Magic BitBoards are an efficient way to take a position and obtain the legal moves for a sliding piece.

The occupancy bits for a specific piece on a specific square can be multiplied against a “magic” number, and then shifted, to obtain an index in a per-initialized attack table.

Calculate Magic Numbers

Magic BitBoard Principle

https://stackoverflow.com/questions/7365562/de-bruijn-like-sequence-for-2n-1-how-is-it-constructed

https://www.stmintz.com/ccc/index.php?id=306404