Author: KarinsDad
Date: 13:28:57 05/20/99
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On May 20, 1999 at 15:17:35, Dann Corbit wrote: >On May 20, 1999 at 14:49:37, KarinsDad wrote: >[snip] >>This being the case Dann, why not just use the internal structure from EPD? It's >>about as fast as you can probably get and takes up 24 bytes per position. >What internal structure? The binary EPD specification is not complete, as far >as I can tell. I have settled on a 22 byte format. See the section under Hashing in the EPD: http://reality.sgi.com/pmk_craypark/Internal.txt The compression scheme is real good for the 24 byte version, however, like most good engineers, they overdesigned it (similar to how the mars lander had sensors in the containment unit to determine WHICH side of the pyramid was face down before opening 1 side as opposed to just opening all 3 sides automatically). 64 bit bitboard 4 bit piece types * 32 pieces = 128 bits total bits = 192 = 24 bytes The piece types are: 12 chess pieces 1 rook can castle piece 1 en-passant pawn 1 side to move pawn (not needed if en-passant pawn exists) They have a side to move indicator pawn which replaces a normal pawn and if no pawns are there, they put side to move after the structure (effectively). Instead, they could have just created a 2nd white king to indicate side to move and it would always be available (i.e. white king white to move, white king black to move). Oh well. KarinsDad :)
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