public ulong PawnsAbleToDoublePushDown(ulong emptySquares)
{
ulong rank5 = 0x000000FF00000000UL;
ulong emptyRank4 = BitBoardHelper.ShiftNorthOne(emptySquares & rank5) & emptySquares;
return(this.PawnsAbleToPushUp(emptyRank4));
}
public ulong DoubleUpPushTargets(ulong emptySquares)
{
ulong rank4 = 0x00000000FF000000UL;
ulong singlePushs = this.SingleUpPushTargets(emptySquares);
return(BitBoardHelper.ShiftNorthOne(singlePushs) & emptySquares & rank4);
}
protected ulong GetFileMask(int file)
{
ulong board = 1UL << file;
int count = 8;
while (--count > 0)
{
board |= BitBoardHelper.ShiftNorthOne(board);
}
return(board);
}
private ulong GetKingMoves(int i, int j)
{
int index = i * 8 + j;
ulong initialPos = 1UL << index;
ulong board = initialPos;
ulong attacks = BitBoardHelper.ShiftEastOne(board) | BitBoardHelper.ShiftWestOne(board);
board = initialPos | attacks;
attacks |= BitBoardHelper.ShiftNorthOne(board) | BitBoardHelper.ShiftSouthOne(board);
return(attacks);
}
public ulong PawnsAbleToPushDown(ulong emptySquares)
{
return(BitBoardHelper.ShiftNorthOne(emptySquares) & this.board);
}
public ulong SingleUpPushTargets(ulong emptySquares)
{
return(BitBoardHelper.ShiftNorthOne(this.board) & emptySquares);
}
// all pawns that are blocked by the opponent's pawns
public ulong DownRam(PawnBitBoard opponentPawns)
{
return(BitBoardHelper.ShiftNorthOne(this.board) & opponentPawns.board);
}