Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Question about data structures

Author: Hristo

Date: 17:29:59 12/01/98

Go up one level in this thread


On December 01, 1998 at 18:26:44, Bruce Moreland wrote:

>
>On December 01, 1998 at 18:02:47, Bruce Moreland wrote:
>
>>
>>On November 30, 1998 at 12:01:05, Tom Kerrigan wrote:
>>
>>>This is all fine and good for larger arrays that you don't access a lot, but if
>>>you're talking about your representation of the board,
>>>
>>>int chess_board[64];
>>>
>>>will be a serious win over
>>>
>>>char chess_board[64];
>>
>>I don't know why you are saying this in the face of at least two people saying
>>that they tried this exact thing and it was slow.
>>
>>On an Intel machine you have to do an extra instruction to read a char into EAX,
>>unless you use movzx or movsx, which suck.
>>
>>On an Alpha you have to deal with the alpha (21164) not even having an
>>instruction that will read a byte.
>>
>>These are reasons why I intuit that it might go slower, but if I used this data
>>structure I would surely test it and know for sure.
>>
>>I think that discussions of which implementation will go faster, that are based
>>upon predicted instruction timing or cache behavior, are almost always useless.
>
>I realized about fifteen minutes of lag ago that I am arguing the opposite side
>of this argument than I'd intended to.
>
>I think that this doesn't matter very much.
>
>This all has to be solvable with experiments.  If there isn't an easily measured
>difference, then there is no practical difference, so why conjecture about this,
>it's better just to do the experiment.
>
>bruce


Now ... you are posting to yourself ? .. :))))
hristo



This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.