Author: Jay Scott
Date: 12:27:30 02/27/01
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On February 25, 2001 at 05:39:55, TEERAPONG TOVIRAT wrote: >Actually,I work on a checkers program. A lot of people here said >they are dissapointed with bitboard for chess program. Yes, chess >has 64 squares but checkers has 32 squares. At first, I think >it must be perfectly matched with checkers . I think so, too. Move generation reduces to a short sequence of mask-shift-and operations, then simply look for 1 bits. The entire board state fits into three 32-bit integers: red pieces, white pieces, kings of either side; everything else of interest can be computed with no more than a few logical operations. On a modern processor, surely that will beat walking around in an array of bytes. You might want to use this correspondence between bits and squares, instead of the obvious one. You will need to use rotates instead of shifts to find moves, but there are fewer cases so it should be faster. --00--08--16--24 01--09--17--25-- --10--18--26--02 11--19--27--03-- --20--28--04--12 21--29--05--13-- --30--06--14--22 31--07--15--23-- I came up with this ordering, but it's fairly obvious if you think about it, so I doubt it's new. It's exactly analogous to a Hyattian rotated bitboard, after all, except that you don't need to keep an unrotated version. :-) Jay
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