Changes

Based on a fixed piece-type and bit-position relation with usual material dispositions (for each side, no more than one queen, two rooks, one bishop per square color, two knights), 32-bit [[Piece-Sets]] already inherit the information which pieces (and how many of both sides) attack a particular square, one can even imagine a 16-bit lookup inside a 64KByte table to get an denser attack indicator/count byte for each color a lá [[Attack and Defend Maps#EDsLookup|Ed Schröder]]. [[MS-DOS]] [[IsiChess]] maintained an [[Array|array]] of 64 32-bit piece-sets for every square, and an array of up to 32 attack-to bitboards for every piece. However working with piece-sets requires an additional indirection via a [[Piece-listsLists|Piece-list]] to get the square of that piece.