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Subject: Re: A question about speed and bitboard

Author: Robert Hyatt

Date: 07:36:20 09/19/04

Go up one level in this thread


On September 18, 2004 at 14:16:03, Stuart Cracraft wrote:

>On September 17, 2004 at 20:52:19, Robert Hyatt wrote:
>
>>On September 16, 2004 at 21:20:50, Uri Blass wrote:
>>
>>>What is faster doing a loop on the 1's of a bitboard or doing a loop on array of
>>>integers
>>>
>>>I simply consider to change my knight move generator to bitboards
>>>
>>>Today I have array
>>>int knightmove[64][8] and the question is if getting
>>>knightmove[c3][0],...knightmove[c3][7] is faster or slower than getting the same
>>>squares by calculating the 1's of knightoption[c3] in order to get the squares
>>>that the knight can go.
>>>
>>>I also consider to have bitboard knightcapturewhite[64] knightcaptureblack[64]
>>>and knightquietmoves[64] that are going to be updated incrementally after every
>>>move and the question is what is the price of this in speed.
>>>
>>>Do people who use bitboards have experience with it?
>>>
>>>Uri
>>
>>
>>You are asking the wrong question.  Bitboards are simply a way of doing
>>_everything_ differently from array-based board representations.  There are
>>gains and losses (of course you should ignore the naysayers like you-know-who as
>>bitboards can and do work fine).  But when you start to mix things, the only way
>>to see if it is faster is to simply implement and test.  That's what I did with
>>rotated bitboards when I first thought of the idea.  It seemed like a good idea,
>>but there were issues to overcome...  It takes time and testing...
>
>If one doesn't want to go full bitboard for everything,
>then partial bitboard for evaluation...
>
>Speed of evaluation without the hassle of rotation...
>
>Stuart

Then you have to convert mailbox to bitboard at _every_ q-search position.  That
won't be fast...




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