Retire KingExposed[] array

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 1ee727da59773a5920835db74eb5f6e6bf6ea855..6acaaad0e0eaf1cc30e2222032772f4ecf553e36 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -207,19 +207,6 @@ namespace {
   const int BishopCheck       = 2;
   const int KnightCheck       = 3;
 
-  // KingExposed[Square] contains penalties based on the position of the
-  // defending king, indexed by king's square (from white's point of view).
-  const int KingExposed[] = {
-     2,  0,  2,  5,  5,  2,  0,  2,
-     2,  2,  4,  8,  8,  4,  2,  2,
-     7, 10, 12, 12, 12, 12, 10,  7,
-    15, 15, 15, 15, 15, 15, 15, 15,
-    15, 15, 15, 15, 15, 15, 15, 15,
-    15, 15, 15, 15, 15, 15, 15, 15,
-    15, 15, 15, 15, 15, 15, 15, 15,
-    15, 15, 15, 15, 15, 15, 15, 15
-  };
-
   // KingDanger[Color][attackUnits] contains the actual king danger weighted
   // scores, indexed by color and by a calculated integer number.
   Score KingDanger[COLOR_NB][128];
@@ -434,7 +421,7 @@ Value do_evaluate(const Position& pos) {
     {
         ei.kingRing[Them] = b | shift_bb<Down>(b);
         b &= ei.attackedBy[Us][PAWN];
-        ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) / 2 : 0;
+        ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) : 0;
         ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
     }
     else
@@ -640,8 +627,7 @@ Value do_evaluate(const Position& pos) {
     Score score = ei.pi->king_safety<Us>(pos, ksq);
 
     // Main king safety evaluation
-    if (   ei.kingAttackersCount[Them] >= 2
-        && ei.kingAdjacentZoneAttacksCount[Them])
+    if (ei.kingAttackersCount[Them])
     {
         // Find the attacked squares around the king which have no defenders
         // apart from the king itself
@@ -654,11 +640,10 @@ Value do_evaluate(const Position& pos) {
         // Initialize the 'attackUnits' variable, which is used later on as an
         // index to the KingDanger[] array. The initial value is based on the
         // number and types of the enemy's attacking pieces, the number of
-        // attacked and undefended squares around our king, the square of the
-        // king, and the quality of the pawn shelter.
+        // attacked and undefended squares around our king and the quality of
+        // the pawn shelter (current 'score' value).
         attackUnits =  std::min(20, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
                      + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
-                     + KingExposed[relative_square(Us, ksq)]
                      - mg_value(score) / 32;
 
         // Analyse the enemy's safe queen contact checks. Firstly, find the