/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
constexpr Piece Pieces[] = { W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING,
B_PAWN, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING };
-
-// min_attacker() is a helper function used by see_ge() to locate the least
-// valuable attacker for the side to move, remove the attacker we just found
-// from the bitboards and scan for new X-ray attacks behind it.
-
-template<PieceType Pt>
-PieceType min_attacker(const Bitboard* byTypeBB, Square to, Bitboard stmAttackers,
- Bitboard& occupied, Bitboard& attackers) {
-
- Bitboard b = stmAttackers & byTypeBB[Pt];
- if (!b)
- return min_attacker<PieceType(Pt + 1)>(byTypeBB, to, stmAttackers, occupied, attackers);
-
- occupied ^= lsb(b); // Remove the attacker from occupied
-
- // Add any X-ray attack behind the just removed piece. For instance with
- // rooks in a8 and a7 attacking a1, after removing a7 we add rook in a8.
- // Note that new added attackers can be of any color.
- if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN)
- attackers |= attacks_bb<BISHOP>(to, occupied) & (byTypeBB[BISHOP] | byTypeBB[QUEEN]);
-
- if (Pt == ROOK || Pt == QUEEN)
- attackers |= attacks_bb<ROOK>(to, occupied) & (byTypeBB[ROOK] | byTypeBB[QUEEN]);
-
- // X-ray may add already processed pieces because byTypeBB[] is constant: in
- // the rook example, now attackers contains _again_ rook in a7, so remove it.
- attackers &= occupied;
- return Pt;
-}
-
-template<>
-PieceType min_attacker<KING>(const Bitboard*, Square, Bitboard, Bitboard&, Bitboard&) {
- return KING; // No need to update bitboards: it is the last cycle
-}
-
} // namespace
for (File f = FILE_A; f <= FILE_H; ++f)
os << " | " << PieceToChar[pos.piece_on(make_square(f, r))];
- os << " |\n +---+---+---+---+---+---+---+---+\n";
+ os << " | " << (1 + r) << "\n +---+---+---+---+---+---+---+---+\n";
}
- os << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase
+ os << " a b c d e f g h\n"
+ << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase
<< std::setfill('0') << std::setw(16) << pos.key()
<< std::setfill(' ') << std::dec << "\nCheckers: ";
Move cuckooMove[8192];
-/// Position::init() initializes at startup the various arrays used to compute
-/// hash keys.
+/// Position::init() initializes at startup the various arrays used to compute hash keys
void Position::init() {
Zobrist::enpassant[f] = rng.rand<Key>();
for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr)
- {
- Zobrist::castling[cr] = 0;
- Bitboard b = cr;
- while (b)
- {
- Key k = Zobrist::castling[1ULL << pop_lsb(&b)];
- Zobrist::castling[cr] ^= k ? k : rng.rand<Key>();
- }
- }
+ Zobrist::castling[cr] = rng.rand<Key>();
Zobrist::side = rng.rand<Key>();
Zobrist::noPawns = rng.rand<Key>();
for (Piece pc : Pieces)
for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
for (Square s2 = Square(s1 + 1); s2 <= SQ_H8; ++s2)
- if (PseudoAttacks[type_of(pc)][s1] & s2)
+ if ((type_of(pc) != PAWN) && (attacks_bb(type_of(pc), s1, 0) & s2))
{
Move move = make_move(s1, s2);
Key key = Zobrist::psq[pc][s1] ^ Zobrist::psq[pc][s2] ^ Zobrist::side;
4) En passant target square (in algebraic notation). If there's no en passant
target square, this is "-". If a pawn has just made a 2-square move, this
- is the position "behind" the pawn. This is recorded only if there is a pawn
- in position to make an en passant capture, and if there really is a pawn
- that might have advanced two squares.
+ is the position "behind" the pawn. Following X-FEN standard, this is recorded only
+ if there is a pawn in position to make an en passant capture, and if there really
+ is a pawn that might have advanced two squares.
5) Halfmove clock. This is the number of halfmoves since the last pawn advance
or capture. This is used to determine if a draw can be claimed under the
else if (token == '/')
sq += 2 * SOUTH;
- else if ((idx = PieceToChar.find(token)) != string::npos)
- {
+ else if ((idx = PieceToChar.find(token)) != string::npos) {
put_piece(Piece(idx), sq);
++sq;
}
set_castling_right(c, rsq);
}
- // 4. En passant square. Ignore if no pawn capture is possible
+ // 4. En passant square.
+ // Ignore if square is invalid or not on side to move relative rank 6.
+ bool enpassant = false;
+
if ( ((ss >> col) && (col >= 'a' && col <= 'h'))
- && ((ss >> row) && (row == '3' || row == '6')))
+ && ((ss >> row) && (row == (sideToMove == WHITE ? '6' : '3'))))
{
st->epSquare = make_square(File(col - 'a'), Rank(row - '1'));
- if ( !(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))
- || !(pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove))))
- st->epSquare = SQ_NONE;
+ // En passant square will be considered only if
+ // a) side to move have a pawn threatening epSquare
+ // b) there is an enemy pawn in front of epSquare
+ // c) there is no piece on epSquare or behind epSquare
+ enpassant = pawn_attacks_bb(~sideToMove, st->epSquare) & pieces(sideToMove, PAWN)
+ && (pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove)))
+ && !(pieces() & (st->epSquare | (st->epSquare + pawn_push(sideToMove))));
}
- else
+
+ if (!enpassant)
st->epSquare = SQ_NONE;
// 5-6. Halfmove clock and fullmove number
Square rto = relative_square(c, cr & KING_SIDE ? SQ_F1 : SQ_D1);
castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto)
- & ~(square_bb(kfrom) | rfrom);
+ & ~(kfrom | rfrom);
}
Square ksq = square<KING>(~sideToMove);
- si->checkSquares[PAWN] = attacks_from<PAWN>(ksq, ~sideToMove);
- si->checkSquares[KNIGHT] = attacks_from<KNIGHT>(ksq);
- si->checkSquares[BISHOP] = attacks_from<BISHOP>(ksq);
- si->checkSquares[ROOK] = attacks_from<ROOK>(ksq);
+ si->checkSquares[PAWN] = pawn_attacks_bb(~sideToMove, ksq);
+ si->checkSquares[KNIGHT] = attacks_bb<KNIGHT>(ksq);
+ si->checkSquares[BISHOP] = attacks_bb<BISHOP>(ksq, pieces());
+ si->checkSquares[ROOK] = attacks_bb<ROOK>(ksq, pieces());
si->checkSquares[QUEEN] = si->checkSquares[BISHOP] | si->checkSquares[ROOK];
si->checkSquares[KING] = 0;
}
Position& Position::set(const string& code, Color c, StateInfo* si) {
- assert(code.length() > 0 && code.length() < 8);
assert(code[0] == 'K');
string sides[] = { code.substr(code.find('K', 1)), // Weak
- code.substr(0, code.find('K', 1)) }; // Strong
+ code.substr(0, std::min(code.find('v'), code.find('K', 1))) }; // Strong
+
+ assert(sides[0].length() > 0 && sides[0].length() < 8);
+ assert(sides[1].length() > 0 && sides[1].length() < 8);
std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower);
pinners = 0;
// Snipers are sliders that attack 's' when a piece and other snipers are removed
- Bitboard snipers = ( (PseudoAttacks[ ROOK][s] & pieces(QUEEN, ROOK))
- | (PseudoAttacks[BISHOP][s] & pieces(QUEEN, BISHOP))) & sliders;
+ Bitboard snipers = ( (attacks_bb< ROOK>(s) & pieces(QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(s) & pieces(QUEEN, BISHOP))) & sliders;
Bitboard occupancy = pieces() ^ snipers;
while (snipers)
Bitboard Position::attackers_to(Square s, Bitboard occupied) const {
- return (attacks_from<PAWN>(s, BLACK) & pieces(WHITE, PAWN))
- | (attacks_from<PAWN>(s, WHITE) & pieces(BLACK, PAWN))
- | (attacks_from<KNIGHT>(s) & pieces(KNIGHT))
+ return (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN))
+ | (pawn_attacks_bb(WHITE, s) & pieces(BLACK, PAWN))
+ | (attacks_bb<KNIGHT>(s) & pieces(KNIGHT))
| (attacks_bb< ROOK>(s, occupied) & pieces( ROOK, QUEEN))
| (attacks_bb<BISHOP>(s, occupied) & pieces(BISHOP, QUEEN))
- | (attacks_from<KING>(s) & pieces(KING));
+ | (attacks_bb<KING>(s) & pieces(KING));
}
if ((Rank8BB | Rank1BB) & to)
return false;
- if ( !(attacks_from<PAWN>(from, us) & pieces(~us) & to) // Not a capture
+ if ( !(pawn_attacks_bb(us, from) & pieces(~us) & to) // Not a capture
&& !((from + pawn_push(us) == to) && empty(to)) // Not a single push
&& !( (from + 2 * pawn_push(us) == to) // Not a double push
- && (rank_of(from) == relative_rank(us, RANK_2))
+ && (relative_rank(us, from) == RANK_2)
&& empty(to)
&& empty(to - pawn_push(us))))
return false;
}
- else if (!(attacks_from(type_of(pc), from) & to))
+ else if (!(attacks_bb(type_of(pc), from, pieces()) & to))
return false;
// Evasions generator already takes care to avoid some kind of illegal moves
Square to = to_sq(m);
// Is there a direct check?
- if (st->checkSquares[type_of(piece_on(from))] & to)
+ if (check_squares(type_of(piece_on(from))) & to)
return true;
// Is there a discovered check?
- if ( (st->blockersForKing[~sideToMove] & from)
+ if ( (blockers_for_king(~sideToMove) & from)
&& !aligned(from, to, square<KING>(~sideToMove)))
return true;
case CASTLING:
{
Square kfrom = from;
- Square rfrom = to; // Castling is encoded as 'King captures the rook'
+ Square rfrom = to; // Castling is encoded as 'king captures the rook'
Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1);
Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1);
- return (PseudoAttacks[ROOK][rto] & square<KING>(~sideToMove))
+ return (attacks_bb<ROOK>(rto) & square<KING>(~sideToMove))
&& (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square<KING>(~sideToMove));
}
default:
++st->rule50;
++st->pliesFromNull;
+ // Used by NNUE
+ st->accumulator.computed_accumulation = false;
+ auto& dp = st->dirtyPiece;
+ dp.dirty_num = 1;
+
Color us = sideToMove;
Color them = ~us;
Square from = from_sq(m);
assert(relative_rank(us, to) == RANK_6);
assert(piece_on(to) == NO_PIECE);
assert(piece_on(capsq) == make_piece(them, PAWN));
-
- board[capsq] = NO_PIECE; // Not done by remove_piece()
}
st->pawnKey ^= Zobrist::psq[captured][capsq];
else
st->nonPawnMaterial[them] -= PieceValue[MG][captured];
+ if (Eval::useNNUE)
+ {
+ dp.dirty_num = 2; // 1 piece moved, 1 piece captured
+ dp.piece[1] = captured;
+ dp.from[1] = capsq;
+ dp.to[1] = SQ_NONE;
+ }
+
// Update board and piece lists
- remove_piece(captured, capsq);
+ remove_piece(capsq);
+
+ if (type_of(m) == ENPASSANT)
+ board[capsq] = NO_PIECE;
// Update material hash key and prefetch access to materialTable
k ^= Zobrist::psq[captured][capsq];
// Update castling rights if needed
if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to]))
{
- int cr = castlingRightsMask[from] | castlingRightsMask[to];
- k ^= Zobrist::castling[st->castlingRights & cr];
- st->castlingRights &= ~cr;
+ k ^= Zobrist::castling[st->castlingRights];
+ st->castlingRights &= ~(castlingRightsMask[from] | castlingRightsMask[to]);
+ k ^= Zobrist::castling[st->castlingRights];
}
// Move the piece. The tricky Chess960 castling is handled earlier
if (type_of(m) != CASTLING)
- move_piece(pc, from, to);
+ {
+ if (Eval::useNNUE)
+ {
+ dp.piece[0] = pc;
+ dp.from[0] = from;
+ dp.to[0] = to;
+ }
+
+ move_piece(from, to);
+ }
// If the moving piece is a pawn do some special extra work
if (type_of(pc) == PAWN)
{
// Set en-passant square if the moved pawn can be captured
if ( (int(to) ^ int(from)) == 16
- && (attacks_from<PAWN>(to - pawn_push(us), us) & pieces(them, PAWN)))
+ && (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN)))
{
st->epSquare = to - pawn_push(us);
k ^= Zobrist::enpassant[file_of(st->epSquare)];
assert(relative_rank(us, to) == RANK_8);
assert(type_of(promotion) >= KNIGHT && type_of(promotion) <= QUEEN);
- remove_piece(pc, to);
+ remove_piece(to);
put_piece(promotion, to);
+ if (Eval::useNNUE)
+ {
+ // Promoting pawn to SQ_NONE, promoted piece from SQ_NONE
+ dp.to[0] = SQ_NONE;
+ dp.piece[dp.dirty_num] = promotion;
+ dp.from[dp.dirty_num] = SQ_NONE;
+ dp.to[dp.dirty_num] = to;
+ dp.dirty_num++;
+ }
+
// Update hash keys
k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[promotion][to];
st->pawnKey ^= Zobrist::psq[pc][to];
st->nonPawnMaterial[us] += PieceValue[MG][promotion];
}
- // Update pawn hash key and prefetch access to pawnsTable
+ // Update pawn hash key
st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
// Reset rule 50 draw counter
assert(type_of(pc) == promotion_type(m));
assert(type_of(pc) >= KNIGHT && type_of(pc) <= QUEEN);
- remove_piece(pc, to);
+ remove_piece(to);
pc = make_piece(us, PAWN);
put_piece(pc, to);
}
}
else
{
- move_piece(pc, to, from); // Put the piece back at the source square
+ move_piece(to, from); // Put the piece back at the source square
if (st->capturedPiece)
{
rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
+ if (Do && Eval::useNNUE)
+ {
+ auto& dp = st->dirtyPiece;
+ dp.piece[0] = make_piece(us, KING);
+ dp.from[0] = from;
+ dp.to[0] = to;
+ dp.piece[1] = make_piece(us, ROOK);
+ dp.from[1] = rfrom;
+ dp.to[1] = rto;
+ dp.dirty_num = 2;
+ }
+
// Remove both pieces first since squares could overlap in Chess960
- remove_piece(make_piece(us, KING), Do ? from : to);
- remove_piece(make_piece(us, ROOK), Do ? rfrom : rto);
- board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us
+ remove_piece(Do ? from : to);
+ remove_piece(Do ? rfrom : rto);
+ board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do this for us
put_piece(make_piece(us, KING), Do ? to : from);
put_piece(make_piece(us, ROOK), Do ? rto : rfrom);
}
-/// Position::do(undo)_null_move() is used to do(undo) a "null move": It flips
+/// Position::do(undo)_null_move() is used to do(undo) a "null move": it flips
/// the side to move without executing any move on the board.
void Position::do_null_move(StateInfo& newSt) {
assert(!checkers());
assert(&newSt != st);
- std::memcpy(&newSt, st, sizeof(StateInfo));
+ if (Eval::useNNUE)
+ {
+ std::memcpy(&newSt, st, sizeof(StateInfo));
+ }
+ else
+ std::memcpy(&newSt, st, offsetof(StateInfo, accumulator));
+
newSt.previous = st;
st = &newSt;
if (type_of(m) != NORMAL)
return VALUE_ZERO >= threshold;
- Bitboard stmAttackers;
Square from = from_sq(m), to = to_sq(m);
- PieceType nextVictim = type_of(piece_on(from));
- Color us = color_of(piece_on(from));
- Color stm = ~us; // First consider opponent's move
- Value balance; // Values of the pieces taken by us minus opponent's ones
- // The opponent may be able to recapture so this is the best result
- // we can hope for.
- balance = PieceValue[MG][piece_on(to)] - threshold;
-
- if (balance < VALUE_ZERO)
+ int swap = PieceValue[MG][piece_on(to)] - threshold;
+ if (swap < 0)
return false;
- // Now assume the worst possible result: that the opponent can
- // capture our piece for free.
- balance -= PieceValue[MG][nextVictim];
-
- // If it is enough (like in PxQ) then return immediately. Note that
- // in case nextVictim == KING we always return here, this is ok
- // if the given move is legal.
- if (balance >= VALUE_ZERO)
+ swap = PieceValue[MG][piece_on(from)] - swap;
+ if (swap <= 0)
return true;
- // Find all attackers to the destination square, with the moving piece
- // removed, but possibly an X-ray attacker added behind it.
Bitboard occupied = pieces() ^ from ^ to;
- Bitboard attackers = attackers_to(to, occupied) & occupied;
+ Color stm = color_of(piece_on(from));
+ Bitboard attackers = attackers_to(to, occupied);
+ Bitboard stmAttackers, bb;
+ int res = 1;
while (true)
{
- stmAttackers = attackers & pieces(stm);
+ stm = ~stm;
+ attackers &= occupied;
+
+ // If stm has no more attackers then give up: stm loses
+ if (!(stmAttackers = attackers & pieces(stm)))
+ break;
// Don't allow pinned pieces to attack (except the king) as long as
- // any pinners are on their original square.
- if (st->pinners[~stm] & occupied)
- stmAttackers &= ~st->blockersForKing[stm];
+ // there are pinners on their original square.
+ if (pinners(~stm) & occupied)
+ stmAttackers &= ~blockers_for_king(stm);
- // If stm has no more attackers then give up: stm loses
if (!stmAttackers)
break;
+ res ^= 1;
+
// Locate and remove the next least valuable attacker, and add to
- // the bitboard 'attackers' the possibly X-ray attackers behind it.
- nextVictim = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
+ // the bitboard 'attackers' any X-ray attackers behind it.
+ if ((bb = stmAttackers & pieces(PAWN)))
+ {
+ if ((swap = PawnValueMg - swap) < res)
+ break;
+
+ occupied ^= lsb(bb);
+ attackers |= attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN);
+ }
+
+ else if ((bb = stmAttackers & pieces(KNIGHT)))
+ {
+ if ((swap = KnightValueMg - swap) < res)
+ break;
- stm = ~stm; // Switch side to move
+ occupied ^= lsb(bb);
+ }
- // Negamax the balance with alpha = balance, beta = balance+1 and
- // add nextVictim's value.
- //
- // (balance, balance+1) -> (-balance-1, -balance)
- //
- assert(balance < VALUE_ZERO);
+ else if ((bb = stmAttackers & pieces(BISHOP)))
+ {
+ if ((swap = BishopValueMg - swap) < res)
+ break;
- balance = -balance - 1 - PieceValue[MG][nextVictim];
+ occupied ^= lsb(bb);
+ attackers |= attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN);
+ }
- // If balance is still non-negative after giving away nextVictim then we
- // win. The only thing to be careful about it is that we should revert
- // stm if we captured with the king when the opponent still has attackers.
- if (balance >= VALUE_ZERO)
+ else if ((bb = stmAttackers & pieces(ROOK)))
{
- if (nextVictim == KING && (attackers & pieces(stm)))
- stm = ~stm;
- break;
+ if ((swap = RookValueMg - swap) < res)
+ break;
+
+ occupied ^= lsb(bb);
+ attackers |= attacks_bb<ROOK>(to, occupied) & pieces(ROOK, QUEEN);
+ }
+
+ else if ((bb = stmAttackers & pieces(QUEEN)))
+ {
+ if ((swap = QueenValueMg - swap) < res)
+ break;
+
+ occupied ^= lsb(bb);
+ attackers |= (attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN))
+ | (attacks_bb<ROOK >(to, occupied) & pieces(ROOK , QUEEN));
}
- assert(nextVictim != KING);
+
+ else // KING
+ // If we "capture" with the king but opponent still has attackers,
+ // reverse the result.
+ return (attackers & ~pieces(stm)) ? res ^ 1 : res;
}
- return us != stm; // We break the above loop when stm loses
+
+ return bool(res);
}
// Return a draw score if a position repeats once earlier but strictly
// after the root, or repeats twice before or at the root.
- if (st->repetition && st->repetition < ply)
- return true;
-
- return false;
+ return st->repetition && st->repetition < ply;
}
continue;
if ( piece_on(castlingRookSquare[cr]) != make_piece(c, ROOK)
- || castlingRightsMask[castlingRookSquare[cr]] != (cr)
- || (castlingRightsMask[square<KING>(c)] & (cr)) != (cr))
+ || castlingRightsMask[castlingRookSquare[cr]] != cr
+ || (castlingRightsMask[square<KING>(c)] & cr) != cr)
assert(0 && "pos_is_ok: Castling");
}
projects / stockfish / blobdiff