/// <summary>
/// Constructor form set of history boards.
/// </summary>
/// <param name="history0"></param>
/// <param name="history1"></param>
/// <param name="history2"></param>
/// <param name="history3"></param>
/// <param name="history4"></param>
/// <param name="history5"></param>
/// <param name="history6"></param>
/// <param name="history7"></param>
public EncodedPositionBoards(EncodedPositionBoard history0, EncodedPositionBoard history1, EncodedPositionBoard history2, EncodedPositionBoard history3,
EncodedPositionBoard history4, EncodedPositionBoard history5, EncodedPositionBoard history6, EncodedPositionBoard history7)
{
History_0 = history0;
History_1 = history1;
History_2 = history2;
History_3 = history3;
History_4 = history4;
History_5 = history5;
History_6 = history6;
History_7 = history7;
}
/// <summary>
/// Determines if en passant opportunity
/// exists between two specified consecutive history boards.
/// </summary>
/// <param name="currentBoard"></param>
/// <param name="priorBoard"></param>
/// <returns></returns>
public static PositionMiscInfo.EnPassantFileIndexEnum EnPassantOpportunityBetweenBoards(EncodedPositionBoard currentBoard,
EncodedPositionBoard priorBoard)
{
EncodedPositionBoardPlane pawnsPrior = priorBoard.OurPawns;
EncodedPositionBoardPlane pawnsCurrent = currentBoard.TheirPawns;
// We look for the boards differing only because a pawn moved from rank 7 to rank 5 (from our perspective)
for (int i = 8; i < 16; i++)
{
if (
priorBoard.TheirPawns.BitIsSet(64 - i) &&
!priorBoard.TheirPawns.BitIsSet(64 - i - 16) &&
!currentBoard.TheirPawns.BitIsSet(64 - i) &&
currentBoard.TheirPawns.BitIsSet(64 - i - 16)
)
{
return((PositionMiscInfo.EnPassantFileIndexEnum) new Square(16 - i).File);
}
}
return(PositionMiscInfo.EnPassantFileIndexEnum.FileNone);
}
