[Gnushogi-devel] merging gnushogi and gnuminishogi

[H.G. Muller]

In case it would ever be desirable to play regular and mini-Shogi in the 
same engine,
the following ideas might become useful:

* There is no real need to delete the piece types Knight and Lance. In 
mini-Shogi they would simply not be present.

* The overhead in testing whether a piece is a Lance or Knight, which 
would be done in vain in mini-Shogi,  is quite negligible. It could in 
many places be made to disappear completely, (as well as speed up the 
code for regular Shogi) by testing for groups of piece types through a 
bitmask where each bit represents a type. Tests like "if((piece == pawn) 
|| (piece == lance) || (piece == knight))" could be replaced by 
"if(mask[piece] & (T_PAWN | T_KNIGHT | T_LANCE))", with no penalty for 
including non-participating pieces in the set.

* Some (now complex) code for testing whether a certain piece type is 
(non)promotable in a certain location can be more efficiently and more 
generally done by having a board-size arrays that contains bit flags to 
indicate what each piece can do where (promote or non-promote). These 
could then be initialized depending on the board / promo-zone size.

* From what I understand of the code, it seems that mini-Shogi can be 
easily played in the same board[81] format as regular Shogi, by 
different initialization of the nunmap and inunmap arrays to indicate 
which square numbers are in use.