Changes

OliThink pre 5 versions used [[Rotated Bitboards|rotated bitboards]] to determine [[Sliding Piece Attacks|sliding piece attacks]]. Since version 5, only the usual [[Occupancy|occupancy]] is used to [[Occupancy of any Line|map the masked line to an index]], for [[Files|files]] and [[Diagonals|diagonals]] by a [[General Setwise Operations#Multiplication|north-fill multiplication]] and right shift as also applied in [[Kindergarten Bitboards|kindergarten bitboards]] <ref>[http://www.talkchess.com/forum/viewtopic.php?t=24724 Kindergarten Bitboard Approach by Gerd Isenberg] by [[Edsel Apostol]], [[CCC]], November 05, 2008</ref>, with the addition not only to lookup attack bitboards, but also [[X-ray Attacks (Bitboards)#Xray1|X-ray attacks]] through the first blocking pieces (if any) of both [[Direction|ray-directions]] <ref>[http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=166649&t=18750 Re: Question about SEE (Static exchange evaluation)] by [[Oliver Brausch]], [[CCC]], December 18, 2007</ref> . A pre-initialized [[Array|array]] of 8 times 8K 4K bitboards (512 256 Kbyte in total) is used for attacks on [[Ranks|ranks]], files, diagonals and [[Anti-Diagonals|anti-diagonals]] in its lower half, while the upper half holds appropriate x-ray attacks. Per line, a 12-bit index is composed of the 6-bit square index and a 6-bit occupancy key <ref>[http://www.talkchess.com/forum3/viewtopic.php?f=2&t=77339&start=44 Re: OliThink 5.9.5 is very small] by [[Oliver Brausch]], [[CCC]], June 06, 2021</ref>.