/*
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
+ Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, 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 <cstring>
+#include <iomanip>
#include <iostream>
#include <sstream>
#include <algorithm>
CACHE_LINE_ALIGNMENT
-Score pieceSquareTable[16][64]; // [piece][square]
-Value PieceValue[2][18] = { // [Mg / Eg][piece / pieceType]
+Score pieceSquareTable[PIECE_NB][SQUARE_NB];
+Value PieceValue[PHASE_NB][PIECE_NB] = {
{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } };
namespace Zobrist {
-Key psq[2][8][64]; // [color][pieceType][square / piece count]
-Key enpassant[8]; // [file]
-Key castle[16]; // [castleRight]
+Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+Key enpassant[FILE_NB];
+Key castle[CASTLE_RIGHT_NB];
Key side;
Key exclusion;
for (PieceType pt = PAWN; pt <= KING; pt++)
{
- PieceValue[Mg][make_piece(BLACK, pt)] = PieceValue[Mg][pt];
- PieceValue[Eg][make_piece(BLACK, pt)] = PieceValue[Eg][pt];
+ PieceValue[MG][make_piece(BLACK, pt)] = PieceValue[MG][pt];
+ PieceValue[EG][make_piece(BLACK, pt)] = PieceValue[EG][pt];
- Score v = make_score(PieceValue[Mg][pt], PieceValue[Eg][pt]);
+ Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]);
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
} // namespace Zobrist
+namespace {
+
+/// next_attacker() is an helper function used by see() to locate the least
+/// valuable attacker for the side to move, remove the attacker we just found
+/// from the 'occupied' bitboard and scan for new X-ray attacks behind it.
+
+template<int Pt> FORCE_INLINE
+PieceType next_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers,
+ Bitboard& occupied, Bitboard& attackers) {
+
+ if (stmAttackers & bb[Pt])
+ {
+ Bitboard b = stmAttackers & bb[Pt];
+ occupied ^= b & ~(b - 1);
+
+ if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN)
+ attackers |= attacks_bb<BISHOP>(to, occupied) & (bb[BISHOP] | bb[QUEEN]);
+
+ if (Pt == ROOK || Pt == QUEEN)
+ attackers |= attacks_bb<ROOK>(to, occupied) & (bb[ROOK] | bb[QUEEN]);
+
+ return (PieceType)Pt;
+ }
+ return next_attacker<Pt+1>(bb, to, stmAttackers, occupied, attackers);
+}
+
+template<> FORCE_INLINE
+PieceType next_attacker<KING>(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) {
+ return KING; // No need to update bitboards, it is the last cycle
+}
+
+} // namespace
+
+
/// CheckInfo c'tor
CheckInfo::CheckInfo(const Position& pos) {
}
-/// Position::from_fen() initializes the position object with the given FEN
-/// string. This function is not very robust - make sure that input FENs are
-/// correct (this is assumed to be the responsibility of the GUI).
+/// Position::set() initializes the position object with the given FEN string.
+/// This function is not very robust - make sure that input FENs are correct,
+/// this is assumed to be the responsibility of the GUI.
-void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) {
+void Position::set(const string& fenStr, bool isChess960, Thread* th) {
/*
A FEN string defines a particular position using only the ASCII character set.
char col, row, token;
size_t p;
Square sq = SQ_A8;
- std::istringstream fen(fenStr);
+ std::istringstream ss(fenStr);
clear();
- fen >> std::noskipws;
+ ss >> std::noskipws;
// 1. Piece placement
- while ((fen >> token) && !isspace(token))
+ while ((ss >> token) && !isspace(token))
{
if (isdigit(token))
sq += Square(token - '0'); // Advance the given number of files
}
// 2. Active color
- fen >> token;
+ ss >> token;
sideToMove = (token == 'w' ? WHITE : BLACK);
- fen >> token;
+ ss >> token;
// 3. Castling availability. Compatible with 3 standards: Normal FEN standard,
// Shredder-FEN that uses the letters of the columns on which the rooks began
// the game instead of KQkq and also X-FEN standard that, in case of Chess960,
// if an inner rook is associated with the castling right, the castling tag is
// replaced by the file letter of the involved rook, as for the Shredder-FEN.
- while ((fen >> token) && !isspace(token))
+ while ((ss >> token) && !isspace(token))
{
Square rsq;
Color c = islower(token) ? BLACK : WHITE;
}
// 4. En passant square. Ignore if no pawn capture is possible
- if ( ((fen >> col) && (col >= 'a' && col <= 'h'))
- && ((fen >> row) && (row == '3' || row == '6')))
+ if ( ((ss >> col) && (col >= 'a' && col <= 'h'))
+ && ((ss >> row) && (row == '3' || row == '6')))
{
st->epSquare = File(col - 'a') | Rank(row - '1');
}
// 5-6. Halfmove clock and fullmove number
- fen >> std::skipws >> st->rule50 >> startPosPly;
+ ss >> std::skipws >> st->rule50 >> gamePly;
// Convert from fullmove starting from 1 to ply starting from 0,
// handle also common incorrect FEN with fullmove = 0.
- startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
+ gamePly = std::max(2 * (gamePly - 1), 0) + int(sideToMove == BLACK);
st->key = compute_key();
st->pawnKey = compute_pawn_key();
}
-/// Position::to_fen() returns a FEN representation of the position. In case
+/// Position::fen() returns a FEN representation of the position. In case
/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function.
-const string Position::to_fen() const {
+const string Position::fen() const {
- std::ostringstream fen;
- Square sq;
- int emptyCnt;
+ std::ostringstream ss;
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
{
- emptyCnt = 0;
-
for (File file = FILE_A; file <= FILE_H; file++)
{
- sq = file | rank;
+ Square sq = file | rank;
if (is_empty(sq))
- emptyCnt++;
- else
{
- if (emptyCnt > 0)
- {
- fen << emptyCnt;
- emptyCnt = 0;
- }
- fen << PieceToChar[piece_on(sq)];
+ int emptyCnt = 1;
+
+ for ( ; file < FILE_H && is_empty(sq++); file++)
+ emptyCnt++;
+
+ ss << emptyCnt;
}
+ else
+ ss << PieceToChar[piece_on(sq)];
}
- if (emptyCnt > 0)
- fen << emptyCnt;
-
if (rank > RANK_1)
- fen << '/';
+ ss << '/';
}
- fen << (sideToMove == WHITE ? " w " : " b ");
+ ss << (sideToMove == WHITE ? " w " : " b ");
if (can_castle(WHITE_OO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE))))) : 'K');
+ ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE)), false) : 'K');
if (can_castle(WHITE_OOO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE))))) : 'Q');
+ ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE)), false) : 'Q');
if (can_castle(BLACK_OO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE))) : 'k');
+ ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE)), true) : 'k');
if (can_castle(BLACK_OOO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE))) : 'q');
+ ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE)), true) : 'q');
if (st->castleRights == CASTLES_NONE)
- fen << '-';
+ ss << '-';
- fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
- << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
+ ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
+ << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2;
- return fen.str();
+ return ss.str();
}
-/// Position::print() prints an ASCII representation of the position to
-/// the standard output. If a move is given then also the san is printed.
+/// Position::pretty() returns an ASCII representation of the position to be
+/// printed to the standard output together with the move's san notation.
-void Position::print(Move move) const {
+const string Position::pretty(Move move) const {
const string dottedLine = "\n+---+---+---+---+---+---+---+---+";
const string twoRows = dottedLine + "\n| | . | | . | | . | | . |"
string brd = twoRows + twoRows + twoRows + twoRows + dottedLine;
+ std::ostringstream ss;
+
if (move)
- {
- Position p(*this);
- cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move);
- }
+ ss << "\nMove: " << (sideToMove == BLACK ? ".." : "")
+ << move_to_san(*const_cast<Position*>(this), move);
for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
if (piece_on(sq) != NO_PIECE)
brd[513 - 68*rank_of(sq) + 4*file_of(sq)] = PieceToChar[piece_on(sq)];
- cout << brd << "\nFen is: " << to_fen() << "\nKey is: " << st->key << endl;
+ ss << brd << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase
+ << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: ";
+
+ for (Bitboard b = checkers(); b; )
+ ss << square_to_string(pop_lsb(&b)) << " ";
+
+ ss << "\nLegal moves: ";
+ for (MoveList<LEGAL> ml(*this); !ml.end(); ++ml)
+ ss << move_to_san(*const_cast<Position*>(this), ml.move()) << " ";
+
+ return ss.str();
}
}
-/// Position::move_attacks_square() tests whether a move from the current
-/// position attacks a given square.
-
-bool Position::move_attacks_square(Move m, Square s) const {
-
- assert(is_ok(m));
- assert(is_ok(s));
-
- Bitboard occ, xray;
- Square from = from_sq(m);
- Square to = to_sq(m);
- Piece piece = piece_moved(m);
-
- assert(!is_empty(from));
-
- // Update occupancy as if the piece is moving
- occ = pieces() ^ from ^ to;
-
- // The piece moved in 'to' attacks the square 's' ?
- if (attacks_from(piece, to, occ) & s)
- return true;
-
- // Scan for possible X-ray attackers behind the moved piece
- xray = (attacks_bb< ROOK>(s, occ) & pieces(color_of(piece), QUEEN, ROOK))
- | (attacks_bb<BISHOP>(s, occ) & pieces(color_of(piece), QUEEN, BISHOP));
-
- // Verify attackers are triggered by our move and not already existing
- return xray && (xray ^ (xray & attacks_from<QUEEN>(s)));
-}
-
-
/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
}
-/// Position::move_is_legal() takes a random move and tests whether the move
-/// is legal. This version is not very fast and should be used only in non
-/// time-critical paths.
-
-bool Position::move_is_legal(const Move m) const {
-
- for (MoveList<LEGAL> ml(*this); !ml.end(); ++ml)
- if (ml.move() == m)
- return true;
-
- return false;
-}
-
-
/// Position::is_pseudo_legal() takes a random move and tests whether the move
/// is pseudo legal. It is used to validate moves from TT that can be corrupted
/// due to SMP concurrent access or hash position key aliasing.
bool Position::is_pseudo_legal(const Move m) const {
Color us = sideToMove;
- Color them = ~sideToMove;
Square from = from_sq(m);
Square to = to_sq(m);
Piece pc = piece_moved(m);
// Use a slower but simpler function for uncommon cases
if (type_of(m) != NORMAL)
- return move_is_legal(m);
+ return MoveList<LEGAL>(*this).contains(m);
// Is not a promotion, so promotion piece must be empty
if (promotion_type(m) - 2 != NO_PIECE_TYPE)
return false;
// The destination square cannot be occupied by a friendly piece
- if (color_of(piece_on(to)) == us)
+ if (piece_on(to) != NO_PIECE && color_of(piece_on(to)) == us)
return false;
// Handle the special case of a pawn move
case DELTA_SE:
// Capture. The destination square must be occupied by an enemy
// piece (en passant captures was handled earlier).
- if (color_of(piece_on(to)) != them)
+ if (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us)
return false;
// From and to files must be one file apart, avoids a7h5
// Evasions generator already takes care to avoid some kind of illegal moves
// and pl_move_is_legal() relies on this. So we have to take care that the
// same kind of moves are filtered out here.
- if (in_check())
+ if (checkers())
{
if (type_of(pc) != KING)
{
- Bitboard b = checkers();
- Square checksq = pop_lsb(&b);
-
- if (b) // double check ? In this case a king move is required
+ // Double check? In this case a king move is required
+ if (more_than_one(checkers()))
return false;
// Our move must be a blocking evasion or a capture of the checking piece
- if (!((between_bb(checksq, king_square(us)) | checkers()) & to))
+ if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to))
return false;
}
// In case of king moves under check we have to remove king so to catch
Color us = sideToMove;
Square ksq = king_square(~us);
- // Promotion with check ?
- if (type_of(m) == PROMOTION)
+ switch (type_of(m))
+ {
+ case PROMOTION:
return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq;
// En passant capture with check ? We have already handled the case
// of direct checks and ordinary discovered check, the only case we
// need to handle is the unusual case of a discovered check through
// the captured pawn.
- if (type_of(m) == ENPASSANT)
+ case ENPASSANT:
{
Square capsq = file_of(to) | rank_of(from);
Bitboard b = (pieces() ^ from ^ capsq) | to;
return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK))
| (attacks_bb<BISHOP>(ksq, b) & pieces(us, QUEEN, BISHOP));
}
-
- // Castling with check ?
- if (type_of(m) == CASTLE)
+ case CASTLE:
{
Square kfrom = from;
Square rfrom = to; // 'King captures the rook' notation
return attacks_bb<ROOK>(rto, b) & ksq;
}
-
- return false;
+ default:
+ assert(false);
+ return false;
+ }
}
Key k = st->key;
// Copy some fields of old state to our new StateInfo object except the ones
- // which are recalculated from scratch anyway, then switch our state pointer
- // to point to the new, ready to be updated, state.
- memcpy(&newSt, st, sizeof(ReducedStateInfo));
+ // which are going to be recalculated from scratch anyway, then switch our state
+ // pointer to point to the new, ready to be updated, state.
+ memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t));
newSt.previous = st;
st = &newSt;
// Update side to move
k ^= Zobrist::side;
- // Increment the 50 moves rule draw counter. Resetting it to zero in the
- // case of a capture or a pawn move is taken care of later.
+ // Increment ply counters.In particular rule50 will be later reset it to zero
+ // in case of a capture or a pawn move.
+ gamePly++;
st->rule50++;
st->pliesFromNull++;
- if (type_of(m) == CASTLE)
- {
- st->key = k;
- do_castle_move<true>(m);
- return;
- }
-
Color us = sideToMove;
Color them = ~us;
Square from = from_sq(m);
PieceType capture = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to));
assert(color_of(piece) == us);
- assert(color_of(piece_on(to)) != us);
+ assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLE);
assert(capture != KING);
+ if (type_of(m) == CASTLE)
+ {
+ assert(piece == make_piece(us, KING));
+
+ bool kingSide = to > from;
+ Square rfrom = to; // Castle is encoded as "king captures friendly rook"
+ Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
+ to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
+ capture = NO_PIECE_TYPE;
+
+ do_castle(from, to, rfrom, rto);
+
+ st->psqScore += psq_delta(make_piece(us, ROOK), rfrom, rto);
+ k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
+ }
+
if (capture)
{
Square capsq = to;
st->pawnKey ^= Zobrist::psq[them][PAWN][capsq];
}
else
- st->npMaterial[them] -= PieceValue[Mg][capture];
+ st->npMaterial[them] -= PieceValue[MG][capture];
// Remove the captured piece
byTypeBB[ALL_PIECES] ^= capsq;
// Update piece list, move the last piece at index[capsq] position and
// shrink the list.
//
- // WARNING: This is a not revresible operation. When we will reinsert the
+ // WARNING: This is a not reversible operation. When we will reinsert the
// captured piece in undo_move() we will put it at the end of the list and
// not in its original place, it means index[] and pieceList[] are not
// guaranteed to be invariant to a do_move() + undo_move() sequence.
pieceList[them][capture][index[lastSquare]] = lastSquare;
pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
- // Update hash keys
+ // Update material hash key and prefetch access to materialTable
k ^= Zobrist::psq[them][capture][capsq];
st->materialKey ^= Zobrist::psq[them][capture][pieceCount[them][capture]];
+ prefetch((char*)thisThread->materialTable[st->materialKey]);
// Update incremental scores
st->psqScore -= pieceSquareTable[make_piece(them, capture)][capsq];
st->castleRights &= ~cr;
}
- // Prefetch TT access as soon as we know key is updated
+ // Prefetch TT access as soon as we know the new hash key
prefetch((char*)TT.first_entry(k));
- // Move the piece
- Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
- byTypeBB[ALL_PIECES] ^= from_to_bb;
- byTypeBB[pt] ^= from_to_bb;
- byColorBB[us] ^= from_to_bb;
-
- board[to] = board[from];
- board[from] = NO_PIECE;
-
- // Update piece lists, index[from] is not updated and becomes stale. This
- // works as long as index[] is accessed just by known occupied squares.
- index[to] = index[from];
- pieceList[us][pt][index[to]] = to;
+ // Move the piece. The tricky Chess960 castle is handled earlier
+ if (type_of(m) != CASTLE)
+ {
+ Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
+ byTypeBB[ALL_PIECES] ^= from_to_bb;
+ byTypeBB[pt] ^= from_to_bb;
+ byColorBB[us] ^= from_to_bb;
+
+ board[from] = NO_PIECE;
+ board[to] = piece;
+
+ // Update piece lists, index[from] is not updated and becomes stale. This
+ // works as long as index[] is accessed just by known occupied squares.
+ index[to] = index[from];
+ pieceList[us][pt][index[to]] = to;
+ }
// If the moving piece is a pawn do some special extra work
if (pt == PAWN)
- pieceSquareTable[make_piece(us, PAWN)][to];
// Update material
- st->npMaterial[us] += PieceValue[Mg][promotion];
+ st->npMaterial[us] += PieceValue[MG][promotion];
}
- // Update pawn hash key
+ // Update pawn hash key and prefetch access to pawnsTable
st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to];
+ prefetch((char*)thisThread->pawnsTable[st->pawnKey]);
// Reset rule 50 draw counter
st->rule50 = 0;
}
- // Prefetch pawn and material hash tables
- prefetch((char*)thisThread->pawnTable.entries[st->pawnKey]);
- prefetch((char*)thisThread->materialTable.entries[st->materialKey]);
-
// Update incremental scores
st->psqScore += psq_delta(piece, from, to);
sideToMove = ~sideToMove;
- if (type_of(m) == CASTLE)
- {
- do_castle_move<false>(m);
- return;
- }
-
Color us = sideToMove;
Color them = ~us;
Square from = from_sq(m);
Square to = to_sq(m);
- Piece piece = piece_on(to);
- PieceType pt = type_of(piece);
+ PieceType pt = type_of(piece_on(to));
PieceType capture = st->capturedType;
- assert(is_empty(from));
- assert(color_of(piece) == us);
+ assert(is_empty(from) || type_of(m) == CASTLE);
assert(capture != KING);
if (type_of(m) == PROMOTION)
pt = PAWN;
}
- // Put the piece back at the source square
- Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
- byTypeBB[ALL_PIECES] ^= from_to_bb;
- byTypeBB[pt] ^= from_to_bb;
- byColorBB[us] ^= from_to_bb;
-
- board[from] = board[to];
- board[to] = NO_PIECE;
-
- // Update piece lists, index[to] is not updated and becomes stale. This
- // works as long as index[] is accessed just by known occupied squares.
- index[from] = index[to];
- pieceList[us][pt][index[from]] = from;
+ if (type_of(m) == CASTLE)
+ {
+ bool kingSide = to > from;
+ Square rfrom = to; // Castle is encoded as "king captures friendly rook"
+ Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
+ to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
+ capture = NO_PIECE_TYPE;
+ pt = KING;
+ do_castle(to, from, rto, rfrom);
+ }
+ else
+ {
+ // Put the piece back at the source square
+ Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
+ byTypeBB[ALL_PIECES] ^= from_to_bb;
+ byTypeBB[pt] ^= from_to_bb;
+ byColorBB[us] ^= from_to_bb;
+
+ board[to] = NO_PIECE;
+ board[from] = make_piece(us, pt);
+
+ // Update piece lists, index[to] is not updated and becomes stale. This
+ // works as long as index[] is accessed just by known occupied squares.
+ index[from] = index[to];
+ pieceList[us][pt][index[from]] = from;
+ }
if (capture)
{
// Finally point our state pointer back to the previous state
st = st->previous;
+ gamePly--;
assert(pos_is_ok());
}
-/// Position::do_castle_move() is a private method used to do/undo a castling
-/// move. Note that castling moves are encoded as "king captures friendly rook"
-/// moves, for instance white short castling in a non-Chess960 game is encoded
-/// as e1h1.
-template<bool Do>
-void Position::do_castle_move(Move m) {
-
- assert(is_ok(m));
- assert(type_of(m) == CASTLE);
+/// Position::do_castle() is a helper used to do/undo a castling move. This
+/// is a bit tricky, especially in Chess960.
- Square kto, kfrom, rfrom, rto, kAfter, rAfter;
+void Position::do_castle(Square kfrom, Square kto, Square rfrom, Square rto) {
Color us = sideToMove;
- Square kBefore = from_sq(m);
- Square rBefore = to_sq(m);
-
- // Find after-castle squares for king and rook
- if (rBefore > kBefore) // O-O
- {
- kAfter = relative_square(us, SQ_G1);
- rAfter = relative_square(us, SQ_F1);
- }
- else // O-O-O
- {
- kAfter = relative_square(us, SQ_C1);
- rAfter = relative_square(us, SQ_D1);
- }
-
- kfrom = Do ? kBefore : kAfter;
- rfrom = Do ? rBefore : rAfter;
-
- kto = Do ? kAfter : kBefore;
- rto = Do ? rAfter : rBefore;
-
- assert(piece_on(kfrom) == make_piece(us, KING));
- assert(piece_on(rfrom) == make_piece(us, ROOK));
-
- // Move the pieces, with some care; in chess960 could be kto == rfrom
Bitboard k_from_to_bb = SquareBB[kfrom] ^ SquareBB[kto];
Bitboard r_from_to_bb = SquareBB[rfrom] ^ SquareBB[rto];
byTypeBB[KING] ^= k_from_to_bb;
byTypeBB[ALL_PIECES] ^= k_from_to_bb ^ r_from_to_bb;
byColorBB[us] ^= k_from_to_bb ^ r_from_to_bb;
- // Update board
- Piece king = make_piece(us, KING);
- Piece rook = make_piece(us, ROOK);
+ // Could be from == to, so first set NO_PIECE then KING and ROOK
board[kfrom] = board[rfrom] = NO_PIECE;
- board[kto] = king;
- board[rto] = rook;
+ board[kto] = make_piece(us, KING);
+ board[rto] = make_piece(us, ROOK);
+
+ // Could be kfrom == rto, so use a 'tmp' variable
+ int tmp = index[kfrom];
+ index[rto] = index[rfrom];
+ index[kto] = tmp;
+ pieceList[us][KING][index[kto]] = kto;
+ pieceList[us][ROOK][index[rto]] = rto;
+}
- // Update piece lists
- pieceList[us][KING][index[kfrom]] = kto;
- pieceList[us][ROOK][index[rfrom]] = rto;
- int tmp = index[rfrom]; // In Chess960 could be kto == rfrom
- index[kto] = index[kfrom];
- index[rto] = tmp;
- if (Do)
- {
- // Reset capture field
- st->capturedType = NO_PIECE_TYPE;
+/// 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.
- // Update incremental scores
- st->psqScore += psq_delta(king, kfrom, kto);
- st->psqScore += psq_delta(rook, rfrom, rto);
-
- // Update hash key
- st->key ^= Zobrist::psq[us][KING][kfrom] ^ Zobrist::psq[us][KING][kto];
- st->key ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
+void Position::do_null_move(StateInfo& newSt) {
- // Clear en passant square
- if (st->epSquare != SQ_NONE)
- {
- st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
- st->epSquare = SQ_NONE;
- }
+ assert(!checkers());
- // Update castling rights
- st->key ^= Zobrist::castle[st->castleRights & castleRightsMask[kfrom]];
- st->castleRights &= ~castleRightsMask[kfrom];
+ memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here
- // Update checkers BB
- st->checkersBB = attackers_to(king_square(~us)) & pieces(us);
+ newSt.previous = st;
+ st = &newSt;
- sideToMove = ~sideToMove;
+ if (st->epSquare != SQ_NONE)
+ {
+ st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
+ st->epSquare = SQ_NONE;
}
- else
- // Undo: point our state pointer back to the previous state
- st = st->previous;
-
- assert(pos_is_ok());
-}
+ st->key ^= Zobrist::side;
+ prefetch((char*)TT.first_entry(st->key));
-/// Position::do_null_move() is used to do/undo a "null move": It flips the side
-/// to move and updates the hash key without executing any move on the board.
-template<bool Do>
-void Position::do_null_move(StateInfo& backupSt) {
-
- assert(!in_check());
-
- // Back up the information necessary to undo the null move to the supplied
- // StateInfo object. Note that differently from normal case here backupSt
- // is actually used as a backup storage not as the new state. This reduces
- // the number of fields to be copied.
- StateInfo* src = Do ? st : &backupSt;
- StateInfo* dst = Do ? &backupSt : st;
-
- dst->key = src->key;
- dst->epSquare = src->epSquare;
- dst->psqScore = src->psqScore;
- dst->rule50 = src->rule50;
- dst->pliesFromNull = src->pliesFromNull;
+ st->rule50++;
+ st->pliesFromNull = 0;
sideToMove = ~sideToMove;
- if (Do)
- {
- if (st->epSquare != SQ_NONE)
- st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
+ assert(pos_is_ok());
+}
- st->key ^= Zobrist::side;
- prefetch((char*)TT.first_entry(st->key));
+void Position::undo_null_move() {
- st->epSquare = SQ_NONE;
- st->rule50++;
- st->pliesFromNull = 0;
- }
+ assert(!checkers());
- assert(pos_is_ok());
+ st = st->previous;
+ sideToMove = ~sideToMove;
}
-// Explicit template instantiations
-template void Position::do_null_move<false>(StateInfo& backupSt);
-template void Position::do_null_move<true>(StateInfo& backupSt);
-
/// Position::see() is a static exchange evaluator: It tries to estimate the
/// material gain or loss resulting from a move. There are three versions of
// Early return if SEE cannot be negative because captured piece value
// is not less then capturing one. Note that king moves always return
// here because king midgame value is set to 0.
- if (PieceValue[Mg][piece_on(to_sq(m))] >= PieceValue[Mg][piece_moved(m)])
+ if (PieceValue[MG][piece_on(to_sq(m))] >= PieceValue[MG][piece_moved(m)])
return 1;
return see(m);
int Position::see(Move m) const {
Square from, to;
- Bitboard occ, attackers, stmAttackers, b;
+ Bitboard occupied, attackers, stmAttackers;
int swapList[32], slIndex = 1;
- PieceType capturedType, pt;
+ PieceType captured;
Color stm;
assert(is_ok(m));
- // As castle moves are implemented as capturing the rook, they have
- // SEE == RookValueMidgame most of the times (unless the rook is under
- // attack).
- if (type_of(m) == CASTLE)
- return 0;
-
from = from_sq(m);
to = to_sq(m);
- capturedType = type_of(piece_on(to));
- occ = pieces();
+ captured = type_of(piece_on(to));
+ occupied = pieces() ^ from;
// Handle en passant moves
if (type_of(m) == ENPASSANT)
{
Square capQq = to - pawn_push(sideToMove);
- assert(!capturedType);
+ assert(!captured);
assert(type_of(piece_on(capQq)) == PAWN);
// Remove the captured pawn
- occ ^= capQq;
- capturedType = PAWN;
+ occupied ^= capQq;
+ captured = PAWN;
}
+ else if (type_of(m) == CASTLE)
+ // Castle moves are implemented as king capturing the rook so cannot be
+ // handled correctly. Simply return 0 that is always the correct value
+ // unless the rook is ends up under attack.
+ return 0;
// Find all attackers to the destination square, with the moving piece
// removed, but possibly an X-ray attacker added behind it.
- occ ^= from;
- attackers = attackers_to(to, occ);
+ attackers = attackers_to(to, occupied);
// If the opponent has no attackers we are finished
stm = ~color_of(piece_on(from));
stmAttackers = attackers & pieces(stm);
if (!stmAttackers)
- return PieceValue[Mg][capturedType];
+ return PieceValue[MG][captured];
// The destination square is defended, which makes things rather more
// difficult to compute. We proceed by building up a "swap list" containing
// destination square, where the sides alternately capture, and always
// capture with the least valuable piece. After each capture, we look for
// new X-ray attacks from behind the capturing piece.
- swapList[0] = PieceValue[Mg][capturedType];
- capturedType = type_of(piece_on(from));
+ swapList[0] = PieceValue[MG][captured];
+ captured = type_of(piece_on(from));
do {
- // Locate the least valuable attacker for the side to move. The loop
- // below looks like it is potentially infinite, but it isn't. We know
- // that the side to move still has at least one attacker left.
- for (pt = PAWN; !(stmAttackers & pieces(pt)); pt++)
- assert(pt < KING);
-
- // Remove the attacker we just found from the 'occupied' bitboard,
- // and scan for new X-ray attacks behind the attacker.
- b = stmAttackers & pieces(pt);
- occ ^= (b & (~b + 1));
- attackers |= (attacks_bb<ROOK>(to, occ) & pieces(ROOK, QUEEN))
- | (attacks_bb<BISHOP>(to, occ) & pieces(BISHOP, QUEEN));
-
- attackers &= occ; // Cut out pieces we've already done
+ assert(slIndex < 32);
// Add the new entry to the swap list
- assert(slIndex < 32);
- swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[Mg][capturedType];
+ swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
slIndex++;
- // Remember the value of the capturing piece, and change the side to
- // move before beginning the next iteration.
- capturedType = pt;
+ // Locate and remove from 'occupied' the next least valuable attacker
+ captured = next_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
+
+ attackers &= occupied; // Remove the just found attacker
stm = ~stm;
stmAttackers = attackers & pieces(stm);
- // Stop before processing a king capture
- if (capturedType == KING && stmAttackers)
+ if (captured == KING)
{
- assert(slIndex < 32);
- swapList[slIndex++] = QueenValueMg * 16;
+ // Stop before processing a king capture
+ if (stmAttackers)
+ swapList[slIndex++] = QueenValueMg * 16;
+
break;
}
+
} while (stmAttackers);
// Having built the swap list, we negamax through it to find the best
for (int i = 0; i < 8; i++)
for (int j = 0; j < 16; j++)
pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
-
- for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
- board[sq] = NO_PIECE;
}
Value value = VALUE_ZERO;
for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
- value += piece_count(c, pt) * PieceValue[Mg][pt];
+ value += piece_count(c, pt) * PieceValue[MG][pt];
return value;
}
return true;
// Draw by the 50 moves rule?
- if (st->rule50 > 99 && (!in_check() || MoveList<LEGAL>(*this).size()))
+ if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
return true;
// Draw by repetition?
if (stp->key == st->key)
return true;
- i +=2;
+ i += 2;
} while (i <= e);
}
thisThread = pos.this_thread();
nodes = pos.nodes_searched();
chess960 = pos.is_chess960();
- startPosPly = pos.startpos_ply_counter();
+ gamePly = pos.game_ply();
for (Square s = SQ_A1; s <= SQ_H8; s++)
if (!pos.is_empty(s))
if ((*step)++, debugKingCount)
{
- int kingCount[2] = {};
+ int kingCount[COLOR_NB] = {};
for (Square s = SQ_A1; s <= SQ_H8; s++)
if (type_of(piece_on(s)) == KING)
projects / stockfish / blobdiff