Release King surroundings in late end-game

The bonus for friendly King environment is topped off in the late end-game,
to prevent that many pieces would be prevented from participating in
checkmating the opponent.

diff --git a/hachu.c b/hachu.c
index 086bc90..5893196 100644 (file)
--- a/hachu.c
+++ b/hachu.c
@@ -1613,7 +1613,7 @@ Fortress (int forward, int king, int lion)
 }\r
 \r
 int\r
-Surround (int stm, int king, int start)\r
+Surround (int stm, int king, int start, int max)\r
 {\r
   int i, s=0;\r
   for(i=start; i<9; i++) {\r
@@ -1623,7 +1623,7 @@ Surround (int stm, int king, int start)
     v = p[piece].value;\r
     s += -(v > 70) & v;\r
   }\r
-  return (s > 512 ? 512 : s);\r
+  return (s > max ? max : s);\r
 }\r
 \r
 int\r
@@ -1639,7 +1639,7 @@ Ftest (int side)
 int\r
 Evaluate (int difEval)\r
 {\r
-  int wLion = ABSENT, bLion = ABSENT, wKing, bKing, score=mobilityScore, f, i, j;\r
+  int wLion = ABSENT, bLion = ABSENT, wKing, bKing, score=mobilityScore, f, i, j, max=512;\r
 \r
   if(p[WHITE+2].value == LVAL) wLion = p[WHITE+2].pos;\r
   if(p[BLACK+2].value == LVAL) bLion = p[BLACK+2].pos;\r
@@ -1681,6 +1681,7 @@ Evaluate (int difEval)
     score += (PST[PST_CENTER+wKing] - PST[PST_CENTER+bKing])*(32 - filling) >> 7;\r
     if(lead  > 100) score -= PST[PST_CENTER+bKing]*(32 - filling) >> 3; // white leads, drive black K to corner\r
     if(lead < -100) score += PST[PST_CENTER+wKing]*(32 - filling) >> 3; // black leads, drive white K to corner\r
+    max = 16*filling;\r
   }\r
 \r
 # ifdef FORTRESS\r
@@ -1691,7 +1692,7 @@ Evaluate (int difEval)
 # endif\r
 \r
 # ifdef KSHIELD\r
-  score += Surround(WHITE, wKing, 1) - Surround(BLACK, bKing, 1) >> 3;\r
+  score += Surround(WHITE, wKing, 1, max) - Surround(BLACK, bKing, 1, max) >> 3;\r
 # endif\r
 \r
 #endif\r
@@ -1703,11 +1704,11 @@ Evaluate (int difEval)
     int sq;\r
     if((wLion = kylin[WHITE]) && (sq = p[wLion].pos) != ABSENT) {\r
       int anchor = sq - PST[5*BW*BH - 1 - sq]; // FIXME: PST_ZONDIST indexed backwards\r
-      score += (512 - Surround(BLACK, anchor, 0))*(128 - filling)*PST[p[wLion].pst + sq] >> 15;\r
+      score += (512 - Surround(BLACK, anchor, 0, 512))*(128 - filling)*PST[p[wLion].pst + sq] >> 15;\r
     }\r
     if((bLion = kylin[BLACK]) && (sq = p[bLion].pos) != ABSENT) {\r
       int anchor = sq + PST[PST_ZONDIST + sq];\r
-      score -= (512 - Surround(WHITE, anchor, 0))*(128 - filling)*PST[p[bLion].pst + sq] >> 15;\r
+      score -= (512 - Surround(WHITE, anchor, 0, 512))*(128 - filling)*PST[p[bLion].pst + sq] >> 15;\r
     }\r
   }\r
 #endif\r