Author: Roberto Waldteufel
Date: 00:12:32 10/22/98
Go up one level in this thread
On October 21, 1998 at 04:28:43, Ernst A. Heinz wrote: >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= Hi Ernst, Yes, you see my dilemma. At present my incremental updating is very fast on the attack-from maps, but slower on the attack-to maps. I think this is also the case with attack detection using the rotated bitboards and no attack tables. I intend to try the rotated bitboard method to see if I can make the search faster. Only trouble is, my present code uses the attack tables everywhere, so it will be a big job to rewrite it for the new data structure. Best wishes, Roberto
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.