X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;ds=sidebyside;f=src%2Fposition.cpp;h=244a258071d195fd359776b3650af1ea38a34f81;hb=805afcbf3d5db39c85b759232cfb99ab0a250311;hp=f0bbff449427eaa09509645876532ebfe5b45f8d;hpb=a695ed65a8b98c94a928862be76500485b38c414;p=stockfish
diff --git a/src/position.cpp b/src/position.cpp
index f0bbff44..5b2efabe 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -1,7 +1,8 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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
@@ -17,120 +18,140 @@
along with this program. If not, see .
*/
+#include
#include
-#include
-#include
-#include
+#include // For std::memset, std::memcmp
+#include
#include
-#include
-#include "bitcount.h"
+#include "bitboard.h"
+#include "misc.h"
#include "movegen.h"
#include "position.h"
-#include "psqtab.h"
-#include "rkiss.h"
#include "thread.h"
#include "tt.h"
+#include "uci.h"
using std::string;
-using std::cout;
-using std::endl;
-
-Key Position::zobrist[2][8][64];
-Key Position::zobEp[64];
-Key Position::zobCastle[16];
-Key Position::zobSideToMove;
-Key Position::zobExclusion;
-
-Score Position::pieceSquareTable[16][64];
-
-// Material values arrays, indexed by Piece
-const Value PieceValueMidgame[17] = {
- VALUE_ZERO,
- PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
- RookValueMidgame, QueenValueMidgame,
- VALUE_ZERO, VALUE_ZERO, VALUE_ZERO,
- PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
- RookValueMidgame, QueenValueMidgame
-};
-
-const Value PieceValueEndgame[17] = {
- VALUE_ZERO,
- PawnValueEndgame, KnightValueEndgame, BishopValueEndgame,
- RookValueEndgame, QueenValueEndgame,
- VALUE_ZERO, VALUE_ZERO, VALUE_ZERO,
- PawnValueEndgame, KnightValueEndgame, BishopValueEndgame,
- RookValueEndgame, QueenValueEndgame
-};
+namespace Zobrist {
+
+ Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+ Key enpassant[FILE_NB];
+ Key castling[CASTLING_RIGHT_NB];
+ Key side;
+ Key exclusion;
+}
+
+Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion; }
namespace {
- // Bonus for having the side to move (modified by Joona Kiiski)
- const Score TempoValue = make_score(48, 22);
+const string PieceToChar(" PNBRQK pnbrqk");
- // To convert a Piece to and from a FEN char
- const string PieceToChar(" PNBRQK pnbrqk .");
-}
+// min_attacker() is a helper function used by see() to locate the least
+// valuable attacker for the side to move, remove the attacker we just found
+// from the bitboards and scan for new X-ray attacks behind it.
+template
+PieceType min_attacker(const Bitboard* bb, Square to, Bitboard stmAttackers,
+ Bitboard& occupied, Bitboard& attackers) {
-/// CheckInfo c'tor
+ Bitboard b = stmAttackers & bb[Pt];
+ if (!b)
+ return min_attacker(bb, to, stmAttackers, occupied, attackers);
-CheckInfo::CheckInfo(const Position& pos) {
+ occupied ^= b & ~(b - 1);
- Color them = flip(pos.side_to_move());
- Square ksq = pos.king_square(them);
+ if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN)
+ attackers |= attacks_bb(to, occupied) & (bb[BISHOP] | bb[QUEEN]);
- pinned = pos.pinned_pieces();
- dcCandidates = pos.discovered_check_candidates();
+ if (Pt == ROOK || Pt == QUEEN)
+ attackers |= attacks_bb(to, occupied) & (bb[ROOK] | bb[QUEEN]);
- checkSq[PAWN] = pos.attacks_from(ksq, them);
- checkSq[KNIGHT] = pos.attacks_from(ksq);
- checkSq[BISHOP] = pos.attacks_from(ksq);
- checkSq[ROOK] = pos.attacks_from(ksq);
- checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK];
- checkSq[KING] = 0;
+ attackers &= occupied; // After X-ray that may add already processed pieces
+ return (PieceType)Pt;
}
+template<>
+PieceType min_attacker(const Bitboard*, Square, Bitboard, Bitboard&, Bitboard&) {
+ return KING; // No need to update bitboards: it is the last cycle
+}
-/// Position c'tors. Here we always create a copy of the original position
-/// or the FEN string, we want the new born Position object do not depend
-/// on any external data so we detach state pointer from the source one.
+} // namespace
-void Position::copy(const Position& pos, int th) {
- memcpy(this, &pos, sizeof(Position));
- startState = *st;
- st = &startState;
- threadID = th;
- nodes = 0;
+/// operator<<(Position) returns an ASCII representation of the position
- assert(pos_is_ok());
+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.key() << std::dec << "\nCheckers: ";
+
+ for (Bitboard b = pos.checkers(); b; )
+ os << UCI::square(pop_lsb(&b)) << " ";
+
+ return os;
}
-Position::Position(const string& fen, bool isChess960, int th) {
- from_fen(fen, isChess960);
- threadID = th;
+/// Position::init() initializes at startup the various arrays used to compute
+/// hash keys.
+
+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();
+
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ Zobrist::enpassant[f] = rng.rand();
+
+ for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr)
+ {
+ Zobrist::castling[cr] = 0;
+ Bitboard b = cr;
+ while (b)
+ {
+ Key k = Zobrist::castling[1ULL << pop_lsb(&b)];
+ Zobrist::castling[cr] ^= k ? k : rng.rand();
+ }
+ }
+
+ Zobrist::side = rng.rand();
+ Zobrist::exclusion = rng.rand();
}
-/// Position::from_fen() initializes the position object with the given FEN
-/// string. This function is not very robust - make sure that input FENs are
-/// correct (this is assumed to be the responsibility of the GUI).
+/// Position::set() initializes the position object with the given FEN string.
+/// This function is not very robust - make sure that input FENs are correct,
+/// this is assumed to be the responsibility of the GUI.
-void Position::from_fen(const string& fenStr, bool isChess960) {
+Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Thread* th) {
/*
A FEN string defines a particular position using only the ASCII character set.
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.
@@ -154,41 +175,45 @@ void Position::from_fen(const string& fenStr, bool isChess960) {
incremented after Black's move.
*/
- char col, row, token;
- size_t p;
+ unsigned char col, row, token;
+ size_t idx;
Square sq = SQ_A8;
- std::istringstream fen(fenStr);
+ std::istringstream ss(fenStr);
+
+ std::memset(this, 0, sizeof(Position));
+ std::memset(si, 0, sizeof(StateInfo));
+ std::fill_n(&pieceList[0][0][0], sizeof(pieceList) / sizeof(Square), SQ_NONE);
+ st = si;
- clear();
- fen >> std::noskipws;
+ ss >> std::noskipws;
// 1. Piece placement
- while ((fen >> token) && !isspace(token))
+ while ((ss >> token) && !isspace(token))
{
- if (token == '/')
- sq -= Square(16); // Jump back of 2 rows
+ if (isdigit(token))
+ sq += Square(token - '0'); // Advance the given number of files
- else if (isdigit(token))
- sq += Square(token - '0'); // Skip the given number of files
+ else if (token == '/')
+ sq -= Square(16);
- else if ((p = PieceToChar.find(token)) != string::npos)
+ else if ((idx = PieceToChar.find(token)) != string::npos)
{
- put_piece(Piece(p), sq);
- sq++;
+ put_piece(color_of(Piece(idx)), type_of(Piece(idx)), sq);
+ ++sq;
}
}
// 2. Active color
- fen >> token;
+ ss >> token;
sideToMove = (token == 'w' ? WHITE : BLACK);
- fen >> token;
+ ss >> token;
// 3. Castling availability. Compatible with 3 standards: Normal FEN standard,
// Shredder-FEN that uses the letters of the columns on which the rooks began
// the game instead of KQkq and also X-FEN standard that, in case of Chess960,
// if an inner rook is associated with the castling right, the castling tag is
// replaced by the file letter of the involved rook, as for the Shredder-FEN.
- while ((fen >> token) && !isspace(token))
+ while ((ss >> token) && !isspace(token))
{
Square rsq;
Color c = islower(token) ? BLACK : WHITE;
@@ -197,10 +222,10 @@ void Position::from_fen(const string& fenStr, bool isChess960) {
token = char(toupper(token));
if (token == 'K')
- for (rsq = relative_square(c, SQ_H1); piece_on(rsq) != rook; rsq--) {}
+ for (rsq = relative_square(c, SQ_H1); piece_on(rsq) != rook; --rsq) {}
else if (token == 'Q')
- for (rsq = relative_square(c, SQ_A1); piece_on(rsq) != rook; rsq++) {}
+ for (rsq = relative_square(c, SQ_A1); piece_on(rsq) != rook; ++rsq) {}
else if (token >= 'A' && token <= 'H')
rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1));
@@ -208,510 +233,402 @@ void Position::from_fen(const string& fenStr, bool isChess960) {
else
continue;
- set_castle_right(king_square(c), rsq);
+ set_castling_right(c, rsq);
}
// 4. En passant square. Ignore if no pawn capture is possible
- if ( ((fen >> col) && (col >= 'a' && col <= 'h'))
- && ((fen >> row) && (row == '3' || row == '6')))
+ if ( ((ss >> col) && (col >= 'a' && col <= 'h'))
+ && ((ss >> row) && (row == '3' || row == '6')))
{
st->epSquare = make_square(File(col - 'a'), Rank(row - '1'));
- if (!(attackers_to(st->epSquare) & pieces(PAWN, sideToMove)))
+ if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN)))
st->epSquare = SQ_NONE;
}
+ else
+ st->epSquare = SQ_NONE;
// 5-6. Halfmove clock and fullmove number
- fen >> std::skipws >> st->rule50 >> startPosPly;
+ ss >> std::skipws >> st->rule50 >> gamePly;
// Convert from fullmove starting from 1 to ply starting from 0,
// handle also common incorrect FEN with fullmove = 0.
- startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK);
-
- st->key = compute_key();
- st->pawnKey = compute_pawn_key();
- st->materialKey = compute_material_key();
- st->value = compute_value();
- st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
+ gamePly = std::max(2 * (gamePly - 1), 0) + (sideToMove == BLACK);
+
chess960 = isChess960;
+ thisThread = th;
+ set_state(st);
assert(pos_is_ok());
+
+ return *this;
}
-/// Position::set_castle_right() is an helper function used to set castling
-/// rights given the corresponding king and rook starting squares.
+/// Position::set_castling_right() is a helper function used to set castling
+/// rights given the corresponding color and the rook starting square.
+
+void Position::set_castling_right(Color c, Square rfrom) {
+
+ Square kfrom = square(c);
+ CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE;
+ CastlingRight cr = (c | cs);
-void Position::set_castle_right(Square ksq, Square rsq) {
+ st->castlingRights |= cr;
+ castlingRightsMask[kfrom] |= cr;
+ castlingRightsMask[rfrom] |= cr;
+ castlingRookSquare[cr] = rfrom;
- int f = (rsq < ksq ? WHITE_OOO : WHITE_OO) << color_of(piece_on(ksq));
+ Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1);
- st->castleRights |= f;
- castleRightsMask[ksq] ^= f;
- castleRightsMask[rsq] ^= f;
- castleRookSquare[f] = rsq;
+ for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s)
+ if (s != kfrom && s != rfrom)
+ castlingPath[cr] |= s;
+
+ for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s)
+ if (s != kfrom && s != rfrom)
+ castlingPath[cr] |= s;
}
-/// Position::to_fen() returns a FEN representation of the position. In case
-/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function.
+/// Position::set_check_info() sets king attacks to detect if a move gives check
-const string Position::to_fen() const {
+void Position::set_check_info(CheckInfo* ci) const {
- std::ostringstream fen;
- Square sq;
- int emptyCnt;
+ ci->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE));
+ ci->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK));
- for (Rank rank = RANK_8; rank >= RANK_1; rank--)
- {
- emptyCnt = 0;
+ Square ksq = ci->ksq = square(~sideToMove);
- for (File file = FILE_A; file <= FILE_H; file++)
- {
- sq = make_square(file, rank);
+ ci->checkSquares[PAWN] = attacks_from(ksq, ~sideToMove);
+ ci->checkSquares[KNIGHT] = attacks_from(ksq);
+ ci->checkSquares[BISHOP] = attacks_from(ksq);
+ ci->checkSquares[ROOK] = attacks_from(ksq);
+ ci->checkSquares[QUEEN] = ci->checkSquares[BISHOP] | ci->checkSquares[ROOK];
+ ci->checkSquares[KING] = 0;
+}
- if (square_is_empty(sq))
- emptyCnt++;
- else
- {
- if (emptyCnt > 0)
- {
- fen << emptyCnt;
- emptyCnt = 0;
- }
- fen << PieceToChar[piece_on(sq)];
- }
- }
- if (emptyCnt > 0)
- fen << emptyCnt;
+/// 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.
- if (rank > RANK_1)
- fen << '/';
- }
+void Position::set_state(StateInfo* si) const {
- fen << (sideToMove == WHITE ? " w " : " b ");
+ si->key = si->pawnKey = si->materialKey = 0;
+ si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO;
+ si->psq = SCORE_ZERO;
+ si->checkersBB = attackers_to(square(sideToMove)) & pieces(~sideToMove);
- if (can_castle(WHITE_OO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OO))))) : 'K');
+ set_check_info(&si->ci);
- if (can_castle(WHITE_OOO))
- fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OOO))))) : 'Q');
+ 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 += PSQT::psq[color_of(pc)][type_of(pc)][s];
+ }
- if (can_castle(BLACK_OO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k');
+ if (si->epSquare != SQ_NONE)
+ si->key ^= Zobrist::enpassant[file_of(si->epSquare)];
- if (can_castle(BLACK_OOO))
- fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q');
+ if (sideToMove == BLACK)
+ si->key ^= Zobrist::side;
- if (st->castleRights == CASTLES_NONE)
- fen << '-';
+ si->key ^= Zobrist::castling[si->castlingRights];
- fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
- << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2;
+ for (Bitboard b = pieces(PAWN); b; )
+ {
+ Square s = pop_lsb(&b);
+ si->pawnKey ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s];
+ }
- return fen.str();
-}
+ 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::print() prints an ASCII representation of the position to
-/// the standard output. If a move is given then also the san is printed.
-void Position::print(Move move) const {
+/// 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 char* dottedLine = "\n+---+---+---+---+---+---+---+---+\n";
+const string Position::fen() const {
- if (move)
- {
- Position p(*this, thread());
- cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move);
- }
+ int emptyCnt;
+ std::ostringstream ss;
- for (Rank rank = RANK_8; rank >= RANK_1; rank--)
+ for (Rank r = RANK_8; r >= RANK_1; --r)
{
- cout << dottedLine << '|';
- for (File file = FILE_A; file <= FILE_H; file++)
+ for (File f = FILE_A; f <= FILE_H; ++f)
{
- Square sq = make_square(file, rank);
- Piece piece = piece_on(sq);
- char c = (color_of(piece) == BLACK ? '=' : ' ');
+ for (emptyCnt = 0; f <= FILE_H && empty(make_square(f, r)); ++f)
+ ++emptyCnt;
- if (piece == NO_PIECE && color_of(sq) == DARK)
- piece++; // Index the dot
+ if (emptyCnt)
+ ss << emptyCnt;
- cout << c << PieceToChar[piece] << c << '|';
+ if (f <= FILE_H)
+ ss << PieceToChar[piece_on(make_square(f, r))];
}
- }
- cout << dottedLine << "Fen is: " << to_fen() << "\nKey is: " << st->key << endl;
-}
+ if (r > RANK_1)
+ ss << '/';
+ }
-/// 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
-Bitboard Position::hidden_checkers() const {
-
- // Pinned pieces protect our king, dicovery checks attack the enemy king
- Bitboard b, result = 0;
- Bitboard pinners = pieces(FindPinned ? flip(sideToMove) : sideToMove);
- Square ksq = king_square(FindPinned ? sideToMove : flip(sideToMove));
-
- // Pinners are sliders, that give check when candidate pinned is removed
- pinners &= (pieces(ROOK, QUEEN) & RookPseudoAttacks[ksq])
- | (pieces(BISHOP, QUEEN) & BishopPseudoAttacks[ksq]);
+ ss << (sideToMove == WHITE ? " w " : " b ");
- while (pinners)
- {
- b = squares_between(ksq, pop_1st_bit(&pinners)) & occupied_squares();
+ if (can_castle(WHITE_OO))
+ ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | KING_SIDE))) : 'K');
- // Only one bit set and is an our piece?
- if (b && !(b & (b - 1)) && (b & pieces(sideToMove)))
- result |= b;
- }
- return result;
-}
+ if (can_castle(WHITE_OOO))
+ ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | QUEEN_SIDE))) : 'Q');
-// Explicit template instantiations
-template Bitboard Position::hidden_checkers() const;
-template Bitboard Position::hidden_checkers() const;
+ if (can_castle(BLACK_OO))
+ ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | KING_SIDE))) : 'k');
+ if (can_castle(BLACK_OOO))
+ ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | QUEEN_SIDE))) : 'q');
-/// Position::attackers_to() computes a bitboard of all pieces which attack a
-/// given square. Slider attacks use occ bitboard as occupancy.
+ if (!can_castle(WHITE) && !can_castle(BLACK))
+ ss << '-';
-Bitboard Position::attackers_to(Square s, Bitboard occ) const {
+ ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::square(ep_square()) + " ")
+ << st->rule50 << " " << 1 + (gamePly - (sideToMove == BLACK)) / 2;
- return (attacks_from(s, BLACK) & pieces(PAWN, WHITE))
- | (attacks_from(s, WHITE) & pieces(PAWN, BLACK))
- | (attacks_from(s) & pieces(KNIGHT))
- | (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN))
- | (bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN))
- | (attacks_from(s) & pieces(KING));
+ return ss.str();
}
-/// 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::game_phase() calculates the game phase interpolating total non-pawn
+/// material between endgame and midgame limits.
-Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) {
+Phase Position::game_phase() const {
- assert(square_is_ok(s));
+ Value npm = st->nonPawnMaterial[WHITE] + st->nonPawnMaterial[BLACK];
- switch (type_of(p))
- {
- case BISHOP: return bishop_attacks_bb(s, occ);
- case ROOK : return rook_attacks_bb(s, occ);
- case QUEEN : return bishop_attacks_bb(s, occ) | rook_attacks_bb(s, occ);
- default : return StepAttacksBB[p][s];
- }
+ npm = std::max(EndgameLimit, std::min(npm, MidgameLimit));
+
+ return Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit));
}
-/// Position::move_attacks_square() tests whether a move from the current
-/// position attacks a given square.
+/// Position::slider_blockers() returns a bitboard of all the pieces (both colors) that
+/// are blocking attacks on the square 's' from 'sliders'. A piece blocks a slider
+/// if removing that piece from the board would result in a position where square 's'
+/// is attacked. For example, a king-attack blocking piece can be either a pinned or
+/// a discovered check piece, according if its color is the opposite or the same of
+/// the color of the slider.
-bool Position::move_attacks_square(Move m, Square s) const {
+Bitboard Position::slider_blockers(Bitboard sliders, Square s) const {
- assert(is_ok(m));
- assert(square_is_ok(s));
+ Bitboard b, pinners, result = 0;
- Bitboard occ, xray;
- Square from = move_from(m);
- Square to = move_to(m);
- Piece piece = piece_on(from);
+ // Pinners are sliders that attack 's' when a pinned piece is removed
+ pinners = ( (PseudoAttacks[ROOK ][s] & pieces(QUEEN, ROOK))
+ | (PseudoAttacks[BISHOP][s] & pieces(QUEEN, BISHOP))) & sliders;
- assert(!square_is_empty(from));
+ while (pinners)
+ {
+ b = between_bb(s, pop_lsb(&pinners)) & pieces();
- // Update occupancy as if the piece is moving
- occ = occupied_squares();
- do_move_bb(&occ, make_move_bb(from, to));
+ if (!more_than_one(b))
+ result |= b;
+ }
+ return result;
+}
- // The piece moved in 'to' attacks the square 's' ?
- if (bit_is_set(attacks_from(piece, to, occ), s))
- return true;
- // Scan for possible X-ray attackers behind the moved piece
- xray = (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN, color_of(piece)))
- |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN, color_of(piece)));
+/// Position::attackers_to() computes a bitboard of all pieces which attack a
+/// given square. Slider attacks use the occupied bitboard to indicate occupancy.
- // Verify attackers are triggered by our move and not already existing
- return xray && (xray ^ (xray & attacks_from(s)));
+Bitboard Position::attackers_to(Square s, Bitboard occupied) const {
+
+ return (attacks_from(s, BLACK) & pieces(WHITE, PAWN))
+ | (attacks_from(s, WHITE) & pieces(BLACK, PAWN))
+ | (attacks_from(s) & pieces(KNIGHT))
+ | (attacks_bb(s, occupied) & pieces(ROOK, QUEEN))
+ | (attacks_bb(s, occupied) & pieces(BISHOP, QUEEN))
+ | (attacks_from(s) & pieces(KING));
}
-/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
+/// Position::legal() tests whether a pseudo-legal move is legal
-bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
+bool Position::legal(Move m) const {
assert(is_ok(m));
- assert(pinned == pinned_pieces());
- Color us = side_to_move();
- Square from = move_from(m);
+ Color us = sideToMove;
+ Square from = from_sq(m);
- assert(color_of(piece_on(from)) == us);
- assert(piece_on(king_square(us)) == make_piece(us, KING));
+ assert(color_of(moved_piece(m)) == us);
+ assert(piece_on(square(us)) == make_piece(us, KING));
// En passant captures are a tricky special case. Because they are rather
// uncommon, we do it simply by testing whether the king is attacked after
// the move is made.
- if (is_enpassant(m))
+ if (type_of(m) == ENPASSANT)
{
- Color them = flip(us);
- Square to = move_to(m);
- Square capsq = to + pawn_push(them);
- Square ksq = king_square(us);
- Bitboard b = occupied_squares();
+ Square ksq = square(us);
+ Square to = to_sq(m);
+ Square capsq = to - pawn_push(us);
+ Bitboard occupied = (pieces() ^ from ^ capsq) | to;
assert(to == ep_square());
- assert(piece_on(from) == make_piece(us, PAWN));
- assert(piece_on(capsq) == make_piece(them, PAWN));
+ assert(moved_piece(m) == make_piece(us, PAWN));
+ assert(piece_on(capsq) == make_piece(~us, PAWN));
assert(piece_on(to) == NO_PIECE);
- clear_bit(&b, from);
- clear_bit(&b, capsq);
- set_bit(&b, to);
-
- return !(rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, them))
- && !(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them));
+ return !(attacks_bb< ROOK>(ksq, occupied) & pieces(~us, QUEEN, ROOK))
+ && !(attacks_bb(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 is_castle(m) || !(attackers_to(move_to(m)) & pieces(flip(us)));
+ return type_of(m) == CASTLING || !(attackers_to(to_sq(m)) & pieces(~us));
// A non-king move is legal if and only if it is not pinned or it
// is moving along the ray towards or away from the king.
- return !pinned
- || !bit_is_set(pinned, from)
- || squares_aligned(from, move_to(m), king_square(us));
+ return !(pinned_pieces(us) & from)
+ || aligned(from, to_sq(m), square(us));
}
-/// Position::move_is_legal() takes a random move and tests whether the move
-/// is legal. This version is not very fast and should be used only in non
-/// time-critical paths.
-
-bool Position::move_is_legal(const Move m) const {
-
- for (MoveList 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
+/// Position::pseudo_legal() takes a random move and tests whether the move is
+/// pseudo legal. It is used to validate moves from TT that can be corrupted
/// due to SMP concurrent access or hash position key aliasing.
-bool Position::is_pseudo_legal(const Move m) const {
+bool Position::pseudo_legal(const Move m) const {
Color us = sideToMove;
- Color them = flip(sideToMove);
- Square from = move_from(m);
- Square to = move_to(m);
- Piece pc = piece_on(from);
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ Piece pc = moved_piece(m);
// Use a slower but simpler function for uncommon cases
- if (is_special(m))
- return move_is_legal(m);
+ if (type_of(m) != NORMAL)
+ return MoveList(*this).contains(m);
// Is not a promotion, so promotion piece must be empty
- if (promotion_piece_type(m) - 2 != NO_PIECE_TYPE)
+ if (promotion_type(m) - KNIGHT != 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 (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)
- return false;
-
- // Proceed according to the square delta between the origin and
- // destination squares.
- switch (direction)
- {
- case DELTA_NW:
- case DELTA_NE:
- case DELTA_SW:
- case DELTA_SE:
- // Capture. The destination square must be occupied by an enemy
- // piece (en passant captures was handled earlier).
- if (color_of(piece_on(to)) != them)
+ // cannot be on the 8th/1st rank.
+ if (rank_of(to) == relative_rank(us, RANK_8))
return false;
- // From and to files must be one file apart, avoids a7h5
- if (abs(file_of(from) - file_of(to)) != 1)
+ if ( !(attacks_from(from, us) & pieces(~us) & to) // Not a capture
+ && !((from + pawn_push(us) == to) && empty(to)) // Not a single push
+ && !( (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_N:
- case DELTA_S:
- // Pawn push. The destination square must be empty.
- if (!square_is_empty(to))
- return false;
- break;
-
- case DELTA_NN:
- // Double white pawn push. The destination square must be on the fourth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( rank_of(to) != RANK_4
- || !square_is_empty(to)
- || !square_is_empty(from + DELTA_N))
- return false;
- break;
-
- case DELTA_SS:
- // Double black pawn push. The destination square must be on the fifth
- // rank, and both the destination square and the square between the
- // source and destination squares must be empty.
- if ( rank_of(to) != RANK_5
- || !square_is_empty(to)
- || !square_is_empty(from + DELTA_S))
- return false;
- break;
-
- default:
- return false;
- }
}
- else if (!bit_is_set(attacks_from(pc, from), to))
+ 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.
- if (in_check())
+ // and legal() relies on this. We therefore have to take care that the same
+ // kind of moves are filtered out here.
+ if (checkers())
{
- // In case of king moves under check we have to remove king so to catch
- // as invalid moves like b1a1 when opposite queen is on c1.
- if (type_of(piece_on(from)) == KING)
+ if (type_of(pc) != KING)
{
- Bitboard b = occupied_squares();
- clear_bit(&b, from);
- if (attackers_to(move_to(m), b) & pieces(flip(us)))
- return false;
- }
- else
- {
- Bitboard target = checkers();
- Square checksq = pop_1st_bit(&target);
-
- if (target) // double check ? In this case a king move is required
+ // Double check? In this case a king move is required
+ if (more_than_one(checkers()))
return false;
// Our move must be a blocking evasion or a capture of the checking piece
- target = squares_between(checksq, king_square(us)) | checkers();
- if (!bit_is_set(target, move_to(m)))
+ if (!((between_bb(lsb(checkers()), square(us)) | checkers()) & to))
return false;
}
+ // In case of king moves under check we have to remove king so as to catch
+ // invalid moves like b1a1 when opposite queen is on c1.
+ else if (attackers_to(to, pieces() ^ from) & pieces(~us))
+ return false;
}
return true;
}
-/// Position::move_gives_check() tests whether a pseudo-legal move gives a check
+/// Position::gives_check() tests whether a pseudo-legal move gives a check
-bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
+bool Position::gives_check(Move m) const {
assert(is_ok(m));
- assert(ci.dcCandidates == discovered_check_candidates());
- assert(color_of(piece_on(move_from(m))) == side_to_move());
+ assert(color_of(moved_piece(m)) == sideToMove);
- Square from = move_from(m);
- Square to = move_to(m);
- PieceType pt = type_of(piece_on(from));
+ Square from = from_sq(m);
+ Square to = to_sq(m);
- // Direct check ?
- if (bit_is_set(ci.checkSq[pt], to))
+ // Is there a direct check?
+ if (st->ci.checkSquares[type_of(piece_on(from))] & to)
return true;
- // Discovery check ?
- if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
- {
- // For pawn and king moves we need to verify also direction
- if ( (pt != PAWN && pt != KING)
- || !squares_aligned(from, to, king_square(flip(side_to_move()))))
- return true;
- }
+ // Is there a discovered check?
+ if ( (discovered_check_candidates() & from)
+ && !aligned(from, to, st->ci.ksq))
+ return true;
- // Can we skip the ugly special cases ?
- if (!is_special(m))
+ switch (type_of(m))
+ {
+ case NORMAL:
return false;
- Color us = side_to_move();
- Bitboard b = occupied_squares();
- Square ksq = king_square(flip(us));
+ case PROMOTION:
+ return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & st->ci.ksq;
- // Promotion with check ?
- if (is_promotion(m))
- {
- clear_bit(&b, from);
- return bit_is_set(attacks_from(Piece(promotion_piece_type(m)), to, b), ksq);
- }
-
- // En passant capture with check ? We have already handled the case
- // of direct checks and ordinary discovered check, the only case we
+ // En passant capture with check? We have already handled the case
+ // of direct checks and ordinary discovered check, so the only case we
// need to handle is the unusual case of a discovered check through
// the captured pawn.
- if (is_enpassant(m))
+ case ENPASSANT:
{
Square capsq = make_square(file_of(to), rank_of(from));
- clear_bit(&b, from);
- clear_bit(&b, capsq);
- set_bit(&b, to);
- return (rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, us))
- ||(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, us));
- }
+ Bitboard b = (pieces() ^ from ^ capsq) | to;
- // Castling with check ?
- if (is_castle(m))
+ return (attacks_bb< ROOK>(st->ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK))
+ | (attacks_bb(st->ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP));
+ }
+ case CASTLING:
{
- Square kfrom, kto, rfrom, rto;
- kfrom = from;
- rfrom = to;
+ Square kfrom = from;
+ Square rfrom = to; // Castling is encoded as 'King captures the rook'
+ Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1);
- if (rfrom > kfrom)
- {
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- } else {
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
- }
- clear_bit(&b, kfrom);
- clear_bit(&b, rfrom);
- set_bit(&b, rto);
- set_bit(&b, kto);
- return bit_is_set(rook_attacks_bb(rto, b), ksq);
+ return (PseudoAttacks[ROOK][rto] & st->ci.ksq)
+ && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & st->ci.ksq);
+ }
+ default:
+ assert(false);
+ return false;
}
-
- return false;
}
@@ -719,74 +636,61 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
/// to a StateInfo object. The move is assumed to be legal. Pseudo-legal
/// moves should be filtered out before this function is called.
-void Position::do_move(Move m, StateInfo& newSt) {
-
- CheckInfo ci(*this);
- do_move(m, newSt, ci, move_gives_check(m, ci));
-}
-
-void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) {
+void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
assert(is_ok(m));
assert(&newSt != st);
- nodes++;
- Key k = st->key;
-
- // Copy some fields of old state to our new StateInfo object except the ones
- // which are recalculated from scratch anyway, then switch our state pointer
- // to point to the new, ready to be updated, state.
- struct ReducedStateInfo {
- Key pawnKey, materialKey;
- Value npMaterial[2];
- int castleRights, rule50, pliesFromNull;
- Score value;
- Square epSquare;
- };
-
- memcpy(&newSt, st, sizeof(ReducedStateInfo));
+ ++nodes;
+ Key k = st->key ^ Zobrist::side;
+ // 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, offsetof(StateInfo, key));
newSt.previous = st;
st = &newSt;
- // Update side to move
- k ^= zobSideToMove;
+ // 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;
- // Increment the 50 moves rule draw counter. Resetting it to zero in the
- // case of non-reversible moves is taken care of later.
- st->rule50++;
- st->pliesFromNull++;
+ Color us = sideToMove;
+ Color them = ~us;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ PieceType pt = type_of(piece_on(from));
+ PieceType captured = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to));
+
+ assert(color_of(piece_on(from)) == us);
+ assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == (type_of(m) != CASTLING ? them : us));
+ assert(captured != KING);
- if (is_castle(m))
+ if (type_of(m) == CASTLING)
{
- st->key = k;
- do_castle_move(m);
- return;
- }
+ assert(pt == KING);
- Color us = side_to_move();
- Color them = flip(us);
- Square from = move_from(m);
- Square to = move_to(m);
- Piece piece = piece_on(from);
- PieceType pt = type_of(piece);
- PieceType capture = is_enpassant(m) ? PAWN : type_of(piece_on(to));
+ Square rfrom, rto;
+ do_castling(us, from, to, rfrom, rto);
- assert(color_of(piece) == us);
- assert(color_of(piece_on(to)) != us);
- assert(capture != KING);
+ captured = NO_PIECE_TYPE;
+ st->psq += PSQT::psq[us][ROOK][rto] - PSQT::psq[us][ROOK][rfrom];
+ k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
+ }
- 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 (is_enpassant(m))
+ if (type_of(m) == ENPASSANT)
{
- capsq += pawn_push(them);
+ capsq -= pawn_push(us);
assert(pt == PAWN);
assert(to == st->epSquare);
@@ -794,172 +698,109 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
assert(piece_on(to) == NO_PIECE);
assert(piece_on(capsq) == make_piece(them, PAWN));
- board[capsq] = NO_PIECE;
+ board[capsq] = NO_PIECE; // Not done by remove_piece()
}
- st->pawnKey ^= zobrist[them][PAWN][capsq];
+ st->pawnKey ^= Zobrist::psq[them][PAWN][capsq];
}
else
- st->npMaterial[them] -= PieceValueMidgame[capture];
-
- // Remove the captured piece
- clear_bit(&byColorBB[them], capsq);
- clear_bit(&byTypeBB[capture], capsq);
- clear_bit(&occupied, capsq);
-
- // Update piece list, move the last piece at index[capsq] position and
- // shrink the list.
- //
- // WARNING: This is a not revresible operation. When we will reinsert the
- // captured piece in undo_move() we will put it at the end of the list and
- // not in its original place, it means index[] and pieceList[] are not
- // guaranteed to be invariant to a do_move() + undo_move() sequence.
- Square lastSquare = pieceList[them][capture][--pieceCount[them][capture]];
- index[lastSquare] = index[capsq];
- pieceList[them][capture][index[lastSquare]] = lastSquare;
- pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
-
- // Update hash keys
- k ^= zobrist[them][capture][capsq];
- st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]];
+ st->nonPawnMaterial[them] -= PieceValue[MG][captured];
+
+ // Update board and piece lists
+ remove_piece(them, captured, capsq);
+
+ // Update material hash key and prefetch access to materialTable
+ k ^= Zobrist::psq[them][captured][capsq];
+ st->materialKey ^= Zobrist::psq[them][captured][pieceCount[them][captured]];
+ prefetch(thisThread->materialTable[st->materialKey]);
// Update incremental scores
- st->value -= pst(make_piece(them, capture), capsq);
+ st->psq -= PSQT::psq[them][captured][capsq];
// Reset rule 50 counter
st->rule50 = 0;
}
// Update hash key
- k ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
+ k ^= Zobrist::psq[us][pt][from] ^ Zobrist::psq[us][pt][to];
// Reset en passant square
if (st->epSquare != SQ_NONE)
{
- k ^= zobEp[st->epSquare];
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
st->epSquare = SQ_NONE;
}
- // Update castle rights if needed
- if ( st->castleRights != CASTLES_NONE
- && (castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES)
+ // Update castling rights if needed
+ if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to]))
{
- k ^= zobCastle[st->castleRights];
- st->castleRights &= castleRightsMask[from] & castleRightsMask[to];
- k ^= zobCastle[st->castleRights];
+ int cr = castlingRightsMask[from] | castlingRightsMask[to];
+ k ^= Zobrist::castling[st->castlingRights & cr];
+ st->castlingRights &= ~cr;
}
- // Prefetch TT access as soon as we know key is updated
- prefetch((char*)TT.first_entry(k));
-
- // Move the piece
- Bitboard move_bb = make_move_bb(from, to);
- do_move_bb(&byColorBB[us], move_bb);
- do_move_bb(&byTypeBB[pt], move_bb);
- do_move_bb(&occupied, move_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 castling is handled earlier
+ if (type_of(m) != CASTLING)
+ move_piece(us, pt, from, to);
// If the moving piece is a pawn do some special extra work
if (pt == PAWN)
{
- // Set en-passant square, only if moved pawn can be captured
- if ( (to ^ from) == 16
- && (attacks_from(from + pawn_push(us), us) & pieces(PAWN, them)))
+ // Set en-passant square if the moved pawn can be captured
+ if ( (int(to) ^ int(from)) == 16
+ && (attacks_from(to - pawn_push(us), us) & pieces(them, PAWN)))
{
- st->epSquare = Square((from + to) / 2);
- k ^= zobEp[st->epSquare];
+ st->epSquare = (from + to) / 2;
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
}
- if (is_promotion(m))
+ else if (type_of(m) == PROMOTION)
{
- PieceType promotion = promotion_piece_type(m);
+ PieceType promotion = promotion_type(m);
assert(relative_rank(us, to) == RANK_8);
assert(promotion >= KNIGHT && promotion <= QUEEN);
- // Replace the pawn with the promoted piece
- clear_bit(&byTypeBB[PAWN], to);
- set_bit(&byTypeBB[promotion], to);
- board[to] = make_piece(us, promotion);
-
- // Update piece 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(us, PAWN, to);
+ put_piece(us, promotion, to);
// Update hash keys
- k ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to];
- st->pawnKey ^= zobrist[us][PAWN][to];
- st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]++]
- ^ zobrist[us][PAWN][pieceCount[us][PAWN]];
+ k ^= Zobrist::psq[us][PAWN][to] ^ Zobrist::psq[us][promotion][to];
+ st->pawnKey ^= Zobrist::psq[us][PAWN][to];
+ st->materialKey ^= Zobrist::psq[us][promotion][pieceCount[us][promotion]-1]
+ ^ Zobrist::psq[us][PAWN][pieceCount[us][PAWN]];
// Update incremental score
- st->value += pst(make_piece(us, promotion), to)
- - pst(make_piece(us, PAWN), to);
+ st->psq += PSQT::psq[us][promotion][to] - PSQT::psq[us][PAWN][to];
// Update material
- st->npMaterial[us] += PieceValueMidgame[promotion];
+ st->nonPawnMaterial[us] += PieceValue[MG][promotion];
}
- // Update pawn hash key
- st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
+ // Update pawn hash key and prefetch access to pawnsTable
+ st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to];
+ prefetch(thisThread->pawnsTable[st->pawnKey]);
// Reset rule 50 draw counter
st->rule50 = 0;
}
- // Prefetch pawn and material hash tables
- Threads[threadID].pawnTable.prefetch(st->pawnKey);
- Threads[threadID].materialTable.prefetch(st->materialKey);
-
// Update incremental scores
- st->value += pst_delta(piece, from, to);
+ st->psq += PSQT::psq[us][pt][to] - PSQT::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
- st->checkersBB = 0;
+ // Calculate checkers bitboard (if move gives check)
+ st->checkersBB = givesCheck ? attackers_to(square(them)) & pieces(us) : 0;
- if (moveIsCheck)
- {
- if (is_special(m))
- st->checkersBB = attackers_to(king_square(them)) & pieces(us);
- else
- {
- // Direct checks
- if (bit_is_set(ci.checkSq[pt], to))
- st->checkersBB = SetMaskBB[to];
+ sideToMove = ~sideToMove;
- // Discovery checks
- if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from))
- {
- if (pt != ROOK)
- st->checkersBB |= attacks_from(king_square(them)) & pieces(ROOK, QUEEN, us);
-
- if (pt != BISHOP)
- st->checkersBB |= attacks_from(king_square(them)) & pieces(BISHOP, QUEEN, us);
- }
- }
- }
-
- // Finish
- sideToMove = flip(sideToMove);
- st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
+ // Update CheckInfo
+ set_check_info(&st->ci);
assert(pos_is_ok());
}
@@ -972,318 +813,196 @@ void Position::undo_move(Move m) {
assert(is_ok(m));
- sideToMove = flip(sideToMove);
+ sideToMove = ~sideToMove;
- if (is_castle(m))
- {
- do_castle_move(m);
- return;
- }
-
- Color us = side_to_move();
- Color them = flip(us);
- Square from = move_from(m);
- Square to = move_to(m);
- Piece piece = piece_on(to);
- PieceType pt = type_of(piece);
- PieceType capture = st->capturedType;
+ Color us = sideToMove;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ PieceType pt = type_of(piece_on(to));
- assert(square_is_empty(from));
- assert(color_of(piece) == us);
- assert(capture != KING);
+ assert(empty(from) || type_of(m) == CASTLING);
+ assert(st->capturedType != KING);
- if (is_promotion(m))
+ if (type_of(m) == PROMOTION)
{
- PieceType promotion = promotion_piece_type(m);
-
- assert(promotion == pt);
assert(relative_rank(us, to) == RANK_8);
- assert(promotion >= KNIGHT && promotion <= QUEEN);
-
- // Replace the promoted piece with the pawn
- clear_bit(&byTypeBB[promotion], to);
- set_bit(&byTypeBB[PAWN], to);
- board[to] = make_piece(us, PAWN);
-
- // Update piece 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(pt == promotion_type(m));
+ assert(pt >= KNIGHT && pt <= QUEEN);
+ remove_piece(us, pt, to);
+ put_piece(us, PAWN, to);
pt = PAWN;
}
- // Put the piece back at the source square
- Bitboard move_bb = make_move_bb(to, from);
- do_move_bb(&byColorBB[us], move_bb);
- do_move_bb(&byTypeBB[pt], move_bb);
- do_move_bb(&occupied, move_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 (capture)
+ if (type_of(m) == CASTLING)
{
- Square capsq = to;
+ Square rfrom, rto;
+ do_castling(us, from, to, rfrom, rto);
+ }
+ else
+ {
+ move_piece(us, pt, to, from); // Put the piece back at the source square
- if (is_enpassant(m))
+ if (st->capturedType)
{
- capsq -= pawn_push(us);
-
- assert(pt == PAWN);
- assert(to == st->previous->epSquare);
- assert(relative_rank(us, to) == RANK_6);
- assert(piece_on(capsq) == NO_PIECE);
- }
+ Square capsq = to;
- // Restore the captured piece
- set_bit(&byColorBB[them], capsq);
- set_bit(&byTypeBB[capture], capsq);
- set_bit(&occupied, 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);
+ assert(st->capturedType == PAWN);
+ }
- // Update piece list, add a new captured piece in capsq square
- index[capsq] = pieceCount[them][capture]++;
- pieceList[them][capture][index[capsq]] = capsq;
+ put_piece(~us, st->capturedType, capsq); // 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.
+/// Position::do_castling() is a helper used to do/undo a castling move. This
+/// is a bit tricky, especially in Chess960.
template
-void Position::do_castle_move(Move m) {
+void Position::do_castling(Color us, 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(us, kingSide ? SQ_F1 : SQ_D1);
+ to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
+
+ // Remove both pieces first since squares could overlap in Chess960
+ remove_piece(us, KING, Do ? from : to);
+ remove_piece(us, ROOK, Do ? rfrom : rto);
+ board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us
+ put_piece(us, KING, Do ? to : from);
+ put_piece(us, ROOK, Do ? rto : rfrom);
+}
- assert(is_ok(m));
- assert(is_castle(m));
- Square kto, kfrom, rfrom, rto, kAfter, rAfter;
+/// 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.
- Color us = side_to_move();
- Square kBefore = move_from(m);
- Square rBefore = move_to(m);
+void Position::do_null_move(StateInfo& newSt) {
- // 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);
- }
-
- kfrom = Do ? kBefore : kAfter;
- rfrom = Do ? rBefore : rAfter;
-
- kto = Do ? kAfter : kBefore;
- rto = Do ? rAfter : rBefore;
-
- assert(piece_on(kfrom) == make_piece(us, KING));
- assert(piece_on(rfrom) == make_piece(us, ROOK));
-
- // Remove pieces from source squares
- clear_bit(&byColorBB[us], kfrom);
- clear_bit(&byTypeBB[KING], kfrom);
- clear_bit(&occupied, kfrom);
- clear_bit(&byColorBB[us], rfrom);
- clear_bit(&byTypeBB[ROOK], rfrom);
- clear_bit(&occupied, rfrom);
-
- // Put pieces on destination squares
- set_bit(&byColorBB[us], kto);
- set_bit(&byTypeBB[KING], kto);
- set_bit(&occupied, kto);
- set_bit(&byColorBB[us], rto);
- set_bit(&byTypeBB[ROOK], rto);
- set_bit(&occupied, rto);
-
- // Update board
- Piece king = make_piece(us, KING);
- Piece rook = make_piece(us, ROOK);
- board[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->value += pst_delta(king, kfrom, kto);
- st->value += pst_delta(rook, rfrom, rto);
+ assert(!checkers());
+ assert(&newSt != st);
- // Update hash key
- st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
- st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
+ std::memcpy(&newSt, st, sizeof(StateInfo));
+ newSt.previous = st;
+ st = &newSt;
- // Clear en passant square
- if (st->epSquare != SQ_NONE)
- {
- st->key ^= zobEp[st->epSquare];
- st->epSquare = SQ_NONE;
- }
+ if (st->epSquare != SQ_NONE)
+ {
+ st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
+ st->epSquare = SQ_NONE;
+ }
- // Update castling rights
- st->key ^= zobCastle[st->castleRights];
- st->castleRights &= castleRightsMask[kfrom];
- st->key ^= zobCastle[st->castleRights];
+ st->key ^= Zobrist::side;
+ prefetch(TT.first_entry(st->key));
- // Reset rule 50 counter
- st->rule50 = 0;
+ ++st->rule50;
+ st->pliesFromNull = 0;
- // Update checkers BB
- st->checkersBB = attackers_to(king_square(flip(us))) & pieces(us);
+ sideToMove = ~sideToMove;
- // Finish
- sideToMove = flip(sideToMove);
- st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
- }
- else
- // Undo: point our state pointer back to the previous state
- st = st->previous;
+ set_check_info(&st->ci);
assert(pos_is_ok());
}
+void Position::undo_null_move() {
-/// Position::do_null_move() is used to do/undo a "null move": It flips the side
-/// to move and updates the hash key without executing any move on the board.
-template
-void Position::do_null_move(StateInfo& backupSt) {
-
- assert(!in_check());
+ assert(!checkers());
- // Back up the information necessary to undo the null move to the supplied
- // StateInfo object. Note that differently from normal case here backupSt
- // is actually used as a backup storage not as the new state. This reduces
- // the number of fields to be copied.
- StateInfo* src = Do ? st : &backupSt;
- StateInfo* dst = Do ? &backupSt : st;
+ st = st->previous;
+ sideToMove = ~sideToMove;
+}
- dst->key = src->key;
- dst->epSquare = src->epSquare;
- dst->value = src->value;
- dst->rule50 = src->rule50;
- dst->pliesFromNull = src->pliesFromNull;
- sideToMove = flip(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.
- if (Do)
- {
- if (st->epSquare != SQ_NONE)
- st->key ^= zobEp[st->epSquare];
+Key Position::key_after(Move m) const {
- st->key ^= zobSideToMove;
- prefetch((char*)TT.first_entry(st->key));
+ 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;
- st->epSquare = SQ_NONE;
- st->rule50++;
- st->pliesFromNull = 0;
- st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
- }
+ if (captured)
+ k ^= Zobrist::psq[~us][captured][to];
- assert(pos_is_ok());
+ return k ^ Zobrist::psq[us][pt][to] ^ Zobrist::psq[us][pt][from];
}
-// Explicit template instantiations
-template void Position::do_null_move(StateInfo& backupSt);
-template void Position::do_null_move(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.
-int Position::see_sign(Move m) const {
+Value Position::see_sign(Move m) const {
assert(is_ok(m));
- Square from = move_from(m);
- Square to = move_to(m);
-
// Early return if SEE cannot be negative because captured piece value
// is not less then capturing one. Note that king moves always return
// here because king midgame value is set to 0.
- if (PieceValueMidgame[piece_on(to)] >= PieceValueMidgame[piece_on(from)])
- return 1;
+ if (PieceValue[MG][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))])
+ return VALUE_KNOWN_WIN;
return see(m);
}
-int Position::see(Move m) const {
+Value Position::see(Move m) const {
Square from, to;
- Bitboard occ, attackers, stmAttackers, b;
- int swapList[32], slIndex = 1;
- PieceType capturedType, pt;
+ Bitboard occupied, attackers, stmAttackers;
+ Value swapList[32];
+ int slIndex = 1;
+ PieceType captured;
Color stm;
assert(is_ok(m));
- // As castle moves are implemented as capturing the rook, they have
- // SEE == RookValueMidgame most of the times (unless the rook is under
- // attack).
- if (is_castle(m))
- return 0;
+ from = from_sq(m);
+ to = to_sq(m);
+ swapList[0] = PieceValue[MG][piece_on(to)];
+ stm = color_of(piece_on(from));
+ occupied = pieces() ^ from;
- from = move_from(m);
- to = move_to(m);
- capturedType = type_of(piece_on(to));
- occ = occupied_squares();
+ // Castling moves are implemented as king capturing the rook so cannot
+ // be handled correctly. Simply return VALUE_ZERO that is always correct
+ // unless in the rare case the rook ends up under attack.
+ if (type_of(m) == CASTLING)
+ return VALUE_ZERO;
- // Handle en passant moves
- if (is_enpassant(m))
+ if (type_of(m) == ENPASSANT)
{
- Square capQq = to - pawn_push(side_to_move());
-
- assert(capturedType == NO_PIECE_TYPE);
- assert(type_of(piece_on(capQq)) == PAWN);
-
- // Remove the captured pawn
- clear_bit(&occ, capQq);
- capturedType = PAWN;
+ occupied ^= to - pawn_push(stm); // Remove the captured pawn
+ swapList[0] = PieceValue[MG][PAWN];
}
// Find all attackers to the destination square, with the moving piece
// removed, but possibly an X-ray attacker added behind it.
- clear_bit(&occ, from);
- attackers = attackers_to(to, occ);
+ attackers = attackers_to(to, occupied) & occupied;
// If the opponent has no attackers we are finished
- stm = flip(color_of(piece_on(from)));
+ stm = ~stm;
stmAttackers = attackers & pieces(stm);
if (!stmAttackers)
- return PieceValueMidgame[capturedType];
+ return swapList[0];
// The destination square is defended, which makes things rather more
// difficult to compute. We proceed by building up a "swap list" containing
@@ -1291,505 +1010,161 @@ int Position::see(Move m) const {
// destination square, where the sides alternately capture, and always
// capture with the least valuable piece. After each capture, we look for
// new X-ray attacks from behind the capturing piece.
- swapList[0] = PieceValueMidgame[capturedType];
- capturedType = type_of(piece_on(from));
+ captured = type_of(piece_on(from));
do {
- // Locate the least valuable attacker for the side to move. The loop
- // below looks like it is potentially infinite, but it isn't. We know
- // that the side to move still has at least one attacker left.
- for (pt = PAWN; !(stmAttackers & pieces(pt)); pt++)
- assert(pt < KING);
-
- // Remove the attacker we just found from the 'occupied' bitboard,
- // and scan for new X-ray attacks behind the attacker.
- b = stmAttackers & pieces(pt);
- occ ^= (b & (~b + 1));
- attackers |= (rook_attacks_bb(to, occ) & pieces(ROOK, QUEEN))
- | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN));
-
- attackers &= occ; // Cut out pieces we've already done
+ assert(slIndex < 32);
// Add the new entry to the swap list
- assert(slIndex < 32);
- swapList[slIndex] = -swapList[slIndex - 1] + PieceValueMidgame[capturedType];
- slIndex++;
+ swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
- // Remember the value of the capturing piece, and change the side to
- // move before beginning the next iteration.
- capturedType = pt;
- stm = flip(stm);
+ // Locate and remove the next least valuable attacker
+ captured = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers);
+ stm = ~stm;
stmAttackers = attackers & pieces(stm);
+ ++slIndex;
- // Stop before processing a king capture
- if (capturedType == KING && stmAttackers)
- {
- assert(slIndex < 32);
- swapList[slIndex++] = QueenValueMidgame*10;
- break;
- }
- } while (stmAttackers);
+ } while (stmAttackers && (captured != KING || (--slIndex, false))); // Stop before a king capture
// 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() {
-
- st = &startState;
- memset(st, 0, sizeof(StateInfo));
- st->epSquare = SQ_NONE;
-
- memset(byColorBB, 0, sizeof(Bitboard) * 2);
- memset(byTypeBB, 0, sizeof(Bitboard) * 8);
- memset(pieceCount, 0, sizeof(int) * 2 * 8);
- memset(index, 0, sizeof(int) * 64);
-
- for (int i = 0; i < 8; i++)
- for (int j = 0; j < 16; j++)
- pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
-
- for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
- {
- board[sq] = NO_PIECE;
- castleRightsMask[sq] = ALL_CASTLES;
- }
- sideToMove = WHITE;
- nodes = 0;
- occupied = 0;
-}
-
-
-/// Position::put_piece() puts a piece on the given square of the board,
-/// updating the board array, pieces list, bitboards, and piece counts.
-
-void Position::put_piece(Piece p, Square s) {
-
- Color c = color_of(p);
- PieceType pt = type_of(p);
-
- board[s] = p;
- index[s] = pieceCount[c][pt]++;
- pieceList[c][pt][index[s]] = s;
-
- set_bit(&byTypeBB[pt], s);
- set_bit(&byColorBB[c], s);
- set_bit(&occupied, 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 result = zobCastle[st->castleRights];
-
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (!square_is_empty(s))
- result ^= zobrist[color_of(piece_on(s))][type_of(piece_on(s))][s];
-
- if (ep_square() != SQ_NONE)
- result ^= zobEp[ep_square()];
-
- if (side_to_move() == BLACK)
- result ^= zobSideToMove;
-
- return result;
-}
-
-
-/// Position::compute_pawn_key() computes the hash key of the position. The
-/// hash key is usually updated incrementally as moves are made and unmade,
-/// the compute_pawn_key() function is only used when a new position is set
-/// up, and to verify the correctness of the pawn hash key when running in
-/// debug mode.
-
-Key Position::compute_pawn_key() const {
-
- Bitboard b;
- Key result = 0;
-
- for (Color c = WHITE; c <= BLACK; c++)
- {
- b = pieces(PAWN, c);
- while (b)
- result ^= zobrist[c][PAWN][pop_1st_bit(&b)];
- }
- return result;
-}
-
-
-/// Position::compute_material_key() computes the hash key of the position.
-/// The hash key is usually updated incrementally as moves are made and unmade,
-/// the compute_material_key() function is only used when a new position is set
-/// up, and to verify the correctness of the material hash key when running in
-/// debug mode.
-
-Key Position::compute_material_key() const {
-
- Key result = 0;
-
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= QUEEN; pt++)
- for (int i = 0; i < piece_count(c, pt); i++)
- result ^= zobrist[c][pt][i];
-
- return result;
-}
-
-
-/// Position::compute_value() compute the incremental scores for the middle
-/// game and the endgame. These functions are used to initialize the incremental
-/// scores when a new position is set up, and to verify that the scores are correctly
-/// updated by do_move and undo_move when the program is running in debug mode.
-Score Position::compute_value() const {
-
- Bitboard b;
- Score result = SCORE_ZERO;
-
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- {
- b = pieces(pt, c);
- while (b)
- result += pst(make_piece(c, pt), pop_1st_bit(&b));
- }
-
- result += (side_to_move() == WHITE ? TempoValue / 2 : -TempoValue / 2);
- return result;
-}
-
-
-/// Position::compute_non_pawn_material() computes the total non-pawn middle
-/// game material value for the given side. Material values are updated
-/// incrementally during the search, this function is only used while
-/// initializing a new Position object.
-
-Value Position::compute_non_pawn_material(Color c) const {
-
- Value result = VALUE_ZERO;
-
- for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
- result += piece_count(c, pt) * PieceValueMidgame[pt];
-
- return result;
-}
-
+/// Position::is_draw() tests whether the position is drawn by 50-move rule
+/// or by repetition. It does not detect stalemates.
-/// 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 Position::is_draw() const {
- // Draw by material?
- if ( !pieces(PAWN)
- && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame))
+ if (st->rule50 > 99 && (!checkers() || MoveList(*this).size()))
return true;
- // Draw by the 50 moves rule?
- if (st->rule50 > 99 && !is_mate())
- return true;
-
- // Draw by repetition?
- if (!SkipRepetition)
+ StateInfo* stp = st;
+ for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2)
{
- int i = 4, e = std::min(st->rule50, st->pliesFromNull);
+ stp = stp->previous->previous;
- if (i <= e)
- {
- StateInfo* stp = st->previous->previous;
-
- do {
- stp = stp->previous->previous;
-
- if (stp->key == st->key)
- return true;
-
- i +=2;
-
- } while (i <= e);
- }
+ if (stp->key == st->key)
+ return true; // Draw at first repetition
}
return false;
}
-// Explicit template instantiations
-template bool Position::is_draw() const;
-template bool Position::is_draw() const;
-
-
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated.
-
-bool Position::is_mate() const {
-
- return in_check() && !MoveList(*this).size();
-}
-
-/// Position::init() is a static member function which initializes at startup
-/// the various arrays used to compute hash keys and the piece square tables.
-/// The latter is a two-step operation: First, the white halves of the tables
-/// are copied from PSQT[] tables. Second, the black halves of the tables are
-/// initialized by flipping and changing the sign of the white scores.
+/// Position::flip() flips position with the white and black sides reversed. This
+/// is only useful for debugging e.g. for finding evaluation symmetry bugs.
-void Position::init() {
-
- RKISS rk;
-
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- zobrist[c][pt][s] = rk.rand();
+void Position::flip() {
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- zobEp[s] = rk.rand();
+ string f, token;
+ std::stringstream ss(fen());
- for (int i = 0; i < 16; i++)
- zobCastle[i] = rk.rand();
-
- zobSideToMove = rk.rand();
- zobExclusion = rk.rand();
-
- for (Piece p = W_PAWN; p <= W_KING; p++)
+ for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement
{
- Score ps = make_score(PieceValueMidgame[p], PieceValueEndgame[p]);
-
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- {
- pieceSquareTable[p][s] = ps + PSQT[p][s];
- pieceSquareTable[p+8][flip(s)] = -pieceSquareTable[p][s];
- }
+ std::getline(ss, token, r > RANK_1 ? '/' : ' ');
+ f.insert(0, token + (f.empty() ? " " : "/"));
}
-}
-
-
-/// Position::flip_me() flips position with the white and black sides reversed. This
-/// is only useful for debugging especially for finding evaluation symmetry bugs.
-
-void Position::flip_me() {
- // Make a copy of current position before to start changing
- const Position pos(*this, threadID);
+ ss >> token; // Active color
+ f += (token == "w" ? "B " : "W "); // Will be lowercased later
- clear();
- threadID = pos.thread();
+ ss >> token; // Castling availability
+ f += token + " ";
- // Board
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (!pos.square_is_empty(s))
- put_piece(Piece(pos.piece_on(s) ^ 8), flip(s));
+ std::transform(f.begin(), f.end(), f.begin(),
+ [](char c) { return char(islower(c) ? toupper(c) : tolower(c)); });
- // Side to move
- sideToMove = flip(pos.side_to_move());
+ ss >> token; // En passant square
+ f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3"));
- // Castling rights
- if (pos.can_castle(WHITE_OO))
- set_castle_right(king_square(BLACK), flip(pos.castle_rook_square(WHITE_OO)));
- if (pos.can_castle(WHITE_OOO))
- set_castle_right(king_square(BLACK), flip(pos.castle_rook_square(WHITE_OOO)));
- if (pos.can_castle(BLACK_OO))
- set_castle_right(king_square(WHITE), flip(pos.castle_rook_square(BLACK_OO)));
- if (pos.can_castle(BLACK_OOO))
- set_castle_right(king_square(WHITE), flip(pos.castle_rook_square(BLACK_OOO)));
+ std::getline(ss, token); // Half and full moves
+ f += token;
- // En passant square
- if (pos.st->epSquare != SQ_NONE)
- st->epSquare = flip(pos.st->epSquare);
-
- // Checkers
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove));
-
- // Hash keys
- st->key = compute_key();
- st->pawnKey = compute_pawn_key();
- st->materialKey = compute_material_key();
-
- // Incremental scores
- st->value = compute_value();
-
- // Material
- st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ set(f, is_chess960(), st, 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 {
- // What features of the position should be verified?
- const bool debugAll = false;
-
- const bool debugBitboards = debugAll || false;
- const bool debugKingCount = debugAll || false;
- const bool debugKingCapture = debugAll || false;
- const bool debugCheckerCount = debugAll || false;
- const bool debugKey = debugAll || false;
- const bool debugMaterialKey = debugAll || false;
- const bool debugPawnKey = debugAll || false;
- const bool debugIncrementalEval = debugAll || false;
- const bool debugNonPawnMaterial = debugAll || false;
- const bool debugPieceCounts = debugAll || false;
- const bool debugPieceList = debugAll || false;
- const bool debugCastleSquares = debugAll || false;
-
- if (failedStep) *failedStep = 1;
-
- // Side to move OK?
- if (side_to_move() != WHITE && side_to_move() != BLACK)
- return false;
+ const bool Fast = true; // Quick (default) or full check?
- // Are the king squares in the position correct?
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(WHITE)) != W_KING)
- return false;
+ enum { Default, King, Bitboards, State, Lists, Castling };
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(BLACK)) != B_KING)
- return false;
-
- // Do both sides have exactly one king?
- if (failedStep) (*failedStep)++;
- if (debugKingCount)
+ for (int step = Default; step <= (Fast ? Default : Castling); step++)
{
- int kingCount[2] = {0, 0};
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (type_of(piece_on(s)) == KING)
- kingCount[color_of(piece_on(s))]++;
-
- if (kingCount[0] != 1 || kingCount[1] != 1)
- return false;
- }
-
- // Can the side to move capture the opponent's king?
- if (failedStep) (*failedStep)++;
- if (debugKingCapture)
- {
- Color us = side_to_move();
- Color them = flip(us);
- Square ksq = king_square(them);
- if (attackers_to(ksq) & pieces(us))
- return false;
- }
-
- // Is there more than 2 checkers?
- if (failedStep) (*failedStep)++;
- if (debugCheckerCount && count_1s(st->checkersBB) > 2)
- return false;
-
- // Bitboards OK?
- if (failedStep) (*failedStep)++;
- if (debugBitboards)
- {
- // The intersection of the white and black pieces must be empty
- if (!(pieces(WHITE) & pieces(BLACK)))
- return false;
-
- // The union of the white and black pieces must be equal to all
- // occupied squares
- if ((pieces(WHITE) | pieces(BLACK)) != occupied_squares())
- return false;
-
- // Separate piece type bitboards must have empty intersections
- for (PieceType p1 = PAWN; p1 <= KING; p1++)
- for (PieceType p2 = PAWN; p2 <= KING; p2++)
- if (p1 != p2 && (pieces(p1) & pieces(p2)))
- return false;
- }
-
- // En passant square OK?
- if (failedStep) (*failedStep)++;
- if (ep_square() != SQ_NONE)
- {
- // The en passant square must be on rank 6, from the point of view of the
- // side to move.
- if (relative_rank(side_to_move(), ep_square()) != RANK_6)
- return false;
- }
-
- // Hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugKey && st->key != compute_key())
- return false;
-
- // Pawn hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugPawnKey && st->pawnKey != compute_pawn_key())
- return false;
+ if (failedStep)
+ *failedStep = step;
+
+ if (step == Default)
+ if ( (sideToMove != WHITE && sideToMove != BLACK)
+ || piece_on(square(WHITE)) != W_KING
+ || piece_on(square(BLACK)) != B_KING
+ || ( ep_square() != SQ_NONE
+ && relative_rank(sideToMove, ep_square()) != RANK_6))
+ return false;
- // Material hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugMaterialKey && st->materialKey != compute_material_key())
- return false;
+ if (step == King)
+ if ( std::count(board, board + SQUARE_NB, W_KING) != 1
+ || std::count(board, board + SQUARE_NB, B_KING) != 1
+ || attackers_to(square(~sideToMove)) & pieces(sideToMove))
+ return false;
- // Incremental eval OK?
- if (failedStep) (*failedStep)++;
- if (debugIncrementalEval && st->value != compute_value())
- return false;
+ if (step == Bitboards)
+ {
+ if ( (pieces(WHITE) & pieces(BLACK))
+ ||(pieces(WHITE) | pieces(BLACK)) != pieces())
+ return false;
- // Non-pawn material OK?
- if (failedStep) (*failedStep)++;
- if (debugNonPawnMaterial)
- {
- if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE))
- return false;
+ for (PieceType p1 = PAWN; p1 <= KING; ++p1)
+ for (PieceType p2 = PAWN; p2 <= KING; ++p2)
+ if (p1 != p2 && (pieces(p1) & pieces(p2)))
+ return false;
+ }
- if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
- return false;
- }
+ if (step == State)
+ {
+ StateInfo si = *st;
+ set_state(&si);
+ if (std::memcmp(&si, st, sizeof(StateInfo)))
+ return false;
+ }
- // Piece counts OK?
- if (failedStep) (*failedStep)++;
- if (debugPieceCounts)
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- if (pieceCount[c][pt] != count_1s(pieces(pt, c)))
- return false;
-
- if (failedStep) (*failedStep)++;
- if (debugPieceList)
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- for (int i = 0; i < pieceCount[c][pt]; i++)
+ if (step == Lists)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
{
- if (piece_on(piece_list(c, pt)[i]) != make_piece(c, pt))
+ if (pieceCount[c][pt] != popcount(pieces(c, pt)))
return false;
- if (index[piece_list(c, pt)[i]] != i)
- return false;
+ 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 (failedStep) (*failedStep)++;
- if (debugCastleSquares)
- for (CastleRight f = WHITE_OO; f <= BLACK_OOO; f = CastleRight(f << 1))
- {
- if (!can_castle(f))
- continue;
-
- Piece rook = (f & (WHITE_OO | WHITE_OOO) ? W_ROOK : B_ROOK);
+ if (step == Castling)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1))
+ {
+ if (!can_castle(c | s))
+ continue;
- if ( castleRightsMask[castleRookSquare[f]] != (ALL_CASTLES ^ f)
- || piece_on(castleRookSquare[f]) != rook)
- return false;
- }
+ if ( piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK)
+ || castlingRightsMask[castlingRookSquare[c | s]] != (c | s)
+ ||(castlingRightsMask[square(c)] & (c | s)) != (c | s))
+ return false;
+ }
+ }
- if (failedStep) *failedStep = 0;
return true;
}