Author: Robert Hyatt
Date: 11:21:36 04/15/04
Go up one level in this thread
On April 15, 2004 at 14:05:42, rasjid chan wrote: >On April 15, 2004 at 12:22:43, Stefano Gemma wrote: > >>On April 15, 2004 at 05:01:54, rasjid chan wrote: >> >>>After reading the recent post on non-recursive search, I decided to >>>implement it. My guess is that maybe search function call overhead >>>may be too high as I have a host of local variables that cannot be reduced. >>> >>>My approach is direct and simple, an attempt to immitate recursion by >>>creating my own search stack and managing it instead of allowing C function >>[...] >> >>In my old program Drago for Dos (1993's sources are at www.linformatica.com), i >>don't use recursive search. The same was for Raffaela. Both are written in >>assembly. I use a fixed area of memory to old variables for any node (it is >>something like an array of struct, but in assembly). Debugging a non-recursive >>engine in assembly, with a lot of conditional jump was very hard. My last >>engine, Freccia, don't use non-recursive search but still i don't use stack for >>variables but the old array of struct. I think this is the better way to do, in >>my program. Debugging is easyer and i can preset some fixed constant depending >>on the node depth. >> >>Ciao!!! >> >>Stefano Gemma > >To do non-recursive search in assembly would be too tough for me, even with >easy C the debugging can be tricky. > >I am not sure I know or use programming terms / naming correct. What I mean >by stack is my data of array of search_stack_struct type which I create. >Then make/unmake a move becomes ++ply, ++ps, --ply, --ps >where ps is a pointer to my search_stack_struct. So using this pointer ps, >I store / restore my alpha,depth,pointer to current move made / first or >last move in my move list, etc. In this way and with care we can try >non-recursive search and I think there should not be reasons why it cannot >be made better than recursive search. I don't think there is enough difference to measure. Cray Blitz was non-recursive as early Fortran didn't allow recursion. Crafty has been recursive from the start. Procedure call overhead is _not_ significant on a PC, compared to all the work done inside one such call. Non-recursive offers some advantages in a parallel search, but as Crafty shows, a recursive parallel search can (and does) work well. It is just more complicated in a recursive search and there are things you can do in non-recursive that you can't do in recursive easily. > >Best Regards >Rasjid
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