/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
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> // For std::memset, std::memcmp
+#include <cstddef> // For offsetof()
+#include <cstring> // For std::memset, std::memcmp
#include <iomanip>
#include <sstream>
#include "thread.h"
#include "tt.h"
#include "uci.h"
+#include "syzygy/tbprobe.h"
using std::string;
namespace Zobrist {
- Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+ Key psq[PIECE_NB][SQUARE_NB];
Key enpassant[FILE_NB];
Key castling[CASTLING_RIGHT_NB];
- Key side;
- Key exclusion;
+ Key side, noPawns;
}
-Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion; }
-
namespace {
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<int Pt>
-PieceType min_attacker(const Bitboard* bb, Square to, Bitboard stmAttackers,
- Bitboard& occupied, Bitboard& attackers) {
-
- Bitboard b = stmAttackers & bb[Pt];
- if (!b)
- return min_attacker<Pt+1>(bb, to, stmAttackers, occupied, attackers);
-
- occupied ^= b & ~(b - 1);
-
- if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN)
- attackers |= attacks_bb<BISHOP>(to, occupied) & (bb[BISHOP] | bb[QUEEN]);
-
- if (Pt == ROOK || Pt == QUEEN)
- attackers |= attacks_bb<ROOK>(to, occupied) & (bb[ROOK] | bb[QUEEN]);
-
- attackers &= occupied; // After X-ray that may add already processed pieces
- return (PieceType)Pt;
-}
-
-template<>
-PieceType min_attacker<KING>(const Bitboard*, Square, Bitboard, Bitboard&, Bitboard&) {
- return KING; // No need to update bitboards: it is the last cycle
-}
-
+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 };
} // namespace
for (File f = FILE_A; f <= FILE_H; ++f)
os << " | " << PieceToChar[pos.piece_on(make_square(f, r))];
- os << " |\n +---+---+---+---+---+---+---+---+\n";
+ os << " | " << (1 + r) << "\n +---+---+---+---+---+---+---+---+\n";
}
- os << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase
- << std::setfill('0') << std::setw(16) << pos.key() << std::dec << "\nCheckers: ";
+ os << " a b c d e f g h\n"
+ << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase
+ << std::setfill('0') << std::setw(16) << pos.key()
+ << std::setfill(' ') << std::dec << "\nCheckers: ";
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;
}
-/// Position::init() initializes at startup the various arrays used to compute
-/// hash keys.
+// 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
void Position::init() {
PRNG rng(1070372);
- for (Color c = WHITE; c <= BLACK; ++c)
- for (PieceType pt = PAWN; pt <= KING; ++pt)
- for (Square s = SQ_A1; s <= SQ_H8; ++s)
- Zobrist::psq[c][pt][s] = rng.rand<Key>();
+ for (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] = rng.rand<Key>();
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<Key>();
- }
- }
+ Zobrist::castling[cr] = rng.rand<Key>();
Zobrist::side = rng.rand<Key>();
- Zobrist::exclusion = 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 ((type_of(pc) != PAWN) && (attacks_bb(type_of(pc), s1, 0) & 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);
}
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. Following X-FEN standard, 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
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);
+ std::fill_n(&pieceList[0][0], sizeof(pieceList) / sizeof(Square), SQ_NONE);
st = si;
ss >> std::noskipws;
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 ((idx = PieceToChar.find(token)) != string::npos)
- {
- put_piece(color_of(Piece(idx)), type_of(Piece(idx)), sq);
+ else if ((idx = PieceToChar.find(token)) != string::npos) {
+ put_piece(Piece(idx), sq);
++sq;
}
}
set_castling_right(c, rsq);
}
- // 4. En passant square. Ignore if no pawn capture is possible
+ // 4. En passant square.
+ // Ignore if square is invalid or not on side to move relative rank 6.
+ bool enpassant = false;
+
if ( ((ss >> col) && (col >= 'a' && col <= 'h'))
- && ((ss >> row) && (row == '3' || row == '6')))
+ && ((ss >> row) && (row == (sideToMove == WHITE ? '6' : '3'))))
{
st->epSquare = make_square(File(col - 'a'), Rank(row - '1'));
- if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN)))
- st->epSquare = SQ_NONE;
+ // En passant square will be considered only if
+ // a) side to move have a pawn threatening epSquare
+ // b) there is an enemy pawn in front of epSquare
+ // c) there is no piece on epSquare or behind epSquare
+ enpassant = pawn_attacks_bb(~sideToMove, st->epSquare) & pieces(sideToMove, PAWN)
+ && (pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove)))
+ && !(pieces() & (st->epSquare | (st->epSquare + pawn_push(sideToMove))));
}
- else
+
+ if (!enpassant)
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) + (sideToMove == BLACK);
void Position::set_castling_right(Color c, Square rfrom) {
Square kfrom = square<KING>(c);
- CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE;
- CastlingRight cr = (c | cs);
+ CastlingRights cr = c & (kfrom < rfrom ? KING_SIDE: QUEEN_SIDE);
st->castlingRights |= cr;
castlingRightsMask[kfrom] |= cr;
castlingRightsMask[rfrom] |= cr;
castlingRookSquare[cr] = rfrom;
- Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1);
- Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1);
-
- for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s)
- if (s != kfrom && s != rfrom)
- castlingPath[cr] |= 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)
- castlingPath[cr] |= s;
+ castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto)
+ & ~(kfrom | rfrom);
}
void Position::set_check_info(StateInfo* si) const {
- si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square<KING>(WHITE));
- si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square<KING>(BLACK));
+ 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]);
Square ksq = square<KING>(~sideToMove);
- 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[PAWN] = pawn_attacks_bb(~sideToMove, ksq);
+ si->checkSquares[KNIGHT] = attacks_bb<KNIGHT>(ksq);
+ si->checkSquares[BISHOP] = attacks_bb<BISHOP>(ksq, pieces());
+ si->checkSquares[ROOK] = attacks_bb<ROOK>(ksq, pieces());
si->checkSquares[QUEEN] = si->checkSquares[BISHOP] | si->checkSquares[ROOK];
si->checkSquares[KING] = 0;
}
void Position::set_state(StateInfo* si) const {
- si->key = si->pawnKey = si->materialKey = 0;
+ si->key = si->materialKey = 0;
+ si->pawnKey = Zobrist::noPawns;
si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO;
- si->psq = SCORE_ZERO;
si->checkersBB = attackers_to(square<KING>(sideToMove)) & pieces(~sideToMove);
set_check_info(si);
{
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];
+ si->key ^= Zobrist::psq[pc][s];
+
+ if (type_of(pc) == PAWN)
+ si->pawnKey ^= Zobrist::psq[pc][s];
+
+ else if (type_of(pc) != KING)
+ si->nonPawnMaterial[color_of(pc)] += PieceValue[MG][pc];
}
if (si->epSquare != SQ_NONE)
si->key ^= Zobrist::castling[si->castlingRights];
- for (Bitboard b = pieces(PAWN); b; )
- {
- Square s = pop_lsb(&b);
- si->pawnKey ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s];
- }
+ for (Piece pc : Pieces)
+ for (int cnt = 0; cnt < pieceCount[pc]; ++cnt)
+ si->materialKey ^= Zobrist::psq[pc][cnt];
+}
+
+
+/// 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.
+
+Position& Position::set(const string& code, Color c, StateInfo* si) {
+
+ assert(code[0] == 'K');
+
+ string sides[] = { code.substr(code.find('K', 1)), // Weak
+ code.substr(0, std::min(code.find('v'), code.find('K', 1))) }; // Strong
- 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];
+ assert(sides[0].length() > 0 && sides[0].length() < 8);
+ assert(sides[1].length() > 0 && sides[1].length() < 8);
- for (Color c = WHITE; c <= BLACK; ++c)
- for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt)
- si->nonPawnMaterial[c] += pieceCount[c][pt] * PieceValue[MG][pt];
+ std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower);
+
+ 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";
+
+ return set(fenStr, false, si, nullptr);
}
ss << (sideToMove == WHITE ? " w " : " b ");
if (can_castle(WHITE_OO))
- ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | KING_SIDE))) : 'K');
+ ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OO ))) : 'K');
if (can_castle(WHITE_OOO))
- ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | QUEEN_SIDE))) : 'Q');
+ 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 | KING_SIDE))) : 'k');
+ ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OO ))) : 'k');
if (can_castle(BLACK_OOO))
- ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | QUEEN_SIDE))) : 'q');
+ ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OOO))) : 'q');
- if (!can_castle(WHITE) && !can_castle(BLACK))
+ if (!can_castle(ANY_CASTLING))
ss << '-';
ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::square(ep_square()) + " ")
}
-/// Position::game_phase() calculates the game phase interpolating total non-pawn
-/// material between endgame and midgame limits.
-
-Phase Position::game_phase() const {
-
- Value npm = st->nonPawnMaterial[WHITE] + st->nonPawnMaterial[BLACK];
-
- npm = std::max(EndgameLimit, std::min(npm, MidgameLimit));
-
- return Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit));
-}
-
-
-/// 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.
+/// 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) const {
+Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const {
- Bitboard b, pinners, result = 0;
+ Bitboard blockers = 0;
+ pinners = 0;
- // 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;
+ // Snipers are sliders that attack 's' when a piece and other snipers are removed
+ Bitboard snipers = ( (attacks_bb< ROOK>(s) & pieces(QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(s) & pieces(QUEEN, BISHOP))) & sliders;
+ Bitboard occupancy = pieces() ^ snipers;
- while (pinners)
+ while (snipers)
{
- b = between_bb(s, pop_lsb(&pinners)) & pieces();
-
- if (!more_than_one(b))
- result |= b;
+ 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 result;
+ return blockers;
}
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))
+ return (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN))
+ | (pawn_attacks_bb(WHITE, s) & pieces(BLACK, PAWN))
+ | (attacks_bb<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));
+ | (attacks_bb<KING>(s) & pieces(KING));
}
Color us = sideToMove;
Square from = from_sq(m);
+ Square to = to_sq(m);
assert(color_of(moved_piece(m)) == us);
assert(piece_on(square<KING>(us)) == make_piece(us, KING));
if (type_of(m) == ENPASSANT)
{
Square ksq = square<KING>(us);
- Square to = to_sq(m);
Square capsq = to - pawn_push(us);
Bitboard occupied = (pieces() ^ from ^ capsq) | to;
&& !(attacks_bb<BISHOP>(ksq, occupied) & pieces(~us, QUEEN, BISHOP));
}
- // If the moving piece is a king, check whether the destination
- // square is attacked by the opponent. Castling moves are checked
- // for legality during move generation.
+ // 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.
if (type_of(piece_on(from)) == KING)
- return type_of(m) == CASTLING || !(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_pieces(us) & from)
- || aligned(from, to_sq(m), square<KING>(us));
+ return !(blockers_for_king(us) & from)
+ || aligned(from, to, square<KING>(us));
}
{
// We have already handled promotion moves, so destination
// cannot be on the 8th/1st rank.
- if (rank_of(to) == relative_rank(us, RANK_8))
+ if ((Rank8BB | Rank1BB) & to)
return false;
- if ( !(attacks_from<PAWN>(from, us) & pieces(~us) & to) // Not a capture
+ if ( !(pawn_attacks_bb(us, from) & 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))
+ && (relative_rank(us, from) == RANK_2)
&& empty(to)
&& empty(to - pawn_push(us))))
return false;
}
- else if (!(attacks_from(pc, from) & to))
+ else if (!(attacks_bb(type_of(pc), from, pieces()) & to))
return false;
// Evasions generator already takes care to avoid some kind of illegal moves
Square to = to_sq(m);
// Is there a direct check?
- if (st->checkSquares[type_of(piece_on(from))] & to)
+ if (check_squares(type_of(piece_on(from))) & to)
return true;
// Is there a discovered check?
- if ( (discovered_check_candidates() & from)
+ if ( (blockers_for_king(~sideToMove) & from)
&& !aligned(from, to, square<KING>(~sideToMove)))
return true;
return false;
case PROMOTION:
- return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & square<KING>(~sideToMove);
+ 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, so the only case we
case CASTLING:
{
Square kfrom = from;
- Square rfrom = to; // Castling is encoded as 'King captures the rook'
+ 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] & square<KING>(~sideToMove))
+ return (attacks_bb<ROOK>(rto) & square<KING>(~sideToMove))
&& (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square<KING>(~sideToMove));
}
default:
assert(is_ok(m));
assert(&newSt != st);
- ++nodes;
+ 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
++st->rule50;
++st->pliesFromNull;
+ // Used by NNUE
+ st->accumulator.computed_accumulation = false;
+ st->accumulator.computed_score = false;
+ auto& dp = st->dirtyPiece;
+ dp.dirty_num = 1;
+
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));
+ Piece pc = piece_on(from);
+ Piece captured = type_of(m) == ENPASSANT ? make_piece(them, PAWN) : 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);
+ assert(color_of(pc) == us);
+ assert(captured == NO_PIECE || color_of(captured) == (type_of(m) != CASTLING ? them : us));
+ assert(type_of(captured) != KING);
if (type_of(m) == CASTLING)
{
- assert(pt == KING);
+ assert(pc == make_piece(us, KING));
+ assert(captured == make_piece(us, ROOK));
Square rfrom, rto;
do_castling<true>(us, from, to, rfrom, rto);
- 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];
+ 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(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; // Not done by remove_piece()
}
- st->pawnKey ^= Zobrist::psq[them][PAWN][capsq];
+ st->pawnKey ^= Zobrist::psq[captured][capsq];
}
else
st->nonPawnMaterial[them] -= PieceValue[MG][captured];
+ if (Eval::useNNUE)
+ {
+ dp.dirty_num = 2; // 1 piece moved, 1 piece captured
+ dp.piece[1] = captured;
+ dp.from[1] = capsq;
+ dp.to[1] = SQ_NONE;
+ }
+
// Update board and piece lists
- remove_piece(them, captured, capsq);
+ remove_piece(capsq);
+
+ if (type_of(m) == ENPASSANT)
+ board[capsq] = NO_PIECE;
// Update material hash key and prefetch access to materialTable
- k ^= Zobrist::psq[them][captured][capsq];
- st->materialKey ^= Zobrist::psq[them][captured][pieceCount[them][captured]];
+ k ^= Zobrist::psq[captured][capsq];
+ st->materialKey ^= Zobrist::psq[captured][pieceCount[captured]];
prefetch(thisThread->materialTable[st->materialKey]);
- // Update incremental scores
- st->psq -= PSQT::psq[them][captured][capsq];
-
// 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)
// Update castling rights if needed
if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to]))
{
- int cr = castlingRightsMask[from] | castlingRightsMask[to];
- k ^= Zobrist::castling[st->castlingRights & cr];
- st->castlingRights &= ~cr;
+ k ^= Zobrist::castling[st->castlingRights];
+ st->castlingRights &= ~(castlingRightsMask[from] | castlingRightsMask[to]);
+ k ^= Zobrist::castling[st->castlingRights];
}
// Move the piece. The tricky Chess960 castling is handled earlier
if (type_of(m) != CASTLING)
- move_piece(us, pt, from, to);
+ {
+ if (Eval::useNNUE)
+ {
+ dp.piece[0] = pc;
+ dp.from[0] = from;
+ dp.to[0] = to;
+ }
+
+ move_piece(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 if the moved pawn can be captured
if ( (int(to) ^ int(from)) == 16
- && (attacks_from<PAWN>(to - pawn_push(us), us) & pieces(them, PAWN)))
+ && (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN)))
{
- st->epSquare = (from + to) / 2;
+ st->epSquare = to - pawn_push(us);
k ^= Zobrist::enpassant[file_of(st->epSquare)];
}
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(us, PAWN, to);
- put_piece(us, promotion, to);
+ remove_piece(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]];
+ if (Eval::useNNUE)
+ {
+ // Promoting pawn to SQ_NONE, promoted piece from SQ_NONE
+ dp.to[0] = SQ_NONE;
+ dp.piece[dp.dirty_num] = promotion;
+ dp.from[dp.dirty_num] = SQ_NONE;
+ dp.to[dp.dirty_num] = to;
+ dp.dirty_num++;
+ }
- // Update incremental score
- st->psq += PSQT::psq[us][promotion][to] - PSQT::psq[us][PAWN][to];
+ // Update hash keys
+ 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->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(thisThread->pawnsTable[st->pawnKey]);
+ // Update pawn hash key
+ st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
// Reset rule 50 draw counter
st->rule50 = 0;
}
- // Update incremental scores
- st->psq += PSQT::psq[us][pt][to] - PSQT::psq[us][pt][from];
-
// Set capture piece
- st->capturedType = captured;
+ st->capturedPiece = captured;
// Update the key with the final value
st->key = k;
// 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)
+ {
+ StateInfo* stp = st->previous->previous;
+ for (int i = 4; i <= end; i += 2)
+ {
+ stp = stp->previous->previous;
+ if (stp->key == st->key)
+ {
+ st->repetition = stp->repetition ? -i : i;
+ break;
+ }
+ }
+ }
+
assert(pos_is_ok());
}
Color us = sideToMove;
Square from = from_sq(m);
Square to = to_sq(m);
- PieceType pt = type_of(piece_on(to));
+ Piece pc = piece_on(to);
assert(empty(from) || type_of(m) == CASTLING);
- assert(st->capturedType != KING);
+ assert(type_of(st->capturedPiece) != KING);
if (type_of(m) == PROMOTION)
{
assert(relative_rank(us, to) == RANK_8);
- assert(pt == promotion_type(m));
- assert(pt >= KNIGHT && pt <= QUEEN);
+ assert(type_of(pc) == promotion_type(m));
+ assert(type_of(pc) >= KNIGHT && type_of(pc) <= QUEEN);
- remove_piece(us, pt, to);
- put_piece(us, PAWN, to);
- pt = PAWN;
+ remove_piece(to);
+ pc = make_piece(us, PAWN);
+ put_piece(pc, to);
}
if (type_of(m) == CASTLING)
}
else
{
- move_piece(us, pt, to, from); // Put the piece back at the source square
+ move_piece(to, from); // Put the piece back at the source square
- if (st->capturedType)
+ if (st->capturedPiece)
{
Square capsq = to;
{
capsq -= pawn_push(us);
- assert(pt == PAWN);
+ 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->capturedType == PAWN);
+ assert(st->capturedPiece == make_piece(~us, PAWN));
}
- put_piece(~us, st->capturedType, capsq); // Restore the captured piece
+ put_piece(st->capturedPiece, capsq); // Restore the captured piece
}
}
/// Position::do_castling() is a helper used to do/undo a castling move. This
-/// is a bit tricky, especially in Chess960.
+/// 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) {
rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
+ if (Do && Eval::useNNUE)
+ {
+ auto& dp = st->dirtyPiece;
+ dp.piece[0] = make_piece(us, KING);
+ dp.from[0] = from;
+ dp.to[0] = to;
+ dp.piece[1] = make_piece(us, ROOK);
+ dp.from[1] = rfrom;
+ dp.to[1] = rto;
+ dp.dirty_num = 2;
+ }
+
// 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);
+ remove_piece(Do ? from : to);
+ remove_piece(Do ? rfrom : rto);
+ board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do this for us
+ put_piece(make_piece(us, KING), Do ? to : from);
+ put_piece(make_piece(us, ROOK), Do ? rto : rfrom);
}
-/// Position::do(undo)_null_move() is used to do(undo) a "null move": It flips
+/// 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.
void Position::do_null_move(StateInfo& newSt) {
assert(!checkers());
assert(&newSt != st);
- std::memcpy(&newSt, st, sizeof(StateInfo));
+ if (Eval::useNNUE)
+ {
+ std::memcpy(&newSt, st, sizeof(StateInfo));
+ st->accumulator.computed_score = false;
+ }
+ else
+ std::memcpy(&newSt, st, offsetof(StateInfo, accumulator));
+
newSt.previous = st;
st = &newSt;
set_check_info(st);
+ st->repetition = 0;
+
assert(pos_is_ok());
}
Key Position::key_after(Move m) const {
- Color us = sideToMove;
Square from = from_sq(m);
Square to = to_sq(m);
- PieceType pt = type_of(piece_on(from));
- PieceType captured = type_of(piece_on(to));
+ Piece pc = piece_on(from);
+ Piece captured = piece_on(to);
Key k = st->key ^ Zobrist::side;
if (captured)
- k ^= Zobrist::psq[~us][captured][to];
+ k ^= Zobrist::psq[captured][to];
- return k ^ Zobrist::psq[us][pt][to] ^ Zobrist::psq[us][pt][from];
+ return k ^ Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from];
}
-/// Position::see() is a static exchange evaluator: It tries to estimate the
-/// material gain or loss resulting from a move.
+/// 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.
-Value Position::see_sign(Move m) const {
+bool Position::see_ge(Move m, Value threshold) const {
assert(is_ok(m));
- // Early return if SEE cannot be negative because captured piece value
- // is not less then capturing one. Note that king moves always return
- // here because king midgame value is set to 0.
- if (PieceValue[MG][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))])
- return VALUE_KNOWN_WIN;
+ // Only deal with normal moves, assume others pass a simple see
+ if (type_of(m) != NORMAL)
+ return VALUE_ZERO >= threshold;
- return see(m);
-}
+ Square from = from_sq(m), to = to_sq(m);
-Value Position::see(Move m) const {
+ int swap = PieceValue[MG][piece_on(to)] - threshold;
+ if (swap < 0)
+ return false;
- Square from, to;
- Bitboard occupied, attackers, stmAttackers;
- Value swapList[32];
- int slIndex = 1;
- PieceType captured;
- Color stm;
+ swap = PieceValue[MG][piece_on(from)] - swap;
+ if (swap <= 0)
+ return true;
- assert(is_ok(m));
+ Bitboard occupied = pieces() ^ from ^ to;
+ Color stm = color_of(piece_on(from));
+ Bitboard attackers = attackers_to(to, occupied);
+ Bitboard stmAttackers, bb;
+ int res = 1;
- from = from_sq(m);
- to = to_sq(m);
- swapList[0] = PieceValue[MG][piece_on(to)];
- stm = color_of(piece_on(from));
- occupied = pieces() ^ from;
+ while (true)
+ {
+ stm = ~stm;
+ attackers &= occupied;
- // 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;
+ // If stm has no more attackers then give up: stm loses
+ if (!(stmAttackers = attackers & pieces(stm)))
+ break;
- if (type_of(m) == ENPASSANT)
- {
- occupied ^= to - pawn_push(stm); // Remove the captured pawn
- swapList[0] = PieceValue[MG][PAWN];
- }
+ // Don't allow pinned pieces to attack (except the king) as long as
+ // there are pinners on their original square.
+ if (pinners(~stm) & occupied)
+ stmAttackers &= ~blockers_for_king(stm);
- // 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 (!stmAttackers)
+ break;
- // If the opponent has no attackers we are finished
- stm = ~stm;
- stmAttackers = attackers & pieces(stm);
- if (!stmAttackers)
- return swapList[0];
+ res ^= 1;
- // 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));
+ // Locate and remove the next least valuable attacker, and add to
+ // the bitboard 'attackers' any X-ray attackers behind it.
+ if ((bb = stmAttackers & pieces(PAWN)))
+ {
+ if ((swap = PawnValueMg - swap) < res)
+ break;
- do {
- assert(slIndex < 32);
+ occupied ^= lsb(bb);
+ attackers |= attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN);
+ }
- // Add the new entry to the swap list
- swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
+ else if ((bb = stmAttackers & pieces(KNIGHT)))
+ {
+ if ((swap = KnightValueMg - swap) < res)
+ break;
- // Locate and remove the next least valuable attacker
- captured = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
- stm = ~stm;
- stmAttackers = attackers & pieces(stm);
- ++slIndex;
+ occupied ^= lsb(bb);
+ }
- } while (stmAttackers && (captured != KING || (--slIndex, false))); // Stop before a king capture
+ else if ((bb = stmAttackers & pieces(BISHOP)))
+ {
+ if ((swap = BishopValueMg - swap) < res)
+ break;
- // 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]);
+ occupied ^= lsb(bb);
+ attackers |= attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN);
+ }
- return swapList[0];
+ else if ((bb = stmAttackers & pieces(ROOK)))
+ {
+ if ((swap = RookValueMg - swap) < res)
+ break;
+
+ occupied ^= lsb(bb);
+ attackers |= attacks_bb<ROOK>(to, occupied) & pieces(ROOK, QUEEN);
+ }
+
+ else if ((bb = stmAttackers & pieces(QUEEN)))
+ {
+ if ((swap = QueenValueMg - swap) < res)
+ break;
+
+ occupied ^= lsb(bb);
+ attackers |= (attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN))
+ | (attacks_bb<ROOK >(to, occupied) & pieces(ROOK , QUEEN));
+ }
+
+ else // KING
+ // If we "capture" with the king but opponent still has attackers,
+ // reverse the result.
+ return (attackers & ~pieces(stm)) ? res ^ 1 : res;
+ }
+
+ return bool(res);
}
/// Position::is_draw() tests whether the position is drawn by 50-move rule
/// or by repetition. It does not detect stalemates.
-bool Position::is_draw() const {
+bool Position::is_draw(int ply) const {
if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
return true;
- StateInfo* stp = st;
- for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2)
+ // Return a draw score if a position repeats once earlier but strictly
+ // after the root, or repeats twice before or at the root.
+ return st->repetition && st->repetition < ply;
+}
+
+
+// Position::has_repeated() tests whether there has been at least one repetition
+// of positions since the last capture or pawn move.
+
+bool Position::has_repeated() const {
+
+ StateInfo* stc = st;
+ int end = std::min(st->rule50, st->pliesFromNull);
+ while (end-- >= 4)
+ {
+ if (stc->repetition)
+ return true;
+
+ stc = stc->previous;
+ }
+ return false;
+}
+
+
+/// 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.
+
+bool Position::has_game_cycle(int ply) const {
+
+ int j;
+
+ int end = std::min(st->rule50, st->pliesFromNull);
+
+ if (end < 3)
+ return false;
+
+ Key originalKey = st->key;
+ StateInfo* stp = st->previous;
+
+ for (int i = 3; i <= end; i += 2)
{
stp = stp->previous->previous;
- if (stp->key == st->key)
- return true; // Draw at 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);
+ 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;
+
+ // For repetitions before or at the root, require one more
+ if (stp->repetition)
+ return true;
+ }
+ }
+ }
return false;
}
}
-/// Position::pos_is_ok() performs some consistency 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 {
+bool Position::pos_is_ok() const {
- const bool Fast = true; // Quick (default) or full check?
+ constexpr bool Fast = true; // Quick (default) or full check?
- enum { Default, King, Bitboards, State, Lists, Castling };
+ 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");
- for (int step = Default; step <= (Fast ? Default : Castling); step++)
+ if (Fast)
+ return true;
+
+ 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)
{
- if (failedStep)
- *failedStep = step;
-
- if (step == Default)
- 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))
- 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");
- 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<KING>(~sideToMove)) & pieces(sideToMove))
- 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 == Bitboards)
+ for (Color c : { WHITE, BLACK })
+ for (CastlingRights cr : {c & KING_SIDE, c & QUEEN_SIDE})
{
- if ( (pieces(WHITE) & pieces(BLACK))
- ||(pieces(WHITE) | pieces(BLACK)) != pieces())
- 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 (!can_castle(cr))
+ continue;
- if (step == State)
- {
- StateInfo si = *st;
- set_state(&si);
- if (std::memcmp(&si, st, sizeof(StateInfo)))
- 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");
}
- if (step == Lists)
- for (Color c = WHITE; c <= BLACK; ++c)
- for (PieceType pt = PAWN; pt <= KING; ++pt)
- {
- if (pieceCount[c][pt] != popcount(pieces(c, pt)))
- 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 (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 ( piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK)
- || castlingRightsMask[castlingRookSquare[c | s]] != (c | s)
- ||(castlingRightsMask[square<KING>(c)] & (c | s)) != (c | s))
- return false;
- }
- }
-
return true;
}