By 🦉 for the iChess.io

[sowson]

Hi @kz04px, I simplified my case, I would like to contribute if you agree? Thanks! ;-).

[kz04px]

The perft values should already be correct, but you've changed them. I don't think this can be right. Perhaps there's a misunderstanding in how castling works under chess 960?

Take this code when castling king side, for example:

-const auto king_path = (squares_between(ksq, squares::G1) | Bitboard(squares::G1)) & ~Bitboard(ksq);
+const auto king_path = (squares_between(ksq, castle_king_to[0]) | Bitboard(castle_king_to[0])) & ~Bitboard(ksq);

king_path is a mask of the squares the king travels through to get to its destination square of g1. This never changes no matter what the starting position is.

[sowson]

Can you please take a look at https://support.chess.com/en/articles/8614060-how-do-i-castle-in-chess960 ? It explains what I did.

[sowson]

Hi @kz04px, can you reconsider using this change? ;-).