Author: Gerd Isenberg
Date: 10:05:32 10/09/04
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On October 09, 2004 at 10:02:13, Stuart Cracraft wrote: >On October 09, 2004 at 09:58:38, Gerd Isenberg wrote: > >>On October 08, 2004 at 20:03:43, Zach Wegner wrote: >> >>>I don't know how to get WAC 141 in one second, but I know some things in your >>>code to improve it. First, you should not dynamically allocate storage for moves >>>(do not declare the array in search()), but rather have a large array of size >>>MAXMOVES * MAXPLY (it can probably be less) that is indexed by a pointer array >>>indexed by ply. >> >>I prefere your approach too, one huge move array and keeping index or pointer >>per ply, but don't confuse Stuart's local move array on the stack with >>dynamically allocated storage, which is usually got with alloc/malloc or >>operator new[] and freed with operator delete[] in C++. >> >>Keeping things on the stack frame is only about sub esp,LOCAL_SIZE. >>That's not that bad - at least there are no allocation/freeing costs. >> >>Gerd >> >> >>>If this seems confusing, heres some pseudo-code: >>> >>>mv movestack[MAXMOVES * MAXPLY]; >>>mv *firstmove[MAXPLY]; >>>... >>>firstmove[ply + 1] = gen(firstmove[ply]); >>> >>>This requires your gen() to return a pointer to the element after the last move >>>used, which shouldn't be too difficult. >>> >>>Second, it seems you are not using fractional extensions the way most people do. >>>The depth parameter is measured in some constant > 1 that is proportional to a >>>ply. I suppose floats could be used, but is important that the depth parameter >>>is not an int with 1 equal to a ply. The idea is that for some extensions you do >>>not want to extend a whole ply for just one occurence, but add a little bit of a >>>ply to the depth that could help trigger an extension later. As an example, at >>>ply X you have a condition met and you want to extend a half of a ply. Then at >>>ply X + 2(say) you have the same (or other) condition met, and you extend a half >>>of a ply again. The net extension is then just one ply, while in your >>>implementation it would not be extended because the half ply would be rounded >>>off at each ply. Or maybe I just misunderstood your code... >>> >>>Regards, >>>Zach > >Okay if I hear you right, I can get rid of memory allocation and deallocation >calls by maintaining my own move stack. How much is that really worth? Difficult to say, probably negligible and not worth to change it. The advantage of an own move stack is that you can keep it gap-less and therefore you may need less cachelines and memory resources. OTOH you need an additional pointer/index per ply. Again, your local move[MAXMOVES] array on the stack is not as far expensive as dynamic memory allocation on the heap via operator new[] and operator delete[]. But you allways reserve MAXMOVES for each ply - most often not needed at all. Therefore you have some gaps on your stack, which makes it less efficient in terms of cachelines and 4 KPages. Gerd
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