Let bare King paint itself out of a corner

A bare King now increses the centralization bonus of any square it
visits at game level. This implements a perpetually increasing
'stay-put bonus' for loitering in the same location, and makes the
strong side eventually decide to drive the bare King out of a corner
where it cannot be checkmated.
  This only works in games where the white and black King are defined
as separate piece types (as there is no bare-King recognition otherwise)!

diff --git a/fairymax.c b/fairymax.c
index 9b80061..281ccbf 100644 (file)
--- a/fairymax.c
+++ b/fairymax.c
@@ -238,6 +238,7 @@ int k,q,l,e,E,z,n;      /* (q,l)=window, e=current eval. score, E=e.p. sqr.*/
           a->D=99;a->V=0;                      /* lock game in hash as draw*/\r
           R-=i/FAC;                            /*** total captd material ***/\r
           Fifty = t|p<3?0:Fifty+1;\r
+          if(centr[p]==5)b[257+y]-=5;\r
           sp=ps;\r
                      return l;}                /*   & not in check, signal */\r
          v=m;                                  /* (prevent fail-lows on    */\r
@@ -582,7 +583,7 @@ int main(int argc, char **argv)
                         PromPiece = 0; /* Always promote to Queen ourselves */\r
                         for(N=K=0;K<S;K++)N+=b[K]?b[K]&16?S:1:0; /* count pieces for detecting bare King */\r
                         if(w[3]<0&w[4]<0){if(N>>8<2)centr[4]=5;if(!(N&S-2))centr[3]=5;Z+=R>4;R=4;}\r
-printf("# %04x pieces, centr = (%d,%d)\n", N, centr[3], centr[4]);\r
+printf("# %d+%d pieces, centr = (%d,%d)\n", N&63, N>>7, centr[3], centr[4]);\r
                         N=0;K=I;\r
                         if(hill) centr[3] = R>20 ? 1 : 22-R;\r
                         if (D(Side,-I,I,Q,O,LL|S,3)==I) {\r