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Subject: Re: I do not understand the code that is supposed to be Fritz's code

Author: José Carlos

Date: 16:45:03 09/03/02

Go up one level in this thread


On September 03, 2002 at 06:25:18, Uri Blass wrote:

>On September 02, 2002 at 20:26:30, Vincent Diepeveen wrote:
>
>>On September 01, 2002 at 12:08:21, Uri Blass wrote:
>>
>>Uri, i posted my answer at 11:55, you answerred at 12:08.
>>That's 13 minutes.
>>
>>How the HELL can you have looked up MTD in the meantime,
>>what it is and what it is doing, and where are your experiments
>>with MTD?
>>
>>For MOVEI it sure works as long are your eval is stupid.
>>
>>It would remove a lot of discussion about fritz here too.
>>like the stupid comments you don't nullmove in your PV.
>>
>>WHICH PV DO YOU TALK ABOUT?
>>
>>What kind of nonsense do you do in your program.
>>
>>CODE PLEASE.
>>
>>In fritz it's very easy i bet:
>>
>>int mtd() {  // of course with a goto instead of a very slow function call
>>  // hashtable probe
>>  if( depth <= verysmalldepth ) {
>>    lookupfasthahstable(L1 cache) // L2 cache lookup too slow of course
>>    return(qsearch(bound)); // of course no function call but a goto, faster...
>>  }
>>  else if( depth < mediumdepth ) {
>>    lookupslowhashtable(L2 cache); // main memory factor 100 slower
>>  else // depth movei nevergets
>>    lookupveryslowmemory(main memory);
>>  // no returns of course in case of a truebound, because returns are too
>>  // slow. Only a jump
>>
>>  if( !incheck )
>>    TryNullmove(); // best move to make first
>
>I admit that I do not understand this code
>
>I do not know how to tell my program to look at L1 cache or L2 cache.
>Maybe I will know better after I read the books that I ordered from amazon.

  There's no instruction to tell the program to read from L1 or L2. What Vincent
means (if I get him right) is using very small tables that fit in cache (when
you have a small piece of data that you use very often, it's very likely to stay
in cache).
  Apart from this, I think the above code is simply ridiculous.

  José C.


>The only optimization that I cared about in movei is optimization of the
>algorithm.
>
>I guess that the only place that I use the very slow memory is in book moves(I
>do not use tablebases).
>
>Uri



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