Author: Ernst A. Heinz
Date: 01:28:43 10/21/98
Go up one level in this thread
On October 20, 1998 at 18:13:24, Robert Hyatt wrote: > >The main idea of rotated bitmaps is that it eliminates that incremental >updating >of the attack bitmaps as pieces are moved. If I understood Roberto correctly, he is primarily concerned about the full "attack tables" which is obviously different from what you call "attack bitmaps". Without incremental updating the whole bitboard stuff (normal & rotated) allows *only* for the quick detection of the "attack-from" relation, i.e., which squares does a piece attack when it resides on location X. The bitboard stuff answers this question by means of pre-computed attack bitboards and some masking operations to account for other pieces on the board. Unfortunately, however, the bitboard stuff does not fundamentally simplify the calculation of the "attack-to" relation (i.e., which pieces attack location X). Without incrementally updated "attack-to" tables you still need to loop in order to determine the relation. As usual it therefore depends on your specific program if incrementally updated "attack-to" tables are to be preferred or not. =Ernst=
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.