if (is_castle(m))
{
st->key = key;
- do_castle_move(m);
+ do_castle_move<true>(m);
return;
}
assert(color_of(piece_on(from)) == us);
assert(color_of(piece_on(to)) == them || square_is_empty(to));
- assert(!(ep || pm) || piece == make_piece(us, PAWN));
- assert(!pm || relative_rank(us, to) == RANK_8);
+ assert(capture != KING);
if (capture)
- do_capture_move(key, capture, them, to, ep);
+ {
+ Square capsq = to;
+
+ // If the captured piece was a pawn, update pawn hash key, otherwise
+ // update non-pawn material.
+ if (capture == PAWN)
+ {
+ if (ep) // En passant?
+ {
+ capsq += pawn_push(them);
+
+ assert(pt == PAWN);
+ assert(to == st->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(to) == PIECE_NONE);
+ assert(piece_on(capsq) == make_piece(them, PAWN));
+
+ board[capsq] = PIECE_NONE;
+ }
+
+ st->pawnKey ^= zobrist[them][PAWN][capsq];
+ }
+ else
+ st->npMaterial[them] -= PieceValueMidgame[capture];
+
+ // Remove captured piece
+ clear_bit(&byColorBB[them], capsq);
+ clear_bit(&byTypeBB[capture], capsq);
+ clear_bit(&byTypeBB[0], capsq);
+
+ // Update hash key
+ key ^= zobrist[them][capture][capsq];
+
+ // Update incremental scores
+ st->value -= pst(make_piece(them, capture), capsq);
+
+ // Update piece count
+ pieceCount[them][capture]--;
+
+ // Update material hash key
+ st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]];
+
+ // Update piece list, move the last piece at index[capsq] position
+ //
+ // WARNING: This is a not perfectly revresible operation. When we
+ // will reinsert the captured piece in undo_move() we will put it
+ // at the end of the list and not in its original place, it means
+ // index[] and pieceList[] are not guaranteed to be invariant to a
+ // do_move() + undo_move() sequence.
+ Square lastPieceSquare = pieceList[them][capture][pieceCount[them][capture]];
+ index[lastPieceSquare] = index[capsq];
+ pieceList[them][capture][index[lastPieceSquare]] = lastPieceSquare;
+ pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
+
+ // Reset rule 50 counter
+ st->rule50 = 0;
+ }
// Update hash key
key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
}
-/// Position::do_capture_move() is a private method used to update captured
-/// piece info. It is called from the main Position::do_move function.
-
-void Position::do_capture_move(Key& key, PieceType capture, Color them, Square to, bool ep) {
-
- assert(capture != KING);
-
- Square capsq = to;
-
- // If the captured piece was a pawn, update pawn hash key,
- // otherwise update non-pawn material.
- if (capture == PAWN)
- {
- if (ep) // en passant ?
- {
- capsq = to + pawn_push(them);
-
- assert(to == st->epSquare);
- assert(relative_rank(flip(them), to) == RANK_6);
- assert(piece_on(to) == PIECE_NONE);
- assert(piece_on(capsq) == make_piece(them, PAWN));
-
- board[capsq] = PIECE_NONE;
- }
- st->pawnKey ^= zobrist[them][PAWN][capsq];
- }
- else
- st->npMaterial[them] -= PieceValueMidgame[capture];
-
- // Remove captured piece
- clear_bit(&byColorBB[them], capsq);
- clear_bit(&byTypeBB[capture], capsq);
- clear_bit(&byTypeBB[0], capsq);
-
- // Update hash key
- key ^= zobrist[them][capture][capsq];
-
- // Update incremental scores
- st->value -= pst(make_piece(them, capture), capsq);
-
- // Update piece count
- pieceCount[them][capture]--;
-
- // Update material hash key
- st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]];
-
- // Update piece list, move the last piece at index[capsq] position
- //
- // WARNING: This is a not perfectly revresible operation. When we
- // will reinsert the captured piece in undo_move() we will put it
- // at the end of the list and not in its original place, it means
- // index[] and pieceList[] are not guaranteed to be invariant to a
- // do_move() + undo_move() sequence.
- Square lastPieceSquare = pieceList[them][capture][pieceCount[them][capture]];
- index[lastPieceSquare] = index[capsq];
- pieceList[them][capture][index[lastPieceSquare]] = lastPieceSquare;
- pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE;
-
- // Reset rule 50 counter
- st->rule50 = 0;
-}
-
-
-/// Position::do_castle_move() is a private method used to make a castling
-/// move. It is called from the main Position::do_move function. Note that
-/// castling moves are encoded as "king captures friendly rook" moves, for
-/// instance white short castling in a non-Chess960 game is encoded as e1h1.
-
+/// Position::do_castle_move() is a private method used to do/undo a castling
+/// move. Note that castling moves are encoded as "king captures friendly rook"
+/// moves, for instance white short castling in a non-Chess960 game is encoded
+/// as e1h1.
+template<bool Do>
void Position::do_castle_move(Move m) {
assert(is_ok(m));
assert(is_castle(m));
- Color us = side_to_move();
- Color them = flip(us);
+ Square kto, kfrom, rfrom, rto, kAfter, rAfter;
- // Find source squares for king and rook
- Square kfrom = move_from(m);
- Square rfrom = move_to(m);
- Square kto, rto;
-
- assert(piece_on(kfrom) == make_piece(us, KING));
- assert(piece_on(rfrom) == make_piece(us, ROOK));
+ Color us = side_to_move();
+ Square kBefore = move_from(m);
+ Square rBefore = move_to(m);
- // Find destination squares for king and rook
- if (rfrom > kfrom) // O-O
+ // Find after-castle squares for king and rook
+ if (rBefore > kBefore) // O-O
{
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
+ kAfter = relative_square(us, SQ_G1);
+ rAfter = relative_square(us, SQ_F1);
}
else // O-O-O
{
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
+ kAfter = relative_square(us, SQ_C1);
+ rAfter = relative_square(us, SQ_D1);
}
+ kfrom = Do ? kBefore : kAfter;
+ rfrom = Do ? rBefore : rAfter;
+
+ kto = Do ? kAfter : kBefore;
+ rto = Do ? rAfter : rBefore;
+
+ assert(piece_on(kfrom) == make_piece(us, KING));
+ assert(piece_on(rfrom) == make_piece(us, ROOK));
+
// Remove pieces from source squares
clear_bit(&byColorBB[us], kfrom);
clear_bit(&byTypeBB[KING], kfrom);
index[kto] = index[kfrom];
index[rto] = tmp;
- // Reset capture field
- st->capturedType = PIECE_TYPE_NONE;
+ if (Do)
+ {
+ // Reset capture field
+ st->capturedType = PIECE_TYPE_NONE;
- // Update incremental scores
- st->value += pst_delta(king, kfrom, kto);
- st->value += pst_delta(rook, rfrom, rto);
+ // Update incremental scores
+ st->value += pst_delta(king, kfrom, kto);
+ st->value += pst_delta(rook, rfrom, rto);
- // Update hash key
- st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
- st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
+ // Update hash key
+ st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
+ st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
- // Clear en passant square
- if (st->epSquare != SQ_NONE)
- {
- st->key ^= zobEp[st->epSquare];
- st->epSquare = SQ_NONE;
- }
+ // Clear en passant square
+ if (st->epSquare != SQ_NONE)
+ {
+ st->key ^= zobEp[st->epSquare];
+ st->epSquare = SQ_NONE;
+ }
- // Update castling rights
- st->key ^= zobCastle[st->castleRights];
- st->castleRights &= castleRightsMask[kfrom];
- st->key ^= zobCastle[st->castleRights];
+ // Update castling rights
+ st->key ^= zobCastle[st->castleRights];
+ st->castleRights &= castleRightsMask[kfrom];
+ st->key ^= zobCastle[st->castleRights];
- // Reset rule 50 counter
- st->rule50 = 0;
+ // Reset rule 50 counter
+ st->rule50 = 0;
- // Update checkers BB
- st->checkersBB = attackers_to(king_square(them)) & pieces(us);
+ // Update checkers BB
+ st->checkersBB = attackers_to(king_square(flip(us))) & pieces(us);
- // Finish
- sideToMove = flip(sideToMove);
- st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
+ // Finish
+ sideToMove = flip(sideToMove);
+ st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
+ }
+ else
+ // Undo: point our state pointer back to the previous state
+ st = st->previous;
assert(pos_is_ok());
}
if (is_castle(m))
{
- undo_castle_move(m);
+ do_castle_move<false>(m);
return;
}
}
-/// Position::undo_castle_move() is a private method used to unmake a castling
-/// move. It is called from the main Position::undo_move function. Note that
-/// castling moves are encoded as "king captures friendly rook" moves, for
-/// instance white short castling in a non-Chess960 game is encoded as e1h1.
-
-void Position::undo_castle_move(Move m) {
-
- assert(is_ok(m));
- assert(is_castle(m));
-
- // When we have arrived here, some work has already been done by
- // Position::undo_move. In particular, the side to move has been switched,
- // so the code below is correct.
- Color us = side_to_move();
-
- // Find source squares for king and rook
- Square kfrom = move_from(m);
- Square rfrom = move_to(m);
- Square kto, rto;
-
- // Find destination squares for king and rook
- if (rfrom > kfrom) // O-O
- {
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- }
- else // O-O-O
- {
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
- }
-
- assert(piece_on(kto) == make_piece(us, KING));
- assert(piece_on(rto) == make_piece(us, ROOK));
-
- // Remove pieces from destination squares
- clear_bit(&byColorBB[us], kto);
- clear_bit(&byTypeBB[KING], kto);
- clear_bit(&byTypeBB[0], kto);
- clear_bit(&byColorBB[us], rto);
- clear_bit(&byTypeBB[ROOK], rto);
- clear_bit(&byTypeBB[0], rto);
-
- // Put pieces on source squares
- set_bit(&byColorBB[us], kfrom);
- set_bit(&byTypeBB[KING], kfrom);
- set_bit(&byTypeBB[0], kfrom);
- set_bit(&byColorBB[us], rfrom);
- set_bit(&byTypeBB[ROOK], rfrom);
- set_bit(&byTypeBB[0], rfrom);
-
- // Update board
- Piece king = make_piece(us, KING);
- Piece rook = make_piece(us, ROOK);
- board[kto] = board[rto] = PIECE_NONE;
- board[kfrom] = king;
- board[rfrom] = rook;
-
- // Update piece lists
- pieceList[us][KING][index[kto]] = kfrom;
- pieceList[us][ROOK][index[rto]] = rfrom;
- int tmp = index[rto]; // In Chess960 could be rto == kfrom
- index[kfrom] = index[kto];
- index[rfrom] = tmp;
-
- // Finally point our state pointer back to the previous state
- st = st->previous;
-
- assert(pos_is_ok());
-}
-
-
-/// Position::do_null_move makes() a "null move": It switches the side to move
-/// and updates the hash key without executing any move on the board.
-
+/// Position::do_null_move() is used to do/undo a "null move": It flips the side
+/// to move and updates the hash key without executing any move on the board.
+template<bool Do>
void Position::do_null_move(StateInfo& backupSt) {
assert(!in_check());
// Back up the information necessary to undo the null move to the supplied
- // StateInfo object.
- // Note that differently from normal case here backupSt is actually used as
- // a backup storage not as a new state to be used.
- backupSt.key = st->key;
- backupSt.epSquare = st->epSquare;
- backupSt.value = st->value;
- backupSt.previous = st->previous;
- backupSt.pliesFromNull = st->pliesFromNull;
- st->previous = &backupSt;
-
- // Update the necessary information
- if (st->epSquare != SQ_NONE)
- st->key ^= zobEp[st->epSquare];
-
- st->key ^= zobSideToMove;
- prefetch((char*)TT.first_entry(st->key));
+ // StateInfo object. Note that differently from normal case here backupSt
+ // is actually used as a backup storage not as the new state. This reduces
+ // the number of fields to be copied.
+ StateInfo* src = Do ? st : &backupSt;
+ StateInfo* dst = Do ? &backupSt : st;
+
+ dst->key = src->key;
+ dst->epSquare = src->epSquare;
+ dst->value = src->value;
+ dst->rule50 = src->rule50;
+ dst->pliesFromNull = src->pliesFromNull;
sideToMove = flip(sideToMove);
- st->epSquare = SQ_NONE;
- st->rule50++;
- st->pliesFromNull = 0;
- st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
- assert(pos_is_ok());
-}
-
-
-/// Position::undo_null_move() unmakes a "null move".
-
-void Position::undo_null_move() {
-
- assert(!in_check());
+ if (Do)
+ {
+ if (st->epSquare != SQ_NONE)
+ st->key ^= zobEp[st->epSquare];
- // Restore information from the our backup StateInfo object
- StateInfo* backupSt = st->previous;
- st->key = backupSt->key;
- st->epSquare = backupSt->epSquare;
- st->value = backupSt->value;
- st->previous = backupSt->previous;
- st->pliesFromNull = backupSt->pliesFromNull;
+ st->key ^= zobSideToMove;
+ prefetch((char*)TT.first_entry(st->key));
- // Update the necessary information
- sideToMove = flip(sideToMove);
- st->rule50--;
+ st->epSquare = SQ_NONE;
+ st->rule50++;
+ st->pliesFromNull = 0;
+ st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
+ }
assert(pos_is_ok());
}
+// Explicit template instantiations
+template void Position::do_null_move<false>(StateInfo& backupSt);
+template void Position::do_null_move<true>(StateInfo& backupSt);
+
/// Position::see() is a static exchange evaluator: It tries to estimate the
/// material gain or loss resulting from a move. There are three versions of