Do not consider discovered checks in king safety

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 73ded33bd1cae4ee2a6e3b5eb51500ca71fe276d..e44bcdcc64aa942f0bb6206f87dad3543f809631 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -134,10 +134,10 @@ namespace {
   // piece type attacks which one.
   const Score ThreatBonus[8][8] = {
     {}, {},
-    { S(0, 0), S(18,37), S( 0, 0), S(37,47), S(55,97), S(55,97) }, // KNIGHT
-    { S(0, 0), S(18,37), S(37,47), S( 0, 0), S(55,97), S(55,97) }, // BISHOP
-    { S(0, 0), S( 9,27), S(27,47), S(27,47), S( 0, 0), S(37,47) }, // ROOK
-    { S(0, 0), S(27,37), S(27,37), S(27,37), S(27,37), S( 0, 0) }  // QUEEN
+    { S(0, 0), S( 7, 39), S( 0,  0), S(24, 49), S(41,100), S(41,100) }, // KNIGHT
+    { S(0, 0), S( 7, 39), S(24, 49), S( 0,  0), S(41,100), S(41,100) }, // BISHOP
+    { S(0, 0), S(-1, 29), S(15, 49), S(15, 49), S( 0,  0), S(24, 49) }, // ROOK
+    { S(0, 0), S(15, 39), S(15, 39), S(15, 39), S(15, 39), S( 0,  0) }  // QUEEN
   };
 
   // ThreatedByPawnPenalty[] contains a penalty according to which piece
@@ -556,7 +556,7 @@ namespace {
             ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
 
         // Bishop and knight outposts squares
-        if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Them))
+        if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Us))
             evaluate_outposts<Piece, Us>(pos, ei, s);
 
         // Special patterns: trapped bishops on a7/h7/a2/h2
@@ -761,12 +761,6 @@ namespace {
         if (b)
             attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b);
 
-        // Analyse enemy's discovered checks (only for non-pawns right now,
-        // consider adding pawns later).
-        b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
-        if (b)
-            attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
-
         // To index KingDangerTable[] attackUnits must be in [0, 99] range
         attackUnits = Min(99, Max(0, attackUnits));
 
@@ -799,7 +793,7 @@ namespace {
         assert(pos.pawn_is_passed(Us, s));
 
         int r = int(relative_rank(Us, s) - RANK_2);
-        int tr = Max(0, r * (r - 1));
+        int tr = r * (r - 1);
 
         // Base bonus based on rank
         Value mbonus = Value(20 * tr);
@@ -1046,14 +1040,12 @@ namespace {
     // Find the safe squares for our pieces inside the area defined by
     // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
     // pawn, or if it is undefended and attacked by an enemy piece.
-
     Bitboard safeSquares =   SpaceMask[Us]
                           & ~pos.pieces(PAWN, Us)
                           & ~ei.attacked_by(Them, PAWN)
-                          & ~(~ei.attacked_by(Us) & ei.attacked_by(Them));
+                          & (ei.attacked_by(Us) | ~ei.attacked_by(Them));
 
-    // Find all squares which are at most three squares behind some friendly
-    // pawn.
+    // Find all squares which are at most three squares behind some friendly pawn
     Bitboard behindFriendlyPawns = pos.pieces(PAWN, Us);
     behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >>  8 : behindFriendlyPawns <<  8);
     behindFriendlyPawns |= (Us == WHITE ? behindFriendlyPawns >> 16 : behindFriendlyPawns << 16);
@@ -1094,17 +1086,11 @@ namespace {
 
   Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
 
-    Score uciWeight = make_score(get_option_value_int(mgOpt), get_option_value_int(egOpt));
-
-    // Convert to integer to prevent overflow
-    int mg = mg_value(uciWeight);
-    int eg = eg_value(uciWeight);
+    // Scale option value from 100 to 256
+    int mg = get_option_value_int(mgOpt) * 256 / 100;
+    int eg = get_option_value_int(egOpt) * 256 / 100;
 
-    mg = (mg * 0x100) / 100;
-    eg = (eg * 0x100) / 100;
-    mg = (mg * mg_value(internalWeight)) / 0x100;
-    eg = (eg * eg_value(internalWeight)) / 0x100;
-    return make_score(mg, eg);
+    return apply_weight(make_score(mg, eg), internalWeight);
   }
 
   // init_safety() initizes the king safety evaluation, based on UCI
@@ -1112,28 +1098,19 @@ namespace {
 
   void init_safety() {
 
-    int maxSlope = 30;
-    int peak     = 0x500;
-    double a     = 0.4;
-    double b     = 0.0;
+    const Value MaxSlope = Value(30);
+    const Value Peak = Value(1280);
     Value t[100];
 
     // First setup the base table
     for (int i = 0; i < 100; i++)
     {
-        if (i < b)
-            t[i] = Value(0);
-        else
-            t[i] = Value((int)(a * (i - b) * (i - b)));
-    }
+        t[i] = Value(int(0.4 * i * i));
 
-    for (int i = 1; i < 100; i++)
-    {
-        if (t[i] - t[i - 1] > maxSlope)
-            t[i] = t[i - 1] + Value(maxSlope);
+        if (i > 0)
+            t[i] = Min(t[i], t[i - 1] + MaxSlope);
 
-        if (t[i]  > Value(peak))
-            t[i] = Value(peak);
+        t[i] = Min(t[i], Peak);
     }
 
     // Then apply the weights and get the final KingDangerTable[] array