Simplify the shelter mask

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 7e90089ce7921ba7d1d666c4eb965b8e04a00676..7b3dd8181ef9fc602b6868a4eba4a1d1a81bef77 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -32,20 +32,20 @@ namespace {
   #define S(mg, eg) make_score(mg, eg)
 
   // Isolated pawn penalty
-  const Score Isolated = S(13, 18);
+  constexpr Score Isolated = S(13, 18);
 
   // Backward pawn penalty
-  const Score Backward = S(24, 12);
+  constexpr Score Backward = S(24, 12);
 
   // Connected pawn bonus by opposed, phalanx, #support and rank
   Score Connected[2][2][3][RANK_NB];
 
   // Doubled pawn penalty
-  const Score Doubled = S(18, 38);
+  constexpr Score Doubled = S(18, 38);
 
   // Weakness of our pawn shelter in front of the king by [isKingFile][distance from edge][rank].
   // RANK_1 = 0 is used for files where we have no pawns or our pawn is behind our king.
-  const Value ShelterWeakness[][int(FILE_NB) / 2][RANK_NB] = {
+  constexpr Value ShelterWeakness[][int(FILE_NB) / 2][RANK_NB] = {
     { { V( 98), V(20), V(11), V(42), V( 83), V( 84), V(101) }, // Not On King file
       { V(103), V( 8), V(33), V(86), V( 87), V(105), V(113) },
       { V(100), V( 2), V(65), V(95), V( 59), V( 89), V(115) },
@@ -59,7 +59,7 @@ namespace {
   // Danger of enemy pawns moving toward our king by [type][distance from edge][rank].
   // For the unopposed and unblocked cases, RANK_1 = 0 is used when opponent has
   // no pawn on the given file, or their pawn is behind our king.
-  const Value StormDanger[][4][RANK_NB] = {
+  constexpr Value StormDanger[][4][RANK_NB] = {
     { { V( 0),  V(-290), V(-274), V(57), V(41) },  // BlockedByKing
       { V( 0),  V(  60), V( 144), V(39), V(13) },
       { V( 0),  V(  65), V( 141), V(41), V(34) },
@@ -68,10 +68,10 @@ namespace {
       { V( 1),  V(  64), V( 143), V(26), V(13) },
       { V( 1),  V(  47), V( 110), V(44), V(24) },
       { V( 0),  V(  72), V( 127), V(50), V(31) } },
-    { { V( 0),  V(   0), V(  79), V(23), V( 1) },  // BlockedByPawn
-      { V( 0),  V(   0), V( 148), V(27), V( 2) },
-      { V( 0),  V(   0), V( 161), V(16), V( 1) },
-      { V( 0),  V(   0), V( 171), V(22), V(15) } },
+    { { V( 0),  V(   0), V(  19), V(23), V( 1) },  // BlockedByPawn
+      { V( 0),  V(   0), V(  88), V(27), V( 2) },
+      { V( 0),  V(   0), V( 101), V(16), V( 1) },
+      { V( 0),  V(   0), V( 111), V(22), V(15) } },
     { { V(22),  V(  45), V( 104), V(62), V( 6) },  // Unblocked
       { V(31),  V(  30), V(  99), V(39), V(19) },
       { V(23),  V(  29), V(  96), V(41), V(15) },
@@ -80,7 +80,7 @@ namespace {
 
   // Max bonus for king safety. Corresponds to start position with all the pawns
   // in front of the king and no enemy pawn on the horizon.
-  const Value MaxSafetyBonus = V(258);
+  constexpr Value MaxSafetyBonus = V(258);
 
   #undef S
   #undef V
@@ -88,8 +88,8 @@ namespace {
   template<Color Us>
   Score evaluate(const Position& pos, Pawns::Entry* e) {
 
-    const Color     Them = (Us == WHITE ? BLACK : WHITE);
-    const Direction Up   = (Us == WHITE ? NORTH : SOUTH);
+    constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Direction Up   = (Us == WHITE ? NORTH : SOUTH);
 
     Bitboard b, neighbours, stoppers, doubled, supported, phalanx;
     Bitboard lever, leverPush;
@@ -151,7 +151,7 @@ namespace {
         // not attacked more times than defended.
         if (   !(stoppers ^ lever ^ leverPush)
             && !(ourPawns & forward_file_bb(Us, s))
-            && popcount(supported) >= popcount(lever)
+            && popcount(supported) >= popcount(lever) - 1
             && popcount(phalanx)   >= popcount(leverPush))
             e->passedPawns[Us] |= s;
 
@@ -191,7 +191,7 @@ namespace Pawns {
 
 void init() {
 
-  static const int Seed[RANK_NB] = { 0, 13, 24, 18, 76, 100, 175, 330 };
+  static constexpr int Seed[RANK_NB] = { 0, 13, 24, 18, 76, 100, 175, 330 };
 
   for (int opposed = 0; opposed <= 1; ++opposed)
       for (int phalanx = 0; phalanx <= 1; ++phalanx)
@@ -236,7 +236,7 @@ Entry* probe(const Position& pos) {
 template<Color Us>
 Value Entry::shelter_storm(const Position& pos, Square ksq) {
 
-  const Color Them = (Us == WHITE ? BLACK : WHITE);
+  constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
 
   enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked };
 
@@ -244,8 +244,8 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) {
   Bitboard ourPawns = b & pos.pieces(Us);
   Bitboard theirPawns = b & pos.pieces(Them);
   Value safety = MaxSafetyBonus;
-  File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
 
+  File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
   for (File f = File(center - 1); f <= File(center + 1); ++f)
   {
       b = ourPawns & file_bb(f);