/// <summary>
/// Adds or removes piece from Zobrist hash.
/// </summary>
/// <param name="color">The piece color.</param>
/// <param name="pieceType">The piece type.</param>
/// <param name="field">The field bitboard.</param>
/// <param name="bitboard">The bitboard.</param>
public static void AddOrRemovePiece(Color color, PieceType pieceType, ulong field, Bitboard bitboard)
{
var fieldIndex = BitOperations.GetBitIndex(field);
var index = FastArray.GetZobristPieceIndex(color, pieceType, fieldIndex);
bitboard.Hash ^= ZobristContainer.Pieces[index];
}
/// <summary>
/// Calculates Zobrist hash for pieces.
/// </summary>
/// <param name="hash">The current hash.</param>
/// <param name="pieces">The array of pieces.</param>
/// <returns>The updated Zobrist hash.</returns>
private static ulong CalculatePieces(ulong hash, ulong[] pieces)
{
for (var colorIndex = 0; colorIndex < 2; colorIndex++)
{
var color = (Color)colorIndex;
for (var pieceIndex = 0; pieceIndex < 6; pieceIndex++)
{
var piece = (PieceType)pieceIndex;
var piecesArray = pieces[FastArray.GetPieceIndex(color, piece)];
while (piecesArray != 0)
{
var pieceLSB = BitOperations.GetLSB(piecesArray);
piecesArray = BitOperations.PopLSB(piecesArray);
var fieldIndex = BitOperations.GetBitIndex(pieceLSB);
hash ^= ZobristContainer.Pieces[FastArray.GetZobristPieceIndex(color, piece, fieldIndex)];
}
}
}
return(hash);
}