Fix a comment

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 9c35a0dbb6c61cda3bab77ad64766e3e984af94e..12329fcdceef82a7872aa2f43af3c8dfd1344e2f 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -64,8 +64,8 @@ namespace {
   const int WeightPawnStructureEndgameInternal = 0x100;
   const int WeightPassedPawnsMidgameInternal   = 0x100;
   const int WeightPassedPawnsEndgameInternal   = 0x100;
-  const int WeightKingSafetyInternal           = 0x100;
-  const int WeightKingOppSafetyInternal        = 0x100;
+  const int WeightKingSafetyInternal           = 0x110;
+  const int WeightKingOppSafetyInternal        = 0x110;
   const int WeightSpaceInternal                = 0x30;
 
   // Visually better to define tables constants
@@ -230,8 +230,7 @@ namespace {
   const int KnightAttackWeight = 2;
 
   // Bonuses for safe checks for each piece type.
-  int QueenContactCheckBonus = 4;
-  int RookContactCheckBonus  = 2;
+  int QueenContactCheckBonus = 3;
   int QueenCheckBonus        = 2;
   int RookCheckBonus         = 1;
   int BishopCheckBonus       = 1;
@@ -637,7 +636,6 @@ namespace {
 
   void evaluate_rook(const Position &p, Square s, Color us, EvalInfo &ei) {
 
-    //Bitboard b = p.rook_attacks(s);
     Bitboard b = rook_attacks_bb(s, p.occupied_squares() & ~p.rooks_and_queens(us));
     ei.attackedBy[us][ROOK] |= b;
 
@@ -768,14 +766,14 @@ namespace {
       Bitboard occ = p.occupied_squares(), b, b2;
 
       // Initialize the 'attackUnits' variable, which is used later on as an
-      // index to the SafetyTable[] array.  The initial is based on the number
-      // and types of the attacking pieces, the number of attacked and
+      // index to the SafetyTable[] array.  The initial value is based on the
+      // number and types of the attacking pieces, the number of attacked and
       // undefended squares around the king, the square of the king, and the
       // quality of the pawn shelter.
       int attackUnits =
             Min((ei.kingAttackersCount[them] * ei.kingAttackersWeight[them]) / 2, 25)
           + (ei.kingAdjacentZoneAttacksCount[them] + count_1s_max_15(undefended)) * 3
-          + InitKingDanger[relative_square(us, s)] - shelter / 32;
+          + InitKingDanger[relative_square(us, s)] - (shelter >> 5);
 
       // Analyse safe queen contact checks
       b = undefended & ei.attacked_by(them, QUEEN) & ~p.pieces_of_color(them);
@@ -821,25 +819,8 @@ namespace {
           }
         }
       }
-      // Analyse safe rook contact checks:
-      if (RookContactCheckBonus)
-      {
-          b = undefended & ei.attacked_by(them, ROOK) & ~p.pieces_of_color(them);
-          if (b)
-          {
-              Bitboard attackedByOthers =
-                    ei.attacked_by(them, PAWN)   | ei.attacked_by(them, KNIGHT)
-                  | ei.attacked_by(them, BISHOP) | ei.attacked_by(them, QUEEN);
-
-              b &= attackedByOthers;
-              if (b)
-              {
-                  int count = count_1s_max_15(b);
-                  attackUnits += (RookContactCheckBonus * count * (sente? 2 : 1));
-              }
-          }
-      }
-      // Analyse safe distance checks:
+
+      // Analyse safe distance checks
       if (QueenCheckBonus > 0 || RookCheckBonus > 0)
       {
           b = p.piece_attacks<ROOK>(s) & ~p.pieces_of_color(them) & ~ei.attacked_by(us);
@@ -955,6 +936,13 @@ namespace {
           b2 = squares_in_front_of(us, s);
           b3 = b2 & ei.attacked_by(them);
           b4 = b2 & ei.attacked_by(us);
+
+          // If there is an enemy rook or queen attacking the pawn from behind,
+          // add all X-ray attacks by the rook or queen.
+          if(bit_is_set(ei.attacked_by(them,ROOK)|ei.attacked_by(them,QUEEN),s)
+             && squares_behind(us, s) & pos.rooks_and_queens(them))
+            b3 = b2;
+
           if((b2 & pos.pieces_of_color(them)) == EmptyBoardBB) {
             // There are no enemy pieces in the pawn's path!  Are any of the
             // squares in the pawn's path attacked by the enemy?
@@ -1220,7 +1208,6 @@ namespace {
   void init_safety() {
 
     QueenContactCheckBonus = get_option_value_int("Queen Contact Check Bonus");
-    RookContactCheckBonus  = get_option_value_int("Rook Contact Check Bonus");
     QueenCheckBonus        = get_option_value_int("Queen Check Bonus");
     RookCheckBonus         = get_option_value_int("Rook Check Bonus");
     BishopCheckBonus       = get_option_value_int("Bishop Check Bonus");