// Load custom position from fen string
public void LoadPosition(string fen)
{
Initialize();
var loadedPosition = FenUtility.PositionFromFen(fen);
// Load pieces into board array and piece lists
for (int squareIndex = 0; squareIndex < 64; squareIndex++)
{
int piece = loadedPosition.squares[squareIndex];
Square[squareIndex] = piece;
if (piece != Piece.None)
{
int pieceType = Piece.PieceType(piece);
int pieceColourIndex = (Piece.IsColour(piece, Piece.White)) ? WhiteIndex : BlackIndex;
if (Piece.IsSlidingPiece(piece))
{
if (pieceType == Piece.Queen)
{
queens[pieceColourIndex].AddPieceAtSquare(squareIndex);
}
else if (pieceType == Piece.Rook)
{
rooks[pieceColourIndex].AddPieceAtSquare(squareIndex);
}
else if (pieceType == Piece.Bishop)
{
bishops[pieceColourIndex].AddPieceAtSquare(squareIndex);
}
}
else if (pieceType == Piece.Knight)
{
knights[pieceColourIndex].AddPieceAtSquare(squareIndex);
}
else if (pieceType == Piece.Pawn)
{
pawns[pieceColourIndex].AddPieceAtSquare(squareIndex);
}
else if (pieceType == Piece.King)
{
KingSquare[pieceColourIndex] = squareIndex;
}
}
}
// Side to move
WhiteToMove = loadedPosition.whiteToMove;
ColourToMove = (WhiteToMove) ? Piece.White : Piece.Black;
OpponentColour = (WhiteToMove) ? Piece.Black : Piece.White;
ColourToMoveIndex = (WhiteToMove) ? 0 : 1;
// Create gamestate
int whiteCastle = ((loadedPosition.whiteCastleKingside) ? 1 << 0 : 0) | ((loadedPosition.whiteCastleQueenside) ? 1 << 1 : 0);
int blackCastle = ((loadedPosition.blackCastleKingside) ? 1 << 2 : 0) | ((loadedPosition.blackCastleQueenside) ? 1 << 3 : 0);
int epState = loadedPosition.epFile << 4;
ushort initialGameState = (ushort)(whiteCastle | blackCastle | epState);
gameStateHistory.Push(initialGameState);
currentGameState = initialGameState;
plyCount = loadedPosition.plyCount;
// Initialize zobrist key
ZobristKey = Zobrist.CalculateZobristKey(this);
}
public void StartSearch()
{
InitDebugInfo();
// Initialize search settings
bestEvalThisIteration = bestEval = 0;
bestMoveThisIteration = bestMove = Move.InvalidMove;
tt.enabled = settings.useTranspositionTable;
// Clearing the transposition table before each search seems to help
// This makes no sense to me, I presume there is a bug somewhere but haven't been able to track it down yet
if (settings.clearTTEachMove)
{
tt.Clear();
}
moveGenerator.promotionsToGenerate = settings.promotionsToSearch;
currentIterativeSearchDepth = 0;
abortSearch = false;
searchDiagnostics = new SearchDiagnostics();
// Iterative deepening. This means doing a full search with a depth of 1, then with a depth of 2, and so on.
// This allows the search to be aborted at any time, while still yielding a useful result from the last search.
if (settings.useIterativeDeepening)
{
var targetDepth = settings.useFixedDepthSearch ? settings.depth : int.MaxValue;
for (var searchDepth = 1; searchDepth <= targetDepth; searchDepth++)
{
SearchMoves(searchDepth, 0, negativeInfinity, positiveInfinity);
if (abortSearch)
{
break;
}
currentIterativeSearchDepth = searchDepth;
bestMove = bestMoveThisIteration;
bestEval = bestEvalThisIteration;
// Update diagnostics
searchDiagnostics.lastCompletedDepth = searchDepth;
searchDiagnostics.move = bestMove.Name;
searchDiagnostics.eval = bestEval;
searchDiagnostics.moveVal = PGNCreator.NotationFromMove(FenUtility.CurrentFen(board), bestMove);
// Exit search if found a mate
if (IsMateScore(bestEval) && !settings.endlessSearchMode)
{
break;
}
}
}
else
{
SearchMoves(settings.depth, 0, negativeInfinity, positiveInfinity);
bestMove = bestMoveThisIteration;
bestEval = bestEvalThisIteration;
}
onSearchComplete?.Invoke(bestMove);
if (!settings.useThreading)
{
LogDebugInfo();
}
}
