/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm>
#include <cassert>
#include <cstring>
#include <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"
+#include "misc.h"
#include "thread.h"
#include "tt.h"
+#include "uci.h"
using std::string;
-using std::cout;
-using std::endl;
-
-static const string PieceToChar(" PNBRQK pnbrqk");
-CACHE_LINE_ALIGNMENT
-
-Score pieceSquareTable[PIECE_NB][SQUARE_NB];
Value PieceValue[PHASE_NB][PIECE_NB] = {
{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } };
namespace Zobrist {
-Key psq[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 (Piece pc = W_PAWN; pc <= W_KING; pc++)
- {
- PieceValue[MG][~pc] = PieceValue[MG][pc];
- PieceValue[EG][~pc] = PieceValue[EG][pc];
-
- Score v = make_score(PieceValue[MG][pc], PieceValue[EG][pc]);
-
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- {
- pieceSquareTable[ pc][ s] = (v + PSQT[pc][s]);
- pieceSquareTable[~pc][~s] = -(v + PSQT[pc][s]);
- }
- }
+ Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+ Key enpassant[FILE_NB];
+ Key castling[CASTLING_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
+const string PieceToChar(" PNBRQK pnbrqk");
+Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+
+// min_attacker() is a helper function used by see() to locate the least
// valuable attacker for the side to move, remove the attacker we just found
-// from the 'occupied' bitboard and scan for new X-ray attacks behind it.
+// 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&) {
- return KING; // No need to update bitboards, it is the last cycle
+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
Color them = ~pos.side_to_move();
ksq = pos.king_square(them);
- pinned = pos.pinned_pieces();
+ pinned = pos.pinned_pieces(pos.side_to_move());
dcCandidates = pos.discovered_check_candidates();
checkSq[PAWN] = pos.attacks_from<PAWN>(ksq, them);
}
+/// operator<<(Position) returns an ASCII representation of the position
+
+std::ostream& operator<<(std::ostream& os, const Position& pos) {
+
+ os << "\n +---+---+---+---+---+---+---+---+\n";
+
+ for (Rank r = RANK_8; r >= RANK_1; --r)
+ {
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ os << " | " << PieceToChar[pos.piece_on(make_square(f, r))];
+
+ os << " |\n +---+---+---+---+---+---+---+---+\n";
+ }
+
+ os << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase
+ << std::setfill('0') << std::setw(16) << pos.st->key << std::dec << "\nCheckers: ";
+
+ for (Bitboard b = pos.checkers(); b; )
+ os << UCI::format_square(pop_lsb(&b)) << " ";
+
+ return os;
+}
+
+
+/// Position::init() initializes at startup the various arrays used to compute
+/// hash keys and the piece square tables. The latter is a two-step operation:
+/// Firstly, the white halves of the tables are copied from PSQT[] tables.
+/// Secondly, the black halves of the tables are initialized by flipping and
+/// changing the sign of the white scores.
+
+void Position::init() {
+
+ PRNG rng(1070372);
+
+ 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] = rng.rand<Key>();
+
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ Zobrist::enpassant[f] = rng.rand<Key>();
+
+ for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr)
+ {
+ Bitboard b = cr;
+ while (b)
+ {
+ Key k = Zobrist::castling[1ULL << pop_lsb(&b)];
+ Zobrist::castling[cr] ^= k ? k : rng.rand<Key>();
+ }
+ }
+
+ Zobrist::side = rng.rand<Key>();
+ Zobrist::exclusion = rng.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
+/// object to 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;
}
+/// Position::clear() erases the position object to a pristine state, with an
+/// empty board, white to move, and no castling rights.
+
+void Position::clear() {
+
+ std::memset(this, 0, sizeof(Position));
+ startState.epSquare = SQ_NONE;
+ st = &startState;
+
+ for (int i = 0; i < PIECE_TYPE_NB; ++i)
+ for (int j = 0; j < 16; ++j)
+ pieceList[WHITE][i][j] = pieceList[BLACK][i][j] = SQ_NONE;
+}
+
+
/// Position::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.
A FEN string contains six fields separated by a space. The fields are:
1) Piece placement (from white's perspective). Each rank is described, starting
- with rank 8 and ending with rank 1; within each rank, the contents of each
+ with rank 8 and ending with rank 1. Within each rank, the contents of each
square are described from file A through file H. Following the Standard
Algebraic Notation (SAN), each piece is identified by a single letter taken
from the standard English names. White pieces are designated using upper-case
- letters ("PNBRQK") while Black take lowercase ("pnbrqk"). Blank squares are
+ letters ("PNBRQK") whilst Black uses lowercase ("pnbrqk"). Blank squares are
noted using digits 1 through 8 (the number of blank squares), and "/"
separates ranks.
incremented after Black's move.
*/
- char col, row, token;
- size_t p;
+ unsigned char col, row, token;
+ size_t idx;
Square sq = SQ_A8;
std::istringstream ss(fenStr);
else if (token == '/')
sq -= Square(16);
- else if ((p = PieceToChar.find(token)) != string::npos)
+ else if ((idx = PieceToChar.find(token)) != string::npos)
{
- put_piece(Piece(p), sq);
- sq++;
+ put_piece(sq, color_of(Piece(idx)), type_of(Piece(idx)));
+ ++sq;
}
}
token = char(toupper(token));
if (token == 'K')
- for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; rsq--) {}
+ for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; --rsq) {}
else if (token == 'Q')
- for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; rsq++) {}
+ for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; ++rsq) {}
else if (token >= 'A' && token <= 'H')
- rsq = File(token - 'A') | relative_rank(c, RANK_1);
+ rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1));
else
continue;
- set_castle_right(c, rsq);
+ set_castling_right(c, rsq);
}
// 4. En passant square. Ignore if no pawn capture is possible
if ( ((ss >> col) && (col >= 'a' && col <= 'h'))
&& ((ss >> row) && (row == '3' || row == '6')))
{
- st->epSquare = File(col - 'a') | Rank(row - '1');
+ st->epSquare = make_square(File(col - 'a'), Rank(row - '1'));
if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN)))
st->epSquare = SQ_NONE;
// Convert from fullmove starting from 1 to ply starting from 0,
// handle also common incorrect FEN with fullmove = 0.
- 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->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
+ gamePly = std::max(2 * (gamePly - 1), 0) + (sideToMove == BLACK);
+
chess960 = isChess960;
thisThread = th;
+ set_state(st);
assert(pos_is_ok());
}
-/// Position::set_castle_right() is an helper function used to set castling
+/// Position::set_castling_right() is a helper function used to set castling
/// rights given the corresponding color and the rook starting square.
-void Position::set_castle_right(Color c, Square rfrom) {
+void Position::set_castling_right(Color c, Square rfrom) {
Square kfrom = king_square(c);
CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE;
- CastleRight cr = make_castle_right(c, cs);
+ CastlingRight cr = (c | cs);
- st->castleRights |= cr;
- castleRightsMask[kfrom] |= cr;
- castleRightsMask[rfrom] |= cr;
- castleRookSquare[c][cs] = rfrom;
+ st->castlingRights |= cr;
+ castlingRightsMask[kfrom] |= cr;
+ castlingRightsMask[rfrom] |= cr;
+ castlingRookSquare[cr] = rfrom;
Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1);
Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1);
- for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); s++)
+ for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s)
if (s != kfrom && s != rfrom)
- castlePath[c][cs] |= s;
+ castlingPath[cr] |= s;
- for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); s++)
+ for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s)
if (s != kfrom && s != rfrom)
- castlePath[c][cs] |= s;
+ castlingPath[cr] |= s;
}
-/// Position::fen() returns a FEN representation of the position. In case
-/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function.
+/// Position::set_state() computes the hash keys of the position, and other
+/// data that once computed is updated incrementally as moves are made.
+/// The function is only used when a new position is set up, and to verify
+/// the correctness of the StateInfo data when running in debug mode.
+
+void Position::set_state(StateInfo* si) const {
+
+ si->key = si->pawnKey = si->materialKey = 0;
+ si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO;
+ si->psq = SCORE_ZERO;
+
+ si->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
+
+ for (Bitboard b = pieces(); b; )
+ {
+ Square s = pop_lsb(&b);
+ Piece pc = piece_on(s);
+ si->key ^= Zobrist::psq[color_of(pc)][type_of(pc)][s];
+ si->psq += psq[color_of(pc)][type_of(pc)][s];
+ }
+
+ if (ep_square() != SQ_NONE)
+ si->key ^= Zobrist::enpassant[file_of(ep_square())];
+
+ if (sideToMove == BLACK)
+ si->key ^= Zobrist::side;
+
+ si->key ^= Zobrist::castling[st->castlingRights];
+
+ for (Bitboard b = pieces(PAWN); b; )
+ {
+ Square s = pop_lsb(&b);
+ si->pawnKey ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s];
+ }
+
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ for (int cnt = 0; cnt < pieceCount[c][pt]; ++cnt)
+ si->materialKey ^= Zobrist::psq[c][pt][cnt];
+
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt)
+ si->nonPawnMaterial[c] += pieceCount[c][pt] * PieceValue[MG][pt];
+}
+
+
+/// Position::fen() returns a FEN representation of the position. In case of
+/// Chess960 the Shredder-FEN notation is used. This is mainly a debugging function.
const string Position::fen() const {
+ int emptyCnt;
std::ostringstream ss;
- for (Rank rank = RANK_8; rank >= RANK_1; rank--)
+ for (Rank r = RANK_8; r >= RANK_1; --r)
{
- for (File file = FILE_A; file <= FILE_H; file++)
+ for (File f = FILE_A; f <= FILE_H; ++f)
{
- Square sq = file | rank;
-
- if (is_empty(sq))
- {
- int emptyCnt = 1;
-
- for ( ; file < FILE_H && is_empty(sq++); file++)
- emptyCnt++;
+ for (emptyCnt = 0; f <= FILE_H && empty(make_square(f, r)); ++f)
+ ++emptyCnt;
+ if (emptyCnt)
ss << emptyCnt;
- }
- else
- ss << PieceToChar[piece_on(sq)];
+
+ if (f <= FILE_H)
+ ss << PieceToChar[piece_on(make_square(f, r))];
}
- if (rank > RANK_1)
+ if (r > RANK_1)
ss << '/';
}
ss << (sideToMove == WHITE ? " w " : " b ");
if (can_castle(WHITE_OO))
- ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE)), false) : 'K');
+ ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | KING_SIDE))) : 'K');
if (can_castle(WHITE_OOO))
- ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE)), false) : 'Q');
+ ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | QUEEN_SIDE))) : 'Q');
if (can_castle(BLACK_OO))
- ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE)), true) : 'k');
+ ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | KING_SIDE))) : 'k');
if (can_castle(BLACK_OOO))
- ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE)), true) : 'q');
+ ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | QUEEN_SIDE))) : 'q');
- if (st->castleRights == CASTLES_NONE)
+ if (!can_castle(WHITE) && !can_castle(BLACK))
ss << '-';
- ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
- << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2;
+ ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::format_square(ep_square()) + " ")
+ << st->rule50 << " " << 1 + (gamePly - (sideToMove == BLACK)) / 2;
return ss.str();
}
-/// Position::pretty() returns an ASCII representation of the position to be
-/// printed to the standard output together with the move's san notation.
+/// Position::game_phase() calculates the game phase interpolating total non-pawn
+/// material between endgame and midgame limits.
-const string Position::pretty(Move move) const {
+Phase Position::game_phase() const {
- const string dottedLine = "\n+---+---+---+---+---+---+---+---+";
- const string twoRows = dottedLine + "\n| | . | | . | | . | | . |"
- + dottedLine + "\n| . | | . | | . | | . | |";
+ Value npm = st->nonPawnMaterial[WHITE] + st->nonPawnMaterial[BLACK];
- string brd = twoRows + twoRows + twoRows + twoRows + dottedLine;
+ npm = std::max(EndgameLimit, std::min(npm, MidgameLimit));
- std::ostringstream ss;
-
- if (move)
- ss << "\nMove: " << (sideToMove == BLACK ? ".." : "")
- << move_to_san(*const_cast<Position*>(this), move);
-
- for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
- if (piece_on(sq) != NO_PIECE)
- brd[513 - 68*rank_of(sq) + 4*file_of(sq)] = PieceToChar[piece_on(sq)];
-
- 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();
+ return Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit));
}
-/// 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::check_blockers() returns a bitboard of all the pieces with color
+/// 'c' that are blocking check on the king with color 'kingColor'. A piece
+/// blocks a check if removing that piece from the board would result in a
+/// position where the king is in check. A check blocking piece can be either a
+/// pinned or a discovered check piece, according if its color 'c' is the same
+/// or the opposite of 'kingColor'.
- // 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 Position::check_blockers(Color c, Color kingColor) const {
- // Pinners are sliders, that give check when candidate pinned is removed
- pinners &= (pieces(ROOK, QUEEN) & PseudoAttacks[ROOK][ksq])
- | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq]);
+ Bitboard b, pinners, result = 0;
+ Square ksq = king_square(kingColor);
+
+ // Pinners are sliders that give check when a pinned piece is removed
+ pinners = ( (pieces( ROOK, QUEEN) & PseudoAttacks[ROOK ][ksq])
+ | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(~kingColor);
while (pinners)
{
b = 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(c);
}
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.
+/// given square. Slider attacks use the occupied bitboard to indicate occupancy.
-Bitboard Position::attackers_to(Square s, Bitboard occ) const {
+Bitboard Position::attackers_to(Square s, Bitboard occupied) const {
- 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))
- | (attacks_from<KING>(s) & pieces(KING));
+ 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, occupied) & pieces(ROOK, QUEEN))
+ | (attacks_bb<BISHOP>(s, occupied) & pieces(BISHOP, QUEEN))
+ | (attacks_from<KING>(s) & pieces(KING));
}
-/// Position::attacks_from() computes a bitboard of all attacks of a given piece
-/// put in a given square. Slider attacks use occ bitboard as occupancy.
+/// Position::legal() tests whether a pseudo-legal move is legal
-Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) {
-
- assert(is_ok(s));
-
- switch (type_of(p))
- {
- case BISHOP: return attacks_bb<BISHOP>(s, occ);
- case ROOK : return attacks_bb<ROOK>(s, occ);
- case QUEEN : return attacks_bb<BISHOP>(s, occ) | attacks_bb<ROOK>(s, occ);
- default : return StepAttacksBB[p][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 {
+bool Position::legal(Move m, Bitboard pinned) const {
assert(is_ok(m));
- assert(pinned == pinned_pieces());
+ assert(pinned == pinned_pieces(sideToMove));
Color us = sideToMove;
Square from = from_sq(m);
- assert(color_of(piece_moved(m)) == us);
+ assert(color_of(moved_piece(m)) == us);
assert(piece_on(king_square(us)) == make_piece(us, KING));
// En passant captures are a tricky special case. Because they are rather
// the move is made.
if (type_of(m) == ENPASSANT)
{
- Color them = ~us;
- Square to = to_sq(m);
- Square capsq = to + pawn_push(them);
Square ksq = king_square(us);
- Bitboard b = (pieces() ^ from ^ capsq) | to;
+ Square to = to_sq(m);
+ Square capsq = to - pawn_push(us);
+ Bitboard occupied = (pieces() ^ from ^ capsq) | to;
assert(to == ep_square());
- assert(piece_moved(m) == make_piece(us, PAWN));
- assert(piece_on(capsq) == make_piece(them, PAWN));
+ assert(moved_piece(m) == make_piece(us, PAWN));
+ assert(piece_on(capsq) == make_piece(~us, PAWN));
assert(piece_on(to) == NO_PIECE);
- return !(attacks_bb< ROOK>(ksq, b) & pieces(them, QUEEN, ROOK))
- && !(attacks_bb<BISHOP>(ksq, b) & pieces(them, QUEEN, BISHOP));
+ return !(attacks_bb< ROOK>(ksq, occupied) & pieces(~us, QUEEN, ROOK))
+ && !(attacks_bb<BISHOP>(ksq, occupied) & pieces(~us, QUEEN, BISHOP));
}
// If the moving piece is a king, check whether the destination
// square is attacked by the opponent. Castling moves are checked
// for legality during move generation.
if (type_of(piece_on(from)) == KING)
- return type_of(m) == CASTLE || !(attackers_to(to_sq(m)) & pieces(~us));
+ return type_of(m) == CASTLING || !(attackers_to(to_sq(m)) & pieces(~us));
// A non-king move is legal if and only if it is not pinned or it
// is moving along the ray towards or away from the king.
return !pinned
|| !(pinned & from)
- || squares_aligned(from, to_sq(m), king_square(us));
+ || aligned(from, to_sq(m), king_square(us));
}
-/// Position::is_pseudo_legal() takes a random move and tests whether the move
-/// is pseudo legal. It is used to validate moves from TT that can be corrupted
+/// Position::pseudo_legal() takes a random move and tests whether the move is
+/// pseudo legal. It is used to validate moves from TT that can be corrupted
/// due to SMP concurrent access or hash position key aliasing.
-bool Position::is_pseudo_legal(const Move m) const {
+bool Position::pseudo_legal(const Move m) const {
Color us = sideToMove;
Square from = from_sq(m);
Square to = to_sq(m);
- Piece pc = piece_moved(m);
+ Piece pc = moved_piece(m);
// Use a slower but simpler function for uncommon cases
if (type_of(m) != NORMAL)
if (promotion_type(m) - 2 != NO_PIECE_TYPE)
return false;
- // If the from square is not occupied by a piece belonging to the side to
+ // If the 'from' square is not occupied by a piece belonging to the side to
// move, the move is obviously not legal.
if (pc == NO_PIECE || color_of(pc) != us)
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
if (type_of(pc) == PAWN)
{
- // Move direction must be compatible with pawn color
- int direction = to - from;
- if ((us == WHITE) != (direction > 0))
- return false;
-
// We have already handled promotion moves, so destination
- // cannot be on the 8/1th rank.
- if (rank_of(to) == RANK_8 || rank_of(to) == RANK_1)
+ // cannot be on the 8th/1st rank.
+ if (rank_of(to) == relative_rank(us, RANK_8))
return false;
- // Proceed according to the square delta between the origin and
- // destination squares.
- switch (direction)
- {
- case DELTA_NW:
- case DELTA_NE:
- case DELTA_SW:
- case DELTA_SE:
- // Capture. The destination square must be occupied by an enemy
- // piece (en passant captures was handled earlier).
- if (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us)
- return false;
+ if ( !(attacks_from<PAWN>(from, us) & pieces(~us) & to) // Not a capture
- // From and to files must be one file apart, avoids a7h5
- if (abs(file_of(from) - file_of(to)) != 1)
- return false;
- break;
+ && !((from + pawn_push(us) == to) && empty(to)) // Not a single push
- case DELTA_N:
- case DELTA_S:
- // Pawn push. The destination square must be empty.
- if (!is_empty(to))
- return false;
- break;
-
- case DELTA_NN:
- // Double white pawn push. The destination square must be on the fourth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( rank_of(to) != RANK_4
- || !is_empty(to)
- || !is_empty(from + DELTA_N))
+ && !( (from + 2 * pawn_push(us) == to) // Not a double push
+ && (rank_of(from) == relative_rank(us, RANK_2))
+ && empty(to)
+ && empty(to - pawn_push(us))))
return false;
- break;
-
- case DELTA_SS:
- // Double black pawn push. The destination square must be on the fifth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( rank_of(to) != RANK_5
- || !is_empty(to)
- || !is_empty(from + DELTA_S))
- return false;
- break;
-
- default:
- return false;
- }
}
else if (!(attacks_from(pc, from) & to))
return false;
// 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.
+ // and legal() relies on this. We therefore have to take care that the same
+ // kind of moves are filtered out here.
if (checkers())
{
if (type_of(pc) != KING)
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
- // as invalid moves like b1a1 when opposite queen is on c1.
+ // In case of king moves under check we have to remove king so as to catch
+ // invalid moves like b1a1 when opposite queen is on c1.
else if (attackers_to(to, pieces() ^ from) & pieces(~us))
return false;
}
}
-/// Position::move_gives_check() tests whether a pseudo-legal move gives a check
+/// Position::gives_check() tests whether a pseudo-legal move gives a check
-bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
+bool Position::gives_check(Move m, const CheckInfo& ci) const {
assert(is_ok(m));
assert(ci.dcCandidates == discovered_check_candidates());
- assert(color_of(piece_moved(m)) == sideToMove);
+ assert(color_of(moved_piece(m)) == sideToMove);
Square from = from_sq(m);
Square to = to_sq(m);
PieceType pt = type_of(piece_on(from));
- // Direct check ?
+ // Is there a direct check?
if (ci.checkSq[pt] & to)
return true;
- // Discovery check ?
- if (ci.dcCandidates && (ci.dcCandidates & from))
- {
- // For pawn and king moves we need to verify also direction
- if ( (pt != PAWN && pt != KING)
- || !squares_aligned(from, to, king_square(~sideToMove)))
- return true;
- }
-
- // Can we skip the ugly special cases ?
- if (type_of(m) == NORMAL)
- return false;
-
- Color us = sideToMove;
- Square ksq = king_square(~us);
+ // Is there a discovered check?
+ if ( unlikely(ci.dcCandidates)
+ && (ci.dcCandidates & from)
+ && !aligned(from, to, ci.ksq))
+ return true;
switch (type_of(m))
{
+ case NORMAL:
+ return false;
+
case PROMOTION:
- return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq;
+ return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq;
- // En passant capture with check ? We have already handled the case
- // of direct checks and ordinary discovered check, the only case we
+ // En passant capture with check? We have already handled the case
+ // of direct checks and ordinary discovered check, so the only case we
// need to handle is the unusual case of a discovered check through
// the captured pawn.
case ENPASSANT:
{
- Square capsq = file_of(to) | rank_of(from);
+ Square capsq = make_square(file_of(to), rank_of(from));
Bitboard b = (pieces() ^ from ^ capsq) | to;
- return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK))
- | (attacks_bb<BISHOP>(ksq, b) & pieces(us, QUEEN, BISHOP));
+ return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP));
}
- case CASTLE:
+ case CASTLING:
{
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;
+ Square rfrom = to; // Castling is encoded as 'King captures the rook'
+ Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1);
- return attacks_bb<ROOK>(rto, b) & ksq;
+ return (PseudoAttacks[ROOK][rto] & ci.ksq)
+ && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq);
}
default:
assert(false);
void Position::do_move(Move m, StateInfo& newSt) {
CheckInfo ci(*this);
- do_move(m, newSt, ci, move_gives_check(m, ci));
+ do_move(m, newSt, ci, gives_check(m, ci));
}
void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) {
assert(is_ok(m));
assert(&newSt != st);
- nodes++;
+ ++nodes;
Key k = st->key;
- // 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));
+ // Copy some fields of the old state to our new StateInfo object except the
+ // ones which are going to be recalculated from scratch anyway and then switch
+ // our state pointer to point to the new (ready to be updated) state.
+ std::memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t));
newSt.previous = st;
st = &newSt;
// Update side to move
k ^= Zobrist::side;
- // Increment ply counters.In particular rule50 will be later reset it to zero
+ // Increment ply counters. In particular, rule50 will be reset to zero later on
// in case of a capture or a pawn move.
- gamePly++;
- st->rule50++;
- st->pliesFromNull++;
+ ++gamePly;
+ ++st->rule50;
+ ++st->pliesFromNull;
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 = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to));
+ Piece pc = piece_on(from);
+ PieceType pt = type_of(pc);
+ PieceType captured = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to));
- assert(color_of(piece) == us);
- assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLE);
- assert(capture != KING);
+ assert(color_of(pc) == us);
+ assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLING);
+ assert(captured != KING);
- if (type_of(m) == CASTLE)
+ if (type_of(m) == CASTLING)
{
- assert(piece == make_piece(us, KING));
-
- bool kingSide = to > from;
- Square rfrom = to; // Castle is encoded as "king captures friendly rook"
- Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
- to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
- capture = NO_PIECE_TYPE;
+ assert(pc == make_piece(us, KING));
- do_castle(from, to, rfrom, rto);
+ Square rfrom, rto;
+ do_castling<true>(from, to, rfrom, rto);
+ captured = NO_PIECE_TYPE;
+ st->psq += psq[us][ROOK][rto] - psq[us][ROOK][rfrom];
k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
- st->psqScore += pieceSquareTable[make_piece(us, ROOK)][rto]
- - pieceSquareTable[make_piece(us, ROOK)][rfrom];
}
- if (capture)
+ if (captured)
{
Square capsq = to;
// If the captured piece is a pawn, update pawn hash key, otherwise
// update non-pawn material.
- if (capture == PAWN)
+ if (captured == PAWN)
{
if (type_of(m) == ENPASSANT)
{
st->pawnKey ^= Zobrist::psq[them][PAWN][capsq];
}
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 reversible operation. When we will reinsert the
- // captured piece in undo_move() we will put it at the end of the list and
- // not in its original place, it means index[] and pieceList[] are not
- // guaranteed to be invariant to a do_move() + undo_move() sequence.
- 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;
+ st->nonPawnMaterial[them] -= PieceValue[MG][captured];
+
+ // Update board and piece lists
+ remove_piece(capsq, them, captured);
// Update material hash key and prefetch access to materialTable
- k ^= Zobrist::psq[them][capture][capsq];
- st->materialKey ^= Zobrist::psq[them][capture][pieceCount[them][capture]];
+ k ^= Zobrist::psq[them][captured][capsq];
+ st->materialKey ^= Zobrist::psq[them][captured][pieceCount[them][captured]];
prefetch((char*)thisThread->materialTable[st->materialKey]);
// Update incremental scores
- st->psqScore -= pieceSquareTable[make_piece(them, capture)][capsq];
+ st->psq -= psq[them][captured][capsq];
// Reset rule 50 counter
st->rule50 = 0;
st->epSquare = SQ_NONE;
}
- // Update castle rights if needed
- if (st->castleRights && (castleRightsMask[from] | castleRightsMask[to]))
+ // Update castling rights if needed
+ if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to]))
{
- int cr = castleRightsMask[from] | castleRightsMask[to];
- k ^= Zobrist::castle[st->castleRights & cr];
- st->castleRights &= ~cr;
+ int cr = castlingRightsMask[from] | castlingRightsMask[to];
+ k ^= Zobrist::castling[st->castlingRights & cr];
+ st->castlingRights &= ~cr;
}
- // Prefetch TT access as soon as we know the new hash key
- prefetch((char*)TT.first_entry(k));
-
- // Move the piece. The tricky Chess960 castle is handled earlier
- if (type_of(m) != CASTLE)
- {
- Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
- byTypeBB[ALL_PIECES] ^= from_to_bb;
- byTypeBB[pt] ^= from_to_bb;
- byColorBB[us] ^= from_to_bb;
-
- board[from] = NO_PIECE;
- board[to] = piece;
-
- // Update piece lists, index[from] is not updated and becomes stale. This
- // works as long as index[] is accessed just by known occupied squares.
- index[to] = index[from];
- pieceList[us][pt][index[to]] = to;
- }
+ // Move the piece. The tricky Chess960 castling is handled earlier
+ if (type_of(m) != CASTLING)
+ 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
+ // Set en-passant square if the moved pawn can be captured
if ( (int(to) ^ int(from)) == 16
&& (attacks_from<PAWN>(from + pawn_push(us), us) & pieces(them, PAWN)))
{
k ^= Zobrist::enpassant[file_of(st->epSquare)];
}
- if (type_of(m) == PROMOTION)
+ else 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::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];
+ st->nonPawnMaterial[us] += PieceValue[MG][promotion];
}
// Update pawn hash key and prefetch access to pawnsTable
}
// Update incremental scores
- st->psqScore += pieceSquareTable[piece][to] - pieceSquareTable[piece][from];
+ st->psq += psq[us][pt][to] - psq[us][pt][from];
// Set capture piece
- st->capturedType = capture;
+ st->capturedType = captured;
// Update the key with the final value
st->key = k;
- // Update checkers bitboard, piece must be already moved
+ // Update checkers bitboard: piece must be already moved due to attacks_from()
st->checkersBB = 0;
if (moveIsCheck)
if (ci.checkSq[pt] & to)
st->checkersBB |= to;
- // Discovery checks
- if (ci.dcCandidates && (ci.dcCandidates & from))
+ // Discovered checks
+ if (unlikely(ci.dcCandidates) && (ci.dcCandidates & from))
{
if (pt != ROOK)
st->checkersBB |= attacks_from<ROOK>(king_square(them)) & pieces(us, QUEEN, ROOK);
sideToMove = ~sideToMove;
Color us = sideToMove;
- Color them = ~us;
Square from = from_sq(m);
Square to = to_sq(m);
PieceType pt = type_of(piece_on(to));
- PieceType capture = st->capturedType;
- assert(is_empty(from) || type_of(m) == CASTLE);
- assert(capture != KING);
+ assert(empty(from) || type_of(m) == CASTLING);
+ assert(st->capturedType != KING);
if (type_of(m) == PROMOTION)
{
- PieceType promotion = promotion_type(m);
-
- assert(promotion == pt);
+ assert(pt == 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;
+ assert(promotion_type(m) >= KNIGHT && promotion_type(m) <= QUEEN);
+ remove_piece(to, us, promotion_type(m));
+ put_piece(to, us, PAWN);
pt = PAWN;
}
- if (type_of(m) == CASTLE)
+ if (type_of(m) == CASTLING)
{
- 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);
+ Square rfrom, rto;
+ do_castling<false>(from, to, rfrom, rto);
}
else
{
- // Put the piece back at the source square
- Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
- byTypeBB[ALL_PIECES] ^= from_to_bb;
- byTypeBB[pt] ^= from_to_bb;
- byColorBB[us] ^= from_to_bb;
-
- board[to] = NO_PIECE;
- board[from] = make_piece(us, pt);
-
- // Update piece lists, index[to] is not updated and becomes stale. This
- // works as long as index[] is accessed just by known occupied squares.
- index[from] = index[to];
- pieceList[us][pt][index[from]] = from;
- }
-
- if (capture)
- {
- Square capsq = to;
+ move_piece(to, from, us, pt); // Put the piece back at the source square
- if (type_of(m) == ENPASSANT)
+ if (st->capturedType)
{
- capsq -= pawn_push(us);
+ Square capsq = to;
- assert(pt == PAWN);
- assert(to == st->previous->epSquare);
- assert(relative_rank(us, to) == RANK_6);
- assert(piece_on(capsq) == NO_PIECE);
- }
-
- // Restore the captured piece
- byTypeBB[ALL_PIECES] |= capsq;
- byTypeBB[capture] |= capsq;
- byColorBB[them] |= capsq;
+ if (type_of(m) == ENPASSANT)
+ {
+ capsq -= pawn_push(us);
- board[capsq] = make_piece(them, capture);
+ assert(pt == PAWN);
+ assert(to == st->previous->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(capsq) == NO_PIECE);
+ }
- // Update piece list, add a new captured piece in capsq square
- index[capsq] = pieceCount[them][capture]++;
- pieceList[them][capture][index[capsq]] = capsq;
+ put_piece(capsq, ~us, st->capturedType); // Restore the captured piece
+ }
}
// Finally point our state pointer back to the previous state
st = st->previous;
- gamePly--;
+ --gamePly;
assert(pos_is_ok());
}
-/// Position::do_castle() is a helper used to do/undo a castling move. This
+/// Position::do_castling() is a helper used to do/undo a castling move. This
/// is a bit tricky, especially in Chess960.
-
-void Position::do_castle(Square kfrom, Square kto, Square rfrom, Square rto) {
-
- Color us = sideToMove;
- 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;
-
- // Could be from == to, so first set NO_PIECE then KING and ROOK
- board[kfrom] = board[rfrom] = NO_PIECE;
- board[kto] = make_piece(us, KING);
- board[rto] = make_piece(us, ROOK);
-
- // Could be kfrom == rto, so use a 'tmp' variable
- int tmp = index[kfrom];
- index[rto] = index[rfrom];
- index[kto] = tmp;
- pieceList[us][KING][index[kto]] = kto;
- pieceList[us][ROOK][index[rto]] = rto;
+template<bool Do>
+void Position::do_castling(Square from, Square& to, Square& rfrom, Square& rto) {
+
+ bool kingSide = to > from;
+ rfrom = to; // Castling is encoded as "king captures friendly rook"
+ rto = relative_square(sideToMove, kingSide ? SQ_F1 : SQ_D1);
+ to = relative_square(sideToMove, kingSide ? SQ_G1 : SQ_C1);
+
+ // Remove both pieces first since squares could overlap in Chess960
+ remove_piece(Do ? from : to, sideToMove, KING);
+ remove_piece(Do ? rfrom : rto, sideToMove, ROOK);
+ board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us
+ put_piece(Do ? to : from, sideToMove, KING);
+ put_piece(Do ? rto : rfrom, sideToMove, ROOK);
}
assert(!checkers());
- memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here
+ std::memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here
newSt.previous = st;
st = &newSt;
st->key ^= Zobrist::side;
prefetch((char*)TT.first_entry(st->key));
- st->rule50++;
+ ++st->rule50;
st->pliesFromNull = 0;
sideToMove = ~sideToMove;
}
+/// Position::key_after() computes the new hash key after the given move. Needed
+/// for speculative prefetch. It doesn't recognize special moves like castling,
+/// en-passant and promotions.
+
+Key Position::key_after(Move m) const {
+
+ Color us = sideToMove;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ PieceType pt = type_of(piece_on(from));
+ PieceType captured = type_of(piece_on(to));
+ Key k = st->key ^ Zobrist::side;
+
+ if (captured)
+ k ^= Zobrist::psq[~us][captured][to];
+
+ return k ^ Zobrist::psq[us][pt][to] ^ Zobrist::psq[us][pt][from];
+}
+
+
/// Position::see() is a static exchange evaluator: It tries to estimate the
-/// 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.
+/// material gain or loss resulting from a move.
-int Position::see_sign(Move m) const {
+Value Position::see_sign(Move m) const {
assert(is_ok(m));
// 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)])
- return 1;
+ if (PieceValue[MG][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))])
+ return VALUE_KNOWN_WIN;
return see(m);
}
-int Position::see(Move m, int asymmThreshold) const {
+Value Position::see(Move m) const {
Square from, to;
Bitboard occupied, attackers, stmAttackers;
- int swapList[32], slIndex = 1;
+ Value swapList[32];
+ int slIndex = 1;
PieceType captured;
Color stm;
from = from_sq(m);
to = to_sq(m);
- captured = type_of(piece_on(to));
+ swapList[0] = PieceValue[MG][piece_on(to)];
+ stm = color_of(piece_on(from));
occupied = pieces() ^ from;
- // Handle en passant moves
+ // Castling moves are implemented as king capturing the rook so cannot be
+ // handled correctly. Simply return 0 that is always the correct value
+ // unless in the rare case the rook ends up under attack.
+ if (type_of(m) == CASTLING)
+ return VALUE_ZERO;
+
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 {
// Add the new entry to the swap list
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
- stm = ~stm;
- stmAttackers = attackers & pieces(stm);
+ // Locate and remove the next least valuable attacker
+ captured = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
+ // Stop before processing a king capture
if (captured == KING)
{
- // Stop before processing a king capture
- if (stmAttackers)
- swapList[slIndex++] = QueenValueMg * 16;
+ if (stmAttackers == attackers)
+ ++slIndex;
break;
}
- } while (stmAttackers);
+ stm = ~stm;
+ stmAttackers = attackers & pieces(stm);
+ ++slIndex;
- // 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;
+ } while (stmAttackers);
// Having built the swap list, we negamax through it to find the best
// achievable score from the point of view of the side to move.
while (--slIndex)
- swapList[slIndex-1] = std::min(-swapList[slIndex], swapList[slIndex-1]);
+ swapList[slIndex - 1] = std::min(-swapList[slIndex], swapList[slIndex - 1]);
return swapList[0];
}
-/// Position::clear() erases the position object to a pristine state, with an
-/// empty board, white to move, and no castling rights.
-
-void Position::clear() {
-
- memset(this, 0, sizeof(Position));
- startState.epSquare = SQ_NONE;
- st = &startState;
-
- for (int i = 0; i < 8; i++)
- for (int j = 0; j < 16; j++)
- pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
-}
-
-
-/// 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
-/// to verify the correctness of the hash key when running in debug mode.
-
-Key Position::compute_key() const {
-
- Key k = Zobrist::castle[st->castleRights];
+/// Position::is_draw() tests whether the position is drawn by material, 50 moves
+/// rule or repetition. It does not detect stalemates.
- 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)
- k ^= Zobrist::enpassant[file_of(ep_square())];
-
- if (sideToMove == BLACK)
- k ^= Zobrist::side;
-
- return k;
-}
-
-
-/// Position::compute_pawn_key() computes the hash key of the position. The
-/// hash key is usually updated incrementally as moves are made and unmade,
-/// the compute_pawn_key() function is only used when a new position is set
-/// up, and to verify the correctness of the pawn hash key when running in
-/// debug mode.
-
-Key Position::compute_pawn_key() const {
+bool Position::is_draw() const {
- Key k = 0;
+ if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
+ return true;
- for (Bitboard b = pieces(PAWN); b; )
+ StateInfo* stp = st;
+ for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2)
{
- Square s = pop_lsb(&b);
- k ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s];
- }
-
- return k;
-}
-
-
-/// Position::compute_material_key() computes the hash key of the position.
-/// The hash key is usually updated incrementally as moves are made and unmade,
-/// the compute_material_key() function is only used when a new position is set
-/// up, and to verify the correctness of the material hash key when running in
-/// debug mode.
-
-Key Position::compute_material_key() const {
-
- Key k = 0;
-
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= QUEEN; pt++)
- for (int cnt = 0; cnt < piece_count(c, pt); cnt++)
- k ^= Zobrist::psq[c][pt][cnt];
-
- return k;
-}
+ stp = stp->previous->previous;
-
-/// Position::compute_psq_score() computes the incremental scores for the middle
-/// game and the endgame. These functions are used to initialize the incremental
-/// scores when a new position is set up, and to verify that the scores are correctly
-/// updated by do_move and undo_move when the program is running in debug mode.
-Score Position::compute_psq_score() const {
-
- Score score = SCORE_ZERO;
-
- for (Bitboard b = pieces(); b; )
- {
- Square s = pop_lsb(&b);
- score += pieceSquareTable[piece_on(s)][s];
+ if (stp->key == st->key)
+ return true; // Draw at first repetition
}
- return score;
+ return false;
}
-/// Position::compute_non_pawn_material() computes the total non-pawn middle
-/// game material value for the given side. Material values are updated
-/// incrementally during the search, this function is only used while
-/// initializing a new Position object.
-
-Value Position::compute_non_pawn_material(Color c) const {
-
- Value value = VALUE_ZERO;
-
- for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
- value += piece_count(c, pt) * PieceValue[MG][pt];
+/// Position::flip() flips position with the white and black sides reversed. This
+/// is only useful for debugging e.g. for finding evaluation symmetry bugs.
- return value;
+static char toggle_case(char c) {
+ return char(islower(c) ? toupper(c) : tolower(c));
}
+void Position::flip() {
-/// 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.
-bool Position::is_draw() const {
-
- // Draw by material?
- if ( !pieces(PAWN)
- && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMg))
- return true;
-
- // Draw by the 50 moves rule?
- if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
- return true;
-
- // Draw by repetition?
- int i = 4, e = std::min(st->rule50, st->pliesFromNull);
+ string f, token;
+ std::stringstream ss(fen());
- if (i <= e)
+ for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement
{
- StateInfo* stp = st->previous->previous;
-
- do {
- stp = stp->previous->previous;
-
- if (stp->key == st->key)
- return true;
-
- i += 2;
-
- } while (i <= e);
+ std::getline(ss, token, r > RANK_1 ? '/' : ' ');
+ f.insert(0, token + (f.empty() ? " " : "/"));
}
- return false;
-}
+ ss >> token; // Active color
+ f += (token == "w" ? "B " : "W "); // Will be lowercased later
+ ss >> token; // Castling availability
+ f += token + " ";
-/// Position::flip() flips position with the white and black sides reversed. This
-/// is only useful for debugging especially for finding evaluation symmetry bugs.
+ std::transform(f.begin(), f.end(), f.begin(), toggle_case);
-void Position::flip() {
+ ss >> token; // En passant square
+ f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3"));
- const Position pos(*this);
+ std::getline(ss, token); // Half and full moves
+ f += token;
- clear();
-
- sideToMove = ~pos.side_to_move();
- thisThread = pos.this_thread();
- nodes = pos.nodes_searched();
- chess960 = pos.is_chess960();
- gamePly = pos.game_ply();
-
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (!pos.is_empty(s))
- put_piece(Piece(pos.piece_on(s) ^ 8), ~s);
-
- 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));
-
- if (pos.st->epSquare != SQ_NONE)
- st->epSquare = ~pos.st->epSquare;
-
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
-
- 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());
}
-/// Position::pos_is_ok() performs some consitency checks for the position object.
+/// Position::pos_is_ok() performs some consistency checks for the position object.
/// This is meant to be helpful when debugging.
-bool Position::pos_is_ok(int* failedStep) const {
-
- int dummy, *step = failedStep ? failedStep : &dummy;
+bool Position::pos_is_ok(int* step) const {
- // What features of the position should be verified?
+ // Which parts of the position should be verified?
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;
-
- if ((*step)++, piece_on(king_square(WHITE)) != W_KING)
- return false;
-
- if ((*step)++, piece_on(king_square(BLACK)) != B_KING)
+ const bool testBitboards = all || false;
+ const bool testState = all || false;
+ const bool testKingCount = all || false;
+ const bool testKingCapture = all || false;
+ const bool testPieceCounts = all || false;
+ const bool testPieceList = all || false;
+ const bool testCastlingSquares = all || false;
+
+ if (step)
+ *step = 1;
+
+ if ( (sideToMove != WHITE && sideToMove != BLACK)
+ || piece_on(king_square(WHITE)) != W_KING
+ || piece_on(king_square(BLACK)) != B_KING
+ || ( ep_square() != SQ_NONE
+ && relative_rank(sideToMove, ep_square()) != RANK_6))
return false;
- if ((*step)++, debugKingCount)
- {
- 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))]++;
-
- if (kingCount[0] != 1 || kingCount[1] != 1)
- return false;
- }
-
- if ((*step)++, debugKingCapture)
- if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove))
- return false;
-
- if ((*step)++, debugCheckerCount && popcount<Full>(st->checkersBB) > 2)
- return false;
-
- if ((*step)++, debugBitboards)
+ if (step && ++*step, testBitboards)
{
// The intersection of the white and black pieces must be empty
if (pieces(WHITE) & pieces(BLACK))
return false;
// Separate piece type bitboards must have empty intersections
- for (PieceType p1 = PAWN; p1 <= KING; p1++)
- for (PieceType p2 = PAWN; p2 <= KING; p2++)
+ for (PieceType p1 = PAWN; p1 <= KING; ++p1)
+ for (PieceType p2 = PAWN; p2 <= KING; ++p2)
if (p1 != p2 && (pieces(p1) & pieces(p2)))
return false;
}
- if ((*step)++, ep_square() != SQ_NONE && relative_rank(sideToMove, ep_square()) != RANK_6)
- return false;
-
- if ((*step)++, debugKey && st->key != compute_key())
- return false;
-
- if ((*step)++, debugPawnKey && st->pawnKey != compute_pawn_key())
- return false;
-
- if ((*step)++, debugMaterialKey && st->materialKey != compute_material_key())
- return false;
-
- if ((*step)++, debugIncrementalEval && st->psqScore != compute_psq_score())
- return false;
-
- if ((*step)++, debugNonPawnMaterial)
+ if (step && ++*step, testState)
{
- if ( st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)
- || st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
+ StateInfo si;
+ set_state(&si);
+ if ( st->key != si.key
+ || st->pawnKey != si.pawnKey
+ || st->materialKey != si.materialKey
+ || st->nonPawnMaterial[WHITE] != si.nonPawnMaterial[WHITE]
+ || st->nonPawnMaterial[BLACK] != si.nonPawnMaterial[BLACK]
+ || st->psq != si.psq
+ || st->checkersBB != si.checkersBB)
return false;
}
- if ((*step)++, debugPieceCounts)
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
+ if (step && ++*step, testKingCount)
+ if ( std::count(board, board + SQUARE_NB, W_KING) != 1
+ || std::count(board, board + SQUARE_NB, B_KING) != 1)
+ return false;
+
+ if (step && ++*step, testKingCapture)
+ if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove))
+ return false;
+
+ if (step && ++*step, testPieceCounts)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
if (pieceCount[c][pt] != popcount<Full>(pieces(c, pt)))
return false;
- if ((*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))
+ if (step && ++*step, testPieceList)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ for (int i = 0; i < pieceCount[c][pt]; ++i)
+ if ( board[pieceList[c][pt][i]] != make_piece(c, pt)
+ || index[pieceList[c][pt][i]] != i)
return false;
- if (index[piece_list(c, pt)[i]] != i)
- return false;
- }
-
- if ((*step)++, debugCastleSquares)
- for (Color c = WHITE; c <= BLACK; c++)
+ if (step && ++*step, testCastlingSquares)
+ for (Color c = WHITE; c <= BLACK; ++c)
for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1))
{
- CastleRight cr = make_castle_right(c, s);
-
- if (!can_castle(cr))
+ if (!can_castle(c | s))
continue;
- if ((castleRightsMask[king_square(c)] & cr) != cr)
- return false;
-
- if ( piece_on(castleRookSquare[c][s]) != make_piece(c, ROOK)
- || castleRightsMask[castleRookSquare[c][s]] != cr)
+ if ( (castlingRightsMask[king_square(c)] & (c | s)) != (c | s)
+ || piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK)
+ || castlingRightsMask[castlingRookSquare[c | s]] != (c | s))
return false;
}
- *step = 0;
return true;
}
projects / stockfish / blobdiff