Author: KarinsDad
Date: 15:22:39 05/14/99
Go up one level in this thread
On May 14, 1999 at 18:13:10, Charles L. Williams wrote: >On May 14, 1999 at 18:11:04, Charles L. Williams wrote: > >>On May 14, 1999 at 17:10:38, KarinsDad wrote: >> >>>On May 14, 1999 at 15:21:57, Dann Corbit wrote: >>> >>>>0: >>>>Title says it all. What binary format does your program use when you want to >>>>store a board position in the smallest space possible? >>> >>>Without thinking about it alot, here is my first cut (my program does not do >>>this yet): >>> >>>10 bits for side to move, en passant possible, en passant to square (4 bits >>>since there are only 16 legal squares for this), white kingside castle possible, >>>white queenside castle possible), black kingside castle possible, black >>>queenside castle possible (note: for a program, it may be better to know if a >>>rook moved and if the king moved, but you save 2 bits without that info here) >>> >> >> >>The en passant can be reduced to three bits because you already have the side to >>move. The three bits represent the file. >> >>My program doesn't do any of this either. >> >> >>Chuck >> >> >><snipped> > > >Sorry, KarinsDad. I just read your followup. I think we may be posting here >nearly simultaneously. > >Chuck Yes, it looked that way. I have a further correction. Since pawns cannot exist on the 1st and 8th rank, we can minimize the structures there to: 0 blank 100x knight 101x bishop 110x rook 111x queen This will save 1 bit for every minor piece on the 1st or 8th row. Slick, huh? This also allows the 1 bit savings on the en passant to be worthwhile and the starting position of the game can be represented in 157 bits or 20 bytes. Getting better all of the time!!! KarinsDad :)
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