public ulong Perft(int depth)
{
var mg = new MoveGenerator(Position);
mg.GenerateMoves();
if (depth == 1)
{
return((ulong)mg.Moves.Count);
}
var(found, entry) = Table.Probe(Position.State.Key);
if (found && entry.Key32 == (uint)(Position.State.Key >> 32) && entry.Depth == depth)
{
return((ulong)entry.Value);
}
var tot = 0ul;
var move = MoveExtensions.EmptyMove;
for (var i = 0; i < mg.Moves.Count; ++i)
{
move = mg.Moves.GetMove(i);
MakeMove(move);
tot += Perft(depth - 1);
TakeMove();
}
if (move != MoveExtensions.EmptyMove)
{
Table.Store(Position.State.Key, (int)tot, Bound.Exact, (sbyte)depth, move, 0);
}
return(tot);
}
/// <summary>
/// <para>"Validates" a move using simple logic. For example that the piece actually being moved exists etc.</para>
/// <para>This is basically only useful while developing and/or debugging</para>
/// </summary>
/// <param name="move">The move to check for logical errors</param>
/// <returns>True if move "appears" to be legal, otherwise false</returns>
public bool IsPseudoLegal(Move move)
{
// Verify that the piece actually exists on the board at the location defined by the move struct
if ((_bitboardPieces[move.GetMovingPiece().ToInt()] & move.GetFromSquare()).Empty())
{
return(false);
}
var to = move.GetToSquare();
if (move.IsCastlelingMove())
{
// TODO : Basic castleling verification
if (CanCastle(move.GetFromSquare() < to ? ECastleling.Short : ECastleling.Long))
{
return(true);
}
var mg = new MoveGenerator(Position);
mg.GenerateMoves();
return(mg.Moves.Contains(move));
}
else if (move.IsEnPassantMove())
{
// TODO : En-passant here
// TODO : Test with unit test
var opponent = ~move.GetMovingSide();
if (EnPassantSquare.PawnAttack(opponent) & Position.Pieces(EPieceType.Pawn, opponent))
{
return(true);
}
}
else if (move.IsCaptureMove())
{
var opponent = ~move.GetMovingSide();
if ((_occupiedBySide[opponent.Side] & to).Empty())
{
return(false);
}
if ((_bitboardPieces[move.GetCapturedPiece().ToInt()] & to).Empty())
{
return(false);
}
}
else if ((_occupied & to) != 0)
{
return(false);
}
// ReSharper disable once SwitchStatementMissingSomeCases
switch (move.GetMovingPiece().Type())
{
case EPieceType.Bishop:
case EPieceType.Rook:
case EPieceType.Queen:
if (move.GetFromSquare().BitboardBetween(to) & _occupied)
{
return(false);
}
break;
}
return(true);
}
