- stmAttackers = attackers & pieces(stm);
-
- } while (stmAttackers);
-
- // 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;
-
- // 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.
-
-void Position::clear() {
-
- std::memset(this, 0, sizeof(Position));
- startState.epSquare = SQ_NONE;
- st = &startState;
-
- for (int i = 0; i < 8; i++)
- for (int j = 0; j < 16; j++)
- pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
-}
-
-
-/// Position::put_piece() puts a piece on the given square of the board,
-/// updating the board array, pieces list, bitboards, and piece counts.
-
-void Position::put_piece(Piece p, Square s) {