/// 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.
public static int generate_quiet_checks(Position pos, ExtMove[] mlist, int mPos)
{
Debug.Assert(0 == pos.checkers());
Color us = pos.side_to_move();
CheckInfo ci = new CheckInfo(pos);
Bitboard dc = ci.dcCandidates;
while (dc != 0)
{
Square from = BitBoard.pop_lsb(ref dc);
PieceType pt = Types.type_of_piece(pos.piece_on(from));
if (pt == PieceTypeS.PAWN)
{
continue; // Will be generated togheter with direct checks
}
Bitboard b = pos.attacks_from_piece_square((Piece)pt, from) & ~pos.pieces();
if (pt == PieceTypeS.KING)
{
b &= ~BitBoard.PseudoAttacks[PieceTypeS.QUEEN][ci.ksq];
}
while (b != 0)
{
mlist[mPos++].move = Types.make_move(from, BitBoard.pop_lsb(ref b));
}
}
return(us == ColorS.WHITE ? generate_all(pos, mlist, mPos, ~pos.pieces(), ColorS.WHITE, GenTypeS.QUIET_CHECKS, ci) :
generate_all(pos, mlist, mPos, ~pos.pieces(), ColorS.BLACK, GenTypeS.QUIET_CHECKS, ci));
}
public static int generate_moves(Position pos, ExtMove[] mlist, int mPos, Color us, Bitboard target, CheckInfo ci, PieceType Pt, bool Checks)
{
Debug.Assert(Pt != PieceTypeS.KING && Pt != PieceTypeS.PAWN);
Square[] pieceList = pos.list(us, Pt);
int pl = 0;
for (Square from = pieceList[pl]; from != SquareS.SQ_NONE; from = pieceList[++pl])
{
if (Checks)
{
if ((Pt == PieceTypeS.BISHOP || Pt == PieceTypeS.ROOK || Pt == PieceTypeS.QUEEN) &&
0 == (BitBoard.PseudoAttacks[Pt][from] & target & ci.checkSq[Pt]))
{
continue;
}
if (ci.dcCandidates != 0 && (ci.dcCandidates & BitBoard.SquareBB[from]) != 0)
{
continue;
}
}
Bitboard b = pos.attacks_from_square_piecetype(from, Pt) & target;
if (Checks)
{
b &= ci.checkSq[Pt];
}
while (b != 0)
{
mlist[mPos++].move = Types.make_move(from, BitBoard.pop_lsb(ref b));
}
}
return(mPos);
}
/// 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.
public static int generate_evasions(Position pos, ExtMove[] mlist, int mPos)
{
Debug.Assert(pos.checkers() != 0);
Color us = pos.side_to_move();
Square ksq = pos.king_square(us);
Bitboard sliderAttacks = 0;
Bitboard sliders = pos.checkers() & ~pos.pieces_piecetype(PieceTypeS.KNIGHT, PieceTypeS.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 != 0)
{
Square checksq = BitBoard.pop_lsb(ref sliders);
sliderAttacks |= BitBoard.LineBB[checksq][ksq] ^ BitBoard.SquareBB[checksq];
}
// Generate evasions for king, capture and non capture moves
Bitboard b = pos.attacks_from_square_piecetype(ksq, PieceTypeS.KING) & ~pos.pieces_color(us) & ~sliderAttacks;
while (b != 0)
{
mlist[mPos++].move = Types.make_move(ksq, BitBoard.pop_lsb(ref b));
}
if (BitBoard.more_than_one(pos.checkers()))
{
return(mPos); // Double check, only a king move can save the day
}
// Generate blocking evasions or captures of the checking piece
Square checksq2 = BitBoard.lsb(pos.checkers());
Bitboard target = BitBoard.between_bb(checksq2, ksq) | BitBoard.SquareBB[checksq2];
return(us == ColorS.WHITE ? generate_all(pos, mlist, mPos, target, ColorS.WHITE, GenTypeS.EVASIONS) :
generate_all(pos, mlist, mPos, target, ColorS.BLACK, GenTypeS.EVASIONS));
}
public static int generate_all(Position pos, ExtMove[] mlist, int mPos, Bitboard target, Color us, GenType Type, CheckInfo ci = null)
{
bool Checks = Type == GenTypeS.QUIET_CHECKS;
mPos = generate_pawn_moves(pos, mlist, mPos, target, ci, us, Type);
mPos = generate_moves(pos, mlist, mPos, us, target, ci, PieceTypeS.KNIGHT, Checks);
mPos = generate_moves(pos, mlist, mPos, us, target, ci, PieceTypeS.BISHOP, Checks);
mPos = generate_moves(pos, mlist, mPos, us, target, ci, PieceTypeS.ROOK, Checks);
mPos = generate_moves(pos, mlist, mPos, us, target, ci, PieceTypeS.QUEEN, Checks);
if (Type != GenTypeS.QUIET_CHECKS && Type != GenTypeS.EVASIONS)
{
Square ksq = pos.king_square(us);
Bitboard b = pos.attacks_from_square_piecetype(ksq, PieceTypeS.KING) & target;
while (b != 0)
{
mlist[mPos++].move = Types.make_move(ksq, BitBoard.pop_lsb(ref b));
}
}
if (Type != GenTypeS.CAPTURES && Type != GenTypeS.EVASIONS && pos.can_castle_color(us) != 0)
{
if (pos.is_chess960() != 0)
{
mPos = generate_castling(pos, mlist, mPos, us, ci, (new MakeCastlingS(us, CastlingSideS.KING_SIDE)).right, Checks, true);
mPos = generate_castling(pos, mlist, mPos, us, ci, (new MakeCastlingS(us, CastlingSideS.QUEEN_SIDE)).right, Checks, true);
}
else
{
mPos = generate_castling(pos, mlist, mPos, us, ci, (new MakeCastlingS(us, CastlingSideS.KING_SIDE)).right, Checks, false);
mPos = generate_castling(pos, mlist, mPos, us, ci, (new MakeCastlingS(us, CastlingSideS.QUEEN_SIDE)).right, Checks, false);
}
}
return(mPos);
}
/// move_to_san() takes a position and a legal Move as input and returns its
/// short algebraic notation representation.
public static string move_to_san(Position pos, Move m)
{
if (m == MoveS.MOVE_NONE)
{
return("(none)");
}
if (m == MoveS.MOVE_NULL)
{
return("(null)");
}
Debug.Assert((new MoveList(pos, GenTypeS.LEGAL).contains(m)));
Bitboard others, b;
string san = "";
Color us = pos.side_to_move();
Square from = Types.from_sq(m);
Square to = Types.to_sq(m);
Piece pc = pos.piece_on(from);
PieceType pt = Types.type_of_piece(pc);
if (Types.type_of_move(m) == MoveTypeS.CASTLING)
{
san = to > from ? "O-O" : "O-O-O";
}
else
{
if (pt != PieceTypeS.PAWN)
{
san = "" + PieceToChar[ColorS.WHITE][pt]; // Upper case
// A disambiguation occurs if we have more then one piece of type 'pt'
// that can reach 'to' with a legal move.
others = b = (pos.attacks_from_piece_square(pc, to) & pos.pieces_color_piecetype(us, pt)) ^ BitBoard.SquareBB[from];
while (b != 0)
{
Square s = BitBoard.pop_lsb(ref b);
if (!pos.legal(Types.make_move(s, to), pos.pinned_pieces(us)))
{
others ^= BitBoard.SquareBB[s];
}
}
if (0 == others)
{ /* Disambiguation is not needed */
}
else if (0 == (others & BitBoard.file_bb_square(from)))
{
san += Types.file_to_char(Types.file_of(from));
}
else if (0 == (others & BitBoard.rank_bb_square(from)))
{
san += Types.rank_to_char(Types.rank_of(from));
}
else
{
san += Types.square_to_string(from);
}
}
else if (pos.capture(m))
{
san = "" + Types.file_to_char(Types.file_of(from));
}
if (pos.capture(m))
{
san += 'x';
}
san += Types.square_to_string(to);
if (Types.type_of_move(m) == MoveTypeS.PROMOTION)
{
san += "=" + PieceToChar[ColorS.WHITE][Types.promotion_type(m)];
}
}
if (pos.gives_check(m, new CheckInfo(pos)))
{
StateInfo st = new StateInfo();
pos.do_move(m, st);
san += (new MoveList(pos, GenTypeS.LEGAL)).size() > 0 ? "+" : "#";
pos.undo_move(m);
}
return(san);
}
public static int generate_pawn_moves(Position pos, ExtMove[] mlist, int mPos, Bitboard target, CheckInfo ci, Color Us, GenType Type)
{
// Compute our parametrized parameters at compile time, named according to
// the point of view of white side.
Color Them = (Us == ColorS.WHITE ? ColorS.BLACK : ColorS.WHITE);
Bitboard TRank8BB = (Us == ColorS.WHITE ? BitBoard.Rank8BB : BitBoard.Rank1BB);
Bitboard TRank7BB = (Us == ColorS.WHITE ? BitBoard.Rank7BB : BitBoard.Rank2BB);
Bitboard TRank3BB = (Us == ColorS.WHITE ? BitBoard.Rank3BB : BitBoard.Rank6BB);
Square Up = (Us == ColorS.WHITE ? SquareS.DELTA_N : SquareS.DELTA_S);
Square Right = (Us == ColorS.WHITE ? SquareS.DELTA_NE : SquareS.DELTA_SW);
Square Left = (Us == ColorS.WHITE ? SquareS.DELTA_NW : SquareS.DELTA_SE);
Bitboard b1, b2, dc1, dc2, emptySquares = 0;
Bitboard pawnsOn7 = pos.pieces_color_piecetype(Us, PieceTypeS.PAWN) & TRank7BB;
Bitboard pawnsNotOn7 = pos.pieces_color_piecetype(Us, PieceTypeS.PAWN) & ~TRank7BB;
Bitboard enemies = (Type == GenTypeS.EVASIONS ? pos.pieces_color(Them) & target :
Type == GenTypeS.CAPTURES ? target : pos.pieces_color(Them));
// Single and double pawn pushes, no promotions
if (Type != GenTypeS.CAPTURES)
{
emptySquares = (Type == GenTypeS.QUIETS || Type == GenTypeS.QUIET_CHECKS ? target : ~pos.pieces());
b1 = BitBoard.shift_bb(pawnsNotOn7, Up) & emptySquares;
b2 = BitBoard.shift_bb(b1 & TRank3BB, Up) & emptySquares;
if (Type == GenTypeS.EVASIONS) // Consider only blocking squares
{
b1 &= target;
b2 &= target;
}
if (Type == GenTypeS.QUIET_CHECKS)
{
b1 &= pos.attacks_from_pawn(ci.ksq, Them);
b2 &= pos.attacks_from_pawn(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) != 0)
{
dc1 = BitBoard.shift_bb(pawnsNotOn7 & ci.dcCandidates, Up) & emptySquares & ~BitBoard.file_bb_square(ci.ksq);
dc2 = BitBoard.shift_bb(dc1 & TRank3BB, Up) & emptySquares;
b1 |= dc1;
b2 |= dc2;
}
}
while (b1 != 0)
{
Square to = BitBoard.pop_lsb(ref b1);
mlist[mPos++].move = Types.make_move(to - Up, to);
}
while (b2 != 0)
{
Square to = BitBoard.pop_lsb(ref b2);
mlist[mPos++].move = Types.make_move(to - Up - Up, to);
}
}
// Promotions and underpromotions
if (pawnsOn7 != 0 && (Type != GenTypeS.EVASIONS || (target & TRank8BB) != 0))
{
if (Type == GenTypeS.CAPTURES)
{
emptySquares = ~pos.pieces();
}
if (Type == GenTypeS.EVASIONS)
{
emptySquares &= target;
}
mPos = generate_promotions(mlist, mPos, pawnsOn7, enemies, ci, Type, Right);
mPos = generate_promotions(mlist, mPos, pawnsOn7, enemies, ci, Type, Left);
mPos = generate_promotions(mlist, mPos, pawnsOn7, emptySquares, ci, Type, Up);
}
// Standard and en-passant captures
if (Type == GenTypeS.CAPTURES || Type == GenTypeS.EVASIONS || Type == GenTypeS.NON_EVASIONS)
{
b1 = BitBoard.shift_bb(pawnsNotOn7, Right) & enemies;
b2 = BitBoard.shift_bb(pawnsNotOn7, Left) & enemies;
while (b1 != 0)
{
Square to = BitBoard.pop_lsb(ref b1);
mlist[mPos++].move = Types.make_move(to - Right, to);
}
while (b2 != 0)
{
Square to = BitBoard.pop_lsb(ref b2);
mlist[mPos++].move = Types.make_move(to - Left, to);
}
if (pos.ep_square() != SquareS.SQ_NONE)
{
Debug.Assert(Types.rank_of(pos.ep_square()) == Types.relative_rank_rank(Us, RankS.RANK_6));
// 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 == GenTypeS.EVASIONS && (target & BitBoard.SquareBB[(pos.ep_square() - Up)]) == 0)
{
return(mPos);
}
b1 = pawnsNotOn7 & pos.attacks_from_pawn(pos.ep_square(), Them);
Debug.Assert(b1 != 0);
while (b1 != 0)
{
mlist[mPos++].move = Types.make(BitBoard.pop_lsb(ref b1), pos.ep_square(), MoveTypeS.ENPASSANT);
}
}
}
return(mPos);
}
