Author: Dieter Buerssner
Date: 10:06:43 06/27/02
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On June 27, 2002 at 00:11:41, Robert Hyatt wrote: >On June 26, 2002 at 01:57:01, Gian-Carlo Pascutto wrote: > >>On June 25, 2002 at 20:07:42, Robert Hyatt wrote: >> >>>OK... "is the king in the square of the pawn?" You can't hash that with >>>pawn hashing because the king can be on 64 different squares. >> >>Actually, one wouldn't need a bitboard program to take advantage >>of the bitboard technique to do this. >> >>if (pawn_run_mask[pawn_loc] & BitMask[king_loc]) Or without any bitboard type at all: extern int /* or char */ king_in_sq[64 /* or 48 */][64]; /* For one color */ if (king_in_square[pawn_sq][king_sq]) >ahem... that _is_ a bitmap approach... > >:) Yes. I think a point is that the masks are all precalculated without taking the board position into account. So, it is more or less just an obvious space saving in a precalculated table, just like one may use a char array above instead of an int array. IHMO a pretty straightforward idea (used in many other algorithms), that many people would use, even without ever having heard of a "bitboard engine". Also, in this case one does not need some of the more sophisticated ideas in bitboards, like the possiblility to check for whole files/ranks etc. Regards, Dieter
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