Customizable score weights

[Xan Gregg]

Developers,

I can't find it now, but I remember something customizable weighting 
being on a GNU Chess to-do list.  I've made a first step in that 
direction using the 5.05 distribution,  which I am happy to share with 
you if you like.

Basic summary:

--- OLD eval.h ---

#define TRADEPIECE   4
#define TRADEPAWNS   8
#define HUNGPENALTY  -20
#define ROOKMOVED    -20
#define KINGMOVED    -20
...

--- NEW eval.h ---

typedef struct
{  /* all values in centipawns from perspective of current side */
   int tradePieces;     /* reward for piece trade when ahead in material */
   int tradePawns;      /* reward for pawn trade when behind in material */
   int hungPenalty;     /* penalty for hung pieces */
   int rookMoved;       /* penalty for rook having been moved */
   int kingMoved;       /* penalty for king having been moved */
   ...
} Profile;

extern Profile profile; /* the current profile in use */

#define TRADEPIECE   profile.tradePieces
#define TRADEPAWNS   profile.tradePawns
#define HUNGPENALTY  profile.hungPenalty
#define ROOKMOVED    profile.rookMoved
#define KINGMOVED    profile.kingMoved

--- NEW eval.c ---

Profile defaultProfile; /* profile used unless overridden */
Profile profile;        /* the current profile in use */

void InitDefaultProfile()
{       /* defaults from 5.05 eval.h */
   defaultProfile.tradePieces = 4;
   defaultProfile.tradePawns = 8;
   defaultProfile.hungPenalty = -20;
   defaultProfile.rookMoved = -20;
   defaultProfile.kingMoved = -20;
   ...
   profile = defaultProfile;
}

---
Having #defines that expand to struct members creates minimal impact on 
the rest of the code. (The only other changes were to declare and call 
the InitDefaultProfile() function.)  The idea is that other profiles 
can be read from files, or that the current profile could be changed at 
run-time via commands, but I haven't pursued those possibilities.

Let me know if you would like the whole files.

xan