Author: Dave Gomboc
Date: 19:49:30 06/20/00
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On June 20, 2000 at 14:58:54, James Robertson wrote: >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 Can you elaborate on what you are doing, how you are doing it, and why you are doing it? 256 Kb sounds like quite a lot of storage. Dave
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