Author: Brian Richardson
Date: 07:32:38 12/07/99
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On December 07, 1999 at 08:28:53, Vincent Diepeveen wrote: >On December 06, 1999 at 15:20:39, Brian Richardson wrote: > >>On December 06, 1999 at 11:29:56, Bas Hamstra wrote: >> >>>Hi Bob and other bb experts, >>> >>>What do you use the rotated bb's for, exactly: only for movegeneration, or also >>>for attack detection? >>> >>>I ask this because I saw in Crafty some code to detect blocking of sliding >>>attacks, like I do it. Whith a BlockMask[File][Rank]. I thought the essence of >>>the rotated bb's is that you can avoid this block checking, so why this >>>block-code in Crafty? >>> >>> >>> >>>Regards, >>>Bas Hamstra. >> >>I had done some informal testing of rotated vs non for move generation with >>Crafty and found non to be slightly faster (<10%) for move generation (I suspect >>due to less overhead updating). However, for attack detection and eval >>functions, I think rotated more than makes up for the additional complexity... >> >>Nonetheless, I do not use rotated in my program for simplicity (at this stage of >>development, I prefer KISS to maximum performance). >> >>An easy test would be rotated vs non in Crafty's Attacked() function. >>Differences probably vary significantly by game stage and mobility. > >Can you please post at what outdated hardware you tested that? Tested on PII 266, 512K cache, 64MB back in Sept 98 under Win95, MSVC 5. Cut'n paste Crafty move generation, stripped hashing updates, but left incremental material updates. Tried with and without rotated bitmaps. This was before vcinline.h ! Certainly not a "fair" comparison, but I was only looking for "big" differences (turned out much faster than gnuchess pointer method, and my much older method, which I abandonded). Tested with perft timing using starting position, which is another "problem". I am not a bitmap guru. Currently my program only does about 1M per second (with vcinline.h), so perft to depth 6 takes about 130 secs, which is about the same as Crafty 16.18 Again, for my purposes this informal testing was adequate, since my program spends about 50% of the time in eval(). I am sure well-done rotated bitmaps are a significant improvement, but I am postponing rotated bitmaps until after the eval() gets smarter, and pondering, books, learning and EGTBs get implemented.
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