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
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 <iomanip>
#include <sstream>
-#include "bitcount.h"
+#include "bitboard.h"
#include "misc.h"
#include "movegen.h"
#include "position.h"
using std::string;
-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 castling[CASTLING_RIGHT_NB];
Key side;
- Key exclusion;
}
-Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion; }
-
namespace {
const string PieceToChar(" PNBRQK pnbrqk");
} // namespace
-/// CheckInfo constructor
-
-CheckInfo::CheckInfo(const Position& pos) {
-
- Color them = ~pos.side_to_move();
- ksq = pos.square<KING>(them);
-
- pinned = pos.pinned_pieces(pos.side_to_move());
- dcCandidates = pos.discovered_check_candidates();
-
- checkSquares[PAWN] = pos.attacks_from<PAWN>(ksq, them);
- checkSquares[KNIGHT] = pos.attacks_from<KNIGHT>(ksq);
- checkSquares[BISHOP] = pos.attacks_from<BISHOP>(ksq);
- checkSquares[ROOK] = pos.attacks_from<ROOK>(ksq);
- checkSquares[QUEEN] = checkSquares[BISHOP] | checkSquares[ROOK];
- checkSquares[KING] = 0;
-}
-
-
/// operator<<(Position) returns an ASCII representation of the position
std::ostream& operator<<(std::ostream& os, const Position& pos) {
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>();
}
Zobrist::side = rng.rand<Key>();
- Zobrist::exclusion = rng.rand<Key>();
-}
-
-
-/// Position::operator=() creates a copy of 'pos' but detaching the state pointer
-/// from the source to be self-consistent and not depending on any external data.
-
-Position& Position::operator=(const Position& pos) {
-
- std::memcpy(this, &pos, sizeof(Position));
- std::memcpy(&startState, st, sizeof(StateInfo));
- st = &startState;
- nodes = 0;
-
- assert(pos_is_ok());
-
- return *this;
-}
-
-
-/// Position::clear() erases the position object to a pristine state, with an
-/// empty board, white to move, and no castling rights.
-
-void Position::clear() {
-
- std::memset(this, 0, sizeof(Position));
- startState.epSquare = SQ_NONE;
- st = &startState;
-
- for (int i = 0; i < PIECE_TYPE_NB; ++i)
- for (int j = 0; j < 16; ++j)
- pieceList[WHITE][i][j] = pieceList[BLACK][i][j] = SQ_NONE;
}
/// 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.
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
else if ((idx = PieceToChar.find(token)) != string::npos)
{
- put_piece(color_of(Piece(idx)), type_of(Piece(idx)), sq);
+ put_piece(Piece(idx), sq);
++sq;
}
}
if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN)))
st->epSquare = SQ_NONE;
}
+ else
+ st->epSquare = SQ_NONE;
// 5-6. Halfmove clock and fullmove number
ss >> std::skipws >> st->rule50 >> gamePly;
set_state(st);
assert(pos_is_ok());
+
+ return *this;
}
}
+/// Position::set_check_info() sets king attacks to detect if a move gives check
+
+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));
+
+ 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[QUEEN] = si->checkSquares[BISHOP] | si->checkSquares[ROOK];
+ si->checkSquares[KING] = 0;
+}
+
+
/// 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
si->key = si->pawnKey = si->materialKey = 0;
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);
+
for (Bitboard b = pieces(); b; )
{
Square s = pop_lsb(&b);
Piece pc = piece_on(s);
- si->key ^= Zobrist::psq[color_of(pc)][type_of(pc)][s];
- si->psq += PSQT::psq[color_of(pc)][type_of(pc)][s];
+ si->key ^= Zobrist::psq[pc][s];
+ si->psq += PSQT::psq[pc][s];
}
if (si->epSquare != SQ_NONE)
for (Bitboard b = pieces(PAWN); b; )
{
Square s = pop_lsb(&b);
- si->pawnKey ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s];
+ si->pawnKey ^= Zobrist::psq[piece_on(s)][s];
}
- for (Color c = WHITE; c <= BLACK; ++c)
- for (PieceType pt = PAWN; pt <= KING; ++pt)
- for (int cnt = 0; cnt < pieceCount[c][pt]; ++cnt)
- si->materialKey ^= Zobrist::psq[c][pt][cnt];
+ for (Piece pc : Pieces)
+ {
+ if (type_of(pc) != PAWN && type_of(pc) != KING)
+ si->nonPawnMaterial[color_of(pc)] += pieceCount[pc] * PieceValue[MG][pc];
- for (Color c = WHITE; c <= BLACK; ++c)
- for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt)
- si->nonPawnMaterial[c] += pieceCount[c][pt] * PieceValue[MG][pt];
+ for (int cnt = 0; cnt < pieceCount[pc]; ++cnt)
+ si->materialKey ^= Zobrist::psq[pc][cnt];
+ }
}
}
-/// Position::check_blockers() returns a bitboard of all the pieces with color
-/// 'c' that are blocking check on the king with color 'kingColor'. A piece
-/// blocks a check if removing that piece from the board would result in a
-/// position where the king is in check. A check blocking piece can be either a
-/// pinned or a discovered check piece, according if its color 'c' is the same
-/// or the opposite of 'kingColor'.
+/// 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::check_blockers(Color c, Color kingColor) const {
+Bitboard Position::slider_blockers(Bitboard sliders, Square s) const {
Bitboard b, pinners, result = 0;
- Square ksq = square<KING>(kingColor);
- // Pinners are sliders that give check when a pinned piece is removed
- pinners = ( (pieces( ROOK, QUEEN) & PseudoAttacks[ROOK ][ksq])
- | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(~kingColor);
+ // 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;
while (pinners)
{
- b = between_bb(ksq, pop_lsb(&pinners)) & pieces();
+ b = between_bb(s, pop_lsb(&pinners)) & pieces();
if (!more_than_one(b))
- result |= b & pieces(c);
+ result |= b;
}
return result;
}
/// 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(sideToMove));
Color us = sideToMove;
Square from = from_sq(m);
// 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)
+ return !(pinned_pieces(us) & from)
|| aligned(from, to_sq(m), square<KING>(us));
}
/// 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);
// Is there a direct check?
- if (ci.checkSquares[type_of(piece_on(from))] & to)
+ if (st->checkSquares[type_of(piece_on(from))] & to)
return true;
// Is there a discovered check?
- if ( ci.dcCandidates
- && (ci.dcCandidates & from)
- && !aligned(from, to, ci.ksq))
+ if ( (discovered_check_candidates() & from)
+ && !aligned(from, to, square<KING>(~sideToMove)))
return true;
switch (type_of(m))
return false;
case PROMOTION:
- return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq;
+ return attacks_bb(Piece(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
Square capsq = make_square(file_of(to), rank_of(from));
Bitboard b = (pieces() ^ from ^ capsq) | to;
- return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK))
- | (attacks_bb<BISHOP>(ci.ksq, b) & pieces(sideToMove, 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 CASTLING:
{
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] & ci.ksq)
- && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq);
+ return (PseudoAttacks[ROOK][rto] & square<KING>(~sideToMove))
+ && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square<KING>(~sideToMove));
}
default:
assert(false);
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];
+ st->psq += PSQT::psq[captured][rto] - PSQT::psq[captured][rfrom];
+ 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);
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];
// Update board and piece lists
- remove_piece(them, captured, capsq);
+ 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]];
+ 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];
+ st->psq -= PSQT::psq[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)
// Move the piece. The tricky Chess960 castling is handled earlier
if (type_of(m) != CASTLING)
- move_piece(us, pt, from, to);
+ 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 if the moved pawn can be captured
if ( (int(to) ^ int(from)) == 16
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(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]];
+ 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 incremental score
- st->psq += PSQT::psq[us][promotion][to] - PSQT::psq[us][PAWN][to];
+ st->psq += PSQT::psq[promotion][to] - PSQT::psq[pc][to];
// 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];
+ st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
prefetch(thisThread->pawnsTable[st->pawnKey]);
// Reset rule 50 draw counter
}
// Update incremental scores
- st->psq += PSQT::psq[us][pt][to] - PSQT::psq[us][pt][from];
+ st->psq += PSQT::psq[pc][to] - PSQT::psq[pc][from];
// Set capture piece
- st->capturedType = captured;
+ st->capturedPiece = captured;
// Update the key with the final value
st->key = k;
sideToMove = ~sideToMove;
+ // Update king attacks used for fast check detection
+ set_check_info(st);
+
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(pc, 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(pc, 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) {
to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
// Remove both pieces first since squares could overlap in Chess960
- remove_piece(us, KING, Do ? from : to);
- remove_piece(us, ROOK, Do ? rfrom : rto);
+ 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(us, KING, Do ? to : from);
- put_piece(us, ROOK, Do ? rto : rfrom);
+ put_piece(make_piece(us, KING), Do ? to : from);
+ put_piece(make_piece(us, ROOK), Do ? rto : rfrom);
}
sideToMove = ~sideToMove;
+ set_check_info(st);
+
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];
}
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());
}
}
if (step == Lists)
- 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;
+ for (Piece pc : Pieces)
+ {
+ if (pieceCount[pc] != popcount(pieces(color_of(pc), type_of(pc))))
+ 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;
- }
+ for (int i = 0; i < pieceCount[pc]; ++i)
+ if (board[pieceList[pc][i]] != pc || index[pieceList[pc][i]] != i)
+ return false;
+ }
if (step == Castling)
for (Color c = WHITE; c <= BLACK; ++c)
projects / stockfish / blobdiff