int AddUpPieceSquareValues(Board board, byte piece)
{
var kind = Pieces.GetKind(piece);
var score = 0;
if (kind == Pieces.King)
{
int sq = Pieces.IsWhite(piece) ? board.WhiteKingSquare : board.BlackKingSquare;
score += PieceSquareTable[(int)board.GameStage, kind, sq];
}
else
{
var squares = board.BitBoard[piece];
while (squares != 0)
{
int sq = BitOperations.FindAndZeroLeastSignificantBit(ref squares);
score += PieceSquareTable[(int)board.GameStage, kind, sq];
}
}
return(Pieces.IsWhite(piece) ? score : -score);
}
protected virtual int QuiescenceSearch(int alpha, int beta, int currentPly, Sides currentSide)
{
_NodesEvaluated++;
_PlyInfo[currentPly].PrincipalVariationLength = currentPly;
if (currentPly >= PlyInfo.MaxPly)
{
return(beta);
}
int staticScore = _StaticEvaluator.Evaluate(_ScratchBoard, currentSide);
if (staticScore >= beta)
{
return(beta);
}
if (staticScore > alpha)
{
alpha = staticScore;
}
List <Move> moves;
GenerateQuiescenceMoves(currentPly, currentSide, out moves);
_PlyInfo[currentPly].Board.CopyFrom(_ScratchBoard);
foreach (Move move in moves)
{
if (move.IsCapture)
{
var value = _StaticEvaluator.PieceValue[Pieces.GetKind(move.CapturedPiece)];
if (move.IsPromotion)
{
value += _StaticEvaluator.PieceValue[Pieces.GetKind(move.PromotionPiece)];
}
value += _StaticEvaluator.PieceValue[Pieces.Pawn];
if (staticScore + value < alpha)
{
continue;
}
}
if (_ScratchBoard.MakeMove(move) == MakeMoveResults.UndoMove)
{
UndoMove(currentPly);
continue;
}
int score = -QuiescenceSearch(-beta, -alpha, currentPly + 1, Board.OtherSide(currentSide));
UndoMove(currentPly);
if (score >= beta)
{
return(score);
}
if (score > alpha)
{
alpha = score;
UpdatePrincipalVariation(move, currentPly);
}
}
return(alpha);
}
