Author: Vincent Diepeveen
Date: 08:51:10 09/16/02
Go up one level in this thread
On September 15, 2002 at 15:01:54, Tony Werten wrote:
>On September 15, 2002 at 12:35:16, Vincent Diepeveen wrote:
>
>>On September 15, 2002 at 12:19:59, Tony Werten wrote:
>>
>>>On September 15, 2002 at 12:00:06, Vincent Diepeveen wrote:
>>>
>>>>On September 14, 2002 at 13:27:12, Tony Werten wrote:
>>>>
>>>>2 tables is pretty outdated, because you suffer twice
>>>>latency of DRAM then (about factor 1000 slower than processor
>>>>speed).
>>>
>>>Yes, I know. My implementation is a 2 dimensional table wich uses cache after
>>>the first read.
>>>
>>>Tony
>>
>>2 dimensional table???
>>
>>For some reason i get impression you're not programming very low level...
>
>??? Don't get that. You still seem to think pascal is at a higher level than C ?
>
>Anyway, you create a structure, you create an array of this structure, then you
>create an array of these arrays.
>
>Tony
>
>>
>>>
>>>>
>>>>better is 1 table and doing a number
>>>>of sequential probes in it.
>>>>
>>>>>On September 14, 2002 at 13:00:09, scott farrell wrote:
>>>>>
>>>>>>I have been reading plenty on hash replacement schemes.
>>>>>>
>>>>>>I have read Breuker's thesis, and done some (slow) searching through the CCC
>>>>>>archives.
>>>>>>
>>>>>>I am going over my code and redoing the hashing parts, only to realise I have
>>>>>>borken IID (internal iterative deepening).
>>>>>>
>>>>>>Now I am unsure of what I should be aiming at in relation to hashing code.
>>>>>>
>>>>>>I am also unsure of exactly what multi-probing the hash tables is. I am guessing
>>>>>>there is still only one hashtable, and different equations to go from
>>>>>>key/checkkey to the hashtable index, so that there can be several alternative
>>>>>>slots that a hash entry for a position could appear at. Is Multi-probe just
>>>>>>aiming at reducing collisions - or is the idea to store more than one hash entry
>>>>>>for popular positions (say 1 for "depth based", and one for "replace always")?
>>>>>>
>>>>>>I think I am correct that I need atleast one of the probes as "replace always"
>>>>>>to get IID to work. What else do I need to guarantee that I get the best moves
>>>>>>from IID backed up to the main search?
>>>>>>
>>>>>>When people say "replace always" do that mean literaly, just store it all the
>>>>>>time? It seems over simplistic - but I tried it, and it works pretty much the
>>>>>>same as my code below that tries to keep the deeper entries.
>>>>>>
>>>>>>Any help apprecated.
>>>>>
>>>>>What most people do is have 2 tables. In the first you only store if the
>>>>>searchdepth >= table depth (and you move the former entry to the second table).
>>>>>If not then store in 2nd table.
>>>>>
>>>>>Tony
>>>>>
>>>>>PS I advise you to create a structure and create an array of that. Your
>>>>>implementation of serveral arrays kills the cache.
>>>>>
>>>>>>
>>>>>>Here is some of my code
>>>>>>
>>>>>>//////////////////////////////////////////////////////////////////////////////////////////////////////
>>>>>>// SET A TABLE ENTRY
>>>>>>//////////////////////////////////////////////////////////////////////////////////////////////////////
>>>>>>public final static void store(
>>>>>> int _depth,
>>>>>> int _value,
>>>>>> Move _best,
>>>>>> char _flag,
>>>>>> boolean _estOnly,
>>>>>> short _reqSE,
>>>>>> Board _b,
>>>>>> boolean usingSecondTE_notbeingused,
>>>>>> boolean _dontNullMove)
>>>>>>{
>>>>>> int key= 0;
>>>>>> long checkKeyt= 0;
>>>>>>
>>>>>> if (_b.sideToMove == Board.BLACK)
>>>>>> {
>>>>>> key= ~_b.key & (size - 1);
>>>>>> checkKeyt= ~_b.checkKey;
>>>>>> } else
>>>>>> {
>>>>>> key= _b.key & (size - 1);
>>>>>> checkKeyt= _b.checkKey;
>>>>>> }
>>>>>>
>>>>>> boolean collision=
>>>>>> checkKeyt != checkKey[key] && checkKey[key] != 0 && stale[key] == false;
>>>>>>
>>>>>> if (_best != null)
>>>>>> {
>>>>>> s1[key]= (byte) _best.s1;
>>>>>> s2[key]= (byte) _best.s2;
>>>>>> }
>>>>>>
>>>>>> }
>>>>>>
>>>>>> if (stale[key]
>>>>>> || (_depth > (int) depth[key])
>>>>>> || (_depth == (int) depth[key] && _flag > flag[key]))
>>>>>> {
>>>>>>
>>>>>> depth[key]= _depth;
>>>>>> value[key]= _value;
>>>>>> flag[key]= _flag;
>>>>>> SERequired[key]= _reqSE;
>>>>>> stale[key]= false;
>>>>>> checkKey[key]= checkKeyt;
>>>>>> dontNullMove[key]= _dontNullMove;
>>>>>>
>>>>>> } // end if replace
>>>>>> else
>>>>>> {
>>>>>> // store2nd(_depth, _value, _best, _flag, _reqSE, _b,
>>>>>>_dontNullMove);
>>>>>> }
>>>>>>}
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