/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm>
#include <cassert>
#include <cstring>
+#include <iomanip>
#include <iostream>
#include <sstream>
-#include <algorithm>
#include "bitcount.h"
#include "movegen.h"
+#include "notation.h"
#include "position.h"
#include "psqtab.h"
#include "rkiss.h"
using std::cout;
using std::endl;
-Key Position::zobrist[2][8][64];
-Key Position::zobEp[8];
-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
+Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+Value PieceValue[PHASE_NB][PIECE_NB] = {
+{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
+{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } };
+
+namespace Zobrist {
+
+ Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+ Key enpassant[FILE_NB];
+ Key castle[CASTLE_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 Tempo = make_score(48, 22);
+// min_attacker() is an helper function used by see() to locate the least
+// valuable attacker for the side to move, remove the attacker we just found
+// from the 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);
- // To convert a Piece to and from a FEN char
- const string PieceToChar(" PNBRQK pnbrqk .");
+ 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;
+}
+
+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
}
+/// 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:
+/// 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::psq[c][pt][s] = rk.rand<Key>();
+
+ for (File f = FILE_A; f <= FILE_H; f++)
+ Zobrist::enpassant[f] = rk.rand<Key>();
+
+ for (int cr = CASTLES_NONE; cr <= ALL_CASTLES; cr++)
+ {
+ Bitboard b = cr;
+ while (b)
+ {
+ Key k = Zobrist::castle[1ULL << pop_lsb(&b)];
+ Zobrist::castle[cr] ^= 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::operator=() creates a copy of 'pos'. We want the new born Position
/// object do not depend on any external data so we detach state pointer from
/// the source one.
-void Position::operator=(const Position& pos) {
+Position& Position::operator=(const Position& pos) {
- memcpy(this, &pos, sizeof(Position));
+ std::memcpy(this, &pos, sizeof(Position));
startState = *st;
st = &startState;
nodes = 0;
assert(pos_is_ok());
+
+ return *this;
}
-/// Position::from_fen() initializes the position object with the given FEN
-/// string. This function is not very robust - make sure that input FENs are
-/// correct (this is assumed to be the responsibility of the GUI).
+/// Position::set() initializes the position object with the given FEN string.
+/// This function is not very robust - make sure that input FENs are correct,
+/// this is assumed to be the responsibility of the GUI.
-void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) {
+void Position::set(const string& fenStr, bool isChess960, Thread* th) {
/*
A FEN string defines a particular position using only the ASCII character set.
char col, row, token;
size_t p;
Square sq = SQ_A8;
- std::istringstream fen(fenStr);
+ std::istringstream ss(fenStr);
clear();
- fen >> std::noskipws;
+ ss >> std::noskipws;
// 1. Piece placement
- while ((fen >> token) && !isspace(token))
+ while ((ss >> token) && !isspace(token))
{
if (isdigit(token))
sq += Square(token - '0'); // Advance the given number of files
else if (token == '/')
- sq = make_square(FILE_A, rank_of(sq) - Rank(2));
+ sq -= Square(16);
else if ((p = PieceToChar.find(token)) != string::npos)
{
- put_piece(Piece(p), sq);
+ put_piece(sq, color_of(Piece(p)), type_of(Piece(p)));
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 ((fen >> token) && !isspace(token))
+ while ((ss >> token) && !isspace(token))
{
Square rsq;
Color c = islower(token) ? BLACK : WHITE;
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));
+ rsq = File(token - 'A') | relative_rank(c, RANK_1);
else
continue;
}
// 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'));
+ st->epSquare = File(col - 'a') | Rank(row - '1');
- if (!(attackers_to(st->epSquare) & 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 = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
+ gamePly = std::max(2 * (gamePly - 1), 0) + int(sideToMove == BLACK);
st->key = compute_key();
st->pawnKey = compute_pawn_key();
st->materialKey = compute_material_key();
- st->psqScore = compute_psq_score();
+ st->psq = compute_psq_score();
st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
}
-/// Position::to_fen() returns a FEN representation of the position. In case
+/// Position::fen() returns a FEN representation of the position. In case
/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function.
-const string Position::to_fen() const {
+const string Position::fen() const {
- std::ostringstream fen;
- Square sq;
- int emptyCnt;
+ std::ostringstream ss;
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
{
- emptyCnt = 0;
-
for (File file = FILE_A; file <= FILE_H; file++)
{
- sq = make_square(file, rank);
+ Square sq = file | rank;
- if (square_empty(sq))
- emptyCnt++;
- else
+ if (is_empty(sq))
{
- if (emptyCnt > 0)
- {
- fen << emptyCnt;
- emptyCnt = 0;
- }
- fen << PieceToChar[piece_on(sq)];
+ int emptyCnt = 1;
+
+ for ( ; file < FILE_H && is_empty(sq++); file++)
+ emptyCnt++;
+
+ ss << emptyCnt;
}
+ else
+ ss << PieceToChar[piece_on(sq)];
}
- if (emptyCnt > 0)
- fen << emptyCnt;
-
if (rank > RANK_1)
- fen << '/';
+ ss << '/';
}
- fen << (sideToMove == WHITE ? " w " : " b ");
+ ss << (sideToMove == WHITE ? " w " : " b ");
if (can_castle(WHITE_OO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE))))) : 'K');
+ ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE)), false) : 'K');
if (can_castle(WHITE_OOO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE))))) : 'Q');
+ ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE)), false) : 'Q');
if (can_castle(BLACK_OO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE))) : 'k');
+ ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE)), true) : 'k');
if (can_castle(BLACK_OOO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE))) : 'q');
+ ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE)), true) : 'q');
if (st->castleRights == CASTLES_NONE)
- fen << '-';
+ ss << '-';
- fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
- << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
+ ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
+ << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2;
- return fen.str();
+ return ss.str();
}
-/// Position::print() prints an ASCII representation of the position to
-/// the standard output. If a move is given then also the san is printed.
+/// Position::pretty() returns an ASCII representation of the position to be
+/// printed to the standard output together with the move's san notation.
-void Position::print(Move move) const {
+const string Position::pretty(Move move) const {
- const char* dottedLine = "\n+---+---+---+---+---+---+---+---+\n";
+ const string dottedLine = "\n+---+---+---+---+---+---+---+---+";
+ const string twoRows = dottedLine + "\n| | . | | . | | . | | . |"
+ + dottedLine + "\n| . | | . | | . | | . | |";
- if (move)
+ string brd = twoRows + twoRows + twoRows + twoRows + dottedLine;
+
+ for (Bitboard b = pieces(); b; )
{
- Position p(*this);
- cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move);
+ Square s = pop_lsb(&b);
+ brd[513 - 68 * rank_of(s) + 4 * file_of(s)] = PieceToChar[piece_on(s)];
}
- 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);
- char c = (color_of(piece) == BLACK ? '=' : ' ');
+ std::ostringstream ss;
- if (piece == NO_PIECE && !opposite_colors(sq, SQ_A1))
- piece++; // Index the dot
+ if (move)
+ ss << "\nMove: " << (sideToMove == BLACK ? ".." : "")
+ << move_to_san(*const_cast<Position*>(this), move);
- cout << c << PieceToChar[piece] << c << '|';
- }
- }
- cout << dottedLine << "Fen is: " << to_fen() << "\nKey is: " << st->key << endl;
+ ss << brd << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase
+ << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: ";
+
+ for (Bitboard b = checkers(); b; )
+ ss << square_to_string(pop_lsb(&b)) << " ";
+
+ ss << "\nLegal moves: ";
+ for (MoveList<LEGAL> 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.
-template<bool FindPinned>
-Bitboard Position::hidden_checkers() const {
+/// Position:hidden_checkers() returns a bitboard of all pinned / discovery check
+/// pieces, according to the call parameters. Pinned pieces protect our king,
+/// discovery check pieces attack the enemy king.
+
+Bitboard Position::hidden_checkers(Square ksq, Color c) const {
- // Pinned pieces protect our king, dicovery checks attack the enemy king
- Bitboard b, result = 0;
- Bitboard pinners = pieces(FindPinned ? ~sideToMove : sideToMove);
- Square ksq = king_square(FindPinned ? sideToMove : ~sideToMove);
+ Bitboard b, pinners, result = 0;
- // Pinners are sliders, that give check when candidate pinned is removed
- pinners &= (pieces(ROOK, QUEEN) & PseudoAttacks[ROOK][ksq])
- | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq]);
+ // Pinners are sliders that give check when pinned piece is removed
+ pinners = ( (pieces( ROOK, QUEEN) & PseudoAttacks[ROOK ][ksq])
+ | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(c);
while (pinners)
{
- b = squares_between(ksq, pop_1st_bit(&pinners)) & pieces();
+ b = between_bb(ksq, pop_lsb(&pinners)) & pieces();
- if (b && single_bit(b) && (b & pieces(sideToMove)))
- result |= b;
+ if (!more_than_one(b))
+ result |= b & pieces(sideToMove);
}
return result;
}
-// Explicit template instantiations
-template Bitboard Position::hidden_checkers<true>() const;
-template Bitboard Position::hidden_checkers<false>() const;
-
/// 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 {
- 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))
| (attacks_bb<ROOK>(s, occ) & pieces(ROOK, QUEEN))
| (attacks_bb<BISHOP>(s, occ) & pieces(BISHOP, QUEEN))
}
-/// Position::move_attacks_square() tests whether a move from the current
-/// position attacks a given square.
-
-bool Position::move_attacks_square(Move m, Square s) const {
-
- assert(is_ok(m));
- assert(is_ok(s));
-
- Bitboard occ, xray;
- Square from = from_sq(m);
- Square to = to_sq(m);
- Piece piece = piece_moved(m);
-
- assert(!square_empty(from));
-
- // Update occupancy as if the piece is moving
- occ = pieces() ^ from ^ to;
-
- // The piece moved in 'to' attacks the square 's' ?
- if (attacks_from(piece, to, occ) & s)
- return true;
-
- // Scan for possible X-ray attackers behind the moved piece
- xray = (attacks_bb<ROOK>(s, occ) & pieces(ROOK, QUEEN, color_of(piece)))
- |(attacks_bb<BISHOP>(s, occ) & pieces(BISHOP, QUEEN, color_of(piece)));
-
- // Verify attackers are triggered by our move and not already existing
- return xray && (xray ^ (xray & attacks_from<QUEEN>(s)));
-}
-
-
/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
// 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 = ~us;
Square to = to_sq(m);
assert(piece_on(capsq) == make_piece(them, PAWN));
assert(piece_on(to) == NO_PIECE);
- return !(attacks_bb<ROOK>(ksq, b) & pieces(ROOK, QUEEN, them))
- && !(attacks_bb<BISHOP>(ksq, b) & pieces(BISHOP, QUEEN, them));
+ return !(attacks_bb< ROOK>(ksq, b) & pieces(them, QUEEN, ROOK))
+ && !(attacks_bb<BISHOP>(ksq, b) & pieces(them, 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(to_sq(m)) & pieces(~us));
+ return type_of(m) == CASTLE || !(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.
}
-/// 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;
-}
-
-
/// Position::is_pseudo_legal() takes a random move and tests whether the move
/// is pseudo legal. It is used to validate moves from TT that can be corrupted
/// due to SMP concurrent access or hash position key aliasing.
bool Position::is_pseudo_legal(const Move m) const {
Color us = sideToMove;
- Color them = ~sideToMove;
Square from = from_sq(m);
Square to = to_sq(m);
Piece pc = piece_moved(m);
// Use a slower but simpler function for uncommon cases
- if (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_type(m) - 2 != NO_PIECE_TYPE)
return false;
// The destination square cannot be occupied by a friendly piece
- if (color_of(piece_on(to)) == us)
+ if (pieces(us) & to)
return false;
// Handle the special case of a pawn move
case DELTA_SE:
// Capture. The destination square must be occupied by an enemy
// piece (en passant captures was handled earlier).
- if (color_of(piece_on(to)) != them)
+ if (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us)
return false;
// From and to files must be one file apart, avoids a7h5
case DELTA_N:
case DELTA_S:
// Pawn push. The destination square must be empty.
- if (!square_empty(to))
+ if (!is_empty(to))
return false;
break;
// 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_empty(to)
- || !square_empty(from + DELTA_N))
+ if ( rank_of(to) != RANK_4
+ || !is_empty(to)
+ || !is_empty(from + DELTA_N))
return false;
break;
// 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_empty(to)
- || !square_empty(from + DELTA_S))
+ if ( rank_of(to) != RANK_5
+ || !is_empty(to)
+ || !is_empty(from + DELTA_S))
return false;
break;
// Evasions generator already takes care to avoid some kind of illegal moves
// and pl_move_is_legal() relies on this. So we have to take care that the
// same kind of moves are filtered out here.
- if (in_check())
+ if (checkers())
{
if (type_of(pc) != KING)
{
- Bitboard b = checkers();
- Square checksq = pop_1st_bit(&b);
-
- if (b) // double check ? In this case a king move is required
+ // Double check? In this case a king move is required
+ if (more_than_one(checkers()))
return false;
// Our move must be a blocking evasion or a capture of the checking piece
- if (!((squares_between(checksq, king_square(us)) | checkers()) & to))
+ if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to))
return false;
}
// In case of king moves under check we have to remove king so to catch
return true;
// Discovery check ?
- if (ci.dcCandidates && (ci.dcCandidates & from))
+ if (unlikely(ci.dcCandidates) && (ci.dcCandidates & from))
{
// For pawn and king moves we need to verify also direction
- if ( (pt != PAWN && pt != KING)
+ if ( (pt != PAWN && pt != KING)
|| !squares_aligned(from, to, king_square(~sideToMove)))
return true;
}
// Can we skip the ugly special cases ?
- if (!is_special(m))
+ if (type_of(m) == NORMAL)
return false;
Color us = sideToMove;
Square ksq = king_square(~us);
- // Promotion with check ?
- if (is_promotion(m))
+ switch (type_of(m))
+ {
+ case PROMOTION:
return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq;
// En passant capture with check ? We have already handled the case
// of direct checks and ordinary discovered check, the only case we
// need to handle is the unusual case of a discovered check through
// the captured pawn.
- if (is_enpassant(m))
+ case ENPASSANT:
{
- Square capsq = make_square(file_of(to), rank_of(from));
+ Square capsq = file_of(to) | rank_of(from);
Bitboard b = (pieces() ^ from ^ capsq) | to;
- return (attacks_bb< ROOK>(ksq, b) & pieces( ROOK, QUEEN, us))
- | (attacks_bb<BISHOP>(ksq, b) & pieces(BISHOP, QUEEN, us));
+ return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(ksq, b) & pieces(us, QUEEN, BISHOP));
}
-
- // Castling with check ?
- if (is_castle(m))
+ case CASTLE:
{
Square kfrom = from;
Square rfrom = to; // 'King captures the rook' notation
Square kto = relative_square(us, rfrom > kfrom ? SQ_G1 : SQ_C1);
Square rto = relative_square(us, rfrom > kfrom ? SQ_F1 : SQ_D1);
- Bitboard b = (pieces() ^ kfrom ^ rfrom) | rto | kto;
- return attacks_bb<ROOK>(rto, b) & ksq;
+ return (PseudoAttacks[ROOK][rto] & ksq)
+ && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ksq);
+ }
+ default:
+ assert(false);
+ return false;
}
-
- return false;
}
Key k = st->key;
// Copy some fields of old state to our new StateInfo object except the ones
- // which are recalculated from scratch anyway, then switch our state pointer
- // to point to the new, ready to be updated, state.
- struct ReducedStateInfo {
- Key pawnKey, materialKey;
- Value npMaterial[2];
- int castleRights, rule50, pliesFromNull;
- Score psq_score;
- Square epSquare;
- };
-
- memcpy(&newSt, st, sizeof(ReducedStateInfo));
+ // which are going to be recalculated from scratch anyway, then switch our state
+ // pointer to point to the new, ready to be updated, state.
+ std::memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t));
newSt.previous = st;
st = &newSt;
// Update side to move
- k ^= zobSideToMove;
+ k ^= Zobrist::side;
- // Increment the 50 moves rule draw counter. Resetting it to zero in the
- // case of a capture or a pawn move is taken care of later.
+ // Increment ply counters.In particular rule50 will be later reset it to zero
+ // in case of a capture or a pawn move.
+ gamePly++;
st->rule50++;
st->pliesFromNull++;
- if (is_castle(m))
- {
- st->key = k;
- do_castle_move<true>(m);
- return;
- }
-
Color us = sideToMove;
Color them = ~us;
Square from = from_sq(m);
Square to = to_sq(m);
- Piece piece = piece_on(from);
- PieceType pt = type_of(piece);
- PieceType capture = is_enpassant(m) ? PAWN : type_of(piece_on(to));
+ Piece pc = piece_on(from);
+ PieceType pt = type_of(pc);
+ PieceType capture = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to));
- assert(color_of(piece) == us);
- assert(color_of(piece_on(to)) != us);
+ assert(color_of(pc) == us);
+ assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLE);
assert(capture != KING);
+ if (type_of(m) == CASTLE)
+ {
+ assert(pc == make_piece(us, KING));
+
+ bool kingSide = to > from;
+ Square rfrom = to; // Castle is encoded as "king captures friendly rook"
+ Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
+ to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
+ capture = NO_PIECE_TYPE;
+
+ do_castle(from, to, rfrom, rto);
+
+ st->psq += psq[us][ROOK][rto] - psq[us][ROOK][rfrom];
+ k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
+ }
+
if (capture)
{
Square capsq = to;
// update non-pawn material.
if (capture == PAWN)
{
- if (is_enpassant(m))
+ if (type_of(m) == ENPASSANT)
{
capsq += pawn_push(them);
board[capsq] = NO_PIECE;
}
- st->pawnKey ^= zobrist[them][PAWN][capsq];
+ st->pawnKey ^= Zobrist::psq[them][PAWN][capsq];
}
else
- st->npMaterial[them] -= PieceValueMidgame[capture];
-
- // Remove the captured piece
- byTypeBB[ALL_PIECES] ^= capsq;
- byTypeBB[capture] ^= capsq;
- byColorBB[them] ^= 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
- k ^= zobrist[them][capture][capsq];
- st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]];
+ st->npMaterial[them] -= PieceValue[MG][capture];
+
+ // Update board and piece lists
+ remove_piece(capsq, them, capture);
+
+ // Update material hash key and prefetch access to materialTable
+ k ^= Zobrist::psq[them][capture][capsq];
+ st->materialKey ^= Zobrist::psq[them][capture][pieceCount[them][capture]];
+ prefetch((char*)thisThread->materialTable[st->materialKey]);
// Update incremental scores
- st->psqScore -= pieceSquareTable[make_piece(them, capture)][capsq];
+ st->psq -= psq[them][capture][capsq];
// Reset rule 50 counter
st->rule50 = 0;
}
// Update hash key
- k ^= 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)
{
- k ^= zobEp[file_of(st->epSquare)];
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
st->epSquare = SQ_NONE;
}
if (st->castleRights && (castleRightsMask[from] | castleRightsMask[to]))
{
int cr = castleRightsMask[from] | castleRightsMask[to];
- k ^= zobCastle[st->castleRights & cr];
+ k ^= Zobrist::castle[st->castleRights & cr];
st->castleRights &= ~cr;
}
- // Prefetch TT access as soon as we know key is updated
+ // Prefetch TT access as soon as we know the new hash key
prefetch((char*)TT.first_entry(k));
- // Move the piece
- Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
- byTypeBB[ALL_PIECES] ^= from_to_bb;
- byTypeBB[pt] ^= from_to_bb;
- byColorBB[us] ^= from_to_bb;
-
- board[to] = board[from];
- board[from] = NO_PIECE;
-
- // Update piece lists, index[from] is not updated and becomes stale. This
- // works as long as index[] is accessed just by known occupied squares.
- index[to] = index[from];
- pieceList[us][pt][index[to]] = to;
+ // Move the piece. The tricky Chess960 castle is handled earlier
+ if (type_of(m) != CASTLE)
+ move_piece(from, to, us, pt);
// If the moving piece is a pawn do some special extra work
if (pt == PAWN)
{
// Set en-passant square, only if moved pawn can be captured
if ( (int(to) ^ int(from)) == 16
- && (attacks_from<PAWN>(from + pawn_push(us), us) & pieces(PAWN, them)))
+ && (attacks_from<PAWN>(from + pawn_push(us), us) & pieces(them, PAWN)))
{
st->epSquare = Square((from + to) / 2);
- k ^= zobEp[file_of(st->epSquare)];
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
}
- if (is_promotion(m))
+ if (type_of(m) == PROMOTION)
{
PieceType promotion = promotion_type(m);
assert(relative_rank(us, to) == RANK_8);
assert(promotion >= KNIGHT && promotion <= QUEEN);
- // Replace the pawn with the promoted piece
- byTypeBB[PAWN] ^= to;
- byTypeBB[promotion] |= to;
- board[to] = make_piece(us, promotion);
-
- // Update piece lists, move the last pawn at index[to] position
- // and shrink the list. Add a new promotion piece to the list.
- 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];
- pieceList[us][promotion][index[to]] = to;
+ remove_piece(to, us, PAWN);
+ put_piece(to, us, promotion);
// Update hash keys
- k ^= 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]];
+ 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 incremental score
- st->psqScore += pieceSquareTable[make_piece(us, promotion)][to]
- - pieceSquareTable[make_piece(us, PAWN)][to];
+ st->psq += psq[us][promotion][to] - psq[us][PAWN][to];
// Update material
- st->npMaterial[us] += PieceValueMidgame[promotion];
+ st->npMaterial[us] += PieceValue[MG][promotion];
}
- // Update pawn hash key
- st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
+ // Update pawn hash key and prefetch access to pawnsTable
+ st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to];
+ prefetch((char*)thisThread->pawnsTable[st->pawnKey]);
// Reset rule 50 draw counter
st->rule50 = 0;
}
- // Prefetch pawn and material hash tables
- prefetch((char*)thisThread->pawnTable.entries[st->pawnKey]);
- prefetch((char*)thisThread->materialTable.entries[st->materialKey]);
-
// Update incremental scores
- st->psqScore += psq_delta(piece, from, to);
+ st->psq += psq[us][pt][to] - psq[us][pt][from];
// Set capture piece
st->capturedType = capture;
if (moveIsCheck)
{
- if (is_special(m))
+ if (type_of(m) != NORMAL)
st->checkersBB = attackers_to(king_square(them)) & pieces(us);
else
{
if (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 = ~sideToMove;
- st->psqScore += (sideToMove == WHITE ? Tempo : -Tempo);
assert(pos_is_ok());
}
sideToMove = ~sideToMove;
- if (is_castle(m))
- {
- do_castle_move<false>(m);
- return;
- }
-
Color us = sideToMove;
Color them = ~us;
Square from = from_sq(m);
Square to = to_sq(m);
- Piece piece = piece_on(to);
- PieceType pt = type_of(piece);
+ PieceType pt = type_of(piece_on(to));
PieceType capture = st->capturedType;
- assert(square_empty(from));
- assert(color_of(piece) == us);
+ assert(is_empty(from) || type_of(m) == CASTLE);
assert(capture != KING);
- if (is_promotion(m))
+ if (type_of(m) == PROMOTION)
{
PieceType promotion = promotion_type(m);
assert(relative_rank(us, to) == RANK_8);
assert(promotion >= KNIGHT && promotion <= QUEEN);
- // Replace the promoted piece with the pawn
- byTypeBB[promotion] ^= to;
- byTypeBB[PAWN] |= to;
- board[to] = make_piece(us, PAWN);
-
- // 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]++;
- pieceList[us][PAWN][index[to]] = to;
-
+ remove_piece(to, us, promotion);
+ put_piece(to, us, PAWN);
pt = PAWN;
}
- // Put the piece back at the source square
- Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
- byTypeBB[ALL_PIECES] ^= from_to_bb;
- byTypeBB[pt] ^= from_to_bb;
- byColorBB[us] ^= from_to_bb;
-
- board[from] = board[to];
- board[to] = NO_PIECE;
-
- // Update piece lists, index[to] is not updated and becomes stale. This
- // works as long as index[] is accessed just by known occupied squares.
- index[from] = index[to];
- pieceList[us][pt][index[from]] = from;
+ if (type_of(m) == CASTLE)
+ {
+ bool kingSide = to > from;
+ Square rfrom = to; // Castle is encoded as "king captures friendly rook"
+ Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
+ to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
+ capture = NO_PIECE_TYPE;
+ pt = KING;
+ do_castle(to, from, rto, rfrom);
+ }
+ else
+ move_piece(to, from, us, pt); // Put the piece back at the source square
if (capture)
{
Square capsq = to;
- if (is_enpassant(m))
+ if (type_of(m) == ENPASSANT)
{
capsq -= pawn_push(us);
assert(piece_on(capsq) == NO_PIECE);
}
- // Restore the captured piece
- byTypeBB[ALL_PIECES] |= capsq;
- byTypeBB[capture] |= capsq;
- byColorBB[them] |= capsq;
-
- board[capsq] = make_piece(them, capture);
-
- // Update piece list, add a new captured piece in capsq square
- index[capsq] = pieceCount[them][capture]++;
- pieceList[them][capture][index[capsq]] = capsq;
+ put_piece(capsq, them, capture); // Restore the captured piece
}
// Finally point our state pointer back to the previous state
st = st->previous;
+ gamePly--;
assert(pos_is_ok());
}
-/// Position::do_castle_move() is a private method used to do/undo a castling
-/// move. Note that castling moves are encoded as "king captures friendly rook"
-/// moves, for instance white short castling in a non-Chess960 game is encoded
-/// as e1h1.
-template<bool Do>
-void Position::do_castle_move(Move m) {
-
- assert(is_ok(m));
- assert(is_castle(m));
-
- Square kto, kfrom, rfrom, rto, kAfter, rAfter;
+/// Position::do_castle() is a helper used to do/undo a castling move. This
+/// is a bit tricky, especially in Chess960.
- Color us = sideToMove;
- Square kBefore = from_sq(m);
- Square rBefore = to_sq(m);
+void Position::do_castle(Square kfrom, Square kto, Square rfrom, Square rto) {
- // Find after-castle squares for king and rook
- if (rBefore > kBefore) // O-O
- {
- kAfter = relative_square(us, SQ_G1);
- rAfter = relative_square(us, SQ_F1);
- }
- else // O-O-O
- {
- kAfter = relative_square(us, SQ_C1);
- rAfter = relative_square(us, SQ_D1);
- }
+ // Remove both pieces first since squares could overlap in Chess960
+ remove_piece(kfrom, sideToMove, KING);
+ remove_piece(rfrom, sideToMove, ROOK);
+ board[kfrom] = board[rfrom] = NO_PIECE; // Since remove_piece doesn't do it for us
+ put_piece(kto, sideToMove, KING);
+ put_piece(rto, sideToMove, ROOK);
+}
- kfrom = Do ? kBefore : kAfter;
- rfrom = Do ? rBefore : rAfter;
-
- kto = Do ? kAfter : kBefore;
- rto = Do ? rAfter : rBefore;
-
- assert(piece_on(kfrom) == make_piece(us, KING));
- assert(piece_on(rfrom) == make_piece(us, ROOK));
-
- // Move the pieces, with some care; in chess960 could be kto == rfrom
- Bitboard k_from_to_bb = SquareBB[kfrom] ^ SquareBB[kto];
- Bitboard r_from_to_bb = SquareBB[rfrom] ^ SquareBB[rto];
- byTypeBB[KING] ^= k_from_to_bb;
- byTypeBB[ROOK] ^= r_from_to_bb;
- byTypeBB[ALL_PIECES] ^= k_from_to_bb ^ r_from_to_bb;
- byColorBB[us] ^= k_from_to_bb ^ r_from_to_bb;
-
- // Update board
- Piece king = make_piece(us, KING);
- Piece rook = make_piece(us, ROOK);
- board[kfrom] = board[rfrom] = NO_PIECE;
- 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;
-
- if (Do)
- {
- // Reset capture field
- st->capturedType = NO_PIECE_TYPE;
- // Update incremental scores
- st->psqScore += psq_delta(king, kfrom, kto);
- st->psqScore += psq_delta(rook, rfrom, rto);
+/// Position::do(undo)_null_move() is used to do(undo) a "null move": It flips
+/// the side to move without executing any move on the board.
- // Update 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& newSt) {
- // Clear en passant square
- if (st->epSquare != SQ_NONE)
- {
- st->key ^= zobEp[file_of(st->epSquare)];
- st->epSquare = SQ_NONE;
- }
+ assert(!checkers());
- // Update castling rights
- st->key ^= zobCastle[st->castleRights & castleRightsMask[kfrom]];
- st->castleRights &= ~castleRightsMask[kfrom];
+ std::memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here
- // Update checkers BB
- st->checkersBB = attackers_to(king_square(~us)) & pieces(us);
+ newSt.previous = st;
+ st = &newSt;
- // Finish
- sideToMove = ~sideToMove;
- st->psqScore += (sideToMove == WHITE ? Tempo : -Tempo);
+ if (st->epSquare != SQ_NONE)
+ {
+ st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
+ st->epSquare = SQ_NONE;
}
- else
- // Undo: point our state pointer back to the previous state
- st = st->previous;
-
- assert(pos_is_ok());
-}
+ st->key ^= Zobrist::side;
+ prefetch((char*)TT.first_entry(st->key));
-/// Position::do_null_move() is used to do/undo a "null move": It flips the side
-/// to move and updates the hash key without executing any move on the board.
-template<bool Do>
-void Position::do_null_move(StateInfo& backupSt) {
-
- assert(!in_check());
-
- // Back up the information necessary to undo the null move to the supplied
- // StateInfo object. Note that differently from normal case here backupSt
- // is actually used as a backup storage not as the new state. This reduces
- // the number of fields to be copied.
- StateInfo* src = Do ? st : &backupSt;
- StateInfo* dst = Do ? &backupSt : st;
-
- dst->key = src->key;
- dst->epSquare = src->epSquare;
- dst->psqScore = src->psqScore;
- dst->rule50 = src->rule50;
- dst->pliesFromNull = src->pliesFromNull;
+ st->rule50++;
+ st->pliesFromNull = 0;
sideToMove = ~sideToMove;
- if (Do)
- {
- if (st->epSquare != SQ_NONE)
- st->key ^= zobEp[file_of(st->epSquare)];
+ assert(pos_is_ok());
+}
- st->key ^= zobSideToMove;
- prefetch((char*)TT.first_entry(st->key));
+void Position::undo_null_move() {
- st->epSquare = SQ_NONE;
- st->rule50++;
- st->pliesFromNull = 0;
- st->psqScore += (sideToMove == WHITE ? Tempo : -Tempo);
- }
+ assert(!checkers());
- assert(pos_is_ok());
+ st = st->previous;
+ sideToMove = ~sideToMove;
}
-// Explicit template instantiations
-template void Position::do_null_move<false>(StateInfo& backupSt);
-template void Position::do_null_move<true>(StateInfo& backupSt);
-
/// Position::see() is a static exchange evaluator: It tries to estimate the
-/// material gain or loss resulting from a move. There are three versions of
-/// 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. Parameter 'asymmThreshold' takes
+/// tempi into account. If the side who initiated the capturing sequence does the
+/// last capture, he loses a tempo and if the result is below 'asymmThreshold'
+/// the capturing sequence is considered bad.
int Position::see_sign(Move m) const {
// 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 (PieceValueMidgame[piece_on(to_sq(m))] >= PieceValueMidgame[piece_moved(m)])
+ if (PieceValue[MG][piece_moved(m)] <= PieceValue[MG][piece_on(to_sq(m))])
return 1;
return see(m);
}
-int Position::see(Move m) const {
+int Position::see(Move m, int asymmThreshold) const {
Square from, to;
- Bitboard occ, attackers, stmAttackers, b;
+ Bitboard occupied, attackers, stmAttackers;
int swapList[32], slIndex = 1;
- PieceType capturedType, pt;
+ PieceType captured;
Color stm;
assert(is_ok(m));
- // As castle moves are implemented as capturing the rook, they have
- // SEE == RookValueMidgame most of the times (unless the rook is under
- // attack).
- if (is_castle(m))
- return 0;
-
from = from_sq(m);
to = to_sq(m);
- capturedType = type_of(piece_on(to));
- occ = pieces();
+ swapList[0] = PieceValue[MG][type_of(piece_on(to))];
+ stm = color_of(piece_on(from));
+ occupied = pieces() ^ from;
+
+ // Castle 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) == CASTLE)
+ return 0;
- // Handle en passant moves
- if (is_enpassant(m))
+ if (type_of(m) == ENPASSANT)
{
- Square capQq = to - pawn_push(sideToMove);
-
- assert(!capturedType);
- assert(type_of(piece_on(capQq)) == PAWN);
-
- // Remove the captured pawn
- occ ^= 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.
- occ ^= from;
- attackers = attackers_to(to, occ);
+ attackers = attackers_to(to, occupied) & occupied;
// If the opponent has no attackers we are finished
- stm = ~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);
- occ ^= (b & (~b + 1));
- attackers |= (attacks_bb<ROOK>(to, occ) & pieces(ROOK, QUEEN))
- | (attacks_bb<BISHOP>(to, occ) & pieces(BISHOP, QUEEN));
-
- attackers &= occ; // Cut out pieces we've already done
+ assert(slIndex < 32);
// Add the new entry to the swap list
- assert(slIndex < 32);
- swapList[slIndex] = -swapList[slIndex - 1] + PieceValueMidgame[capturedType];
+ swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
slIndex++;
- // Remember the value of the capturing piece, and change the side to
- // move before beginning the next iteration.
- capturedType = pt;
+ // Locate and remove the next least valuable attacker
+ captured = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
stm = ~stm;
stmAttackers = attackers & pieces(stm);
// Stop before processing a king capture
- if (capturedType == KING && stmAttackers)
+ if (captured == KING && stmAttackers)
{
- assert(slIndex < 32);
- swapList[slIndex++] = QueenValueMidgame*10;
+ swapList[slIndex++] = QueenValueMg * 16;
break;
}
+
} while (stmAttackers);
+ // If we are doing asymmetric SEE evaluation and the same side does the first
+ // and the last capture, he loses a tempo and gain must be at least worth
+ // 'asymmThreshold', otherwise we replace the score with a very low value,
+ // before negamaxing.
+ if (asymmThreshold)
+ for (int i = 0; i < slIndex; i += 2)
+ if (swapList[i] < asymmThreshold)
+ swapList[i] = - QueenValueMg * 16;
+
// 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)
void Position::clear() {
- memset(this, 0, sizeof(Position));
+ std::memset(this, 0, sizeof(Position));
startState.epSquare = SQ_NONE;
st = &startState;
- for (int i = 0; i < 8; i++)
+ for (int i = 0; i < PIECE_TYPE_NB; i++)
for (int j = 0; j < 16; j++)
- pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
-
- for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
- board[sq] = NO_PIECE;
-}
-
-
-/// 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;
-
- byTypeBB[ALL_PIECES] |= s;
- byTypeBB[pt] |= s;
- byColorBB[c] |= s;
+ pieceList[WHITE][i][j] = pieceList[BLACK][i][j] = SQ_NONE;
}
Key Position::compute_key() const {
- Key result = zobCastle[st->castleRights];
+ Key k = Zobrist::castle[st->castleRights];
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (!square_empty(s))
- result ^= zobrist[color_of(piece_on(s))][type_of(piece_on(s))][s];
+ for (Bitboard b = pieces(); b; )
+ {
+ Square s = pop_lsb(&b);
+ k ^= Zobrist::psq[color_of(piece_on(s))][type_of(piece_on(s))][s];
+ }
if (ep_square() != SQ_NONE)
- result ^= zobEp[file_of(ep_square())];
+ k ^= Zobrist::enpassant[file_of(ep_square())];
if (sideToMove == BLACK)
- result ^= zobSideToMove;
+ k ^= Zobrist::side;
- return result;
+ return k;
}
Key Position::compute_pawn_key() const {
- Bitboard b;
- Key result = 0;
+ Key k = 0;
- for (Color c = WHITE; c <= BLACK; c++)
+ for (Bitboard b = pieces(PAWN); b; )
{
- b = pieces(PAWN, c);
- while (b)
- result ^= zobrist[c][PAWN][pop_1st_bit(&b)];
+ Square s = pop_lsb(&b);
+ k ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s];
}
- return result;
+
+ return k;
}
Key Position::compute_material_key() const {
- Key result = 0;
+ Key k = 0;
for (Color c = WHITE; c <= BLACK; c++)
for (PieceType pt = PAWN; pt <= QUEEN; pt++)
- for (int i = 0; i < piece_count(c, pt); i++)
- result ^= zobrist[c][pt][i];
+ for (int cnt = 0; cnt < pieceCount[c][pt]; cnt++)
+ k ^= Zobrist::psq[c][pt][cnt];
- return result;
+ return k;
}
/// 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_psq_score() const {
- Bitboard b;
- Score result = SCORE_ZERO;
+ Score score = SCORE_ZERO;
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- {
- b = pieces(pt, c);
- while (b)
- result += pieceSquareTable[make_piece(c, pt)][pop_1st_bit(&b)];
- }
+ for (Bitboard b = pieces(); b; )
+ {
+ Square s = pop_lsb(&b);
+ Piece pc = piece_on(s);
+ score += psq[color_of(pc)][type_of(pc)][s];
+ }
- result += (sideToMove == WHITE ? Tempo / 2 : -Tempo / 2);
- return result;
+ return score;
}
Value Position::compute_non_pawn_material(Color c) const {
- Value result = VALUE_ZERO;
+ Value value = VALUE_ZERO;
for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
- result += piece_count(c, pt) * PieceValueMidgame[pt];
+ value += pieceCount[c][pt] * PieceValue[MG][pt];
- return result;
+ return value;
}
-/// 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>
+/// Position::is_draw() tests whether the position is drawn by 50 moves rule
+/// or by repetition. It does not detect stalemates.
+
bool Position::is_draw() const {
- // Draw by material?
- if ( !pieces(PAWN)
- && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame))
+ if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
return true;
- // Draw by the 50 moves rule?
- if (st->rule50 > 99 && (!in_check() || MoveList<MV_LEGAL>(*this).size()))
- return true;
+ int i = 4, e = std::min(st->rule50, st->pliesFromNull);
- // Draw by repetition?
- if (!SkipRepetition)
+ if (i <= e)
{
- int i = 4, e = std::min(st->rule50, st->pliesFromNull);
-
- if (i <= e)
- {
- StateInfo* stp = st->previous->previous;
+ StateInfo* stp = st->previous->previous;
- do {
- stp = stp->previous->previous;
+ do {
+ stp = stp->previous->previous;
- if (stp->key == st->key)
- return true;
+ if (stp->key == st->key)
+ return true; // Draw after first repetition
- i +=2;
+ i += 2;
- } while (i <= e);
- }
+ } while (i <= e);
}
return false;
}
-// Explicit template instantiations
-template bool Position::is_draw<false>() const;
-template bool Position::is_draw<true>() const;
-
-
-/// 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>();
+/// Position::flip() flips position with the white and black sides reversed. This
+/// is only useful for debugging especially for finding evaluation symmetry bugs.
- for (File f = FILE_A; f <= FILE_H; f++)
- zobEp[f] = rk.rand<Key>();
+static char toggle_case(char c) {
+ return char(islower(c) ? toupper(c) : tolower(c));
+}
- for (int cr = CASTLES_NONE; cr <= ALL_CASTLES; cr++)
- {
- Bitboard b = cr;
- while (b)
- {
- Key k = zobCastle[1ULL << pop_1st_bit(&b)];
- zobCastle[cr] ^= k ? k : rk.rand<Key>();
- }
- }
+void Position::flip() {
- zobSideToMove = rk.rand<Key>();
- zobExclusion = rk.rand<Key>();
+ string f, token;
+ std::stringstream ss(fen());
- for (Piece p = W_PAWN; p <= W_KING; p++)
+ for (Rank rank = RANK_8; rank >= RANK_1; rank--) // Piece placement
{
- Score ps = make_score(PieceValueMidgame[p], PieceValueEndgame[p]);
-
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- {
- pieceSquareTable[p][s] = ps + PSQT[p][s];
- pieceSquareTable[p+8][~s] = -pieceSquareTable[p][s];
- }
+ std::getline(ss, token, rank > RANK_1 ? '/' : ' ');
+ f.insert(0, token + (f.empty() ? " " : "/"));
}
-}
+ ss >> token; // Active color
+ f += (token == "w" ? "B " : "W "); // Will be lowercased later
-/// Position::flip() flips position with the white and black sides reversed. This
-/// is only useful for debugging especially for finding evaluation symmetry bugs.
-
-void Position::flip() {
-
- const Position pos(*this);
-
- clear();
-
- sideToMove = ~pos.side_to_move();
- thisThread = pos.this_thread();
- nodes = pos.nodes_searched();
- chess960 = pos.is_chess960();
- startPosPly = pos.startpos_ply_counter();
+ ss >> token; // Castling availability
+ f += token + " ";
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (!pos.square_empty(s))
- put_piece(Piece(pos.piece_on(s) ^ 8), ~s);
+ std::transform(f.begin(), f.end(), f.begin(), toggle_case);
- if (pos.can_castle(WHITE_OO))
- set_castle_right(BLACK, ~pos.castle_rook_square(WHITE, KING_SIDE));
- if (pos.can_castle(WHITE_OOO))
- set_castle_right(BLACK, ~pos.castle_rook_square(WHITE, QUEEN_SIDE));
- if (pos.can_castle(BLACK_OO))
- set_castle_right(WHITE, ~pos.castle_rook_square(BLACK, KING_SIDE));
- if (pos.can_castle(BLACK_OOO))
- set_castle_right(WHITE, ~pos.castle_rook_square(BLACK, QUEEN_SIDE));
+ ss >> token; // En passant square
+ f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3"));
- if (pos.st->epSquare != SQ_NONE)
- st->epSquare = ~pos.st->epSquare;
+ std::getline(ss, token); // Half and full moves
+ f += token;
- st->key = compute_key();
- st->pawnKey = compute_pawn_key();
- st->materialKey = compute_material_key();
- st->psqScore = compute_psq_score();
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
- 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());
}
bool Position::pos_is_ok(int* failedStep) const {
+ int dummy, *step = failedStep ? failedStep : &dummy;
+
// What features of the position should be verified?
- const bool debugAll = 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;
-
- if (failedStep) *failedStep = 1;
-
- // Side to move OK?
+ const bool all = false;
+
+ const bool debugBitboards = all || false;
+ const bool debugKingCount = all || false;
+ const bool debugKingCapture = all || false;
+ const bool debugCheckerCount = all || false;
+ const bool debugKey = all || false;
+ const bool debugMaterialKey = all || false;
+ const bool debugPawnKey = all || false;
+ const bool debugIncrementalEval = all || false;
+ const bool debugNonPawnMaterial = all || false;
+ const bool debugPieceCounts = all || false;
+ const bool debugPieceList = all || false;
+ const bool debugCastleSquares = all || false;
+
+ *step = 1;
+
if (sideToMove != WHITE && sideToMove != BLACK)
return false;
- // Are the king squares in the position correct?
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(WHITE)) != W_KING)
+ if ((*step)++, piece_on(king_square(WHITE)) != W_KING)
return false;
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(BLACK)) != B_KING)
+ if ((*step)++, piece_on(king_square(BLACK)) != B_KING)
return false;
- // Do both sides have exactly one king?
- if (failedStep) (*failedStep)++;
- if (debugKingCount)
+ if ((*step)++, debugKingCount)
{
- int kingCount[2] = {0, 0};
+ int kingCount[COLOR_NB] = {};
+
for (Square s = SQ_A1; s <= SQ_H8; s++)
if (type_of(piece_on(s)) == KING)
kingCount[color_of(piece_on(s))]++;
return false;
}
- // Can the side to move capture the opponent's king?
- if (failedStep) (*failedStep)++;
- if (debugKingCapture)
- {
- Color us = sideToMove;
- Color them = ~us;
- Square ksq = king_square(them);
- if (attackers_to(ksq) & pieces(us))
+ if ((*step)++, debugKingCapture)
+ if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove))
return false;
- }
- // Is there more than 2 checkers?
- if (failedStep) (*failedStep)++;
- if (debugCheckerCount && popcount<Full>(st->checkersBB) > 2)
+ if ((*step)++, debugCheckerCount && popcount<Full>(st->checkersBB) > 2)
return false;
- // Bitboards OK?
- if (failedStep) (*failedStep)++;
- if (debugBitboards)
+ if ((*step)++, debugBitboards)
{
// The intersection of the white and black pieces must be empty
if (pieces(WHITE) & pieces(BLACK))
return false;
}
- // En passant square OK?
- if (failedStep) (*failedStep)++;
- if (ep_square() != SQ_NONE)
- {
- // The en passant square must be on rank 6, from the point of view of the
- // side to move.
- if (relative_rank(sideToMove, ep_square()) != RANK_6)
- return false;
- }
-
- // Hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugKey && st->key != compute_key())
+ if ((*step)++, ep_square() != SQ_NONE && relative_rank(sideToMove, ep_square()) != RANK_6)
return false;
- // Pawn hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugPawnKey && st->pawnKey != compute_pawn_key())
+ if ((*step)++, debugKey && st->key != compute_key())
return false;
- // Material hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugMaterialKey && st->materialKey != compute_material_key())
+ if ((*step)++, debugPawnKey && st->pawnKey != compute_pawn_key())
return false;
- // Incremental eval OK?
- if (failedStep) (*failedStep)++;
- if (debugIncrementalEval && st->psqScore != compute_psq_score())
+ if ((*step)++, debugMaterialKey && st->materialKey != compute_material_key())
return false;
- // Non-pawn material OK?
- if (failedStep) (*failedStep)++;
- if (debugNonPawnMaterial)
- {
- if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE))
- return false;
+ if ((*step)++, debugIncrementalEval && st->psq != compute_psq_score())
+ return false;
- if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
+ if ((*step)++, debugNonPawnMaterial)
+ if ( st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)
+ || st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
return false;
- }
- // Piece counts OK?
- if (failedStep) (*failedStep)++;
- if (debugPieceCounts)
+ if ((*step)++, debugPieceCounts)
for (Color c = WHITE; c <= BLACK; c++)
for (PieceType pt = PAWN; pt <= KING; pt++)
- if (pieceCount[c][pt] != popcount<Full>(pieces(pt, c)))
+ if (pieceCount[c][pt] != popcount<Full>(pieces(c, pt)))
return false;
- if (failedStep) (*failedStep)++;
- if (debugPieceList)
+ if ((*step)++, 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))
- return false;
-
- if (index[piece_list(c, pt)[i]] != i)
+ if ( board[pieceList[c][pt][i]] != make_piece(c, pt)
+ || index[pieceList[c][pt][i]] != i)
return false;
- }
- if (failedStep) (*failedStep)++;
- if (debugCastleSquares)
+ if ((*step)++, debugCastleSquares)
for (Color c = WHITE; c <= BLACK; c++)
for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1))
{
- if (!can_castle(make_castle_right(c, s)))
+ CastleRight cr = make_castle_right(c, s);
+
+ if (!can_castle(cr))
continue;
- if ( piece_on(castleRookSquare[c][s]) != make_piece(c, ROOK)
- || castleRightsMask[castleRookSquare[c][s]] != make_castle_right(c, s))
+ if ( (castleRightsMask[king_square(c)] & cr) != cr
+ || piece_on(castleRookSquare[c][s]) != make_piece(c, ROOK)
+ || castleRightsMask[castleRookSquare[c][s]] != cr)
return false;
}
- if (failedStep) *failedStep = 0;
+ *step = 0;
return true;
}
projects / stockfish / blobdiff