Author: Brian Richardson
Date: 17:29:30 08/26/05
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On August 26, 2005 at 16:14:33, Robert Hyatt wrote: >On August 26, 2005 at 15:57:09, Charles Roberson wrote: > >> >> Bob, >> >> In Telepath (bitboard), I matched the ordering from NoonianChess >>(nonbitboard). While this allowed some code reuse, it was somewhat confusing. >> >> The pattern was A1=0, H1=7, A2=8, H2=15 ....... >> >> In hind sight, It may have been better to use A1=7, H1=0, A2=15, H2=8. >> >> Think of each system and how mentally easy or hard it is to calculate >> diagonals. The reason I say "mentally easy" is you have to use your own >> brain to debug as you well know. >> >> Charles > >That is what I used in Crafty originally, which might be why many used the same >numbering. The problem is that this requires you to "mentally" invert things, >which is not necessarily a bad thing. I have considered keeping this the same, >and just having to "mentally mirror" things since in a 64 bit value, bit 0 is >the right-most bit... > >might be the best idea to leave the bit numbers the same, in fact... and just >deal with the visualization issues mentally and not make that many drastic >changes to the engine... Tinker also uses Crafty's bitboard numbering (albeit non-rotated), and yes, sometimes it is a bit of a pain to visualize... But, I would just like to suggest some caution about the bitboard renumbering idea. They are used in soooo many places and there are mask constants and such all over; missing just one will mess things up in hard to find ways. I understand that you will be essentially rewriting the eval, but even so it is just hard to see the benefit relative to the risk, IMO.
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