pt>(from, pos.pieces()) & target;
- if constexpr (Checks)
+
+ // To check, you either move freely a blocker or make a direct check.
+ if (Checks && (Pt == QUEEN || !(pos.blockers_for_king(~Us) & from)))
b &= pos.check_squares(Pt);
while (b)
static_assert(Type != LEGAL, "Unsupported type in generate_all()");
constexpr bool Checks = Type == QUIET_CHECKS; // Reduce template instantiations
- Bitboard target, piecesToMove = pos.pieces(Us);
+ const Square ksq = pos.square<KING>(Us);
+ Bitboard target;
- if(Type == QUIET_CHECKS)
- piecesToMove &= ~pos.blockers_for_king(~Us);
+ if (Type == EVASIONS && more_than_one(pos.checkers()))
+ goto kingMoves; // Double check, only a king move can save the day
- switch (Type)
- {
- case CAPTURES:
- target = pos.pieces(~Us);
- break;
- case QUIETS:
- case QUIET_CHECKS:
- target = ~pos.pieces();
- break;
- case EVASIONS:
- target = between_bb(pos.square<KING>(Us), lsb(pos.checkers()));
- break;
- case NON_EVASIONS:
- target = ~pos.pieces(Us);
- break;
- }
+ target = Type == EVASIONS ? between_bb(ksq, lsb(pos.checkers()))
+ : Type == NON_EVASIONS ? ~pos.pieces( Us)
+ : Type == CAPTURES ? pos.pieces(~Us)
+ : ~pos.pieces( ); // QUIETS || QUIET_CHECKS
moveList = generate_pawn_moves<Us, Type>(pos, moveList, target);
- moveList = generate_moves<KNIGHT, Checks>(pos, moveList, piecesToMove, target);
- moveList = generate_moves<BISHOP, Checks>(pos, moveList, piecesToMove, target);
- moveList = generate_moves< ROOK, Checks>(pos, moveList, piecesToMove, target);
- moveList = generate_moves< QUEEN, Checks>(pos, moveList, piecesToMove, target);
+ moveList = generate_moves<Us, KNIGHT, Checks>(pos, moveList, target);
+ moveList = generate_moves<Us, BISHOP, Checks>(pos, moveList, target);
+ moveList = generate_moves<Us, ROOK, Checks>(pos, moveList, target);
+ moveList = generate_moves<Us, QUEEN, Checks>(pos, moveList, target);
- if (Type != QUIET_CHECKS && Type != EVASIONS)
+kingMoves:
+ if (!Checks || pos.blockers_for_king(~Us) & ksq)
{
- Square ksq = pos.square<KING>(Us);
- Bitboard b = attacks_bb<KING>(ksq) & target;
+ Bitboard b = attacks_bb<KING>(ksq) & (Type == EVASIONS ? ~pos.pieces(Us) : target);
+ if (Checks)
+ b &= ~attacks_bb<QUEEN>(pos.square<KING>(~Us));
+
while (b)
*moveList++ = make_move(ksq, pop_lsb(b));
- if ((Type != CAPTURES) && pos.can_castle(Us & ANY_CASTLING))
+ if ((Type == QUIETS || Type == NON_EVASIONS) && 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));
/// <CAPTURES> Generates all pseudo-legal captures plus queen and checking knight promotions
/// <QUIETS> Generates all pseudo-legal non-captures and underpromotions (except checking knight)
+/// <EVASIONS> Generates all pseudo-legal check evasions when the side to move is in check
+/// <QUIET_CHECKS> Generates all pseudo-legal non-captures giving check, except castling
/// <NON_EVASIONS> Generates all pseudo-legal captures and non-captures
///
/// Returns a pointer to the end of the move list.
template<GenType Type>
ExtMove* generate(const Position& pos, ExtMove* moveList) {
- static_assert(Type == CAPTURES || Type == QUIETS || Type == NON_EVASIONS, "Unsupported type in generate()");
- assert(!pos.checkers());
+ static_assert(Type != LEGAL, "Unsupported type in generate()");
+ assert((Type == EVASIONS) == (bool)pos.checkers());
Color us = pos.side_to_move();
// Explicit template instantiations
template ExtMove* generate<CAPTURES>(const Position&, ExtMove*);
template ExtMove* generate<QUIETS>(const Position&, ExtMove*);
+template ExtMove* generate<EVASIONS>(const Position&, ExtMove*);
+template ExtMove* generate<QUIET_CHECKS>(const Position&, ExtMove*);
template ExtMove* generate<NON_EVASIONS>(const Position&, ExtMove*);
-/// generate<QUIET_CHECKS> generates all pseudo-legal non-captures giving check,
-/// except castling. Returns a pointer to the end of the move list.
-template<>
-ExtMove* generate<QUIET_CHECKS>(const Position& pos, ExtMove* moveList) {
-
- assert(!pos.checkers());
-
- Color us = pos.side_to_move();
- Bitboard dc = pos.blockers_for_king(~us) & pos.pieces(us) & ~pos.pieces(PAWN);
-
- while (dc)
- {
- Square from = pop_lsb(dc);
- PieceType pt = type_of(pos.piece_on(from));
-
- Bitboard b = attacks_bb(pt, from, pos.pieces()) & ~pos.pieces();
-
- if (pt == KING)
- b &= ~attacks_bb<QUEEN>(pos.square<KING>(~us));
-
- while (b)
- *moveList++ = make_move(from, pop_lsb(b));
- }
-
- return us == WHITE ? generate_all<WHITE, QUIET_CHECKS>(pos, moveList)
- : generate_all<BLACK, QUIET_CHECKS>(pos, moveList);
-}
-
-
-/// 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) {
-
- assert(pos.checkers());
-
- Color us = pos.side_to_move();
- Square ksq = pos.square<KING>(us);
-
- // Generate evasions for king
- Bitboard b = attacks_bb<KING>(ksq) & ~pos.pieces(us);
- while (b)
- *moveList++ = make_move(ksq, pop_lsb(b));
-
- if (more_than_one(pos.checkers()))
- return moveList; // Double check, only a king move can save the day
-
- // Generate blocking interpositions or captures of the checking piece
- return us == WHITE ? generate_all<WHITE, EVASIONS>(pos, moveList)
- : generate_all<BLACK, EVASIONS>(pos, moveList);
-}
-
-
/// generate<LEGAL> generates all the legal moves in the given position
template<>
projects / stockfish / blobdiff