Author: Andrew Dados
Date: 16:44:58 03/08/01
Go up one level in this thread
On March 08, 2001 at 15:23:45, Robert Hyatt wrote: >On March 08, 2001 at 11:31:32, Peter Fendrich wrote: > >>I'm completly reorganising my book and also trying to speed it up. >> >>Using the fread(buf,....) how can I find out the most >>efficient buffer size to use? >> >>Currently I'm using an index, that I'm maintaining, to find a place >>somewhere "near" in front of the searched book move where I will start and >>read forward in sequence until the right move is found. >> >>//Peter > > >If you want to go fast, I can suggest the approach I use. My 64 bit hash key >is used to produce book keys, but a book position uses the leftmost 16 bits >of the _parent_ position, and the rightmost 48 bits of the resulting position >after playing the "book move". That much is easy. Now sort all these keys. >That will put all the book moves with the same "parent 16 bits" together. > >I then store a big index on the front of the book file, at present 32768 >indices, with each index pointing to the first move in the book with the >same common parent bits. > >The benefit is that if you read in a complete "cluster" (all positions with >the same 16 parent bits) then you get _all_ the possible book moves from this >position (plus other positions since other parent positions will have the same >16 upper bits of course). But since it takes _one_ I/O you are done. Now you >just search for the right 64 bit key and if you find it you know that move is >a book move... I have to admit I never understood that. What if your 'board parent position' is different from 'book parent position' due to transposition? I.e. on board you got 1. d4 c6 . Now both positions 2. e4 and 2. c4 can be found in the book but from different parents - so they're not in same cluster. Now suppose craftys book does not have such a parent (1. d4 c6) but has entries for both slav and caro-cann defense. How does it choose a book move (and tell that 2. e4 is still book position)? Or does it do many I/O in that case? -Andrew- > >fast, easy, efficient.
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