Fix comments, rename variables

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index b8a002428d5a1a6cc4e9024438a792267b0a7d10..a65f2338d1fee51f3c6301f69d2e383c7e0c6785 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -31,45 +31,37 @@ namespace {
   #define V Value
   #define S(mg, eg) make_score(mg, eg)
 
-  // Isolated pawn penalty
+  // Pawn penalties
   constexpr Score Isolated = S(13, 16);
-
-  // Backward pawn penalty
   constexpr Score Backward = S(17, 11);
+  constexpr Score Doubled = S(13, 40);
 
   // Connected pawn bonus by opposed, phalanx, #support and rank
   Score Connected[2][2][3][RANK_NB];
 
-  // Doubled pawn penalty
-  constexpr Score Doubled = S(13, 40);
-
   // Strength of pawn shelter for our king by [distance from edge][rank].
   // RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
   constexpr Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = {
-    { V( 7), V(76), V(84), V( 38), V( 7), V( 30), V(-19) },
-    { V(-3), V(93), V(52), V(-17), V(12), V(-22), V(-35) },
-    { V(-6), V(83), V(25), V(-24), V(15), V( 22), V(-39) },
-    { V(11), V(83), V(19), V(  8), V(18), V(-21), V(-30) }
+    { V(  7), V(76), V( 84), V( 38), V(  7), V( 30), V(-19) },
+    { V(-13), V(83), V( 42), V(-27), V(  2), V(-32), V(-45) },
+    { V(-26), V(63), V(  5), V(-44), V( -5), V(  2), V(-59) },
+    { V(-19), V(53), V(-11), V(-22), V(-12), V(-51), V(-60) }
   };
 
-  // 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.
-  constexpr Value StormDanger[][4][RANK_NB] = {
-    { { V(11),  V( 79), V(132), V( 68), V( 33) },  // Unopposed
-      { V( 4),  V(104), V(155), V(  4), V( 21) },
-      { V(-7),  V( 59), V(142), V( 45), V( 30) },
-      { V( 0),  V( 62), V(113), V( 43), V( 13) } },
-    { { V( 0),  V(  0), V( 37), V(  5), V(-48) },  // BlockedByPawn
-      { V( 0),  V(  0), V( 68), V(-12), V( 13) },
-      { V( 0),  V(  0), V(111), V(-25), V( -3) },
-      { V( 0),  V(  0), V(108), V( 14), V( 21) } },
-    { { V(38),  V( 78), V( 83), V( 35), V( 22) },  // Unblocked
-      { V(33),  V(-15), V(108), V( 12), V( 28) },
-      { V( 8),  V( 25), V( 94), V( 68), V( 25) },
-      { V( 6),  V( 48), V(120), V( 68), V( 40) } }
+  // Danger of enemy pawns moving toward our king by [distance from edge][rank].
+  // RANK_1 = 0 is used for files where the enemy has no pawn, or their pawn
+  // is behind our king.
+  constexpr Value UnblockedStorm[int(FILE_NB) / 2][RANK_NB] = {
+    { V( 25), V( 79), V(107), V( 51), V( 27), V(  0), V(  0) },
+    { V(  5), V( 35), V(121), V( -2), V( 15), V(-10), V(-10) },
+    { V(-20), V( 22), V( 98), V( 36), V(  7), V(-20), V(-20) },
+    { V(-27), V( 24), V( 80), V( 25), V( -4), V(-30), V(-30) }
   };
 
+  // Danger of blocked enemy pawns storming our king, by rank
+  constexpr Value BlockedStorm[RANK_NB] =
+    { V(  0), V(  0), V( 75), V(-10), V(-20), V(-20), V(-20) };
+
   #undef S
   #undef V
 
@@ -212,7 +204,6 @@ Entry* probe(const Position& pos) {
 template<Color Us>
 Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
 
-  enum { Unopposed, BlockedByPawn, Unblocked };
   constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
   constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
   constexpr Bitboard  BlockRanks = (Us == WHITE ? Rank1BB | Rank2BB : Rank8BB | Rank7BB);
@@ -224,22 +215,21 @@ Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
   Value safety = (ourPawns & file_bb(ksq)) ? Value(5) : Value(-5);
 
   if (shift<Down>(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq)
-      safety += 374;
+      safety += Value(374);
 
   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);
-      Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
+      int ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : 0;
 
       b = theirPawns & file_bb(f);
-      Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
+      int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0;
 
       int d = std::min(f, ~f);
-      safety +=  ShelterStrength[d][rkUs]
-               - StormDanger[rkUs == RANK_1     ? Unopposed     :
-                             rkUs == rkThem - 1 ? BlockedByPawn : Unblocked]
-                            [d][rkThem];
+      safety += ShelterStrength[d][ourRank];
+      safety -= (ourRank && (ourRank == theirRank - 1)) ? BlockedStorm[theirRank]
+                                                        : UnblockedStorm[d][theirRank];
   }
 
   return safety;