Author: James Robertson
Date: 11:58:54 06/20/00
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On June 20, 2000 at 12:18:06, Ralf Elvsén wrote: >I'm asking about things I don't have much personal experience from >so forgive me if this is a stupid question. With BB, as I understand >it, one usually have a lot of precomputed BB-arrays, like bishopsMoves[square], >maybe blocks[from][to] or the rotated BB-stuff. Is this causing problems >for the cache? How much precomputed stuff is needed in 0x88 compared to this? > >Ralf I'll answer your second question first. A tiny amount (guesstimate, maybe 1k) is needed for 0x88. Bitboards require much more... almost 600k for core arrays on my program. Crafty uses some funky thing called compact attacks which I guess compacts the attacks. I don't know how it works. (Dr. Hyatt, could you please explain how it works and what it's advantages are?) The precomputed arrays are usually in the form of attacks for ranks and files. To try to stuff all bishop or rook moves into one array is a bad idea. For instance, in my program, rook moves would require an array of dimensions 8*64*256*256 bytes = 33MB! Taking two arrays, one for ranks and one files (each 8*64*256 = 131072 bytes) is a lot better. James
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