/*
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"
CACHE_LINE_ALIGNMENT
-Score pieceSquareTable[PIECE_NB][SQUARE_NB];
+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;
-
-/// 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 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++)
- psq[c][pt][s] = rk.rand<Key>();
-
- for (File f = FILE_A; f <= FILE_H; f++)
- enpassant[f] = rk.rand<Key>();
-
- for (int cr = CASTLES_NONE; cr <= ALL_CASTLES; cr++)
- {
- Bitboard b = cr;
- while (b)
- {
- Key k = castle[1ULL << pop_lsb(&b)];
- castle[cr] ^= k ? k : rk.rand<Key>();
- }
- }
-
- side = rk.rand<Key>();
- 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++)
- {
- pieceSquareTable[make_piece(WHITE, pt)][ s] = (v + PSQT[pt][s]);
- pieceSquareTable[make_piece(BLACK, pt)][~s] = -(v + PSQT[pt][s]);
- }
- }
+ Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+ Key enpassant[FILE_NB];
+ Key castle[CASTLE_RIGHT_NB];
+ Key side;
+ Key exclusion;
}
-} // namespace Zobrist
-
+Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion;}
namespace {
-/// next_attacker() is an helper function used by see() to locate the least
-/// valuable attacker for the side to move, remove the attacker we just found
-/// from the 'occupied' bitboard and scan for new X-ray attacks behind it.
+// 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 next_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers,
- Bitboard& occupied, Bitboard& attackers) {
+PieceType min_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers,
+ Bitboard& occupied, Bitboard& attackers) {
- if (stmAttackers & bb[Pt])
- {
- Bitboard b = stmAttackers & bb[Pt];
- occupied ^= b & ~(b - 1);
+ Bitboard b = stmAttackers & bb[Pt];
+ if (!b)
+ return min_attacker<Pt+1>(bb, to, stmAttackers, occupied, attackers);
- if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN)
- attackers |= attacks_bb<BISHOP>(to, occupied) & (bb[BISHOP] | bb[QUEEN]);
+ occupied ^= b & ~(b - 1);
- if (Pt == ROOK || Pt == QUEEN)
- attackers |= attacks_bb<ROOK>(to, occupied) & (bb[ROOK] | bb[QUEEN]);
+ if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN)
+ attackers |= attacks_bb<BISHOP>(to, occupied) & (bb[BISHOP] | bb[QUEEN]);
- return (PieceType)Pt;
- }
- return next_attacker<Pt+1>(bb, to, stmAttackers, occupied, attackers);
+ 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 next_attacker<KING>(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) {
+PieceType min_attacker<KING>(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) {
return KING; // No need to update bitboards, it is the last cycle
}
}
+/// 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.
Position& Position::operator=(const Position& pos) {
- memcpy(this, &pos, sizeof(Position));
+ std::memcpy(this, &pos, sizeof(Position));
startState = *st;
st = &startState;
nodes = 0;
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++;
}
}
}
// 5-6. Halfmove clock and fullmove number
- ss >> 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);
const string Position::fen() const {
std::ostringstream ss;
- Square sq;
- int emptyCnt;
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
{
- emptyCnt = 0;
-
for (File file = FILE_A; file <= FILE_H; file++)
{
- sq = file | rank;
+ Square sq = file | rank;
if (is_empty(sq))
- emptyCnt++;
- else
{
- if (emptyCnt > 0)
- {
- ss << emptyCnt;
- emptyCnt = 0;
- }
- ss << 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)
- ss << emptyCnt;
-
if (rank > RANK_1)
ss << '/';
}
ss << (sideToMove == WHITE ? " w " : " b ");
if (can_castle(WHITE_OO))
- ss << (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))
- ss << (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))
- ss << (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))
- ss << (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)
ss << '-';
ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
- << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
+ << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2;
return ss.str();
}
string brd = twoRows + twoRows + twoRows + twoRows + dottedLine;
+ for (Bitboard b = pieces(); b; )
+ {
+ Square s = pop_lsb(&b);
+ brd[513 - 68 * rank_of(s) + 4 * file_of(s)] = PieceToChar[piece_on(s)];
+ }
+
std::ostringstream ss;
if (move)
- ss << "\nMove is: " << (sideToMove == BLACK ? ".." : "")
+ ss << "\nMove: " << (sideToMove == BLACK ? ".." : "")
<< move_to_san(*const_cast<Position*>(this), move);
- for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
- if (piece_on(sq) != NO_PIECE)
- brd[513 - 68*rank_of(sq) + 4*file_of(sq)] = PieceToChar[piece_on(sq)];
+ 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) << " ";
- ss << brd << "\nFen is: " << fen() << "\nKey is: " << st->key;
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 = between_bb(ksq, pop_lsb(&pinners)) & pieces();
- if (b && !more_than_one(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.
}
-/// Position::move_is_legal() takes a random move and tests whether the move
-/// is legal. This version is not very fast and should be used only in non
-/// time-critical paths.
-
-bool Position::move_is_legal(const Move m) const {
-
- for (MoveList<LEGAL> ml(*this); !ml.end(); ++ml)
- if (ml.move() == m)
- return true;
-
- return false;
-}
-
-
/// Position::is_pseudo_legal() takes a random move and tests whether the move
/// is pseudo legal. It is used to validate moves from TT that can be corrupted
/// due to SMP concurrent access or hash position key aliasing.
bool Position::is_pseudo_legal(const Move m) const {
Color us = sideToMove;
- Color them = ~sideToMove;
Square from = from_sq(m);
Square to = to_sq(m);
Piece pc = piece_moved(m);
// Use a slower but simpler function for uncommon cases
if (type_of(m) != NORMAL)
- return move_is_legal(m);
+ return MoveList<LEGAL>(*this).contains(m);
// Is not a promotion, so promotion piece must be empty
if (promotion_type(m) - 2 != NO_PIECE_TYPE)
return false;
// The destination square cannot be occupied by a friendly piece
- if (piece_on(to) != NO_PIECE && 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 (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != them)
+ if (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us)
return false;
// From and to files must be one file apart, avoids a7h5
// Evasions generator already takes care to avoid some kind of illegal moves
// and pl_move_is_legal() relies on this. So we have to take care that the
// same kind of moves are filtered out here.
- if (in_check())
+ if (checkers())
{
if (type_of(pc) != KING)
{
- Bitboard b = checkers();
- Square checksq = pop_lsb(&b);
-
- if (b) // double check ? In this case a king move is required
+ // Double check? In this case a king move is required
+ if (more_than_one(checkers()))
return false;
// Our move must be a blocking evasion or a capture of the checking piece
- if (!((between_bb(checksq, king_square(us)) | checkers()) & to))
+ if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to))
return false;
}
// In case of king moves under check we have to remove king so to catch
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)
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);
// Copy some fields of old state to our new StateInfo object except the ones
// which are going to be recalculated from scratch anyway, then switch our state
// pointer to point to the new, ready to be updated, state.
- memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t));
+ std::memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t));
newSt.previous = st;
st = &newSt;
// Update side to move
k ^= Zobrist::side;
- // Increment the 50 moves rule draw counter. Resetting it to zero in the
- // case of a capture or a pawn move is taken care of later.
+ // Increment ply counters.In particular rule50 will be later reset it to zero
+ // in case of a capture or a pawn move.
+ gamePly++;
st->rule50++;
st->pliesFromNull++;
- if (type_of(m) == CASTLE)
- {
- st->key = k;
- do_castle_move<true>(m);
- return;
- }
-
Color us = sideToMove;
Color them = ~us;
Square from = from_sq(m);
Square to = to_sq(m);
- Piece piece = piece_on(from);
- PieceType pt = type_of(piece);
+ 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(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them);
+ 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;
else
st->npMaterial[them] -= PieceValue[MG][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
+ // 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;
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)
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::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]++]
+ 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] += PieceValue[MG][promotion];
}
- // Update pawn hash key
+ // Update pawn hash key and prefetch access to pawnsTable
st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to];
+ prefetch((char*)thisThread->pawnsTable[st->pawnKey]);
// Reset rule 50 draw counter
st->rule50 = 0;
}
- // Prefetch pawn and material hash tables
- prefetch((char*)thisThread->pawnsTable[st->pawnKey]);
- prefetch((char*)thisThread->materialTable[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;
sideToMove = ~sideToMove;
- if (type_of(m) == CASTLE)
- {
- do_castle_move<false>(m);
- return;
- }
-
Color us = sideToMove;
Color them = ~us;
Square from = from_sq(m);
Square to = to_sq(m);
- Piece piece = piece_on(to);
- PieceType pt = type_of(piece);
+ PieceType pt = type_of(piece_on(to));
PieceType capture = st->capturedType;
- assert(is_empty(from));
- assert(color_of(piece) == us);
+ assert(is_empty(from) || type_of(m) == CASTLE);
assert(capture != KING);
if (type_of(m) == PROMOTION)
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)
{
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) {
+/// Position::do_castle() is a helper used to do/undo a castling move. This
+/// is a bit tricky, especially in Chess960.
- assert(is_ok(m));
- assert(type_of(m) == CASTLE);
+void Position::do_castle(Square kfrom, Square kto, Square rfrom, Square rto) {
- Square kto, kfrom, rfrom, rto, kAfter, rAfter;
-
- Color us = sideToMove;
- Square kBefore = from_sq(m);
- Square rBefore = to_sq(m);
-
- // Find after-castle squares for king and rook
- if (rBefore > kBefore) // O-O
- {
- kAfter = relative_square(us, SQ_G1);
- rAfter = relative_square(us, SQ_F1);
- }
- else // O-O-O
- {
- kAfter = relative_square(us, SQ_C1);
- rAfter = relative_square(us, SQ_D1);
- }
+ // 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::psq[us][KING][kfrom] ^ Zobrist::psq[us][KING][kto];
- st->key ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
+void Position::do_null_move(StateInfo& newSt) {
- // Clear en passant square
- if (st->epSquare != SQ_NONE)
- {
- st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
- st->epSquare = SQ_NONE;
- }
+ assert(!checkers());
- // Update castling rights
- st->key ^= Zobrist::castle[st->castleRights & castleRightsMask[kfrom]];
- st->castleRights &= ~castleRightsMask[kfrom];
+ 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;
- sideToMove = ~sideToMove;
+ if (st->epSquare != SQ_NONE)
+ {
+ st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
+ st->epSquare = SQ_NONE;
}
- else
- // Undo: point our state pointer back to the previous state
- st = st->previous;
-
- assert(pos_is_ok());
-}
-
-
-/// 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;
+ st->key ^= Zobrist::side;
+ prefetch((char*)TT.first_entry(st->key));
- dst->key = src->key;
- dst->epSquare = src->epSquare;
- dst->psqScore = src->psqScore;
- dst->rule50 = src->rule50;
- dst->pliesFromNull = src->pliesFromNull;
+ st->rule50++;
+ st->pliesFromNull = 0;
sideToMove = ~sideToMove;
- if (Do)
- {
- if (st->epSquare != SQ_NONE)
- st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
+ assert(pos_is_ok());
+}
- st->key ^= Zobrist::side;
- prefetch((char*)TT.first_entry(st->key));
+void Position::undo_null_move() {
- st->epSquare = SQ_NONE;
- st->rule50++;
- st->pliesFromNull = 0;
- }
+ assert(!checkers());
- assert(pos_is_ok());
+ st = st->previous;
+ sideToMove = ~sideToMove;
}
-// Explicit template instantiations
-template void Position::do_null_move<false>(StateInfo& backupSt);
-template void Position::do_null_move<true>(StateInfo& backupSt);
-
/// Position::see() is a static exchange evaluator: It tries to estimate the
-/// material gain or loss resulting from a move. There are three versions of
-/// 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 (PieceValue[MG][piece_on(to_sq(m))] >= PieceValue[MG][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 occupied, attackers, stmAttackers;
from = from_sq(m);
to = to_sq(m);
- captured = type_of(piece_on(to));
+ swapList[0] = PieceValue[MG][type_of(piece_on(to))];
+ stm = color_of(piece_on(from));
occupied = pieces() ^ from;
- // Handle en passant moves
+ // 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;
+
if (type_of(m) == ENPASSANT)
{
- Square capQq = to - pawn_push(sideToMove);
-
- assert(!captured);
- assert(type_of(piece_on(capQq)) == PAWN);
-
- // Remove the captured pawn
- occupied ^= capQq;
- captured = PAWN;
+ occupied ^= to - pawn_push(stm); // Remove the captured pawn
+ swapList[0] = PieceValue[MG][PAWN];
}
- else if (type_of(m) == CASTLE)
- // Castle moves are implemented as king capturing the rook so cannot be
- // handled correctly. Simply return 0 that is always the correct value
- // unless the rook is ends up under attack.
- return 0;
// Find all attackers to the destination square, with the moving piece
// removed, but possibly an X-ray attacker added behind it.
- attackers = attackers_to(to, occupied);
+ 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 PieceValue[MG][captured];
+ 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] = PieceValue[MG][captured];
captured = type_of(piece_on(from));
do {
swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
slIndex++;
- // Locate and remove from 'occupied' the next least valuable attacker
- captured = next_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
-
- attackers &= occupied; // Remove the just found attacker
+ // Locate and remove the next least valuable attacker
+ captured = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
stm = ~stm;
stmAttackers = attackers & pieces(stm);
- if (captured == KING)
+ // Stop before processing a king capture
+ if (captured == KING && stmAttackers)
{
- // Stop before processing a king capture
- if (stmAttackers)
- swapList[slIndex++] = QueenValueMg * 16;
-
+ 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;
}
-/// 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;
-}
-
-
/// 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
for (Color c = WHITE; c <= BLACK; c++)
for (PieceType pt = PAWN; pt <= QUEEN; pt++)
- for (int cnt = 0; cnt < piece_count(c, pt); cnt++)
+ for (int cnt = 0; cnt < pieceCount[c][pt]; cnt++)
k ^= Zobrist::psq[c][pt][cnt];
return k;
for (Bitboard b = pieces(); b; )
{
Square s = pop_lsb(&b);
- score += pieceSquareTable[piece_on(s)][s];
+ Piece pc = piece_on(s);
+ score += psq[color_of(pc)][type_of(pc)][s];
}
return score;
Value value = VALUE_ZERO;
for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
- value += piece_count(c, pt) * PieceValue[MG][pt];
+ value += pieceCount[c][pt] * PieceValue[MG][pt];
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 CheckRepetition, bool CheckThreeFold>
bool Position::is_draw() const {
+ // Draw by material?
if ( !pieces(PAWN)
&& (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMg))
return true;
- if (st->rule50 > 99 && (!in_check() || MoveList<LEGAL>(*this).size()))
+ // Draw by the 50 moves rule?
+ if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
return true;
- if (CheckRepetition)
+ // Draw by repetition?
+ int i = 4, e = std::min(st->rule50, st->pliesFromNull);
+
+ if (i <= e)
{
- int i = 4, e = std::min(st->rule50, st->pliesFromNull), cnt;
+ StateInfo* stp = st->previous->previous;
- if (i <= e)
- {
- StateInfo* stp = st->previous->previous;
+ do {
+ stp = stp->previous->previous;
- for (cnt = 0; i <= e; i += 2)
- {
- stp = stp->previous->previous;
+ if (stp->key == st->key)
+ return true;
- if (stp->key == st->key && (!CheckThreeFold || ++cnt >= 2))
- return true;
- }
- }
+ i += 2;
+
+ } while (i <= e);
}
return false;
}
-// Explicit template instantiations
-template bool Position::is_draw<true, true>() const;
-template bool Position::is_draw<true, false>() const;
-template bool Position::is_draw<false,false>() const;
-
/// Position::flip() flips position with the white and black sides reversed. This
/// is only useful for debugging especially for finding evaluation symmetry bugs.
+static char toggle_case(char c) {
+ return char(islower(c) ? toupper(c) : tolower(c));
+}
+
void Position::flip() {
- const Position pos(*this);
+ string f, token;
+ std::stringstream ss(fen());
- clear();
+ for (Rank rank = RANK_8; rank >= RANK_1; rank--) // Piece placement
+ {
+ std::getline(ss, token, rank > RANK_1 ? '/' : ' ');
+ f.insert(0, token + (f.empty() ? " " : "/"));
+ }
- sideToMove = ~pos.side_to_move();
- thisThread = pos.this_thread();
- nodes = pos.nodes_searched();
- chess960 = pos.is_chess960();
- startPosPly = pos.startpos_ply_counter();
+ ss >> token; // Active color
+ f += (token == "w" ? "B " : "W "); // Will be lowercased later
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (!pos.is_empty(s))
- put_piece(Piece(pos.piece_on(s) ^ 8), ~s);
+ ss >> token; // Castling availability
+ f += token + " ";
- 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));
+ std::transform(f.begin(), f.end(), f.begin(), toggle_case);
- if (pos.st->epSquare != SQ_NONE)
- st->epSquare = ~pos.st->epSquare;
+ ss >> token; // En passant square
+ f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3"));
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
+ 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->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());
}
if ((*step)++, debugMaterialKey && st->materialKey != compute_material_key())
return false;
- if ((*step)++, debugIncrementalEval && st->psqScore != compute_psq_score())
+ if ((*step)++, debugIncrementalEval && st->psq != compute_psq_score())
return false;
if ((*step)++, debugNonPawnMaterial)
- {
if ( st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)
|| st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
return false;
- }
if ((*step)++, debugPieceCounts)
for (Color c = WHITE; c <= BLACK; c++)
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 ((*step)++, debugCastleSquares)
for (Color c = WHITE; c <= BLACK; c++)
if (!can_castle(cr))
continue;
- if ((castleRightsMask[king_square(c)] & cr) != cr)
- return false;
-
- if ( piece_on(castleRookSquare[c][s]) != make_piece(c, ROOK)
+ if ( (castleRightsMask[king_square(c)] & cr) != cr
+ || piece_on(castleRookSquare[c][s]) != make_piece(c, ROOK)
|| castleRightsMask[castleRookSquare[c][s]] != cr)
return false;
}