Author: Robert Hyatt
Date: 08:00:19 12/05/99
Go up one level in this thread
On December 05, 1999 at 10:55:45, KarinsDad wrote: >The problem is that some of us do not have access to 64 bit machines (at least I >no longer have access to them). > >My method is similar to Alessandro's with 15 bytes to handle bishop and diagonal >queen attacks and moves. > >The advantage of this for attacks is that you only have to check 1 of the 15 >bytes out of each bitboard (actually, you only need 13 bytes, but my structures >are currently set up as 16 bytes just for boundary convenience) per direction >(2). The same for moves (I would like to use a system in the future of only >creating those diagonal bitmaps that can possibly be used by either side and >then only filling in a new byte in the structure as I go down the tree and move >a bishop or queen). > >The disadvantage is that you have to figure out which 2 bytes to use, but I >think you have a similar issue with 64 bits (although I haven't studied the >Crafty code to figure it out). > >What I haven't figured out from Alessandro's system yet is why he needs such >large bitboard structures (64 * 256). > >KarinsDad :) you need 256 entries because that is the number of possible states of any rank or diagonal. As far as 64 bits goes, within 5 years that is _all_ we will have. Better to plan for the future. It is almost the present. :)
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