#include <fstream>
#include <iostream>
#include <sstream>
+#include <algorithm>
#include "bitcount.h"
#include "movegen.h"
/// or the FEN string, we want the new born Position object do not depend
/// on any external data so we detach state pointer from the source one.
-Position::Position(const Position& pos, int th) {
+void Position::copy(const Position& pos, int th) {
memcpy(this, &pos, sizeof(Position));
threadID = th;
/*
A FEN string defines a particular position using only the ASCII character set.
- A FEN string contains six fields. The separator between fields is a space. The fields are:
+ A FEN string contains six fields separated by a space. The fields are:
- 1) Piece placement (from white's perspective). Each rank is described, starting with rank 8 and ending
- with rank 1; within each rank, the contents of each square are described from file A through file H.
- Following the Standard Algebraic Notation (SAN), each piece is identified by a single letter taken
- from the standard English names. White pieces are designated using upper-case letters ("PNBRQK")
- while Black take lowercase ("pnbrqk"). Blank squares are noted using digits 1 through 8 (the number
- of blank squares), and "/" separate ranks.
+ 1) Piece placement (from white's perspective). Each rank is described, starting
+ with rank 8 and ending with rank 1; within each rank, the contents of each
+ square are described from file A through file H. Following the Standard
+ Algebraic Notation (SAN), each piece is identified by a single letter taken
+ from the standard English names. White pieces are designated using upper-case
+ letters ("PNBRQK") while Black take lowercase ("pnbrqk"). Blank squares are
+ noted using digits 1 through 8 (the number of blank squares), and "/"
+ separates ranks.
2) Active color. "w" means white moves next, "b" means black.
- 3) Castling availability. If neither side can castle, this is "-". Otherwise, this has one or more
- letters: "K" (White can castle kingside), "Q" (White can castle queenside), "k" (Black can castle
- kingside), and/or "q" (Black can castle queenside).
+ 3) Castling availability. If neither side can castle, this is "-". Otherwise,
+ this has one or more letters: "K" (White can castle kingside), "Q" (White
+ can castle queenside), "k" (Black can castle kingside), and/or "q" (Black
+ can castle queenside).
- 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
- regardless of whether there is a pawn in position to make an en passant capture.
+ 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 regardless of whether
+ there is a pawn in position to make an en passant capture.
- 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 fifty-move rule.
+ 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
+ fifty-move rule.
- 6) Fullmove number: The number of the full move. It starts at 1, and is incremented after Black's move.
+ 6) Fullmove number. The number of the full move. It starts at 1, and is
+ incremented after Black's move.
*/
char col, row, token;
sideToMove = (token == 'w' ? WHITE : BLACK);
fen >> token;
- // 3. Castling availability
+ // 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))
- set_castling_rights(token);
+ {
+ Square rsq;
+ Color c = islower(token) ? BLACK : WHITE;
+ Piece rook = make_piece(c, ROOK);
+
+ token = char(toupper(token));
+
+ if (token == 'K')
+ for (rsq = relative_square(c, SQ_H1); piece_on(rsq) != rook; rsq--) {}
+
+ else if (token == 'Q')
+ for (rsq = relative_square(c, SQ_A1); piece_on(rsq) != rook; rsq++) {}
+
+ else if (token >= 'A' && token <= 'H')
+ rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1));
+
+ else
+ continue;
+
+ set_castle_right(king_square(c), rsq);
+ }
// 4. En passant square. Ignore if no pawn capture is possible
if ( ((fen >> col) && (col >= 'a' && col <= 'h'))
&& ((fen >> row) && (row == '3' || row == '6')))
{
st->epSquare = make_square(File(col - 'a'), Rank(row - '1'));
- Color them = flip(sideToMove);
- if (!(attacks_from<PAWN>(st->epSquare, them) & pieces(PAWN, sideToMove)))
+ if (!(attackers_to(st->epSquare) & pieces(PAWN, sideToMove)))
st->epSquare = SQ_NONE;
}
// Convert from fullmove starting from 1 to ply starting from 0,
// handle also common incorrect FEN with fullmove = 0.
- startPosPly = Max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
-
- // Various initialisations
- chess960 = isChess960;
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
+ startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
st->key = compute_key();
st->pawnKey = compute_pawn_key();
st->value = compute_value();
st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
+ chess960 = isChess960;
assert(pos_is_ok());
}
-/// Position::set_castle() is an helper function used to set
-/// correct castling related flags.
+/// Position::set_castle_right() is an helper function used to set castling
+/// rights given the corresponding king and rook starting squares.
+
+void Position::set_castle_right(Square ksq, Square rsq) {
-void Position::set_castle(int f, Square ksq, Square rsq) {
+ int f = (rsq < ksq ? WHITE_OOO : WHITE_OO) << color_of(piece_on(ksq));
st->castleRights |= f;
castleRightsMask[ksq] ^= f;
}
-/// Position::set_castling_rights() sets castling parameters castling avaiability.
-/// This function is 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 traditional castling tag will be replaced
-/// by the file letter of the involved rook as for the Shredder-FEN.
-
-void Position::set_castling_rights(char token) {
-
- Color c = islower(token) ? BLACK : WHITE;
-
- Square sqA = relative_square(c, SQ_A1);
- Square sqH = relative_square(c, SQ_H1);
- Square rsq, ksq = king_square(c);
-
- token = char(toupper(token));
-
- if (token == 'K')
- for (rsq = sqH; piece_on(rsq) != make_piece(c, ROOK); rsq--) {}
-
- else if (token == 'Q')
- for (rsq = sqA; piece_on(rsq) != make_piece(c, ROOK); rsq++) {}
-
- else if (token >= 'A' && token <= 'H')
- rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1));
-
- else return;
-
- if (file_of(rsq) < file_of(ksq))
- set_castle(WHITE_OOO << c, ksq, rsq);
- else
- set_castle(WHITE_OO << c, ksq, rsq);
-}
-
-
/// Position::to_fen() returns a FEN representation of the position. In case
/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function.
{
sq = make_square(file, rank);
- if (!square_is_empty(sq))
+ if (square_is_empty(sq))
+ emptyCnt++;
+ else
{
- if (emptyCnt)
+ if (emptyCnt > 0)
{
fen << emptyCnt;
emptyCnt = 0;
}
fen << PieceToChar[piece_on(sq)];
}
- else
- emptyCnt++;
}
- if (emptyCnt)
+ if (emptyCnt > 0)
fen << emptyCnt;
if (rank > RANK_1)
fen << (sideToMove == WHITE ? " w " : " b ");
- if (st->castleRights != CASTLES_NONE)
- {
- if (can_castle(WHITE_OO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OO))))) : 'K');
+ if (can_castle(WHITE_OO))
+ fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OO))))) : 'K');
+
+ if (can_castle(WHITE_OOO))
+ fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OOO))))) : 'Q');
- if (can_castle(WHITE_OOO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OOO))))) : 'Q');
+ if (can_castle(BLACK_OO))
+ fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k');
- if (can_castle(BLACK_OO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k');
+ if (can_castle(BLACK_OOO))
+ fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q');
- if (can_castle(BLACK_OOO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q');
- } else
+ if (st->castleRights == CASTLES_NONE)
fen << '-';
- fen << (ep_square() == SQ_NONE ? " -" : " " + square_to_string(ep_square()))
- << " " << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
+ fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
+ << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
return fen.str();
}
if (move)
{
Position p(*this, thread());
- string dd = (sideToMove == BLACK ? ".." : "");
- cout << "\nMove is: " << dd << move_to_san(p, move);
+ cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move);
}
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
{
Square sq = make_square(file, rank);
Piece piece = piece_on(sq);
+ char c = (color_of(piece) == BLACK ? '=' : ' ');
if (piece == PIECE_NONE && color_of(sq) == DARK)
piece = PIECE_NONE_DARK_SQ;
- char c = (color_of(piece_on(sq)) == BLACK ? '=' : ' ');
cout << c << PieceToChar[piece] << c << '|';
}
}
/// king) pieces for the given color. Or, when template parameter FindPinned is
/// false, the function return the pieces of the given color candidate for a
/// discovery check against the enemy king.
-
template<bool FindPinned>
Bitboard Position::hidden_checkers() const {
// Pinned pieces protect our king, dicovery checks attack the enemy king
- Bitboard b, result = EmptyBoardBB;
+ Bitboard b, result = 0;
Bitboard pinners = pieces(FindPinned ? flip(sideToMove) : sideToMove);
Square ksq = king_square(FindPinned ? sideToMove : flip(sideToMove));
return result;
}
+// Explicit template instantiations
+template Bitboard Position::hidden_checkers<true>() const;
+template Bitboard Position::hidden_checkers<false>() const;
-/// Position:pinned_pieces() returns a bitboard of all pinned (against the
-/// king) pieces for the side to move.
-
-Bitboard Position::pinned_pieces() const {
-
- return hidden_checkers<true>();
-}
-
-
-/// Position:discovered_check_candidates() returns a bitboard containing all
-/// pieces for the side to move which are candidates for giving a discovered
-/// check.
-
-Bitboard Position::discovered_check_candidates() const {
-
- return hidden_checkers<false>();
-}
-/// Position::attackers_to() computes a bitboard of all pieces which attacks a
+/// Position::attackers_to() computes a bitboard of all pieces which attack a
/// given square. Slider attacks use occ bitboard as occupancy.
Bitboard Position::attackers_to(Square s, Bitboard occ) const {
| (attacks_from<KING>(s) & pieces(KING));
}
+
/// Position::attacks_from() computes a bitboard of all attacks of a given piece
/// put in a given square. Slider attacks use occ bitboard as occupancy.
assert(square_is_ok(s));
Bitboard occ, xray;
- Square f = move_from(m), t = move_to(m);
+ Square from = move_from(m);
+ Square to = move_to(m);
+ Piece piece = piece_on(from);
- assert(!square_is_empty(f));
+ assert(!square_is_empty(from));
- if (bit_is_set(attacks_from(piece_on(f), t), s))
+ // Update occupancy as if the piece is moving
+ occ = occupied_squares();
+ do_move_bb(&occ, make_move_bb(from, to));
+
+ // The piece moved in 'to' attacks the square 's' ?
+ if (bit_is_set(attacks_from(piece, to, occ), s))
return true;
- // Move the piece and scan for X-ray attacks behind it
- occ = occupied_squares();
- do_move_bb(&occ, make_move_bb(f, t));
- xray = ( (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN))
- |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN)))
- & pieces(color_of(piece_on(f)));
+ // Scan for possible X-ray attackers behind the moved piece
+ xray = (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN, color_of(piece)))
+ |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN, color_of(piece)));
- // If we have attacks we need to verify that are caused by our move
- // and are not already existent ones.
+ // Verify attackers are triggered by our move and not already existing
return xray && (xray ^ (xray & attacks_from<QUEEN>(s)));
}
/// 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.
+/// 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 {
nodes++;
Key key = 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.
+ // 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.
struct ReducedStateInfo {
Key pawnKey, materialKey;
Value npMaterial[2];
if (is_castle(m))
{
st->key = key;
- do_castle_move(m);
+ do_castle_move<true>(m);
return;
}
Color them = flip(us);
Square from = move_from(m);
Square to = move_to(m);
- bool ep = is_enpassant(m);
- bool pm = is_promotion(m);
-
Piece piece = piece_on(from);
PieceType pt = type_of(piece);
- PieceType capture = ep ? PAWN : type_of(piece_on(to));
+ PieceType capture = is_enpassant(m) ? PAWN : type_of(piece_on(to));
- assert(color_of(piece_on(from)) == us);
- assert(color_of(piece_on(to)) == them || square_is_empty(to));
- assert(!(ep || pm) || piece == make_piece(us, PAWN));
- assert(!pm || relative_rank(us, to) == RANK_8);
+ assert(color_of(piece) == us);
+ assert(color_of(piece_on(to)) != us);
+ assert(capture != KING);
if (capture)
- do_capture_move(key, capture, them, to, ep);
+ {
+ Square capsq = to;
+
+ // If the captured piece is a pawn, update pawn hash key, otherwise
+ // update non-pawn material.
+ if (capture == PAWN)
+ {
+ if (is_enpassant(m))
+ {
+ capsq += pawn_push(them);
+
+ assert(pt == PAWN);
+ assert(to == st->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(to) == PIECE_NONE);
+ assert(piece_on(capsq) == make_piece(them, PAWN));
+
+ board[capsq] = PIECE_NONE;
+ }
+
+ st->pawnKey ^= zobrist[them][PAWN][capsq];
+ }
+ else
+ st->npMaterial[them] -= PieceValueMidgame[capture];
+
+ // Remove the captured piece
+ clear_bit(&byColorBB[them], capsq);
+ clear_bit(&byTypeBB[capture], capsq);
+ clear_bit(&occupied, 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
+ // 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.
+ Square lastSquare = pieceList[them][capture][--pieceCount[them][capture]];
+ index[lastSquare] = index[capsq];
+ pieceList[them][capture][index[lastSquare]] = lastSquare;
+ pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
+
+ // Update hash keys
+ key ^= zobrist[them][capture][capsq];
+ st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]];
+
+ // Update incremental scores
+ st->value -= pst(make_piece(them, capture), capsq);
+
+ // Reset rule 50 counter
+ st->rule50 = 0;
+ }
// Update hash key
key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
Bitboard move_bb = make_move_bb(from, to);
do_move_bb(&byColorBB[us], move_bb);
do_move_bb(&byTypeBB[pt], move_bb);
- do_move_bb(&byTypeBB[0], move_bb); // HACK: byTypeBB[0] == occupied squares
+ do_move_bb(&occupied, move_bb);
board[to] = board[from];
board[from] = PIECE_NONE;
- // Update piece lists, note that index[from] is not updated and
- // becomes stale. This works as long as index[] is accessed just
- // by known occupied squares.
+ // 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 was a pawn do some special extra work
+ // If the moving piece is a pawn do some special extra work
if (pt == PAWN)
{
- // Reset rule 50 draw counter
- st->rule50 = 0;
-
- // Update pawn hash key and prefetch in L1/L2 cache
- st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
-
- // Set en passant square, only if moved pawn can be captured
- if ((to ^ from) == 16)
+ // Set en-passant square, only if moved pawn can be captured
+ if ( (to ^ from) == 16
+ && (attacks_from<PAWN>(from + pawn_push(us), us) & pieces(PAWN, them)))
{
- if (attacks_from<PAWN>(from + pawn_push(us), us) & pieces(PAWN, them))
- {
- st->epSquare = Square((int(from) + int(to)) / 2);
- key ^= zobEp[st->epSquare];
- }
+ st->epSquare = Square((from + to) / 2);
+ key ^= zobEp[st->epSquare];
}
- if (pm) // promotion ?
+ if (is_promotion(m))
{
PieceType promotion = promotion_piece_type(m);
+ assert(relative_rank(us, to) == RANK_8);
assert(promotion >= KNIGHT && promotion <= QUEEN);
- // Insert promoted piece instead of pawn
+ // Replace the pawn with the promoted piece
clear_bit(&byTypeBB[PAWN], to);
set_bit(&byTypeBB[promotion], to);
board[to] = make_piece(us, promotion);
- // Update piece counts
- pieceCount[us][promotion]++;
- pieceCount[us][PAWN]--;
-
- // Update material key
- st->materialKey ^= zobrist[us][PAWN][pieceCount[us][PAWN]];
- st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]-1];
-
// Update piece lists, move the last pawn at index[to] position
// and shrink the list. Add a new promotion piece to the list.
- Square lastPawnSquare = pieceList[us][PAWN][pieceCount[us][PAWN]];
- index[lastPawnSquare] = index[to];
- pieceList[us][PAWN][index[lastPawnSquare]] = lastPawnSquare;
+ Square lastSquare = pieceList[us][PAWN][--pieceCount[us][PAWN]];
+ index[lastSquare] = index[to];
+ pieceList[us][PAWN][index[lastSquare]] = lastSquare;
pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE;
- index[to] = pieceCount[us][promotion] - 1;
+ index[to] = pieceCount[us][promotion];
pieceList[us][promotion][index[to]] = to;
- // Partially revert hash keys update
+ // Update hash keys
key ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to];
st->pawnKey ^= zobrist[us][PAWN][to];
+ st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]++]
+ ^ zobrist[us][PAWN][pieceCount[us][PAWN]];
- // Partially revert and update incremental scores
- st->value -= pst(make_piece(us, PAWN), to);
- st->value += pst(make_piece(us, promotion), to);
+ // Update incremental score
+ st->value += pst(make_piece(us, promotion), to)
+ - pst(make_piece(us, PAWN), to);
// Update material
st->npMaterial[us] += PieceValueMidgame[promotion];
}
+
+ // Update pawn hash key
+ st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
+
+ // Reset rule 50 draw counter
+ st->rule50 = 0;
}
// Prefetch pawn and material hash tables
if (moveIsCheck)
{
- if (ep | pm)
+ if (is_special(m))
st->checkersBB = attackers_to(king_square(them)) & pieces(us);
else
{
if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
{
if (pt != ROOK)
- st->checkersBB |= (attacks_from<ROOK>(king_square(them)) & pieces(ROOK, QUEEN, us));
+ st->checkersBB |= attacks_from<ROOK>(king_square(them)) & pieces(ROOK, QUEEN, us);
if (pt != BISHOP)
- st->checkersBB |= (attacks_from<BISHOP>(king_square(them)) & pieces(BISHOP, QUEEN, us));
+ st->checkersBB |= attacks_from<BISHOP>(king_square(them)) & pieces(BISHOP, QUEEN, us);
}
}
}
}
-/// Position::do_capture_move() is a private method used to update captured
-/// piece info. It is called from the main Position::do_move function.
-
-void Position::do_capture_move(Key& key, PieceType capture, Color them, Square to, bool ep) {
-
- assert(capture != KING);
-
- Square capsq = to;
-
- // If the captured piece was a pawn, update pawn hash key,
- // otherwise update non-pawn material.
- if (capture == PAWN)
- {
- if (ep) // en passant ?
- {
- capsq = to + pawn_push(them);
-
- assert(to == st->epSquare);
- assert(relative_rank(flip(them), to) == RANK_6);
- assert(piece_on(to) == PIECE_NONE);
- assert(piece_on(capsq) == make_piece(them, PAWN));
-
- board[capsq] = PIECE_NONE;
- }
- st->pawnKey ^= zobrist[them][PAWN][capsq];
- }
- else
- st->npMaterial[them] -= PieceValueMidgame[capture];
-
- // Remove captured piece
- clear_bit(&byColorBB[them], capsq);
- clear_bit(&byTypeBB[capture], capsq);
- clear_bit(&byTypeBB[0], capsq);
-
- // Update hash key
- key ^= zobrist[them][capture][capsq];
-
- // Update incremental scores
- st->value -= pst(make_piece(them, capture), capsq);
-
- // Update piece count
- pieceCount[them][capture]--;
-
- // Update material hash key
- st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]];
-
- // Update piece list, move the last piece at index[capsq] position
- //
- // WARNING: This is a not perfectly revresible 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.
- Square lastPieceSquare = pieceList[them][capture][pieceCount[them][capture]];
- index[lastPieceSquare] = index[capsq];
- pieceList[them][capture][index[lastPieceSquare]] = lastPieceSquare;
- pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
-
- // Reset rule 50 counter
- st->rule50 = 0;
-}
-
-
-/// Position::do_castle_move() is a private method used to make a castling
-/// move. It is called from the main Position::do_move function. 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.
-
-void Position::do_castle_move(Move m) {
-
- assert(is_ok(m));
- assert(is_castle(m));
-
- Color us = side_to_move();
- Color them = flip(us);
-
- // Find source squares for king and rook
- Square kfrom = move_from(m);
- Square rfrom = move_to(m);
- Square kto, rto;
-
- assert(piece_on(kfrom) == make_piece(us, KING));
- assert(piece_on(rfrom) == make_piece(us, ROOK));
-
- // Find destination squares for king and rook
- if (rfrom > kfrom) // O-O
- {
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- }
- else // O-O-O
- {
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
- }
-
- // Remove pieces from source squares
- clear_bit(&byColorBB[us], kfrom);
- clear_bit(&byTypeBB[KING], kfrom);
- clear_bit(&byTypeBB[0], kfrom);
- clear_bit(&byColorBB[us], rfrom);
- clear_bit(&byTypeBB[ROOK], rfrom);
- clear_bit(&byTypeBB[0], rfrom);
-
- // Put pieces on destination squares
- set_bit(&byColorBB[us], kto);
- set_bit(&byTypeBB[KING], kto);
- set_bit(&byTypeBB[0], kto);
- set_bit(&byColorBB[us], rto);
- set_bit(&byTypeBB[ROOK], rto);
- set_bit(&byTypeBB[0], rto);
-
- // Update board
- Piece king = make_piece(us, KING);
- Piece rook = make_piece(us, ROOK);
- board[kfrom] = board[rfrom] = PIECE_NONE;
- board[kto] = king;
- board[rto] = rook;
-
- // 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;
-
- // Reset capture field
- st->capturedType = PIECE_TYPE_NONE;
-
- // Update incremental scores
- st->value += pst_delta(king, kfrom, kto);
- st->value += pst_delta(rook, rfrom, rto);
-
- // Update hash key
- st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
- st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
-
- // Clear en passant square
- if (st->epSquare != SQ_NONE)
- {
- st->key ^= zobEp[st->epSquare];
- st->epSquare = SQ_NONE;
- }
-
- // Update castling rights
- st->key ^= zobCastle[st->castleRights];
- st->castleRights &= castleRightsMask[kfrom];
- st->key ^= zobCastle[st->castleRights];
-
- // Reset rule 50 counter
- st->rule50 = 0;
-
- // Update checkers BB
- st->checkersBB = attackers_to(king_square(them)) & pieces(us);
-
- // Finish
- sideToMove = flip(sideToMove);
- st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
-
- assert(pos_is_ok());
-}
-
-
/// Position::undo_move() unmakes a move. When it returns, the position should
/// be restored to exactly the same state as before the move was made.
if (is_castle(m))
{
- undo_castle_move(m);
+ do_castle_move<false>(m);
return;
}
Color them = flip(us);
Square from = move_from(m);
Square to = move_to(m);
- bool ep = is_enpassant(m);
- bool pm = is_promotion(m);
-
- PieceType pt = type_of(piece_on(to));
+ Piece piece = piece_on(to);
+ PieceType pt = type_of(piece);
+ PieceType capture = st->capturedType;
assert(square_is_empty(from));
- assert(color_of(piece_on(to)) == us);
- assert(!pm || relative_rank(us, to) == RANK_8);
- assert(!ep || to == st->previous->epSquare);
- assert(!ep || relative_rank(us, to) == RANK_6);
- assert(!ep || piece_on(to) == make_piece(us, PAWN));
+ assert(color_of(piece) == us);
+ assert(capture != KING);
- if (pm) // promotion ?
+ if (is_promotion(m))
{
PieceType promotion = promotion_piece_type(m);
- pt = PAWN;
+ assert(promotion == pt);
+ assert(relative_rank(us, to) == RANK_8);
assert(promotion >= KNIGHT && promotion <= QUEEN);
- assert(piece_on(to) == make_piece(us, promotion));
- // Replace promoted piece with a pawn
+ // Replace the promoted piece with the pawn
clear_bit(&byTypeBB[promotion], to);
set_bit(&byTypeBB[PAWN], to);
+ board[to] = make_piece(us, PAWN);
- // Update piece counts
- pieceCount[us][promotion]--;
- pieceCount[us][PAWN]++;
-
- // Update piece list replacing promotion piece with a pawn
- Square lastPromotionSquare = pieceList[us][promotion][pieceCount[us][promotion]];
- index[lastPromotionSquare] = index[to];
- pieceList[us][promotion][index[lastPromotionSquare]] = lastPromotionSquare;
+ // Update piece lists, move the last promoted piece at index[to] position
+ // and shrink the list. Add a new pawn to the list.
+ Square lastSquare = pieceList[us][promotion][--pieceCount[us][promotion]];
+ index[lastSquare] = index[to];
+ pieceList[us][promotion][index[lastSquare]] = lastSquare;
pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE;
- index[to] = pieceCount[us][PAWN] - 1;
+ index[to] = pieceCount[us][PAWN]++;
pieceList[us][PAWN][index[to]] = to;
+
+ pt = PAWN;
}
// Put the piece back at the source square
Bitboard move_bb = make_move_bb(to, from);
do_move_bb(&byColorBB[us], move_bb);
do_move_bb(&byTypeBB[pt], move_bb);
- do_move_bb(&byTypeBB[0], move_bb); // HACK: byTypeBB[0] == occupied squares
+ do_move_bb(&occupied, move_bb);
- board[from] = make_piece(us, pt);
+ board[from] = board[to];
board[to] = PIECE_NONE;
- // Update piece list
+ // 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 (st->capturedType)
+ if (capture)
{
Square capsq = to;
- if (ep)
- capsq = to - pawn_push(us);
+ if (is_enpassant(m))
+ {
+ capsq -= pawn_push(us);
- assert(st->capturedType != KING);
- assert(!ep || square_is_empty(capsq));
+ assert(pt == PAWN);
+ assert(to == st->previous->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(capsq) == PIECE_NONE);
+ }
// Restore the captured piece
set_bit(&byColorBB[them], capsq);
- set_bit(&byTypeBB[st->capturedType], capsq);
- set_bit(&byTypeBB[0], capsq);
+ set_bit(&byTypeBB[capture], capsq);
+ set_bit(&occupied, capsq);
- board[capsq] = make_piece(them, st->capturedType);
-
- // Update piece count
- pieceCount[them][st->capturedType]++;
+ board[capsq] = make_piece(them, capture);
// Update piece list, add a new captured piece in capsq square
- index[capsq] = pieceCount[them][st->capturedType] - 1;
- pieceList[them][st->capturedType][index[capsq]] = capsq;
+ index[capsq] = pieceCount[them][capture]++;
+ pieceList[them][capture][index[capsq]] = capsq;
}
// Finally point our state pointer back to the previous state
}
-/// Position::undo_castle_move() is a private method used to unmake a castling
-/// move. It is called from the main Position::undo_move function. 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.
-
-void Position::undo_castle_move(Move m) {
+/// 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(is_castle(m));
- // When we have arrived here, some work has already been done by
- // Position::undo_move. In particular, the side to move has been switched,
- // so the code below is correct.
- Color us = side_to_move();
+ Square kto, kfrom, rfrom, rto, kAfter, rAfter;
- // Find source squares for king and rook
- Square kfrom = move_from(m);
- Square rfrom = move_to(m);
- Square kto, rto;
+ Color us = side_to_move();
+ Square kBefore = move_from(m);
+ Square rBefore = move_to(m);
- // Find destination squares for king and rook
- if (rfrom > kfrom) // O-O
+ // Find after-castle squares for king and rook
+ if (rBefore > kBefore) // O-O
{
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
+ kAfter = relative_square(us, SQ_G1);
+ rAfter = relative_square(us, SQ_F1);
}
else // O-O-O
{
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
+ kAfter = relative_square(us, SQ_C1);
+ rAfter = relative_square(us, SQ_D1);
}
- assert(piece_on(kto) == make_piece(us, KING));
- assert(piece_on(rto) == make_piece(us, ROOK));
-
- // Remove pieces from destination squares
- clear_bit(&byColorBB[us], kto);
- clear_bit(&byTypeBB[KING], kto);
- clear_bit(&byTypeBB[0], kto);
- clear_bit(&byColorBB[us], rto);
- clear_bit(&byTypeBB[ROOK], rto);
- clear_bit(&byTypeBB[0], rto);
-
- // Put pieces on source squares
- set_bit(&byColorBB[us], kfrom);
- set_bit(&byTypeBB[KING], kfrom);
- set_bit(&byTypeBB[0], kfrom);
- set_bit(&byColorBB[us], rfrom);
- set_bit(&byTypeBB[ROOK], rfrom);
- set_bit(&byTypeBB[0], rfrom);
+ 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));
+
+ // Remove pieces from source squares
+ clear_bit(&byColorBB[us], kfrom);
+ clear_bit(&byTypeBB[KING], kfrom);
+ clear_bit(&occupied, kfrom);
+ clear_bit(&byColorBB[us], rfrom);
+ clear_bit(&byTypeBB[ROOK], rfrom);
+ clear_bit(&occupied, rfrom);
+
+ // Put pieces on destination squares
+ set_bit(&byColorBB[us], kto);
+ set_bit(&byTypeBB[KING], kto);
+ set_bit(&occupied, kto);
+ set_bit(&byColorBB[us], rto);
+ set_bit(&byTypeBB[ROOK], rto);
+ set_bit(&occupied, rto);
// Update board
Piece king = make_piece(us, KING);
Piece rook = make_piece(us, ROOK);
- board[kto] = board[rto] = PIECE_NONE;
- board[kfrom] = king;
- board[rfrom] = rook;
+ board[kfrom] = board[rfrom] = PIECE_NONE;
+ board[kto] = king;
+ board[rto] = rook;
// Update piece lists
- pieceList[us][KING][index[kto]] = kfrom;
- pieceList[us][ROOK][index[rto]] = rfrom;
- int tmp = index[rto]; // In Chess960 could be rto == kfrom
- index[kfrom] = index[kto];
- index[rfrom] = tmp;
-
- // Finally point our state pointer back to the previous state
- st = st->previous;
+ 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;
- assert(pos_is_ok());
-}
+ if (Do)
+ {
+ // Reset capture field
+ st->capturedType = PIECE_TYPE_NONE;
+ // Update incremental scores
+ st->value += pst_delta(king, kfrom, kto);
+ st->value += pst_delta(rook, rfrom, rto);
-/// Position::do_null_move makes() a "null move": It switches the side to move
-/// and updates the hash key without executing any move on the board.
+ // Update hash key
+ st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
+ st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
-void Position::do_null_move(StateInfo& backupSt) {
+ // Clear en passant square
+ if (st->epSquare != SQ_NONE)
+ {
+ st->key ^= zobEp[st->epSquare];
+ st->epSquare = SQ_NONE;
+ }
- assert(!in_check());
+ // Update castling rights
+ st->key ^= zobCastle[st->castleRights];
+ st->castleRights &= castleRightsMask[kfrom];
+ st->key ^= zobCastle[st->castleRights];
- // 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 a new state to be used.
- backupSt.key = st->key;
- backupSt.epSquare = st->epSquare;
- backupSt.value = st->value;
- backupSt.previous = st->previous;
- backupSt.pliesFromNull = st->pliesFromNull;
- st->previous = &backupSt;
-
- // Update the necessary information
- if (st->epSquare != SQ_NONE)
- st->key ^= zobEp[st->epSquare];
+ // Reset rule 50 counter
+ st->rule50 = 0;
- st->key ^= zobSideToMove;
- prefetch((char*)TT.first_entry(st->key));
+ // Update checkers BB
+ st->checkersBB = attackers_to(king_square(flip(us))) & pieces(us);
- sideToMove = flip(sideToMove);
- st->epSquare = SQ_NONE;
- st->rule50++;
- st->pliesFromNull = 0;
- st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
+ // Finish
+ sideToMove = flip(sideToMove);
+ st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
+ }
+ else
+ // Undo: point our state pointer back to the previous state
+ st = st->previous;
assert(pos_is_ok());
}
-/// Position::undo_null_move() unmakes a "null move".
-
-void Position::undo_null_move() {
+/// 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());
- // Restore information from the our backup StateInfo object
- StateInfo* backupSt = st->previous;
- st->key = backupSt->key;
- st->epSquare = backupSt->epSquare;
- st->value = backupSt->value;
- st->previous = backupSt->previous;
- st->pliesFromNull = backupSt->pliesFromNull;
+ // 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->value = src->value;
+ dst->rule50 = src->rule50;
+ dst->pliesFromNull = src->pliesFromNull;
- // Update the necessary information
sideToMove = flip(sideToMove);
- st->rule50--;
+
+ if (Do)
+ {
+ if (st->epSquare != SQ_NONE)
+ st->key ^= zobEp[st->epSquare];
+
+ st->key ^= zobSideToMove;
+ prefetch((char*)TT.first_entry(st->key));
+
+ st->epSquare = SQ_NONE;
+ st->rule50++;
+ st->pliesFromNull = 0;
+ st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
+ }
assert(pos_is_ok());
}
+// 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
int Position::see(Move m) const {
Square from, to;
- Bitboard occupied, attackers, stmAttackers, b;
+ Bitboard occ, attackers, stmAttackers, b;
int swapList[32], slIndex = 1;
PieceType capturedType, pt;
Color stm;
from = move_from(m);
to = move_to(m);
capturedType = type_of(piece_on(to));
- occupied = occupied_squares();
+ occ = occupied_squares();
// Handle en passant moves
- if (st->epSquare == to && type_of(piece_on(from)) == PAWN)
+ if (is_enpassant(m))
{
Square capQq = to - pawn_push(side_to_move());
assert(type_of(piece_on(capQq)) == PAWN);
// Remove the captured pawn
- clear_bit(&occupied, capQq);
+ clear_bit(&occ, capQq);
capturedType = PAWN;
}
// Find all attackers to the destination square, with the moving piece
// removed, but possibly an X-ray attacker added behind it.
- clear_bit(&occupied, from);
- attackers = attackers_to(to, occupied);
+ clear_bit(&occ, from);
+ attackers = attackers_to(to, occ);
// If the opponent has no attackers we are finished
stm = flip(color_of(piece_on(from)));
// Remove the attacker we just found from the 'occupied' bitboard,
// and scan for new X-ray attacks behind the attacker.
b = stmAttackers & pieces(pt);
- occupied ^= (b & (~b + 1));
- attackers |= (rook_attacks_bb(to, occupied) & pieces(ROOK, QUEEN))
- | (bishop_attacks_bb(to, occupied) & pieces(BISHOP, QUEEN));
+ occ ^= (b & (~b + 1));
+ attackers |= (rook_attacks_bb(to, occ) & pieces(ROOK, QUEEN))
+ | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN));
- attackers &= occupied; // Cut out pieces we've already done
+ attackers &= occ; // Cut out pieces we've already done
// Add the new entry to the swap list
assert(slIndex < 32);
// Having built the swap list, we negamax through it to find the best
// achievable score from the point of view of the side to move.
while (--slIndex)
- swapList[slIndex-1] = Min(-swapList[slIndex], swapList[slIndex-1]);
+ swapList[slIndex-1] = std::min(-swapList[slIndex], swapList[slIndex-1]);
return swapList[0];
}
}
sideToMove = WHITE;
nodes = 0;
+ occupied = 0;
}
set_bit(&byTypeBB[pt], s);
set_bit(&byColorBB[c], s);
- set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares.
+ set_bit(&occupied, s);
}
// Draw by repetition?
if (!SkipRepetition)
{
- int i = 4, e = Min(st->rule50, st->pliesFromNull);
+ int i = 4, e = std::min(st->rule50, st->pliesFromNull);
if (i <= e)
{
// Castling rights
if (pos.can_castle(WHITE_OO))
- set_castle(BLACK_OO, king_square(BLACK), flip(pos.castle_rook_square(WHITE_OO)));
+ set_castle_right(king_square(BLACK), flip(pos.castle_rook_square(WHITE_OO)));
if (pos.can_castle(WHITE_OOO))
- set_castle(BLACK_OOO, king_square(BLACK), flip(pos.castle_rook_square(WHITE_OOO)));
+ set_castle_right(king_square(BLACK), flip(pos.castle_rook_square(WHITE_OOO)));
if (pos.can_castle(BLACK_OO))
- set_castle(WHITE_OO, king_square(WHITE), flip(pos.castle_rook_square(BLACK_OO)));
+ set_castle_right(king_square(WHITE), flip(pos.castle_rook_square(BLACK_OO)));
if (pos.can_castle(BLACK_OOO))
- set_castle(WHITE_OOO, king_square(WHITE), flip(pos.castle_rook_square(BLACK_OOO)));
+ set_castle_right(king_square(WHITE), flip(pos.castle_rook_square(BLACK_OOO)));
// En passant square
if (pos.st->epSquare != SQ_NONE)
projects / stockfish / blobdiff