Author: Federico Corigliano
Date: 19:12:33 01/14/04
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On January 14, 2004 at 22:08:11, Ed Trice wrote: >Hello Federico, > >>Hi to all >> >>In my engine I use some bitboards, but nothing about rotated bitboards for >>bishop, rooks and queen moves. >> >>What chess sources or web pages can you recommend me? >> >>One answer can be Crafty. Seems to be a little difficult to understand but I >>don't tried yet :-) >> > >I definitely recommend reading the Crafty code for rotated bitboards. Basically, >you create rotated versions of the board so the shifting left and right "behave" >like diagonal displacements. For example, shifting bits from left to right in >increments of 1 would be like moving a rook horiztonally. > >But, if you lay the board out like this (a 45 degree rotation) > >a1, b1,a2, c1,b2,a3, d1,c2,b3,a4, e1,d2,c3,b4,a5, .... > >you can perform shifts on the BITS corresponding to these squares as if you were >actually doing complex digaonl shifts. > >The hard part for will be keeping track of the length of the diagonals for all >of the rotation possibilies (rotating right 45, rotating left 45, etc.) as well >as all of the rotation data. Well, I will try to see Crafty source code. Thanks! Federico > >--Ed
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