Author: Uri Blass
Date: 14:54:00 12/13/03
I think about rewriting my search code and before doing it may be a good idea if I understand somethings about the search of Crafty. One of the relevant files is hash.c and I think that better comments about it are important for progress in computer chess. I plan to try to understand it and to give also comments. for now I have some questions. 1)I see that the functions get parameters that I have as global varaibles int ply, int wtm Is there an advantage from not having them as global varaibles? I thought that asking a function to get a lot of parameters may make the program slower so varaibles that I need in many functions like side to move are global varaibles. 2)I see temp_hashkey=(wtm) ? HashKey : ~HashKey; My question is where exactly the program remember the hash key of previous positions? (I guess that it needs it to detect repetitions) It is possible that I do not understand the code but it seems to me that here it does not read the hash key from an array like I do because it has #define HashKey (tree->pos.hash_key) I can comment that the ~ that is used in Crafty may be better than what I do I do every time that the side to move is changed BitBoard zob=zobkey[hply]^zobrist[0][0][0]; I think that it may be better and slightly faster to have BitBoard zob=~zobkey[hply]; 3)What is the depth that is stored in HashStorePV? storing depth 0 is logical because I guess that the pv should not be pruned based on hash tables and you can expect depth 0 to be replaced later but I do not see comments about the depth that is stored. If I understand correctly the depth is stored in draft that is 15 bits and depth 1/60 means 2^17 when depth (2^15-1)/60 that is the maximal theoretical depth that can be stored means 2^32-2^17. Even if I understand correctly(I am not sure) I do not understand at this moment from all the varaibles what is the depth that is stored in the hash tables in HashStorePV. Uri
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.