/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2014 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm>
#include <cassert>
#include <cstring>
-#include <fstream>
-#include <iostream>
+#include <iomanip>
#include <sstream>
#include "bitcount.h"
#include "movegen.h"
+#include "notation.h"
#include "position.h"
#include "psqtab.h"
#include "rkiss.h"
#include "tt.h"
using std::string;
-using std::cout;
-using std::endl;
-
-Key Position::zobrist[2][8][64];
-Key Position::zobEp[64];
-Key Position::zobCastle[16];
-Key Position::zobSideToMove;
-Key Position::zobExclusion;
-
-Score Position::pieceSquareTable[16][64];
-
-// Material values arrays, indexed by Piece
-const Value PieceValueMidgame[17] = {
- VALUE_ZERO,
- PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
- RookValueMidgame, QueenValueMidgame,
- VALUE_ZERO, VALUE_ZERO, VALUE_ZERO,
- PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
- RookValueMidgame, QueenValueMidgame
-};
-
-const Value PieceValueEndgame[17] = {
- VALUE_ZERO,
- PawnValueEndgame, KnightValueEndgame, BishopValueEndgame,
- RookValueEndgame, QueenValueEndgame,
- VALUE_ZERO, VALUE_ZERO, VALUE_ZERO,
- PawnValueEndgame, KnightValueEndgame, BishopValueEndgame,
- RookValueEndgame, QueenValueEndgame
-};
+static const string PieceToChar(" PNBRQK pnbrqk");
+
+CACHE_LINE_ALIGNMENT
+
+Value PieceValue[PHASE_NB][PIECE_NB] = {
+{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
+{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } };
+
+static Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+
+namespace Zobrist {
+
+ Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+ Key enpassant[FILE_NB];
+ Key castling[CASTLING_RIGHT_NB];
+ Key side;
+ Key exclusion;
+}
+
+Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion;}
namespace {
- // Bonus for having the side to move (modified by Joona Kiiski)
- const Score TempoValue = make_score(48, 22);
+// min_attacker() is a helper function used by see() 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<int Pt> FORCE_INLINE
+PieceType min_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers,
+ Bitboard& occupied, Bitboard& attackers) {
+
+ Bitboard b = stmAttackers & bb[Pt];
+ if (!b)
+ return min_attacker<Pt+1>(bb, to, stmAttackers, occupied, attackers);
+
+ 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]);
+
+ attackers &= occupied; // After X-ray that may add already processed pieces
+ return (PieceType)Pt;
+}
- // To convert a Piece to and from a FEN char
- const string PieceToChar(".PNBRQK pnbrqk ");
+template<> FORCE_INLINE
+PieceType min_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) {
- Color them = flip(pos.side_to_move());
- Square ksq = pos.king_square(them);
+ Color them = ~pos.side_to_move();
+ ksq = pos.king_square(them);
- pinned = pos.pinned_pieces();
+ pinned = pos.pinned_pieces(pos.side_to_move());
dcCandidates = pos.discovered_check_candidates();
checkSq[PAWN] = pos.attacks_from<PAWN>(ksq, them);
checkSq[BISHOP] = pos.attacks_from<BISHOP>(ksq);
checkSq[ROOK] = pos.attacks_from<ROOK>(ksq);
checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK];
- checkSq[KING] = EmptyBoardBB;
+ checkSq[KING] = 0;
+}
+
+
+/// Position::init() initializes at startup the various arrays used to compute
+/// hash keys and the piece square tables. The latter is a two-step operation:
+/// Firstly, the white halves of the tables are copied from PSQT[] tables.
+/// Secondly, the black halves of the tables are initialized by flipping and
+/// changing the sign of the white scores.
+
+void Position::init() {
+
+ RKISS rk;
+
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ for (Square s = SQ_A1; s <= SQ_H8; ++s)
+ Zobrist::psq[c][pt][s] = rk.rand<Key>();
+
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ Zobrist::enpassant[f] = rk.rand<Key>();
+
+ for (int cf = NO_CASTLING; cf <= ANY_CASTLING; ++cf)
+ {
+ Bitboard b = cf;
+ while (b)
+ {
+ Key k = Zobrist::castling[1ULL << pop_lsb(&b)];
+ Zobrist::castling[cf] ^= k ? k : rk.rand<Key>();
+ }
+ }
+
+ Zobrist::side = rk.rand<Key>();
+ Zobrist::exclusion = rk.rand<Key>();
+
+ 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];
+
+ Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]);
+
+ for (Square s = SQ_A1; s <= SQ_H8; ++s)
+ {
+ psq[WHITE][pt][ s] = (v + PSQT[pt][s]);
+ psq[BLACK][pt][~s] = -(v + PSQT[pt][s]);
+ }
+ }
}
-/// Position c'tors. Here we always create a copy of the original position
-/// 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::operator=() creates a copy of 'pos'. We want the new born Position
+/// object to not depend on any external data so we detach state pointer from
+/// the source one.
-Position::Position(const Position& pos, int th) {
+Position& Position::operator=(const Position& pos) {
- memcpy(this, &pos, sizeof(Position));
- threadID = th;
+ std::memcpy(this, &pos, sizeof(Position));
+ startState = *st;
+ st = &startState;
nodes = 0;
assert(pos_is_ok());
+
+ return *this;
}
-Position::Position(const string& fen, bool isChess960, int th) {
- from_fen(fen, isChess960);
- threadID = th;
+/// Position::clear() erases the position object to a pristine state, with an
+/// empty board, white to move, and no castling rights.
+
+void Position::clear() {
+
+ std::memset(this, 0, sizeof(Position));
+ startState.epSquare = SQ_NONE;
+ st = &startState;
+
+ for (int i = 0; i < PIECE_TYPE_NB; ++i)
+ for (int j = 0; j < 16; ++j)
+ pieceList[WHITE][i][j] = pieceList[BLACK][i][j] = SQ_NONE;
}
-/// 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) {
+void Position::set(const string& fenStr, bool isChess960, Thread* 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") whilst Black uses 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;
- size_t p;
+ unsigned char col, row, token;
+ size_t idx;
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 (token == '/')
- sq -= Square(16); // Jump back of 2 rows
+ if (isdigit(token))
+ sq += Square(token - '0'); // Advance the given number of files
- else if (isdigit(token))
- sq += Square(token - '0'); // Skip the given number of files
+ else if (token == '/')
+ sq -= Square(16);
- else if ((p = PieceToChar.find(token)) != string::npos)
+ else if ((idx = PieceToChar.find(token)) != string::npos)
{
- put_piece(Piece(p), sq);
- sq++;
+ put_piece(sq, color_of(Piece(idx)), type_of(Piece(idx)));
+ ++sq;
}
}
// 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 ((ss >> token) && !isspace(token))
+ {
+ Square rsq;
+ Color c = islower(token) ? BLACK : WHITE;
- // 3. Castling availability
- while ((fen >> token) && !isspace(token))
- set_castling_rights(token);
+ token = char(toupper(token));
+
+ if (token == 'K')
+ for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; --rsq) {}
+
+ else if (token == 'Q')
+ for (rsq = relative_square(c, SQ_A1); type_of(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_castling_right(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')))
+ if ( ((ss >> col) && (col >= 'a' && col <= 'h'))
+ && ((ss >> 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(sideToMove, PAWN)))
st->epSquare = SQ_NONE;
}
// 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 = Max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
+ gamePly = std::max(2 * (gamePly - 1), 0) + (sideToMove == BLACK);
- // Various initialisations
chess960 = isChess960;
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
-
- st->key = compute_key();
- st->pawnKey = compute_pawn_key();
- st->materialKey = compute_material_key();
- st->value = compute_value();
- st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ thisThread = th;
+ set_state(st);
assert(pos_is_ok());
}
-/// Position::set_castle() is an helper function used to set
-/// correct castling related flags.
+/// Position::set_castling_right() is a helper function used to set castling
+/// rights given the corresponding color and the rook starting square.
+
+void Position::set_castling_right(Color c, Square rfrom) {
+
+ Square kfrom = king_square(c);
+ CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE;
+ CastlingRight cr = (c | cs);
-void Position::set_castle(int f, Square ksq, Square rsq) {
+ st->castlingRights |= cr;
+ castlingRightsMask[kfrom] |= cr;
+ castlingRightsMask[rfrom] |= cr;
+ castlingRookSquare[cr] = rfrom;
- st->castleRights |= f;
- castleRightsMask[ksq] ^= f;
- castleRightsMask[rsq] ^= f;
- castleRookSquare[f] = rsq;
+ Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1);
+
+ for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s)
+ if (s != kfrom && s != rfrom)
+ castlingPath[cr] |= s;
+
+ for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s)
+ if (s != kfrom && s != rfrom)
+ castlingPath[cr] |= s;
}
-/// 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.
+/// Position::set_state() computes the hash keys of the position, and other
+/// data that once computed is updated incrementally as moves are made.
+/// The function is only used when a new position is set up, and to verify
+/// the correctness of the StateInfo data when running in debug mode.
+
+void Position::set_state(StateInfo* si) const {
-void Position::set_castling_rights(char token) {
+ si->key = si->pawnKey = si->materialKey = 0;
+ si->npMaterial[WHITE] = si->npMaterial[BLACK] = VALUE_ZERO;
+ si->psq = SCORE_ZERO;
- Color c = islower(token) ? BLACK : WHITE;
+ si->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
- Square sqA = relative_square(c, SQ_A1);
- Square sqH = relative_square(c, SQ_H1);
- Square rsq, ksq = king_square(c);
+ for (Bitboard b = pieces(); b; )
+ {
+ Square s = pop_lsb(&b);
+ Piece pc = piece_on(s);
+ si->key ^= Zobrist::psq[color_of(pc)][type_of(pc)][s];
+ si->psq += psq[color_of(pc)][type_of(pc)][s];
+ }
- token = char(toupper(token));
+ if (ep_square() != SQ_NONE)
+ si->key ^= Zobrist::enpassant[file_of(ep_square())];
- if (token == 'K')
- for (rsq = sqH; piece_on(rsq) != make_piece(c, ROOK); rsq--) {}
+ if (sideToMove == BLACK)
+ si->key ^= Zobrist::side;
- else if (token == 'Q')
- for (rsq = sqA; piece_on(rsq) != make_piece(c, ROOK); rsq++) {}
+ si->key ^= Zobrist::castling[st->castlingRights];
- else if (token >= 'A' && token <= 'H')
- rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1));
+ for (Bitboard b = pieces(PAWN); b; )
+ {
+ Square s = pop_lsb(&b);
+ si->pawnKey ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s];
+ }
- else return;
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ for (int cnt = 0; cnt < pieceCount[c][pt]; ++cnt)
+ si->materialKey ^= Zobrist::psq[c][pt][cnt];
- if (file_of(rsq) < file_of(ksq))
- set_castle(WHITE_OOO << c, ksq, rsq);
- else
- set_castle(WHITE_OO << c, ksq, rsq);
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt)
+ si->npMaterial[c] += pieceCount[c][pt] * PieceValue[MG][pt];
}
-/// Position::to_fen() returns a FEN representation of the position. In case
-/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function.
+/// Position::fen() returns a FEN representation of the position. In case of
+/// Chess960 the Shredder-FEN notation is used. This is 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--)
+ for (Rank r = RANK_8; r >= RANK_1; --r)
{
- emptyCnt = 0;
-
- for (File file = FILE_A; file <= FILE_H; file++)
+ for (File f = FILE_A; f <= FILE_H; ++f)
{
- sq = make_square(file, rank);
+ for (emptyCnt = 0; f <= FILE_H && empty(make_square(f, r)); ++f)
+ ++emptyCnt;
- if (!square_is_empty(sq))
- {
- if (emptyCnt)
- {
- fen << emptyCnt;
- emptyCnt = 0;
- }
- fen << PieceToChar[piece_on(sq)];
- }
- else
- emptyCnt++;
- }
+ if (emptyCnt)
+ ss << emptyCnt;
- if (emptyCnt)
- fen << emptyCnt;
+ if (f <= FILE_H)
+ ss << PieceToChar[piece_on(make_square(f, r))];
+ }
- if (rank > RANK_1)
- fen << '/';
+ if (r > RANK_1)
+ ss << '/';
}
- fen << (sideToMove == WHITE ? " w " : " b ");
+ ss << (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))
+ ss << (chess960 ? to_char(file_of(castling_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_OOO))))) : 'Q');
+ if (can_castle(WHITE_OOO))
+ ss << (chess960 ? to_char(file_of(castling_rook_square(WHITE | QUEEN_SIDE)), false) : 'Q');
- if (can_castle(BLACK_OO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k');
+ if (can_castle(BLACK_OO))
+ ss << (chess960 ? to_char(file_of(castling_rook_square(BLACK | KING_SIDE)), true) : 'k');
- if (can_castle(BLACK_OOO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q');
- } else
- fen << '-';
+ if (can_castle(BLACK_OOO))
+ ss << (chess960 ? to_char(file_of(castling_rook_square(BLACK | QUEEN_SIDE)), true) : 'q');
- fen << (ep_square() == SQ_NONE ? " -" : " " + square_to_string(ep_square()))
- << " " << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
+ if (!can_castle(WHITE) && !can_castle(BLACK))
+ ss << '-';
- return fen.str();
+ ss << (ep_square() == SQ_NONE ? " - " : " " + to_string(ep_square()) + " ")
+ << st->rule50 << " " << 1 + (gamePly - (sideToMove == BLACK)) / 2;
+
+ 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.
+
+const string Position::pretty(Move m) const {
+
+ std::ostringstream ss;
-void Position::print(Move move) const {
+ if (m)
+ ss << "\nMove: " << (sideToMove == BLACK ? ".." : "")
+ << move_to_san(*const_cast<Position*>(this), m);
- const char* dottedLine = "\n+---+---+---+---+---+---+---+---+\n";
+ ss << "\n +---+---+---+---+---+---+---+---+\n";
- if (move)
+ for (Rank r = RANK_8; r >= RANK_1; --r)
{
- Position p(*this, thread());
- string dd = (sideToMove == BLACK ? ".." : "");
- cout << "\nMove is: " << dd << move_to_san(p, move);
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ ss << " | " << PieceToChar[piece_on(make_square(f, r))];
+
+ ss << " |\n +---+---+---+---+---+---+---+---+\n";
}
- for (Rank rank = RANK_8; rank >= RANK_1; rank--)
- {
- cout << dottedLine << '|';
- for (File file = FILE_A; file <= FILE_H; file++)
- {
- Square sq = make_square(file, rank);
- Piece piece = piece_on(sq);
+ ss << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase
+ << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: ";
- if (piece == PIECE_NONE && color_of(sq) == DARK)
- piece = PIECE_NONE_DARK_SQ;
+ for (Bitboard b = checkers(); b; )
+ ss << to_string(pop_lsb(&b)) << " ";
- char c = (color_of(piece_on(sq)) == BLACK ? '=' : ' ');
- cout << c << PieceToChar[piece] << c << '|';
- }
- }
- cout << dottedLine << "Fen is: " << to_fen() << "\nKey is: " << st->key << endl;
+ ss << "\nLegal moves: ";
+ for (MoveList<LEGAL> it(*this); *it; ++it)
+ ss << move_to_san(*const_cast<Position*>(this), *it) << " ";
+
+ return ss.str();
}
-/// Position:hidden_checkers<>() returns a bitboard of all pinned (against the
-/// 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.
+/// Position::check_blockers() returns a bitboard of all the pieces with color
+/// 'c' that are blocking check on the king with color 'kingColor'. A piece
+/// blocks a check if removing that piece from the board would result in a
+/// position where the king is in check. A check blocking piece can be either a
+/// pinned or a discovered check piece, according if its color 'c' is the same
+/// or the opposite of 'kingColor'.
-template<bool FindPinned>
-Bitboard Position::hidden_checkers() const {
+Bitboard Position::check_blockers(Color c, Color kingColor) const {
- // Pinned pieces protect our king, dicovery checks attack the enemy king
- Bitboard b, result = EmptyBoardBB;
- Bitboard pinners = pieces(FindPinned ? flip(sideToMove) : sideToMove);
- Square ksq = king_square(FindPinned ? sideToMove : flip(sideToMove));
+ Bitboard b, pinners, result = 0;
+ Square ksq = king_square(kingColor);
- // Pinners are sliders, that give check when candidate pinned is removed
- pinners &= (pieces(ROOK, QUEEN) & RookPseudoAttacks[ksq])
- | (pieces(BISHOP, QUEEN) & BishopPseudoAttacks[ksq]);
+ // Pinners are sliders that give check when a pinned piece is removed
+ pinners = ( (pieces( ROOK, QUEEN) & PseudoAttacks[ROOK ][ksq])
+ | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(~kingColor);
while (pinners)
{
- b = squares_between(ksq, pop_1st_bit(&pinners)) & occupied_squares();
+ b = between_bb(ksq, pop_lsb(&pinners)) & pieces();
- // Only one bit set and is an our piece?
- if (b && !(b & (b - 1)) && (b & pieces(sideToMove)))
- result |= b;
+ if (!more_than_one(b))
+ result |= b & pieces(c);
}
return result;
}
-/// 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
-/// given square. Slider attacks use occ bitboard as occupancy.
+/// Position::attackers_to() computes a bitboard of all pieces which attack a
+/// given square. Slider attacks use the occ bitboard to indicate occupancy.
Bitboard Position::attackers_to(Square s, Bitboard occ) const {
- return (attacks_from<PAWN>(s, BLACK) & pieces(PAWN, WHITE))
- | (attacks_from<PAWN>(s, WHITE) & pieces(PAWN, BLACK))
+ return (attacks_from<PAWN>(s, BLACK) & pieces(WHITE, PAWN))
+ | (attacks_from<PAWN>(s, WHITE) & pieces(BLACK, PAWN))
| (attacks_from<KNIGHT>(s) & pieces(KNIGHT))
- | (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN))
- | (bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN))
+ | (attacks_bb<ROOK>(s, occ) & pieces(ROOK, QUEEN))
+ | (attacks_bb<BISHOP>(s, occ) & pieces(BISHOP, QUEEN))
| (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.
-
-Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) {
-
- assert(square_is_ok(s));
-
- switch (p)
- {
- case WB: case BB: return bishop_attacks_bb(s, occ);
- case WR: case BR: return rook_attacks_bb(s, occ);
- case WQ: case BQ: return bishop_attacks_bb(s, occ) | rook_attacks_bb(s, occ);
- default: return StepAttacksBB[p][s];
- }
-}
-
-
-/// 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(square_is_ok(s));
-
- Bitboard occ, xray;
- Square f = move_from(m), t = move_to(m);
-
- assert(!square_is_empty(f));
-
- if (bit_is_set(attacks_from(piece_on(f), t), 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)));
-
- // If we have attacks we need to verify that are caused by our move
- // and are not already existent ones.
- return xray && (xray ^ (xray & attacks_from<QUEEN>(s)));
-}
-
-/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
+/// Position::legal() tests whether a pseudo-legal move is legal
-bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
+bool Position::legal(Move m, Bitboard pinned) const {
assert(is_ok(m));
- assert(pinned == pinned_pieces());
+ assert(pinned == pinned_pieces(sideToMove));
- Color us = side_to_move();
- Square from = move_from(m);
+ Color us = sideToMove;
+ Square from = from_sq(m);
- assert(color_of(piece_on(from)) == us);
+ assert(color_of(moved_piece(m)) == us);
assert(piece_on(king_square(us)) == make_piece(us, KING));
// En passant captures are a tricky special case. Because they are rather
// uncommon, we do it simply by testing whether the king is attacked after
// the move is made.
- if (is_enpassant(m))
+ if (type_of(m) == ENPASSANT)
{
- Color them = flip(us);
- Square to = move_to(m);
- Square capsq = to + pawn_push(them);
Square ksq = king_square(us);
- Bitboard b = occupied_squares();
+ Square to = to_sq(m);
+ Square capsq = to - pawn_push(us);
+ Bitboard occ = (pieces() ^ from ^ capsq) | to;
assert(to == ep_square());
- assert(piece_on(from) == make_piece(us, PAWN));
- assert(piece_on(capsq) == make_piece(them, PAWN));
- assert(piece_on(to) == PIECE_NONE);
-
- clear_bit(&b, from);
- clear_bit(&b, capsq);
- set_bit(&b, to);
+ assert(moved_piece(m) == make_piece(us, PAWN));
+ assert(piece_on(capsq) == make_piece(~us, PAWN));
+ assert(piece_on(to) == NO_PIECE);
- return !(rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, them))
- && !(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them));
+ return !(attacks_bb< ROOK>(ksq, occ) & pieces(~us, QUEEN, ROOK))
+ && !(attacks_bb<BISHOP>(ksq, occ) & pieces(~us, QUEEN, BISHOP));
}
// If the moving piece is a king, check whether the destination
// square is attacked by the opponent. Castling moves are checked
// for legality during move generation.
if (type_of(piece_on(from)) == KING)
- return is_castle(m) || !(attackers_to(move_to(m)) & pieces(flip(us)));
+ return type_of(m) == CASTLING || !(attackers_to(to_sq(m)) & pieces(~us));
// A non-king move is legal if and only if it is not pinned or it
// is moving along the ray towards or away from the king.
return !pinned
- || !bit_is_set(pinned, from)
- || squares_aligned(from, move_to(m), king_square(us));
-}
-
-
-/// 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<MV_LEGAL> ml(*this); !ml.end(); ++ml)
- if (ml.move() == m)
- return true;
-
- return false;
+ || !(pinned & from)
+ || aligned(from, to_sq(m), king_square(us));
}
-/// 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
+/// Position::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 {
+bool Position::pseudo_legal(const Move m) const {
Color us = sideToMove;
- Color them = flip(sideToMove);
- Square from = move_from(m);
- Square to = move_to(m);
- Piece pc = piece_on(from);
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ Piece pc = moved_piece(m);
// Use a slower but simpler function for uncommon cases
- if (is_special(m))
- return move_is_legal(m);
+ if (type_of(m) != NORMAL)
+ return MoveList<LEGAL>(*this).contains(m);
// Is not a promotion, so promotion piece must be empty
- if (promotion_piece_type(m) - 2 != PIECE_TYPE_NONE)
+ if (promotion_type(m) - 2 != NO_PIECE_TYPE)
return false;
- // If the from square is not occupied by a piece belonging to the side to
+ // If the 'from' square is not occupied by a piece belonging to the side to
// move, the move is obviously not legal.
- if (pc == PIECE_NONE || color_of(pc) != us)
+ if (pc == NO_PIECE || color_of(pc) != us)
return false;
// The destination square cannot be occupied by a friendly piece
- if (color_of(piece_on(to)) == us)
+ if (pieces(us) & to)
return false;
// Handle the special case of a pawn move
if (type_of(pc) == PAWN)
{
- // Move direction must be compatible with pawn color
- int direction = to - from;
- if ((us == WHITE) != (direction > 0))
- return false;
-
// We have already handled promotion moves, so destination
- // cannot be on the 8/1th rank.
- if (rank_of(to) == RANK_8 || rank_of(to) == RANK_1)
+ // cannot be on the 8th/1st rank.
+ if (rank_of(to) == relative_rank(us, RANK_8))
return false;
- // Proceed according to the square delta between the origin and
- // destination squares.
- switch (direction)
- {
- case DELTA_NW:
- case DELTA_NE:
- case DELTA_SW:
- 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)
- return false;
-
- // From and to files must be one file apart, avoids a7h5
- if (abs(file_of(from) - file_of(to)) != 1)
- return false;
- break;
+ if ( !(attacks_from<PAWN>(from, us) & pieces(~us) & to) // Not a capture
- case DELTA_N:
- case DELTA_S:
- // Pawn push. The destination square must be empty.
- if (!square_is_empty(to))
- return false;
- break;
-
- case DELTA_NN:
- // Double white pawn push. The destination square must be on the fourth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( rank_of(to) != RANK_4
- || !square_is_empty(to)
- || !square_is_empty(from + DELTA_N))
- return false;
- break;
-
- case DELTA_SS:
- // Double black pawn push. The destination square must be on the fifth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( rank_of(to) != RANK_5
- || !square_is_empty(to)
- || !square_is_empty(from + DELTA_S))
- return false;
- break;
+ && !((from + pawn_push(us) == to) && empty(to)) // Not a single push
- default:
+ && !( (from + 2 * pawn_push(us) == to) // Not a double push
+ && (rank_of(from) == relative_rank(us, RANK_2))
+ && empty(to)
+ && empty(to - pawn_push(us))))
return false;
- }
}
- else if (!bit_is_set(attacks_from(pc, from), to))
+ else if (!(attacks_from(pc, from) & to))
return false;
- if (in_check())
+ // Evasions generator already takes care to avoid some kind of illegal moves
+ // and legal() relies on this. We therefore have to take care that the same
+ // kind of moves are filtered out here.
+ if (checkers())
{
- // In case of king moves under check we have to remove king so to catch
- // as invalid moves like b1a1 when opposite queen is on c1.
- if (type_of(piece_on(from)) == KING)
- {
- Bitboard b = occupied_squares();
- clear_bit(&b, from);
- if (attackers_to(move_to(m), b) & pieces(flip(us)))
- return false;
- }
- else
+ if (type_of(pc) != KING)
{
- Bitboard target = checkers();
- Square checksq = pop_1st_bit(&target);
-
- if (target) // 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
- target = squares_between(checksq, king_square(us)) | checkers();
- if (!bit_is_set(target, move_to(m)))
+ 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 as to catch
+ // invalid moves like b1a1 when opposite queen is on c1.
+ else if (attackers_to(to, pieces() ^ from) & pieces(~us))
+ return false;
}
return true;
}
-/// Position::move_gives_check() tests whether a pseudo-legal move gives a check
+/// Position::gives_check() tests whether a pseudo-legal move gives a check
-bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
+bool Position::gives_check(Move m, const CheckInfo& ci) const {
assert(is_ok(m));
assert(ci.dcCandidates == discovered_check_candidates());
- assert(color_of(piece_on(move_from(m))) == side_to_move());
+ assert(color_of(moved_piece(m)) == sideToMove);
- Square from = move_from(m);
- Square to = move_to(m);
+ Square from = from_sq(m);
+ Square to = to_sq(m);
PieceType pt = type_of(piece_on(from));
- // Direct check ?
- if (bit_is_set(ci.checkSq[pt], to))
+ // Is there a direct check?
+ if (ci.checkSq[pt] & to)
return true;
- // Discovery check ?
- if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
- {
- // For pawn and king moves we need to verify also direction
- if ( (pt != PAWN && pt != KING)
- || !squares_aligned(from, to, king_square(flip(side_to_move()))))
- return true;
- }
-
- // Can we skip the ugly special cases ?
- if (!is_special(m))
- return false;
-
- Color us = side_to_move();
- Bitboard b = occupied_squares();
- Square ksq = king_square(flip(us));
+ // Is there a discovered check?
+ if ( unlikely(ci.dcCandidates)
+ && (ci.dcCandidates & from)
+ && !aligned(from, to, ci.ksq))
+ return true;
- // Promotion with check ?
- if (is_promotion(m))
+ switch (type_of(m))
{
- clear_bit(&b, from);
+ case NORMAL:
+ return false;
- switch (promotion_piece_type(m))
- {
- case KNIGHT:
- return bit_is_set(attacks_from<KNIGHT>(to), ksq);
- case BISHOP:
- return bit_is_set(bishop_attacks_bb(to, b), ksq);
- case ROOK:
- return bit_is_set(rook_attacks_bb(to, b), ksq);
- case QUEEN:
- return bit_is_set(queen_attacks_bb(to, b), ksq);
- default:
- assert(false);
- }
- }
+ case PROMOTION:
+ return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq;
- // En passant capture with check ? We have already handled the case
- // of direct checks and ordinary discovered check, the only case we
+ // En passant capture with check? We have already handled the case
+ // of direct checks and ordinary discovered check, so the only case we
// need to handle is the unusual case of a discovered check through
// the captured pawn.
- if (is_enpassant(m))
+ case ENPASSANT:
{
Square capsq = make_square(file_of(to), rank_of(from));
- clear_bit(&b, from);
- clear_bit(&b, capsq);
- set_bit(&b, to);
- return (rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, us))
- ||(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, us));
- }
+ Bitboard b = (pieces() ^ from ^ capsq) | to;
- // Castling with check ?
- if (is_castle(m))
+ return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP));
+ }
+ case CASTLING:
{
- Square kfrom, kto, rfrom, rto;
- kfrom = from;
- rfrom = to;
+ Square kfrom = from;
+ 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);
- if (rfrom > kfrom)
- {
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- } else {
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
- }
- clear_bit(&b, kfrom);
- clear_bit(&b, rfrom);
- set_bit(&b, rto);
- set_bit(&b, kto);
- return bit_is_set(rook_attacks_bb(rto, b), ksq);
+ return (PseudoAttacks[ROOK][rto] & ci.ksq)
+ && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq);
+ }
+ default:
+ assert(false);
+ return false;
}
-
- return false;
}
void Position::do_move(Move m, StateInfo& newSt) {
CheckInfo ci(*this);
- do_move(m, newSt, ci, move_gives_check(m, ci));
+ do_move(m, newSt, ci, gives_check(m, ci));
}
void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) {
assert(is_ok(m));
assert(&newSt != st);
- 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.
- struct ReducedStateInfo {
- Key pawnKey, materialKey;
- Value npMaterial[2];
- int castleRights, rule50, pliesFromNull;
- Score value;
- Square epSquare;
- };
+ ++nodes;
+ Key k = st->key;
- memcpy(&newSt, st, sizeof(ReducedStateInfo));
+ // Copy some fields of the old state to our new StateInfo object except the
+ // ones which are going to be recalculated from scratch anyway and then switch
+ // our state pointer to point to the new (ready to be updated) state.
+ std::memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t));
newSt.previous = st;
st = &newSt;
// Update side to move
- key ^= zobSideToMove;
+ k ^= Zobrist::side;
- // Increment the 50 moves rule draw counter. Resetting it to zero in the
- // case of non-reversible moves is taken care of later.
- st->rule50++;
- st->pliesFromNull++;
+ // Increment ply counters. In particular, rule50 will be reset to zero later on
+ // in case of a capture or a pawn move.
+ ++gamePly;
+ ++st->rule50;
+ ++st->pliesFromNull;
- if (is_castle(m))
+ Color us = sideToMove;
+ Color them = ~us;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ Piece pc = piece_on(from);
+ PieceType pt = type_of(pc);
+ PieceType captured = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to));
+
+ assert(color_of(pc) == us);
+ assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLING);
+ assert(captured != KING);
+
+ if (type_of(m) == CASTLING)
{
- st->key = key;
- do_castle_move(m);
- return;
+ assert(pc == make_piece(us, KING));
+
+ Square rfrom, rto;
+ do_castling<true>(from, to, rfrom, rto);
+
+ captured = NO_PIECE_TYPE;
+ st->psq += psq[us][ROOK][rto] - psq[us][ROOK][rfrom];
+ k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
}
- Color us = side_to_move();
- Color them = flip(us);
- Square from = move_from(m);
- Square to = move_to(m);
- bool ep = is_enpassant(m);
- bool pm = is_promotion(m);
+ if (captured)
+ {
+ Square capsq = to;
+
+ // If the captured piece is a pawn, update pawn hash key, otherwise
+ // update non-pawn material.
+ if (captured == PAWN)
+ {
+ if (type_of(m) == ENPASSANT)
+ {
+ capsq += pawn_push(them);
+
+ assert(pt == PAWN);
+ assert(to == st->epSquare);
+ 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;
+ }
- Piece piece = piece_on(from);
- PieceType pt = type_of(piece);
- PieceType capture = ep ? PAWN : type_of(piece_on(to));
+ st->pawnKey ^= Zobrist::psq[them][PAWN][capsq];
+ }
+ else
+ st->npMaterial[them] -= PieceValue[MG][captured];
- 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);
+ // Update board and piece lists
+ remove_piece(capsq, them, captured);
- if (capture)
- do_capture_move(key, capture, them, to, ep);
+ // Update material hash key and prefetch access to materialTable
+ k ^= Zobrist::psq[them][captured][capsq];
+ st->materialKey ^= Zobrist::psq[them][captured][pieceCount[them][captured]];
+ prefetch((char*)thisThread->materialTable[st->materialKey]);
+
+ // Update incremental scores
+ st->psq -= psq[them][captured][capsq];
+
+ // Reset rule 50 counter
+ st->rule50 = 0;
+ }
// Update hash key
- key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
+ k ^= Zobrist::psq[us][pt][from] ^ Zobrist::psq[us][pt][to];
// Reset en passant square
if (st->epSquare != SQ_NONE)
{
- key ^= zobEp[st->epSquare];
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
st->epSquare = SQ_NONE;
}
- // Update castle rights if needed
- if ( st->castleRights != CASTLES_NONE
- && (castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES)
+ // Update castling rights if needed
+ if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to]))
{
- key ^= zobCastle[st->castleRights];
- st->castleRights &= castleRightsMask[from] & castleRightsMask[to];
- key ^= zobCastle[st->castleRights];
+ int cr = castlingRightsMask[from] | castlingRightsMask[to];
+ k ^= Zobrist::castling[st->castlingRights & cr];
+ st->castlingRights &= ~cr;
}
- // Prefetch TT access as soon as we know key is updated
- prefetch((char*)TT.first_entry(key));
-
- // Move the piece
- 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
+ // Prefetch TT access as soon as we know the new hash key
+ prefetch((char*)TT.first_entry(k));
- board[to] = board[from];
- board[from] = PIECE_NONE;
+ // Move the piece. The tricky Chess960 castling is handled earlier
+ if (type_of(m) != CASTLING)
+ move_piece(from, to, us, pt);
- // 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.
- 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 if the moved pawn can be captured
+ if ( (int(to) ^ int(from)) == 16
+ && (attacks_from<PAWN>(from + pawn_push(us), us) & pieces(them, PAWN)))
{
- 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);
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
}
- if (pm) // promotion ?
+ else if (type_of(m) == PROMOTION)
{
- PieceType promotion = promotion_piece_type(m);
+ PieceType promotion = promotion_type(m);
+ assert(relative_rank(us, to) == RANK_8);
assert(promotion >= KNIGHT && promotion <= QUEEN);
- // Insert promoted piece instead of pawn
- clear_bit(&byTypeBB[PAWN], to);
- set_bit(&byTypeBB[promotion], to);
- board[to] = make_piece(us, promotion);
+ remove_piece(to, us, PAWN);
+ put_piece(to, us, promotion);
- // Update piece counts
- pieceCount[us][promotion]++;
- pieceCount[us][PAWN]--;
+ // Update hash keys
+ k ^= Zobrist::psq[us][PAWN][to] ^ Zobrist::psq[us][promotion][to];
+ st->pawnKey ^= Zobrist::psq[us][PAWN][to];
+ st->materialKey ^= Zobrist::psq[us][promotion][pieceCount[us][promotion]-1]
+ ^ Zobrist::psq[us][PAWN][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;
- pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE;
- index[to] = pieceCount[us][promotion] - 1;
- pieceList[us][promotion][index[to]] = to;
-
- // Partially revert hash keys update
- key ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to];
- st->pawnKey ^= zobrist[us][PAWN][to];
-
- // 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->psq += psq[us][promotion][to] - psq[us][PAWN][to];
// Update material
- st->npMaterial[us] += PieceValueMidgame[promotion];
+ st->npMaterial[us] += PieceValue[MG][promotion];
}
- }
- // Prefetch pawn and material hash tables
- Threads[threadID].pawnTable.prefetch(st->pawnKey);
- Threads[threadID].materialTable.prefetch(st->materialKey);
+ // 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;
+ }
// Update incremental scores
- st->value += pst_delta(piece, from, to);
+ st->psq += psq[us][pt][to] - psq[us][pt][from];
// Set capture piece
- st->capturedType = capture;
+ st->capturedType = captured;
// Update the key with the final value
- st->key = key;
+ st->key = k;
- // Update checkers bitboard, piece must be already moved
- st->checkersBB = EmptyBoardBB;
+ // Update checkers bitboard: piece must be already moved due to attacks_from()
+ st->checkersBB = 0;
if (moveIsCheck)
{
- if (ep | pm)
+ if (type_of(m) != NORMAL)
st->checkersBB = attackers_to(king_square(them)) & pieces(us);
else
{
// Direct checks
- if (bit_is_set(ci.checkSq[pt], to))
- st->checkersBB = SetMaskBB[to];
+ if (ci.checkSq[pt] & to)
+ st->checkersBB |= to;
- // Discovery checks
- if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
+ // Discovered checks
+ if (unlikely(ci.dcCandidates) && (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(us, QUEEN, ROOK);
if (pt != BISHOP)
- st->checkersBB |= (attacks_from<BISHOP>(king_square(them)) & pieces(BISHOP, QUEEN, us));
+ st->checkersBB |= attacks_from<BISHOP>(king_square(them)) & pieces(us, QUEEN, BISHOP);
}
}
}
- // Finish
- sideToMove = flip(sideToMove);
- st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
-
- assert(pos_is_ok());
-}
-
-
-/// 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);
+ sideToMove = ~sideToMove;
assert(pos_is_ok());
}
assert(is_ok(m));
- sideToMove = flip(sideToMove);
-
- if (is_castle(m))
- {
- undo_castle_move(m);
- return;
- }
-
- Color us = side_to_move();
- Color them = flip(us);
- Square from = move_from(m);
- Square to = move_to(m);
- bool ep = is_enpassant(m);
- bool pm = is_promotion(m);
+ sideToMove = ~sideToMove;
+ Color us = sideToMove;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
PieceType pt = type_of(piece_on(to));
- 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(empty(from) || type_of(m) == CASTLING);
+ assert(st->capturedType != KING);
- if (pm) // promotion ?
+ if (type_of(m) == PROMOTION)
{
- PieceType promotion = promotion_piece_type(m);
- pt = PAWN;
-
- assert(promotion >= KNIGHT && promotion <= QUEEN);
- assert(piece_on(to) == make_piece(us, promotion));
-
- // Replace promoted piece with a pawn
- clear_bit(&byTypeBB[promotion], to);
- set_bit(&byTypeBB[PAWN], to);
-
- // Update piece counts
- pieceCount[us][promotion]--;
- pieceCount[us][PAWN]++;
+ assert(pt == promotion_type(m));
+ assert(relative_rank(us, to) == RANK_8);
+ assert(promotion_type(m) >= KNIGHT && promotion_type(m) <= QUEEN);
- // 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;
- pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE;
- index[to] = pieceCount[us][PAWN] - 1;
- pieceList[us][PAWN][index[to]] = to;
+ remove_piece(to, us, promotion_type(m));
+ put_piece(to, us, PAWN);
+ 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
-
- board[from] = make_piece(us, pt);
- board[to] = PIECE_NONE;
-
- // Update piece list
- index[from] = index[to];
- pieceList[us][pt][index[from]] = from;
-
- if (st->capturedType)
+ if (type_of(m) == CASTLING)
{
- Square capsq = to;
-
- if (ep)
- capsq = to - pawn_push(us);
-
- assert(st->capturedType != KING);
- assert(!ep || square_is_empty(capsq));
+ Square rfrom, rto;
+ do_castling<false>(from, to, rfrom, rto);
+ }
+ else
+ {
+ move_piece(to, from, us, pt); // Put the piece back at the source square
- // Restore the captured piece
- set_bit(&byColorBB[them], capsq);
- set_bit(&byTypeBB[st->capturedType], capsq);
- set_bit(&byTypeBB[0], capsq);
+ if (st->capturedType)
+ {
+ Square capsq = to;
- board[capsq] = make_piece(them, st->capturedType);
+ if (type_of(m) == ENPASSANT)
+ {
+ capsq -= pawn_push(us);
- // Update piece count
- pieceCount[them][st->capturedType]++;
+ assert(pt == PAWN);
+ assert(to == st->previous->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(capsq) == NO_PIECE);
+ }
- // 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;
+ put_piece(capsq, ~us, st->capturedType); // Restore the captured piece
+ }
}
// Finally point our state pointer back to the previous state
st = st->previous;
+ --gamePly;
assert(pos_is_ok());
}
-/// 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) {
-
- 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();
-
- // Find source squares for king and rook
- Square kfrom = move_from(m);
- Square rfrom = move_to(m);
- Square kto, rto;
-
- // 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);
- }
+/// Position::do_castling() is a helper used to do/undo a castling move. This
+/// is a bit tricky, especially in Chess960.
+template<bool Do>
+void Position::do_castling(Square from, Square& to, Square& rfrom, Square& rto) {
- 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);
-
- // 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;
-
- // 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;
+ bool kingSide = to > from;
+ rfrom = to; // Castling is encoded as "king captures friendly rook"
+ rto = relative_square(sideToMove, kingSide ? SQ_F1 : SQ_D1);
+ to = relative_square(sideToMove, kingSide ? SQ_G1 : SQ_C1);
- // Finally point our state pointer back to the previous state
- st = st->previous;
-
- assert(pos_is_ok());
+ // Remove both pieces first since squares could overlap in Chess960
+ remove_piece(Do ? from : to, sideToMove, KING);
+ remove_piece(Do ? rfrom : rto, sideToMove, ROOK);
+ board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us
+ put_piece(Do ? to : from, sideToMove, KING);
+ put_piece(Do ? rto : rfrom, sideToMove, ROOK);
}
-/// 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.
+/// 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& backupSt) {
+void Position::do_null_move(StateInfo& newSt) {
- assert(!in_check());
+ assert(!checkers());
- // 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;
+ std::memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here
+
+ newSt.previous = st;
+ st = &newSt;
- // Update the necessary information
if (st->epSquare != SQ_NONE)
- st->key ^= zobEp[st->epSquare];
+ {
+ st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
+ st->epSquare = SQ_NONE;
+ }
- st->key ^= zobSideToMove;
+ st->key ^= Zobrist::side;
prefetch((char*)TT.first_entry(st->key));
- sideToMove = flip(sideToMove);
- st->epSquare = SQ_NONE;
- st->rule50++;
+ ++st->rule50;
st->pliesFromNull = 0;
- st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
+
+ sideToMove = ~sideToMove;
assert(pos_is_ok());
}
-
-/// Position::undo_null_move() unmakes a "null move".
-
void Position::undo_null_move() {
- 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;
+ assert(!checkers());
- // Update the necessary information
- sideToMove = flip(sideToMove);
- st->rule50--;
-
- assert(pos_is_ok());
+ st = st->previous;
+ sideToMove = ~sideToMove;
}
/// 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
-/// this function: One which takes a destination square as input, one takes a
-/// move, and one which takes a 'from' and a 'to' square. The function does
-/// not yet understand promotions captures.
+/// material gain or loss resulting from a move.
-int Position::see_sign(Move m) const {
+Value Position::see_sign(Move m) const {
assert(is_ok(m));
- Square from = move_from(m);
- Square to = move_to(m);
-
// 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 (piece_value_midgame(piece_on(to)) >= piece_value_midgame(piece_on(from)))
- return 1;
+ if (PieceValue[MG][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))])
+ return VALUE_KNOWN_WIN;
return see(m);
}
-int Position::see(Move m) const {
+Value Position::see(Move m) const {
Square from, to;
- Bitboard occupied, attackers, stmAttackers, b;
- int swapList[32], slIndex = 1;
- PieceType capturedType, pt;
+ Bitboard occupied, attackers, stmAttackers;
+ Value swapList[32];
+ int slIndex = 1;
+ 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 (is_castle(m))
- return 0;
+ from = from_sq(m);
+ to = to_sq(m);
+ swapList[0] = PieceValue[MG][piece_on(to)];
+ stm = color_of(piece_on(from));
+ occupied = pieces() ^ from;
- from = move_from(m);
- to = move_to(m);
- capturedType = type_of(piece_on(to));
- occupied = occupied_squares();
+ // Castling moves are implemented as king capturing the rook so cannot be
+ // handled correctly. Simply return 0 that is always the correct value
+ // unless in the rare case the rook ends up under attack.
+ if (type_of(m) == CASTLING)
+ return VALUE_ZERO;
- // Handle en passant moves
- if (st->epSquare == to && type_of(piece_on(from)) == PAWN)
+ if (type_of(m) == ENPASSANT)
{
- Square capQq = to - pawn_push(side_to_move());
-
- assert(capturedType == PIECE_TYPE_NONE);
- assert(type_of(piece_on(capQq)) == PAWN);
-
- // Remove the captured pawn
- clear_bit(&occupied, capQq);
- capturedType = PAWN;
+ occupied ^= to - pawn_push(stm); // Remove the captured pawn
+ swapList[0] = PieceValue[MG][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);
+ attackers = attackers_to(to, occupied) & occupied;
// If the opponent has no attackers we are finished
- stm = flip(color_of(piece_on(from)));
+ stm = ~stm;
stmAttackers = attackers & pieces(stm);
if (!stmAttackers)
- return PieceValueMidgame[capturedType];
+ return swapList[0];
// 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] = PieceValueMidgame[capturedType];
- capturedType = type_of(piece_on(from));
+ 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);
- occupied ^= (b & (~b + 1));
- attackers |= (rook_attacks_bb(to, occupied) & pieces(ROOK, QUEEN))
- | (bishop_attacks_bb(to, occupied) & pieces(BISHOP, QUEEN));
-
- attackers &= occupied; // 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] + PieceValueMidgame[capturedType];
- slIndex++;
+ swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
- // Remember the value of the capturing piece, and change the side to
- // move before beginning the next iteration.
- capturedType = pt;
- stm = flip(stm);
- stmAttackers = attackers & pieces(stm);
+ // Locate and remove the next least valuable attacker
+ captured = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
// Stop before processing a king capture
- if (capturedType == KING && stmAttackers)
+ if (captured == KING)
{
- assert(slIndex < 32);
- swapList[slIndex++] = QueenValueMidgame*10;
+ if (stmAttackers == attackers)
+ ++slIndex;
+
break;
}
+
+ stm = ~stm;
+ stmAttackers = attackers & pieces(stm);
+ ++slIndex;
+
} while (stmAttackers);
// 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];
}
-/// Position::clear() erases the position object to a pristine state, with an
-/// empty board, white to move, and no castling rights.
-
-void Position::clear() {
-
- st = &startState;
- memset(st, 0, sizeof(StateInfo));
- st->epSquare = SQ_NONE;
-
- memset(byColorBB, 0, sizeof(Bitboard) * 2);
- memset(byTypeBB, 0, sizeof(Bitboard) * 8);
- memset(pieceCount, 0, sizeof(int) * 2 * 8);
- memset(index, 0, sizeof(int) * 64);
-
- 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] = PIECE_NONE;
- castleRightsMask[sq] = ALL_CASTLES;
- }
- sideToMove = WHITE;
- nodes = 0;
-}
-
-
-/// Position::put_piece() puts a piece on the given square of the board,
-/// updating the board array, pieces list, bitboards, and piece counts.
-
-void Position::put_piece(Piece p, Square s) {
-
- Color c = color_of(p);
- PieceType pt = type_of(p);
-
- board[s] = p;
- index[s] = pieceCount[c][pt]++;
- pieceList[c][pt][index[s]] = s;
-
- set_bit(&byTypeBB[pt], s);
- set_bit(&byColorBB[c], s);
- set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares.
-}
-
-
-/// Position::compute_key() computes the hash key of the position. The hash
-/// key is usually updated incrementally as moves are made and unmade, the
-/// compute_key() function is only used when a new position is set up, and
-/// to verify the correctness of the hash key when running in debug mode.
-
-Key Position::compute_key() const {
-
- Key result = zobCastle[st->castleRights];
+/// Position::is_draw() tests whether the position is drawn by material, 50 moves
+/// rule or repetition. It does not detect stalemates.
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (!square_is_empty(s))
- result ^= zobrist[color_of(piece_on(s))][type_of(piece_on(s))][s];
-
- if (ep_square() != SQ_NONE)
- result ^= zobEp[ep_square()];
-
- if (side_to_move() == BLACK)
- result ^= zobSideToMove;
-
- return result;
-}
-
-
-/// Position::compute_pawn_key() computes the hash key of the position. The
-/// hash key is usually updated incrementally as moves are made and unmade,
-/// the compute_pawn_key() function is only used when a new position is set
-/// up, and to verify the correctness of the pawn hash key when running in
-/// debug mode.
-
-Key Position::compute_pawn_key() const {
-
- Bitboard b;
- Key result = 0;
-
- for (Color c = WHITE; c <= BLACK; c++)
- {
- b = pieces(PAWN, c);
- while (b)
- result ^= zobrist[c][PAWN][pop_1st_bit(&b)];
- }
- return result;
-}
-
-
-/// Position::compute_material_key() computes the hash key of the position.
-/// The hash key is usually updated incrementally as moves are made and unmade,
-/// the compute_material_key() function is only used when a new position is set
-/// up, and to verify the correctness of the material hash key when running in
-/// debug mode.
-
-Key Position::compute_material_key() const {
-
- Key result = 0;
-
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= QUEEN; pt++)
- for (int i = 0, cnt = piece_count(c, pt); i < cnt; i++)
- result ^= zobrist[c][pt][i];
-
- return result;
-}
-
-
-/// Position::compute_value() compute the incremental scores for the middle
-/// game and the endgame. These functions are used to initialize the incremental
-/// scores when a new position is set up, and to verify that the scores are correctly
-/// updated by do_move and undo_move when the program is running in debug mode.
-Score Position::compute_value() const {
-
- Bitboard b;
- Score result = SCORE_ZERO;
-
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- {
- b = pieces(pt, c);
- while (b)
- result += pst(make_piece(c, pt), pop_1st_bit(&b));
- }
-
- result += (side_to_move() == WHITE ? TempoValue / 2 : -TempoValue / 2);
- return result;
-}
-
-
-/// Position::compute_non_pawn_material() computes the total non-pawn middle
-/// game material value for the given side. Material values are updated
-/// incrementally during the search, this function is only used while
-/// initializing a new Position object.
-
-Value Position::compute_non_pawn_material(Color c) const {
-
- Value result = VALUE_ZERO;
-
- for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
- result += piece_count(c, pt) * PieceValueMidgame[pt];
-
- return result;
-}
-
-
-/// Position::is_draw() tests whether the position is drawn by material,
-/// repetition, or the 50 moves rule. It does not detect stalemates, this
-/// must be done by the search.
-template<bool SkipRepetition>
bool Position::is_draw() const {
- // Draw by material?
if ( !pieces(PAWN)
- && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame))
+ && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMg))
return true;
- // Draw by the 50 moves rule?
- if (st->rule50 > 99 && !is_mate())
+ if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
return true;
- // Draw by repetition?
- if (!SkipRepetition)
+ StateInfo* stp = st;
+ for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2)
{
- int i = 4, e = Min(st->rule50, st->pliesFromNull);
-
- if (i <= e)
- {
- StateInfo* stp = st->previous->previous;
-
- do {
- stp = stp->previous->previous;
-
- if (stp->key == st->key)
- return true;
+ stp = stp->previous->previous;
- i +=2;
-
- } while (i <= e);
- }
+ if (stp->key == st->key)
+ return true; // Draw at first repetition
}
return false;
}
-// Explicit template instantiations
-template bool Position::is_draw<false>() const;
-template bool Position::is_draw<true>() const;
-
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated.
+/// Position::flip() flips position with the white and black sides reversed. This
+/// is only useful for debugging e.g. for finding evaluation symmetry bugs.
-bool Position::is_mate() const {
-
- return in_check() && !MoveList<MV_LEGAL>(*this).size();
+static char toggle_case(char c) {
+ return char(islower(c) ? toupper(c) : tolower(c));
}
+void Position::flip() {
-/// Position::init() is a static member function which initializes at startup
-/// the various arrays used to compute hash keys and the piece square tables.
-/// The latter is a two-step operation: First, the white halves of the tables
-/// are copied from PSQT[] tables. Second, the black halves of the tables are
-/// initialized by flipping and changing the sign of the white scores.
-
-void Position::init() {
-
- RKISS rk;
-
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- zobrist[c][pt][s] = rk.rand<Key>();
-
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- zobEp[s] = rk.rand<Key>();
+ string f, token;
+ std::stringstream ss(fen());
- for (int i = 0; i < 16; i++)
- zobCastle[i] = rk.rand<Key>();
-
- zobSideToMove = rk.rand<Key>();
- zobExclusion = rk.rand<Key>();
-
- for (Piece p = WP; p <= WK; p++)
+ for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement
{
- Score ps = make_score(piece_value_midgame(p), piece_value_endgame(p));
-
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- {
- pieceSquareTable[p][s] = ps + PSQT[p][s];
- pieceSquareTable[p+8][flip(s)] = -pieceSquareTable[p][s];
- }
+ std::getline(ss, token, r > RANK_1 ? '/' : ' ');
+ f.insert(0, token + (f.empty() ? " " : "/"));
}
-}
-
-/// Position::flip_me() flips position with the white and black sides reversed. This
-/// is only useful for debugging especially for finding evaluation symmetry bugs.
+ ss >> token; // Active color
+ f += (token == "w" ? "B " : "W "); // Will be lowercased later
-void Position::flip_me() {
-
- // Make a copy of current position before to start changing
- const Position pos(*this, threadID);
-
- clear();
- threadID = pos.thread();
+ ss >> token; // Castling availability
+ f += token + " ";
- // Board
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (!pos.square_is_empty(s))
- put_piece(Piece(pos.piece_on(s) ^ 8), flip(s));
+ std::transform(f.begin(), f.end(), f.begin(), toggle_case);
- // Side to move
- sideToMove = flip(pos.side_to_move());
+ ss >> token; // En passant square
+ f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3"));
- // Castling rights
- if (pos.can_castle(WHITE_OO))
- set_castle(BLACK_OO, 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)));
- if (pos.can_castle(BLACK_OO))
- set_castle(WHITE_OO, 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)));
+ std::getline(ss, token); // Half and full moves
+ f += token;
- // En passant square
- if (pos.st->epSquare != SQ_NONE)
- st->epSquare = flip(pos.st->epSquare);
-
- // Checkers
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
-
- // Hash keys
- st->key = compute_key();
- st->pawnKey = compute_pawn_key();
- st->materialKey = compute_material_key();
-
- // Incremental scores
- st->value = compute_value();
-
- // Material
- st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ set(f, is_chess960(), this_thread());
assert(pos_is_ok());
}
-/// Position::pos_is_ok() performs some consitency checks for the position object.
+/// Position::pos_is_ok() performs some consistency checks for the position object.
/// This is meant to be helpful when debugging.
-bool Position::pos_is_ok(int* failedStep) const {
+bool Position::pos_is_ok(int* step) const {
- // What features of the position should be verified?
- const bool debugAll = false;
+ // Which parts of the position should be verified?
+ const bool all = false;
- const bool debugBitboards = debugAll || false;
- const bool debugKingCount = debugAll || false;
- const bool debugKingCapture = debugAll || false;
- const bool debugCheckerCount = debugAll || false;
- const bool debugKey = debugAll || false;
- const bool debugMaterialKey = debugAll || false;
- const bool debugPawnKey = debugAll || false;
- const bool debugIncrementalEval = debugAll || false;
- const bool debugNonPawnMaterial = debugAll || false;
- const bool debugPieceCounts = debugAll || false;
- const bool debugPieceList = debugAll || false;
- const bool debugCastleSquares = debugAll || false;
+ const bool testBitboards = all || false;
+ const bool testState = all || false;
+ const bool testKingCount = all || false;
+ const bool testKingCapture = all || false;
+ const bool testPieceCounts = all || false;
+ const bool testPieceList = all || false;
+ const bool testCastlingSquares = all || false;
- if (failedStep) *failedStep = 1;
+ if (step)
+ *step = 1;
- // Side to move OK?
- if (side_to_move() != WHITE && side_to_move() != BLACK)
+ if ( (sideToMove != WHITE && sideToMove != BLACK)
+ || piece_on(king_square(WHITE)) != W_KING
+ || piece_on(king_square(BLACK)) != B_KING
+ || ( ep_square() != SQ_NONE
+ && relative_rank(sideToMove, ep_square()) != RANK_6))
return false;
- // Are the king squares in the position correct?
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(WHITE)) != WK)
- return false;
-
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(BLACK)) != BK)
- return false;
-
- // Do both sides have exactly one king?
- if (failedStep) (*failedStep)++;
- if (debugKingCount)
- {
- int kingCount[2] = {0, 0};
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (type_of(piece_on(s)) == KING)
- kingCount[color_of(piece_on(s))]++;
-
- if (kingCount[0] != 1 || kingCount[1] != 1)
- return false;
- }
-
- // Can the side to move capture the opponent's king?
- if (failedStep) (*failedStep)++;
- if (debugKingCapture)
- {
- Color us = side_to_move();
- Color them = flip(us);
- Square ksq = king_square(them);
- if (attackers_to(ksq) & pieces(us))
- return false;
- }
-
- // Is there more than 2 checkers?
- if (failedStep) (*failedStep)++;
- if (debugCheckerCount && count_1s<CNT32>(st->checkersBB) > 2)
- return false;
-
- // Bitboards OK?
- if (failedStep) (*failedStep)++;
- if (debugBitboards)
+ if (step && ++*step, testBitboards)
{
// The intersection of the white and black pieces must be empty
- if ((pieces(WHITE) & pieces(BLACK)) != EmptyBoardBB)
+ if (pieces(WHITE) & pieces(BLACK))
return false;
// The union of the white and black pieces must be equal to all
// occupied squares
- if ((pieces(WHITE) | pieces(BLACK)) != occupied_squares())
+ if ((pieces(WHITE) | pieces(BLACK)) != pieces())
return false;
// Separate piece type bitboards must have empty intersections
- for (PieceType p1 = PAWN; p1 <= KING; p1++)
- for (PieceType p2 = PAWN; p2 <= KING; p2++)
+ for (PieceType p1 = PAWN; p1 <= KING; ++p1)
+ for (PieceType p2 = PAWN; p2 <= KING; ++p2)
if (p1 != p2 && (pieces(p1) & pieces(p2)))
return false;
}
- // En passant square OK?
- if (failedStep) (*failedStep)++;
- if (ep_square() != SQ_NONE)
+ if (step && ++*step, testState)
{
- // The en passant square must be on rank 6, from the point of view of the
- // side to move.
- if (relative_rank(side_to_move(), ep_square()) != RANK_6)
+ StateInfo si;
+ set_state(&si);
+ if ( st->key != si.key
+ || st->pawnKey != si.pawnKey
+ || st->materialKey != si.materialKey
+ || st->npMaterial[WHITE] != si.npMaterial[WHITE]
+ || st->npMaterial[BLACK] != si.npMaterial[BLACK]
+ || st->psq != si.psq
+ || st->checkersBB != si.checkersBB)
return false;
}
- // Hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugKey && st->key != compute_key())
- return false;
-
- // Pawn hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugPawnKey && st->pawnKey != compute_pawn_key())
- return false;
-
- // Material hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugMaterialKey && st->materialKey != compute_material_key())
- return false;
-
- // Incremental eval OK?
- if (failedStep) (*failedStep)++;
- if (debugIncrementalEval && st->value != compute_value())
- return false;
-
- // Non-pawn material OK?
- if (failedStep) (*failedStep)++;
- if (debugNonPawnMaterial)
- {
- if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE))
+ if (step && ++*step, testKingCount)
+ if ( std::count(board, board + SQUARE_NB, W_KING) != 1
+ || std::count(board, board + SQUARE_NB, B_KING) != 1)
return false;
- if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
+ if (step && ++*step, testKingCapture)
+ if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove))
return false;
- }
- // Piece counts OK?
- if (failedStep) (*failedStep)++;
- if (debugPieceCounts)
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- if (pieceCount[c][pt] != count_1s<CNT32>(pieces(pt, c)))
+ if (step && ++*step, testPieceCounts)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ if (pieceCount[c][pt] != popcount<Full>(pieces(c, pt)))
return false;
- if (failedStep) (*failedStep)++;
- if (debugPieceList)
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- for (int i = 0; i < pieceCount[c][pt]; i++)
- {
- if (piece_on(piece_list(c, pt)[i]) != make_piece(c, pt))
+ if (step && ++*step, testPieceList)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ for (int i = 0; i < pieceCount[c][pt]; ++i)
+ if ( board[pieceList[c][pt][i]] != make_piece(c, pt)
+ || index[pieceList[c][pt][i]] != i)
return false;
- if (index[piece_list(c, pt)[i]] != i)
- return false;
- }
-
- if (failedStep) (*failedStep)++;
- if (debugCastleSquares)
- for (CastleRight f = WHITE_OO; f <= BLACK_OOO; f = CastleRight(f << 1))
- {
- if (!can_castle(f))
- continue;
-
- Piece rook = (f & (WHITE_OO | WHITE_OOO) ? WR : BR);
+ if (step && ++*step, testCastlingSquares)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1))
+ {
+ if (!can_castle(c | s))
+ continue;
- if ( castleRightsMask[castleRookSquare[f]] != (ALL_CASTLES ^ f)
- || piece_on(castleRookSquare[f]) != rook)
- return false;
- }
+ if ( (castlingRightsMask[king_square(c)] & (c | s)) != (c | s)
+ || piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK)
+ || castlingRightsMask[castlingRookSquare[c | s]] != (c | s))
+ return false;
+ }
- if (failedStep) *failedStep = 0;
return true;
}