/*
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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2019 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
#include <algorithm>
#include <cassert>
-#include <cstring>
+#include <cstddef> // For offsetof()
+#include <cstring> // For std::memset, std::memcmp
#include <iomanip>
-#include <iostream>
#include <sstream>
-#include "bitcount.h"
+#include "bitboard.h"
+#include "misc.h"
#include "movegen.h"
-#include "notation.h"
#include "position.h"
-#include "psqtab.h"
-#include "rkiss.h"
#include "thread.h"
#include "tt.h"
+#include "uci.h"
+#include "syzygy/tbprobe.h"
using std::string;
-using std::cout;
-using std::endl;
-
-static const string PieceToChar(" PNBRQK pnbrqk");
-
-CACHE_LINE_ALIGNMENT
-
-Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
-Value PieceValue[PHASE_NB][PIECE_NB] = {
-{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
-{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } };
namespace Zobrist {
- Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+ Key psq[PIECE_NB][SQUARE_NB];
Key enpassant[FILE_NB];
- Key castle[CASTLE_RIGHT_NB];
- Key side;
- Key exclusion;
+ Key castling[CASTLING_RIGHT_NB];
+ Key side, noPawns;
}
-Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion;}
-
namespace {
-// min_attacker() is an helper function used by see() to locate the least
+const string PieceToChar(" PNBRQK pnbrqk");
+
+constexpr Piece Pieces[] = { W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING,
+ B_PAWN, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING };
+
+// min_attacker() is a helper function used by see_ge() to locate the least
// valuable attacker for the side to move, remove the attacker we just found
// from the bitboards and scan for new X-ray attacks behind it.
-template<int Pt> FORCE_INLINE
-PieceType min_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers,
+template<PieceType Pt>
+PieceType min_attacker(const Bitboard* byTypeBB, Square to, Bitboard stmAttackers,
Bitboard& occupied, Bitboard& attackers) {
- Bitboard b = stmAttackers & bb[Pt];
+ Bitboard b = stmAttackers & byTypeBB[Pt];
if (!b)
- return min_attacker<Pt+1>(bb, to, stmAttackers, occupied, attackers);
+ return min_attacker<PieceType(Pt + 1)>(byTypeBB, to, stmAttackers, occupied, attackers);
- occupied ^= b & ~(b - 1);
+ occupied ^= lsb(b); // Remove the attacker from occupied
+ // Add any X-ray attack behind the just removed piece. For instance with
+ // rooks in a8 and a7 attacking a1, after removing a7 we add rook in a8.
+ // Note that new added attackers can be of any color.
if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN)
- attackers |= attacks_bb<BISHOP>(to, occupied) & (bb[BISHOP] | bb[QUEEN]);
+ attackers |= attacks_bb<BISHOP>(to, occupied) & (byTypeBB[BISHOP] | byTypeBB[QUEEN]);
if (Pt == ROOK || Pt == QUEEN)
- attackers |= attacks_bb<ROOK>(to, occupied) & (bb[ROOK] | bb[QUEEN]);
+ attackers |= attacks_bb<ROOK>(to, occupied) & (byTypeBB[ROOK] | byTypeBB[QUEEN]);
- attackers &= occupied; // After X-ray that may add already processed pieces
- return (PieceType)Pt;
+ // X-ray may add already processed pieces because byTypeBB[] is constant: in
+ // the rook example, now attackers contains _again_ rook in a7, so remove it.
+ attackers &= occupied;
+ return Pt;
}
-template<> FORCE_INLINE
-PieceType min_attacker<KING>(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) {
- return KING; // No need to update bitboards, it is the last cycle
+template<>
+PieceType min_attacker<KING>(const Bitboard*, Square, Bitboard, Bitboard&, Bitboard&) {
+ return KING; // No need to update bitboards: it is the last cycle
}
} // namespace
-/// CheckInfo c'tor
+/// operator<<(Position) returns an ASCII representation of the position
+
+std::ostream& operator<<(std::ostream& os, const Position& pos) {
-CheckInfo::CheckInfo(const Position& pos) {
+ os << "\n +---+---+---+---+---+---+---+---+\n";
- Color them = ~pos.side_to_move();
- ksq = pos.king_square(them);
+ 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";
+ }
- pinned = pos.pinned_pieces(pos.side_to_move());
- dcCandidates = pos.discovered_check_candidates();
+ os << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase
+ << std::setfill('0') << std::setw(16) << pos.key()
+ << std::setfill(' ') << std::dec << "\nCheckers: ";
- checkSq[PAWN] = pos.attacks_from<PAWN>(ksq, them);
- checkSq[KNIGHT] = pos.attacks_from<KNIGHT>(ksq);
- checkSq[BISHOP] = pos.attacks_from<BISHOP>(ksq);
- checkSq[ROOK] = pos.attacks_from<ROOK>(ksq);
- checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK];
- checkSq[KING] = 0;
+ for (Bitboard b = pos.checkers(); b; )
+ os << UCI::square(pop_lsb(&b)) << " ";
+
+ if ( int(Tablebases::MaxCardinality) >= popcount(pos.pieces())
+ && !pos.can_castle(ANY_CASTLING))
+ {
+ StateInfo st;
+ Position p;
+ p.set(pos.fen(), pos.is_chess960(), &st, pos.this_thread());
+ Tablebases::ProbeState s1, s2;
+ Tablebases::WDLScore wdl = Tablebases::probe_wdl(p, &s1);
+ int dtz = Tablebases::probe_dtz(p, &s2);
+ os << "\nTablebases WDL: " << std::setw(4) << wdl << " (" << s1 << ")"
+ << "\nTablebases DTZ: " << std::setw(4) << dtz << " (" << s2 << ")";
+ }
+
+ return os;
}
+// Marcel van Kervinck's cuckoo algorithm for fast detection of "upcoming repetition"
+// situations. Description of the algorithm in the following paper:
+// https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf
+
+// First and second hash functions for indexing the cuckoo tables
+inline int H1(Key h) { return h & 0x1fff; }
+inline int H2(Key h) { return (h >> 16) & 0x1fff; }
+
+// Cuckoo tables with Zobrist hashes of valid reversible moves, and the moves themselves
+Key cuckoo[8192];
+Move cuckooMove[8192];
+
+
/// Position::init() initializes at startup the various arrays used to compute
-/// hash keys and the piece square tables. The latter is a two-step operation:
-/// First, the white halves of the tables are copied from PSQT[] tables. Second,
-/// the black halves of the tables are initialized by flipping and changing the
-/// sign of the white scores.
+/// hash keys.
void Position::init() {
- RKISS rk;
+ 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] = rk.rand<Key>();
+ for (Piece pc : Pieces)
+ for (Square s = SQ_A1; s <= SQ_H8; ++s)
+ Zobrist::psq[pc][s] = rng.rand<Key>();
for (File f = FILE_A; f <= FILE_H; ++f)
- Zobrist::enpassant[f] = rk.rand<Key>();
+ Zobrist::enpassant[f] = rng.rand<Key>();
- for (int cr = CASTLES_NONE; cr <= ALL_CASTLES; ++cr)
+ for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr)
{
+ Zobrist::castling[cr] = 0;
Bitboard b = cr;
while (b)
{
- Key k = Zobrist::castle[1ULL << pop_lsb(&b)];
- Zobrist::castle[cr] ^= k ? k : rk.rand<Key>();
+ Key k = Zobrist::castling[1ULL << pop_lsb(&b)];
+ Zobrist::castling[cr] ^= k ? k : rng.rand<Key>();
}
}
- Zobrist::side = rk.rand<Key>();
- Zobrist::exclusion = rk.rand<Key>();
-
- for (PieceType pt = PAWN; pt <= KING; ++pt)
- {
- PieceValue[MG][make_piece(BLACK, pt)] = PieceValue[MG][pt];
- PieceValue[EG][make_piece(BLACK, pt)] = PieceValue[EG][pt];
-
- Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]);
-
- for (Square s = SQ_A1; s <= SQ_H8; ++s)
- {
- psq[WHITE][pt][ s] = (v + PSQT[pt][s]);
- psq[BLACK][pt][~s] = -(v + PSQT[pt][s]);
- }
- }
-}
-
-
-/// Position::operator=() creates a copy of 'pos'. We want the new born Position
-/// object do not depend on any external data so we detach state pointer from
-/// the source one.
-
-Position& Position::operator=(const Position& pos) {
-
- std::memcpy(this, &pos, sizeof(Position));
- startState = *st;
- st = &startState;
- nodes = 0;
-
- assert(pos_is_ok());
-
- return *this;
+ Zobrist::side = rng.rand<Key>();
+ Zobrist::noPawns = rng.rand<Key>();
+
+ // Prepare the cuckoo tables
+ std::memset(cuckoo, 0, sizeof(cuckoo));
+ std::memset(cuckooMove, 0, sizeof(cuckooMove));
+ int count = 0;
+ for (Piece pc : Pieces)
+ for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
+ for (Square s2 = Square(s1 + 1); s2 <= SQ_H8; ++s2)
+ if (PseudoAttacks[type_of(pc)][s1] & s2)
+ {
+ Move move = make_move(s1, s2);
+ Key key = Zobrist::psq[pc][s1] ^ Zobrist::psq[pc][s2] ^ Zobrist::side;
+ int i = H1(key);
+ while (true)
+ {
+ std::swap(cuckoo[i], key);
+ std::swap(cuckooMove[i], move);
+ if (move == MOVE_NONE) // Arrived at empty slot?
+ break;
+ i = (i == H1(key)) ? H2(key) : H1(key); // Push victim to alternative slot
+ }
+ count++;
+ }
+ assert(count == 3668);
}
/// 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::set(const string& fenStr, bool isChess960, Thread* th) {
+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.
4) En passant target square (in algebraic notation). If there's no en passant
target square, this is "-". If a pawn has just made a 2-square move, this
- is the position "behind" the pawn. This is recorded regardless of whether
- there is a pawn in position to make an en passant capture.
+ is the position "behind" the pawn. This is recorded only if there is a pawn
+ in position to make an en passant capture, and if there really is a pawn
+ that might have advanced two squares.
5) Halfmove clock. This is the number of halfmoves since the last pawn advance
or capture. This is used to determine if a draw can be claimed under the
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);
- clear();
+ std::memset(this, 0, sizeof(Position));
+ std::memset(si, 0, sizeof(StateInfo));
+ std::fill_n(&pieceList[0][0], sizeof(pieceList) / sizeof(Square), SQ_NONE);
+ st = si;
+
ss >> std::noskipws;
// 1. Piece placement
while ((ss >> token) && !isspace(token))
{
if (isdigit(token))
- sq += Square(token - '0'); // Advance the given number of files
+ sq += (token - '0') * EAST; // Advance the given number of files
else if (token == '/')
- sq -= Square(16);
+ sq += 2 * SOUTH;
- else if ((p = PieceToChar.find(token)) != string::npos)
+ else if ((idx = PieceToChar.find(token)) != string::npos)
{
- put_piece(sq, color_of(Piece(p)), type_of(Piece(p)));
+ put_piece(Piece(idx), sq);
++sq;
}
}
{
Square rsq;
Color c = islower(token) ? BLACK : WHITE;
+ Piece rook = make_piece(c, ROOK);
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); 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); 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)))
+ if ( !(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))
+ || !(pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove))))
st->epSquare = SQ_NONE;
}
+ else
+ st->epSquare = SQ_NONE;
// 5-6. Halfmove clock and fullmove number
ss >> std::skipws >> st->rule50 >> gamePly;
- // Convert from fullmove starting from 1 to ply starting from 0,
+ // Convert from fullmove starting from 1 to gamePly 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->psq = compute_psq_score();
- st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
- st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
+ 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
+/// 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) {
-
- Square kfrom = king_square(c);
- CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE;
- CastleRight cr = make_castle_right(c, cs);
+void Position::set_castling_right(Color c, Square rfrom) {
- st->castleRights |= cr;
- castleRightsMask[kfrom] |= cr;
- castleRightsMask[rfrom] |= cr;
- castleRookSquare[c][cs] = rfrom;
+ Square kfrom = square<KING>(c);
+ CastlingRights cr = c & (kfrom < rfrom ? KING_SIDE: QUEEN_SIDE);
- 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->castlingRights |= cr;
+ castlingRightsMask[kfrom] |= cr;
+ castlingRightsMask[rfrom] |= cr;
+ castlingRookSquare[cr] = rfrom;
- for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s)
- if (s != kfrom && s != rfrom)
- castlePath[c][cs] |= s;
+ Square kto = relative_square(c, cr & KING_SIDE ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(c, cr & KING_SIDE ? SQ_F1 : SQ_D1);
- for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s)
- if (s != kfrom && s != rfrom)
- castlePath[c][cs] |= s;
+ castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto)
+ & ~(square_bb(kfrom) | rfrom);
}
-/// 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_check_info() sets king attacks to detect if a move gives check
-const string Position::fen() const {
+void Position::set_check_info(StateInfo* si) const {
- std::ostringstream ss;
+ si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square<KING>(WHITE), si->pinners[BLACK]);
+ si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square<KING>(BLACK), si->pinners[WHITE]);
- for (Rank rank = RANK_8; rank >= RANK_1; --rank)
- {
- for (File file = FILE_A; file <= FILE_H; ++file)
- {
- Square sq = file | rank;
+ Square ksq = square<KING>(~sideToMove);
- if (empty(sq))
- {
- int emptyCnt = 1;
+ si->checkSquares[PAWN] = attacks_from<PAWN>(ksq, ~sideToMove);
+ si->checkSquares[KNIGHT] = attacks_from<KNIGHT>(ksq);
+ si->checkSquares[BISHOP] = attacks_from<BISHOP>(ksq);
+ si->checkSquares[ROOK] = attacks_from<ROOK>(ksq);
+ si->checkSquares[QUEEN] = si->checkSquares[BISHOP] | si->checkSquares[ROOK];
+ si->checkSquares[KING] = 0;
+}
- for ( ; file < FILE_H && empty(++sq); ++file)
- ++emptyCnt;
- ss << emptyCnt;
- }
- else
- ss << PieceToChar[piece_on(sq)];
- }
+/// 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)
- ss << '/';
- }
+void Position::set_state(StateInfo* si) const {
- ss << (sideToMove == WHITE ? " w " : " b ");
+ si->key = si->materialKey = 0;
+ si->pawnKey = Zobrist::noPawns;
+ si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO;
+ si->checkersBB = attackers_to(square<KING>(sideToMove)) & pieces(~sideToMove);
- if (can_castle(WHITE_OO))
- ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE)), false) : 'K');
+ set_check_info(si);
- if (can_castle(WHITE_OOO))
- ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE)), false) : 'Q');
+ for (Bitboard b = pieces(); b; )
+ {
+ Square s = pop_lsb(&b);
+ Piece pc = piece_on(s);
+ si->key ^= Zobrist::psq[pc][s];
- if (can_castle(BLACK_OO))
- ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE)), true) : 'k');
+ if (type_of(pc) == PAWN)
+ si->pawnKey ^= Zobrist::psq[pc][s];
- if (can_castle(BLACK_OOO))
- ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE)), true) : 'q');
+ else if (type_of(pc) != KING)
+ si->nonPawnMaterial[color_of(pc)] += PieceValue[MG][pc];
+ }
- if (st->castleRights == CASTLES_NONE)
- ss << '-';
+ if (si->epSquare != SQ_NONE)
+ si->key ^= Zobrist::enpassant[file_of(si->epSquare)];
- ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ")
- << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2;
+ if (sideToMove == BLACK)
+ si->key ^= Zobrist::side;
- return ss.str();
+ si->key ^= Zobrist::castling[si->castlingRights];
+
+ for (Piece pc : Pieces)
+ for (int cnt = 0; cnt < pieceCount[pc]; ++cnt)
+ si->materialKey ^= Zobrist::psq[pc][cnt];
}
-/// Position::pretty() returns an ASCII representation of the position to be
-/// printed to the standard output together with the move's san notation.
+/// Position::set() is an overload to initialize the position object with
+/// the given endgame code string like "KBPKN". It is mainly a helper to
+/// get the material key out of an endgame code.
-const string Position::pretty(Move move) const {
+Position& Position::set(const string& code, Color c, StateInfo* si) {
- const string dottedLine = "\n+---+---+---+---+---+---+---+---+";
- const string twoRows = dottedLine + "\n| | . | | . | | . | | . |"
- + dottedLine + "\n| . | | . | | . | | . | |";
+ assert(code.length() > 0 && code.length() < 8);
+ assert(code[0] == 'K');
- string brd = twoRows + twoRows + twoRows + twoRows + dottedLine;
+ string sides[] = { code.substr(code.find('K', 1)), // Weak
+ code.substr(0, code.find('K', 1)) }; // Strong
- for (Bitboard b = pieces(); b; )
- {
- Square s = pop_lsb(&b);
- brd[513 - 68 * rank_of(s) + 4 * file_of(s)] = PieceToChar[piece_on(s)];
- }
+ std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower);
- std::ostringstream ss;
+ string fenStr = "8/" + sides[0] + char(8 - sides[0].length() + '0') + "/8/8/8/8/"
+ + sides[1] + char(8 - sides[1].length() + '0') + "/8 w - - 0 10";
- if (move)
- ss << "\nMove: " << (sideToMove == BLACK ? ".." : "")
- << move_to_san(*const_cast<Position*>(this), move);
+ return set(fenStr, false, si, nullptr);
+}
- 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)) << " ";
+/// 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.
- ss << "\nLegal moves: ";
- for (MoveList<LEGAL> it(*this); *it; ++it)
- ss << move_to_san(*const_cast<Position*>(this), *it) << " ";
+const string Position::fen() const {
- return ss.str();
-}
+ int emptyCnt;
+ std::ostringstream ss;
+ for (Rank r = RANK_8; r >= RANK_1; --r)
+ {
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ {
+ for (emptyCnt = 0; f <= FILE_H && empty(make_square(f, r)); ++f)
+ ++emptyCnt;
-/// Position:hidden_checkers() returns a bitboard of all pinned / discovery check
-/// pieces, according to the call parameters. Pinned pieces protect our king,
-/// discovery check pieces attack the enemy king.
+ if (emptyCnt)
+ ss << emptyCnt;
-Bitboard Position::hidden_checkers(Square ksq, Color c, Color toMove) const {
+ if (f <= FILE_H)
+ ss << PieceToChar[piece_on(make_square(f, r))];
+ }
- Bitboard b, pinners, result = 0;
+ if (r > RANK_1)
+ ss << '/';
+ }
- // Pinners are sliders that give check when pinned piece is removed
- pinners = ( (pieces( ROOK, QUEEN) & PseudoAttacks[ROOK ][ksq])
- | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(c);
+ ss << (sideToMove == WHITE ? " w " : " b ");
- while (pinners)
- {
- b = between_bb(ksq, pop_lsb(&pinners)) & pieces();
+ if (can_castle(WHITE_OO))
+ ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OO ))) : 'K');
- if (!more_than_one(b))
- result |= b & pieces(toMove);
- }
- return result;
-}
+ if (can_castle(WHITE_OOO))
+ ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OOO))) : 'Q');
+ if (can_castle(BLACK_OO))
+ ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OO ))) : 'k');
-/// Position::attackers_to() computes a bitboard of all pieces which attack a
-/// given square. Slider attacks use occ bitboard as occupancy.
+ if (can_castle(BLACK_OOO))
+ ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OOO))) : 'q');
+
+ if (!can_castle(ANY_CASTLING))
+ 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<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 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::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.
+
+Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const {
-Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) {
+ Bitboard blockers = 0;
+ pinners = 0;
- assert(is_ok(s));
+ // Snipers are sliders that attack 's' when a piece and other snipers are removed
+ Bitboard snipers = ( (PseudoAttacks[ ROOK][s] & pieces(QUEEN, ROOK))
+ | (PseudoAttacks[BISHOP][s] & pieces(QUEEN, BISHOP))) & sliders;
+ Bitboard occupancy = pieces() ^ snipers;
- switch (type_of(p))
+ while (snipers)
{
- 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];
+ Square sniperSq = pop_lsb(&snipers);
+ Bitboard b = between_bb(s, sniperSq) & occupancy;
+
+ if (b && !more_than_one(b))
+ {
+ blockers |= b;
+ if (b & pieces(color_of(piece_on(s))))
+ pinners |= sniperSq;
+ }
}
+ return blockers;
+}
+
+
+/// Position::attackers_to() computes a bitboard of all pieces which attack a
+/// given square. Slider attacks use the occupied bitboard to indicate occupancy.
+
+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, occupied) & pieces( ROOK, QUEEN))
+ | (attacks_bb<BISHOP>(s, occupied) & pieces(BISHOP, QUEEN))
+ | (attacks_from<KING>(s) & pieces(KING));
}
/// Position::legal() tests whether a pseudo-legal move is legal
-bool Position::legal(Move m, Bitboard pinned) const {
+bool Position::legal(Move m) const {
assert(is_ok(m));
- assert(pinned == pinned_pieces(pos.side_to_move()));
Color us = sideToMove;
Square from = from_sq(m);
+ Square to = to_sq(m);
assert(color_of(moved_piece(m)) == us);
- assert(piece_on(king_square(us)) == make_piece(us, KING));
+ assert(piece_on(square<KING>(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 (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 ksq = square<KING>(us);
+ Square capsq = to - pawn_push(us);
+ Bitboard occupied = (pieces() ^ from ^ capsq) | to;
assert(to == ep_square());
assert(moved_piece(m) == make_piece(us, PAWN));
- assert(piece_on(capsq) == make_piece(them, 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));
+ }
+
+ // Castling moves generation does not check if the castling path is clear of
+ // enemy attacks, it is delayed at a later time: now!
+ if (type_of(m) == CASTLING)
+ {
+ // After castling, the rook and king final positions are the same in
+ // Chess960 as they would be in standard chess.
+ to = relative_square(us, to > from ? SQ_G1 : SQ_C1);
+ Direction step = to > from ? WEST : EAST;
+
+ for (Square s = to; s != from; s += step)
+ if (attackers_to(s) & pieces(~us))
+ return false;
+
+ // In case of Chess960, verify that when moving the castling rook we do
+ // not discover some hidden checker.
+ // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
+ return !chess960
+ || !(attacks_bb<ROOK>(to, pieces() ^ to_sq(m)) & pieces(~us, ROOK, QUEEN));
}
- // 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 the moving piece is a king, check whether the destination square is
+ // attacked by the opponent.
if (type_of(piece_on(from)) == KING)
- return type_of(m) == CASTLE || !(attackers_to(to_sq(m)) & pieces(~us));
+ return !(attackers_to(to) & 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));
+ return !(blockers_for_king(us) & from)
+ || aligned(from, to, square<KING>(us));
}
return MoveList<LEGAL>(*this).contains(m);
// Is not a promotion, so promotion piece must be empty
- if (promotion_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;
// 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 (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us)
- return false;
-
- // From and to files must be one file apart, avoids a7h5
- if (abs(file_of(from) - file_of(to)) != 1)
- return false;
- break;
-
- case DELTA_N:
- case DELTA_S:
- // Pawn push. The destination square must be empty.
- if (!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
- || !empty(to)
- || !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
- || !empty(to)
- || !empty(from + DELTA_S))
+ // cannot be on the 8th/1st rank.
+ if ((Rank8BB | Rank1BB) & to)
return false;
- break;
- default:
+ if ( !(attacks_from<PAWN>(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;
- }
}
- else if (!(attacks_from(pc, from) & to))
+ else if (!(attacks_from(type_of(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)
return false;
// Our move must be a blocking evasion or a capture of the checking piece
- if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to))
+ if (!((between_bb(lsb(checkers()), square<KING>(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::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(moved_piece(m)) == sideToMove);
Square from = from_sq(m);
Square to = to_sq(m);
- PieceType pt = type_of(piece_on(from));
- // Direct check ?
- if (ci.checkSq[pt] & to)
+ // Is there a direct check?
+ if (st->checkSquares[type_of(piece_on(from))] & to)
return true;
- // Discovery check ?
- if (unlikely(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 ( (st->blockersForKing[~sideToMove] & from)
+ && !aligned(from, to, square<KING>(~sideToMove)))
+ 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(promotion_type(m), to, pieces() ^ from) & square<KING>(~sideToMove);
- // 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>(square<KING>(~sideToMove), b) & pieces(sideToMove, QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(square<KING>(~sideToMove), 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);
+ 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 (PseudoAttacks[ROOK][rto] & ksq)
- && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ksq);
+ return (PseudoAttacks[ROOK][rto] & square<KING>(~sideToMove))
+ && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square<KING>(~sideToMove));
}
default:
assert(false);
/// 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, 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 going to be recalculated from scratch anyway, then switch our state
- // pointer to point to the new, ready to be updated, state.
- std::memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t));
+ thisThread->nodes.fetch_add(1, std::memory_order_relaxed);
+ 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 ^= 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;
Square from = from_sq(m);
Square to = to_sq(m);
Piece pc = piece_on(from);
- PieceType pt = type_of(pc);
- PieceType captured = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to));
+ Piece captured = type_of(m) == ENPASSANT ? make_piece(them, PAWN) : piece_on(to);
assert(color_of(pc) == us);
- assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLE);
- assert(captured != KING);
+ assert(captured == NO_PIECE || color_of(captured) == (type_of(m) != CASTLING ? them : us));
+ assert(type_of(captured) != KING);
- if (type_of(m) == CASTLE)
+ if (type_of(m) == CASTLING)
{
assert(pc == make_piece(us, KING));
+ assert(captured == make_piece(us, ROOK));
- 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);
- captured = NO_PIECE_TYPE;
-
- do_castle(from, to, rfrom, rto);
+ Square rfrom, rto;
+ do_castling<true>(us, from, to, rfrom, rto);
- st->psq += psq[us][ROOK][rto] - psq[us][ROOK][rfrom];
- k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto];
+ k ^= Zobrist::psq[captured][rfrom] ^ Zobrist::psq[captured][rto];
+ captured = NO_PIECE;
}
if (captured)
// If the captured piece is a pawn, update pawn hash key, otherwise
// update non-pawn material.
- if (captured == PAWN)
+ if (type_of(captured) == PAWN)
{
if (type_of(m) == ENPASSANT)
{
- capsq += pawn_push(them);
+ capsq -= pawn_push(us);
- assert(pt == PAWN);
+ assert(pc == make_piece(us, PAWN));
assert(to == st->epSquare);
assert(relative_rank(us, to) == RANK_6);
assert(piece_on(to) == NO_PIECE);
assert(piece_on(capsq) == make_piece(them, PAWN));
- board[capsq] = NO_PIECE;
+ board[capsq] = NO_PIECE; // Not done by remove_piece()
}
- st->pawnKey ^= Zobrist::psq[them][PAWN][capsq];
+ st->pawnKey ^= Zobrist::psq[captured][capsq];
}
else
- st->npMaterial[them] -= PieceValue[MG][captured];
+ st->nonPawnMaterial[them] -= PieceValue[MG][captured];
// Update board and piece lists
- remove_piece(capsq, them, captured);
+ remove_piece(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((char*)thisThread->materialTable[st->materialKey]);
-
- // Update incremental scores
- st->psq -= psq[them][captured][capsq];
+ k ^= Zobrist::psq[captured][capsq];
+ st->materialKey ^= Zobrist::psq[captured][pieceCount[captured]];
+ prefetch(thisThread->materialTable[st->materialKey]);
// Reset rule 50 counter
st->rule50 = 0;
}
// Update hash key
- k ^= Zobrist::psq[us][pt][from] ^ Zobrist::psq[us][pt][to];
+ k ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
// Reset en passant square
if (st->epSquare != SQ_NONE)
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)
- move_piece(from, to, us, pt);
+ // Move the piece. The tricky Chess960 castling is handled earlier
+ if (type_of(m) != CASTLING)
+ move_piece(pc, from, to);
// If the moving piece is a pawn do some special extra work
- if (pt == PAWN)
+ if (type_of(pc) == 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)))
+ && (attacks_from<PAWN>(to - pawn_push(us), us) & pieces(them, PAWN)))
{
- st->epSquare = Square((from + to) / 2);
+ st->epSquare = to - pawn_push(us);
k ^= Zobrist::enpassant[file_of(st->epSquare)];
}
- if (type_of(m) == PROMOTION)
+ else if (type_of(m) == PROMOTION)
{
- PieceType promotion = promotion_type(m);
+ Piece promotion = make_piece(us, promotion_type(m));
assert(relative_rank(us, to) == RANK_8);
- assert(promotion >= KNIGHT && promotion <= QUEEN);
+ assert(type_of(promotion) >= KNIGHT && type_of(promotion) <= QUEEN);
- remove_piece(to, us, PAWN);
- put_piece(to, us, promotion);
+ remove_piece(pc, to);
+ put_piece(promotion, to);
// Update hash keys
- k ^= Zobrist::psq[us][PAWN][to] ^ Zobrist::psq[us][promotion][to];
- st->pawnKey ^= Zobrist::psq[us][PAWN][to];
- st->materialKey ^= Zobrist::psq[us][promotion][pieceCount[us][promotion]-1]
- ^ Zobrist::psq[us][PAWN][pieceCount[us][PAWN]];
-
- // Update incremental score
- st->psq += psq[us][promotion][to] - psq[us][PAWN][to];
+ k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[promotion][to];
+ st->pawnKey ^= Zobrist::psq[pc][to];
+ st->materialKey ^= Zobrist::psq[promotion][pieceCount[promotion]-1]
+ ^ Zobrist::psq[pc][pieceCount[pc]];
// Update material
- st->npMaterial[us] += PieceValue[MG][promotion];
+ st->nonPawnMaterial[us] += PieceValue[MG][promotion];
}
// Update pawn hash key and prefetch access to pawnsTable
- st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to];
- prefetch((char*)thisThread->pawnsTable[st->pawnKey]);
+ st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
// Reset rule 50 draw counter
st->rule50 = 0;
}
- // Update incremental scores
- st->psq += psq[us][pt][to] - psq[us][pt][from];
-
// Set capture piece
- st->capturedType = captured;
+ st->capturedPiece = 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<KING>(them)) & pieces(us) : 0;
- if (moveIsCheck)
+ sideToMove = ~sideToMove;
+
+ // Update king attacks used for fast check detection
+ set_check_info(st);
+
+ // Calculate the repetition info. It is the ply distance from the previous
+ // occurrence of the same position, negative in the 3-fold case, or zero
+ // if the position was not repeated.
+ st->repetition = 0;
+ int end = std::min(st->rule50, st->pliesFromNull);
+ if (end >= 4)
{
- if (type_of(m) != NORMAL)
- st->checkersBB = attackers_to(king_square(them)) & pieces(us);
- else
+ StateInfo* stp = st->previous->previous;
+ for (int i = 4; i <= end; i += 2)
{
- // Direct checks
- if (ci.checkSq[pt] & to)
- st->checkersBB |= to;
-
- // Discovery checks
- if (ci.dcCandidates && (ci.dcCandidates & from))
+ stp = stp->previous->previous;
+ if (stp->key == st->key)
{
- if (pt != ROOK)
- st->checkersBB |= attacks_from<ROOK>(king_square(them)) & pieces(us, QUEEN, ROOK);
-
- if (pt != BISHOP)
- st->checkersBB |= attacks_from<BISHOP>(king_square(them)) & pieces(us, QUEEN, BISHOP);
+ st->repetition = stp->repetition ? -i : i;
+ break;
}
}
}
- sideToMove = ~sideToMove;
-
assert(pos_is_ok());
}
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 captured = st->capturedType;
+ Piece pc = piece_on(to);
- assert(empty(from) || type_of(m) == CASTLE);
- assert(captured != KING);
+ assert(empty(from) || type_of(m) == CASTLING);
+ assert(type_of(st->capturedPiece) != KING);
if (type_of(m) == PROMOTION)
{
- PieceType promotion = promotion_type(m);
-
- assert(promotion == pt);
assert(relative_rank(us, to) == RANK_8);
- assert(promotion >= KNIGHT && promotion <= QUEEN);
+ assert(type_of(pc) == promotion_type(m));
+ assert(type_of(pc) >= KNIGHT && type_of(pc) <= QUEEN);
- remove_piece(to, us, promotion);
- put_piece(to, us, PAWN);
- pt = PAWN;
+ remove_piece(pc, to);
+ pc = make_piece(us, PAWN);
+ put_piece(pc, to);
}
- 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);
- captured = NO_PIECE_TYPE;
- pt = KING;
- do_castle(to, from, rto, rfrom);
+ Square rfrom, rto;
+ do_castling<false>(us, from, to, rfrom, rto);
}
else
- move_piece(to, from, us, pt); // Put the piece back at the source square
-
- if (captured)
{
- Square capsq = to;
+ move_piece(pc, to, from); // Put the piece back at the source square
- if (type_of(m) == ENPASSANT)
+ if (st->capturedPiece)
{
- 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);
- }
+ if (type_of(m) == ENPASSANT)
+ {
+ capsq -= pawn_push(us);
- put_piece(capsq, them, captured); // Restore the captured piece
+ assert(type_of(pc) == PAWN);
+ assert(to == st->previous->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(capsq) == NO_PIECE);
+ assert(st->capturedPiece == make_piece(~us, PAWN));
+ }
+
+ put_piece(st->capturedPiece, capsq); // Restore the captured piece
+ }
}
// Finally point our state pointer back to the previous state
}
-/// Position::do_castle() is a helper used to do/undo a castling move. This
-/// is a bit tricky, especially in Chess960.
+/// Position::do_castling() is a helper used to do/undo a castling move. This
+/// is a bit tricky in Chess960 where from/to squares can overlap.
+template<bool Do>
+void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto) {
-void Position::do_castle(Square kfrom, Square kto, 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(kfrom, sideToMove, KING);
- remove_piece(rfrom, sideToMove, ROOK);
- board[kfrom] = board[rfrom] = NO_PIECE; // Since remove_piece doesn't do it for us
- put_piece(kto, sideToMove, KING);
- put_piece(rto, sideToMove, ROOK);
+ remove_piece(make_piece(us, KING), Do ? from : to);
+ remove_piece(make_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(make_piece(us, KING), Do ? to : from);
+ put_piece(make_piece(us, ROOK), Do ? rto : rfrom);
}
void Position::do_null_move(StateInfo& newSt) {
assert(!checkers());
+ assert(&newSt != st);
- std::memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here
-
+ std::memcpy(&newSt, st, sizeof(StateInfo));
newSt.previous = st;
st = &newSt;
}
st->key ^= Zobrist::side;
- prefetch((char*)TT.first_entry(st->key));
+ prefetch(TT.first_entry(st->key));
++st->rule50;
st->pliesFromNull = 0;
sideToMove = ~sideToMove;
+ set_check_info(st);
+
+ st->repetition = 0;
+
assert(pos_is_ok());
}
}
-/// 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.
+/// 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.
-int Position::see_sign(Move m) const {
+Key Position::key_after(Move m) const {
- assert(is_ok(m));
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ Piece pc = piece_on(from);
+ Piece captured = piece_on(to);
+ Key k = st->key ^ Zobrist::side;
- // 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][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))])
- return 1;
+ if (captured)
+ k ^= Zobrist::psq[captured][to];
- return see(m);
+ return k ^ Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from];
}
-int Position::see(Move m, int asymmThreshold) const {
-
- Square from, to;
- Bitboard occupied, attackers, stmAttackers;
- int swapList[32], slIndex = 1;
- PieceType captured;
- Color stm;
-
- assert(is_ok(m));
-
- from = from_sq(m);
- to = to_sq(m);
- swapList[0] = PieceValue[MG][piece_on(to)];
- stm = color_of(piece_on(from));
- occupied = pieces() ^ from;
-
- // Castle moves are implemented as king capturing the rook so cannot be
- // handled correctly. Simply return 0 that is always the correct value
- // unless in the rare case the rook ends up under attack.
- if (type_of(m) == CASTLE)
- return 0;
- if (type_of(m) == ENPASSANT)
- {
- 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.
- attackers = attackers_to(to, occupied) & occupied;
-
- // If the opponent has no attackers we are finished
- stm = ~stm;
- stmAttackers = attackers & pieces(stm);
- if (!stmAttackers)
- 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
- // the material gain or loss at each stop in a sequence of captures to the
- // 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.
- captured = type_of(piece_on(from));
-
- do {
- assert(slIndex < 32);
-
- // Add the new entry to the swap list
- swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
- ++slIndex;
-
- // Locate and remove the next least valuable attacker
- captured = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
- stm = ~stm;
- stmAttackers = attackers & pieces(stm);
-
- // Stop before processing a king capture
- if (captured == KING && stmAttackers)
- {
- swapList[slIndex++] = QueenValueMg * 16;
- break;
- }
-
- } while (stmAttackers);
+/// Position::see_ge (Static Exchange Evaluation Greater or Equal) tests if the
+/// SEE value of move is greater or equal to the given threshold. We'll use an
+/// algorithm similar to alpha-beta pruning with a null window.
- // 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;
+bool Position::see_ge(Move m, Value threshold) const {
- // 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]);
-
- return swapList[0];
-}
-
-
-/// Position::clear() erases the position object to a pristine state, with an
-/// empty board, white to move, and no castling rights.
+ assert(is_ok(m));
-void Position::clear() {
+ // Only deal with normal moves, assume others pass a simple see
+ if (type_of(m) != NORMAL)
+ return VALUE_ZERO >= threshold;
- std::memset(this, 0, sizeof(Position));
- startState.epSquare = SQ_NONE;
- st = &startState;
+ Bitboard stmAttackers;
+ Square from = from_sq(m), to = to_sq(m);
+ PieceType nextVictim = type_of(piece_on(from));
+ Color us = color_of(piece_on(from));
+ Color stm = ~us; // First consider opponent's move
+ Value balance; // Values of the pieces taken by us minus opponent's ones
- 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;
-}
+ // The opponent may be able to recapture so this is the best result
+ // we can hope for.
+ balance = PieceValue[MG][piece_on(to)] - threshold;
+ if (balance < VALUE_ZERO)
+ return false;
-/// 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.
+ // Now assume the worst possible result: that the opponent can
+ // capture our piece for free.
+ balance -= PieceValue[MG][nextVictim];
-Key Position::compute_key() const {
+ // If it is enough (like in PxQ) then return immediately. Note that
+ // in case nextVictim == KING we always return here, this is ok
+ // if the given move is legal.
+ if (balance >= VALUE_ZERO)
+ return true;
- Key k = Zobrist::castle[st->castleRights];
+ // Find all attackers to the destination square, with the moving piece
+ // removed, but possibly an X-ray attacker added behind it.
+ Bitboard occupied = pieces() ^ from ^ to;
+ Bitboard attackers = attackers_to(to, occupied) & occupied;
- for (Bitboard b = pieces(); b; )
+ while (true)
{
- 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())];
+ stmAttackers = attackers & pieces(stm);
- if (sideToMove == BLACK)
- k ^= Zobrist::side;
+ // Don't allow pinned pieces to attack (except the king) as long as
+ // any pinners are on their original square.
+ if (st->pinners[~stm] & occupied)
+ stmAttackers &= ~st->blockersForKing[stm];
- return k;
-}
+ // If stm has no more attackers then give up: stm loses
+ if (!stmAttackers)
+ break;
+ // Locate and remove the next least valuable attacker, and add to
+ // the bitboard 'attackers' the possibly X-ray attackers behind it.
+ nextVictim = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
-/// 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.
+ stm = ~stm; // Switch side to move
-Key Position::compute_pawn_key() const {
+ // Negamax the balance with alpha = balance, beta = balance+1 and
+ // add nextVictim's value.
+ //
+ // (balance, balance+1) -> (-balance-1, -balance)
+ //
+ assert(balance < VALUE_ZERO);
- Key k = 0;
+ balance = -balance - 1 - PieceValue[MG][nextVictim];
- for (Bitboard b = pieces(PAWN); b; )
- {
- Square s = pop_lsb(&b);
- k ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s];
+ // If balance is still non-negative after giving away nextVictim then we
+ // win. The only thing to be careful about it is that we should revert
+ // stm if we captured with the king when the opponent still has attackers.
+ if (balance >= VALUE_ZERO)
+ {
+ if (nextVictim == KING && (attackers & pieces(stm)))
+ stm = ~stm;
+ break;
+ }
+ assert(nextVictim != KING);
}
-
- return k;
+ return us != stm; // We break the above loop when stm loses
}
-/// 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.
+/// Position::is_draw() tests whether the position is drawn by 50-move rule
+/// or by repetition. It does not detect stalemates.
-Key Position::compute_material_key() const {
+bool Position::is_draw(int ply) const {
- Key k = 0;
+ if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
+ return true;
- for (Color c = WHITE; c <= BLACK; ++c)
- for (PieceType pt = PAWN; pt <= QUEEN; ++pt)
- for (int cnt = 0; cnt < pieceCount[c][pt]; ++cnt)
- k ^= Zobrist::psq[c][pt][cnt];
+ // Return a draw score if a position repeats once earlier but strictly
+ // after the root, or repeats twice before or at the root.
+ if (st->repetition && st->repetition < ply)
+ return true;
- return k;
+ return false;
}
-/// 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 {
+// Position::has_repeated() tests whether there has been at least one repetition
+// of positions since the last capture or pawn move.
- Score score = SCORE_ZERO;
+bool Position::has_repeated() const {
- for (Bitboard b = pieces(); b; )
- {
- Square s = pop_lsb(&b);
- Piece pc = piece_on(s);
- score += psq[color_of(pc)][type_of(pc)][s];
- }
+ StateInfo* stc = st;
+ int end = std::min(st->rule50, st->pliesFromNull);
+ while (end-- >= 4)
+ {
+ if (stc->repetition)
+ return true;
- return score;
+ stc = stc->previous;
+ }
+ 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.
+/// Position::has_game_cycle() tests if the position has a move which draws by repetition,
+/// or an earlier position has a move that directly reaches the current position.
-Value Position::compute_non_pawn_material(Color c) const {
+bool Position::has_game_cycle(int ply) const {
- Value value = VALUE_ZERO;
+ int j;
- for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt)
- value += pieceCount[c][pt] * PieceValue[MG][pt];
-
- return value;
-}
-
-
-/// Position::is_draw() tests whether the position is drawn by material,
-/// repetition, or the 50 moves rule. It does not detect stalemates, this
-/// must be done by the search.
-bool Position::is_draw() const {
-
- // Draw by material?
- if ( !pieces(PAWN)
- && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMg))
- return true;
+ int end = std::min(st->rule50, st->pliesFromNull);
- // Draw by the 50 moves rule?
- if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
- return true;
+ if (end < 3)
+ return false;
- int i = 4, e = std::min(st->rule50, st->pliesFromNull);
+ Key originalKey = st->key;
+ StateInfo* stp = st->previous;
- if (i <= e)
+ for (int i = 3; i <= end; i += 2)
{
- StateInfo* stp = st->previous->previous;
-
- do {
- stp = stp->previous->previous;
+ stp = stp->previous->previous;
- if (stp->key == st->key)
- return true; // Draw after first repetition
+ Key moveKey = originalKey ^ stp->key;
+ if ( (j = H1(moveKey), cuckoo[j] == moveKey)
+ || (j = H2(moveKey), cuckoo[j] == moveKey))
+ {
+ Move move = cuckooMove[j];
+ Square s1 = from_sq(move);
+ Square s2 = to_sq(move);
- i += 2;
+ if (!(between_bb(s1, s2) & pieces()))
+ {
+ if (ply > i)
+ return true;
+
+ // For nodes before or at the root, check that the move is a
+ // repetition rather than a move to the current position.
+ // In the cuckoo table, both moves Rc1c5 and Rc5c1 are stored in
+ // the same location, so we have to select which square to check.
+ if (color_of(piece_on(empty(s1) ? s2 : s1)) != side_to_move())
+ continue;
- } while (i <= e);
+ // For repetitions before or at the root, require one more
+ if (stp->repetition)
+ return true;
+ }
+ }
}
-
return false;
}
/// Position::flip() flips position with the white and black sides reversed. This
-/// is only useful for debugging especially for finding evaluation symmetry bugs.
-
-static char toggle_case(char c) {
- return char(islower(c) ? toupper(c) : tolower(c));
-}
+/// is only useful for debugging e.g. for finding evaluation symmetry bugs.
void Position::flip() {
string f, token;
std::stringstream ss(fen());
- for (Rank rank = RANK_8; rank >= RANK_1; --rank) // Piece placement
+ for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement
{
- std::getline(ss, token, rank > RANK_1 ? '/' : ' ');
+ std::getline(ss, token, r > RANK_1 ? '/' : ' ');
f.insert(0, token + (f.empty() ? " " : "/"));
}
ss >> token; // Castling availability
f += token + " ";
- std::transform(f.begin(), f.end(), f.begin(), toggle_case);
+ std::transform(f.begin(), f.end(), f.begin(),
+ [](char c) { return char(islower(c) ? toupper(c) : tolower(c)); });
ss >> token; // En passant square
f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3"));
std::getline(ss, token); // Half and full moves
f += token;
- set(f, is_chess960(), this_thread());
+ 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 and raises an asserts if something wrong is detected.
/// This is meant to be helpful when debugging.
-bool Position::pos_is_ok(int* failedStep) const {
-
- int dummy, *step = failedStep ? failedStep : &dummy;
-
- // What features 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;
+bool Position::pos_is_ok() const {
- 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)
- 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))];
+ constexpr bool Fast = true; // Quick (default) or full check?
- if (kingCount[0] != 1 || kingCount[1] != 1)
- return false;
- }
+ if ( (sideToMove != WHITE && sideToMove != BLACK)
+ || piece_on(square<KING>(WHITE)) != W_KING
+ || piece_on(square<KING>(BLACK)) != B_KING
+ || ( ep_square() != SQ_NONE
+ && relative_rank(sideToMove, ep_square()) != RANK_6))
+ assert(0 && "pos_is_ok: Default");
- if ((*step)++, debugKingCapture)
- if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove))
- return false;
-
- if ((*step)++, debugCheckerCount && popcount<Full>(st->checkersBB) > 2)
- return false;
+ if (Fast)
+ return true;
- if ((*step)++, debugBitboards)
+ if ( pieceCount[W_KING] != 1
+ || pieceCount[B_KING] != 1
+ || attackers_to(square<KING>(~sideToMove)) & pieces(sideToMove))
+ assert(0 && "pos_is_ok: Kings");
+
+ if ( (pieces(PAWN) & (Rank1BB | Rank8BB))
+ || pieceCount[W_PAWN] > 8
+ || pieceCount[B_PAWN] > 8)
+ assert(0 && "pos_is_ok: Pawns");
+
+ if ( (pieces(WHITE) & pieces(BLACK))
+ || (pieces(WHITE) | pieces(BLACK)) != pieces()
+ || popcount(pieces(WHITE)) > 16
+ || popcount(pieces(BLACK)) > 16)
+ assert(0 && "pos_is_ok: Bitboards");
+
+ for (PieceType p1 = PAWN; p1 <= KING; ++p1)
+ for (PieceType p2 = PAWN; p2 <= KING; ++p2)
+ if (p1 != p2 && (pieces(p1) & pieces(p2)))
+ assert(0 && "pos_is_ok: Bitboards");
+
+ StateInfo si = *st;
+ set_state(&si);
+ if (std::memcmp(&si, st, sizeof(StateInfo)))
+ assert(0 && "pos_is_ok: State");
+
+ for (Piece pc : Pieces)
{
- // 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)) != pieces())
- return false;
+ if ( pieceCount[pc] != popcount(pieces(color_of(pc), type_of(pc)))
+ || pieceCount[pc] != std::count(board, board + SQUARE_NB, pc))
+ assert(0 && "pos_is_ok: Pieces");
- // 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;
+ for (int i = 0; i < pieceCount[pc]; ++i)
+ if (board[pieceList[pc][i]] != pc || index[pieceList[pc][i]] != i)
+ assert(0 && "pos_is_ok: Index");
}
- 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->psq != compute_psq_score())
- return false;
-
- if ((*step)++, debugNonPawnMaterial)
- if ( st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)
- || st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
- return false;
-
- if ((*step)++, debugPieceCounts)
- for (Color c = WHITE; c <= BLACK; ++c)
- for (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 ( board[pieceList[c][pt][i]] != make_piece(c, pt)
- || index[pieceList[c][pt][i]] != i)
- return false;
-
- if ((*step)++, debugCastleSquares)
- for (Color c = WHITE; c <= BLACK; ++c)
- for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1))
- {
- CastleRight cr = make_castle_right(c, s);
-
- if (!can_castle(cr))
- continue;
+ for (Color c : { WHITE, BLACK })
+ for (CastlingRights cr : {c & KING_SIDE, c & QUEEN_SIDE})
+ {
+ if (!can_castle(cr))
+ continue;
- if ( (castleRightsMask[king_square(c)] & cr) != cr
- || piece_on(castleRookSquare[c][s]) != make_piece(c, ROOK)
- || castleRightsMask[castleRookSquare[c][s]] != cr)
- return false;
- }
+ if ( piece_on(castlingRookSquare[cr]) != make_piece(c, ROOK)
+ || castlingRightsMask[castlingRookSquare[cr]] != cr
+ || (castlingRightsMask[square<KING>(c)] & cr) != cr)
+ assert(0 && "pos_is_ok: Castling");
+ }
- *step = 0;
return true;
}
projects / stockfish / blobdiff