Author: Bas Hamstra
Date: 22:20:11 04/24/00
I have some evidence that an unrotated bb approach can be as fast or faster than a rotated one. - my fastest ever version did it unrotated. I thereafter thought rotated would be even faster, but never got that speed again. (until hopefully now) - Dan Newman reaches almost 600k nps with little eval on a PIII/500, unrotated. While I thought the limit (based on what I see around) for rotated on this hardware is about 500k doing only material! - On this board I saw someone gen moves pretty fast unrotated. Pro unrotated: - you can gen moves in LVA/MVV order right away. You can not do that while rotating, at least not the way Crafty does it. Saves a sort afterwards. Don't know how big a factor this is. - You don't need the expensive 64 bit shifts doing movegeneration (and eval), which saves a lot of overhead. - Your make() is much faster without the 4 Occupied maps. Contra: - You have to scan for blocks, while rotated doesn't need to. However using a int__64 blockmask[From][To] can do this pretty quick (though some say scanning the board is even faster). The big question is: is the extra overhead of rotated bb's justifyable? Could it be non-rotated is faster overall? (Currently I myself have started all over trying to make a really fast rotated BB program. Looks promising so far: make/unmake=2M/sec and movegeneration=12M moves/sec on a Celeron 466)
This page took 0.02 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.