Author: Robert Hyatt
Date: 07:38:03 09/19/04
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On September 18, 2004 at 17:12:23, E. Nielsen wrote: >On September 16, 2004 at 21:20:50, Uri Blass wrote: > >>...doing a loop on the 1's of a bitboard... > >Well, I suppose it depends on which representation you choose for your >bitboard... > >If it is in two's-complement form (i.e. signed) you can find the rightmost 1-bit >with following formula: > > x & (-x) > Finding the bit is not quite the same as finding the identity or number of the bit. IE findihg bit for square e4 is easy. But if you want to know if it is the e4 square, id bit # X, then that is harder. Fortunately modern processors can do this easily... > >Regards, >Eyðun Nielsen > >P.s.: And I would also recommend the book "Hacker's Delight" by Henry S. Warren, >Jr. which is full of stuff like this. :)
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