Author: Paul Clarke
Date: 11:14:15 03/02/06
Go up one level in this thread
On March 02, 2006 at 11:50:56, Robert Hyatt wrote: >On March 02, 2006 at 02:19:04, Tony Werten wrote: > >>On March 01, 2006 at 20:00:40, Robert Hyatt wrote: >> >>>Someone had already emailed me this. I just hadn't looked. Now I am not quite >>>sure what is going on: >>> >>>static const int HistorySize = 12 * 64; >>> >>>That appears to be a dimension for the HistHit[] and HistTot[] arrays, which >>>leaves me lost since the other code sent to me has: >>> >>>index = PIECE_TO_12(board->square[MOVE_FROM(move)]) * 64 + >>>SQUARE_TO_64(MOVE_TO(move)); >>> >>>followed by >>> >>> HistHit[index]++; >>> HistTot[index]++; >>> >>>So I know I am overlooking something. "index" is clearly a 12 bit value between >>>0 and 4095 if I understand it correctly. yet HistHit[] is not nearly that big. >> >>How do you get to 4096 ? > >I'm looking at from*64+to... since either is at least 6 bits, that gives 12. >If piece_to_12 squashes from into 12 bits, that would at least make the index >correct according to the dimension of the array, although then I would not claim >to understand the idea of squashing from from 0-63 into the range 0-11... Are you reading the index calculation as: index = SQUARE_TO_64(MOVE(from)) * 64 + SQUARE_TO_64(MOVE(to)); ? If so then that would explain the confusion: the index calculation is, as Tony mentions below, using the type of piece that moved rather than the square it moved from, hence the use of PIECE_TO_12(board->square[MOVE(from)]). > > >>Piece_to_12 most likely has a 0..11 range (6 pieces, 2 colors), square_to a >>0..63 It's just 12*64=768 >> >>Tony
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