Prefer names to numbers in storm code

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 3634f95746796afef7ab904856629b59d2c970fa..b26b1be656cda8a599ca2a00d8405fd45317ac9b 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -60,20 +60,35 @@ namespace {
   // Unsupported pawn penalty
   const Score UnsupportedPawnPenalty = S(20, 10);
 
-  // Weakness of our pawn shelter in front of the king indexed by [rank]
-  const Value ShelterWeakness[RANK_NB] =
-  { V(100), V(0), V(27), V(73), V(92), V(101), V(101) };
-
-  // Danger of enemy pawns moving toward our king indexed by
-  // [no friendly pawn | pawn unblocked | pawn blocked][rank of enemy pawn]
-  const Value StormDanger[][RANK_NB] = {
-  { V( 0),  V(64), V(128), V(51), V(26) },
-  { V(26),  V(32), V( 96), V(38), V(20) },
-  { V( 0),  V( 0), V(160), V(25), V(13) } };
+  // Weakness of our pawn shelter in front of the king by [distance from edge][rank]
+  const Value ShelterWeakness[][RANK_NB] = {
+  { V(101), V(10), V(24), V(68), V(90), V( 95), V(102) },
+  { V(105), V( 1), V(30), V(76), V(95), V(100), V(105) },
+  { V( 99), V( 0), V(32), V(72), V(92), V(101), V(100) },
+  { V( 94), V( 1), V(31), V(68), V(89), V( 98), V(106) } };
+
+  // Danger of enemy pawns moving toward our king by [type][distance from edge][rank]
+  const Value StormDanger[][4][RANK_NB] = {
+  { { V( 0),  V(  61), V( 128), V(47), V(27) },
+    { V( 0),  V(  66), V( 131), V(49), V(27) },
+    { V( 0),  V(  62), V( 126), V(52), V(23) },
+    { V( 0),  V(  63), V( 128), V(52), V(26) } },
+  { { V(25),  V(  33), V(  95), V(39), V(21) },
+    { V(24),  V(  33), V(  97), V(42), V(22) },
+    { V(24),  V(  33), V(  93), V(35), V(23) },
+    { V(26),  V(  27), V(  96), V(37), V(22) } },
+  { { V( 0),  V(   0), V(  80), V(14), V( 8) },
+    { V( 0),  V(   0), V( 163), V(28), V(12) },
+    { V( 0),  V(   0), V( 163), V(25), V(15) },
+    { V( 0),  V(   0), V( 161), V(24), V(14) } },
+  { { V( 0),  V(-300), V(-300), V(54), V(23) },
+    { V( 0),  V(  67), V( 128), V(46), V(24) },
+    { V( 0),  V(  64), V( 130), V(50), V(29) },
+    { V( 0),  V(  63), V( 127), V(51), V(24) } } };
 
   // 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(263);
+  const Value MaxSafetyBonus = V(261);
 
   #undef S
   #undef V
@@ -165,7 +180,7 @@ namespace {
             value -= UnsupportedPawnPenalty;
 
         if (doubled)
-            value -= Doubled[f] / rank_distance(s, lsb(doubled));
+            value -= Doubled[f] / distance<Rank>(s, frontmost_sq(Us, doubled));
 
         if (backward)
             value -= Backward[opposed][f];
@@ -230,15 +245,16 @@ template<Color Us>
 Value Entry::shelter_storm(const Position& pos, Square ksq) {
 
   const Color Them = (Us == WHITE ? BLACK : WHITE);
-  const Bitboard Edges = (FileABB | FileHBB) & (Rank2BB | Rank3BB);
+
+  enum { NoFriendlyPawn, Unblocked, BlockedByPawn, BlockedByKing };
 
   Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq));
   Bitboard ourPawns = b & pos.pieces(Us);
   Bitboard theirPawns = b & pos.pieces(Them);
   Value safety = MaxSafetyBonus;
-  File kf = 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 = kf - File(1); f <= kf + File(1); ++f)
+  for (File f = center - File(1); f <= center + File(1); ++f)
   {
       b = ourPawns & file_bb(f);
       Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
@@ -246,14 +262,12 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) {
       b  = theirPawns & file_bb(f);
       Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
 
-      if (   (Edges & make_square(f, rkThem))
-          && file_of(ksq) == f
-          && relative_rank(Us, ksq) == rkThem - 1)
-          safety += 200;
-      else
-          safety -=  ShelterWeakness[rkUs]
-                   + StormDanger[rkUs   == RANK_1   ? 0 :
-                                 rkThem != rkUs + 1 ? 1 : 2][rkThem];
+      safety -=  ShelterWeakness[std::min(f, FILE_H - f)][rkUs]
+               + StormDanger
+                 [f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing  :
+                  rkUs   == RANK_1                                          ? NoFriendlyPawn :
+                  rkThem == rkUs + 1                                        ? BlockedByPawn  : Unblocked]
+                 [std::min(f, FILE_H - f)][rkThem];
   }
 
   return safety;
@@ -268,14 +282,14 @@ Score Entry::do_king_safety(const Position& pos, Square ksq) {
 
   kingSquares[Us] = ksq;
   castlingRights[Us] = pos.can_castle(Us);
-  minKPdistance[Us] = 0;
+  minKingPawnDistance[Us] = 0;
 
   Bitboard pawns = pos.pieces(Us, PAWN);
   if (pawns)
-      while (!(DistanceRingsBB[ksq][minKPdistance[Us]++] & pawns)) {}
+      while (!(DistanceRingsBB[ksq][minKingPawnDistance[Us]++] & pawns)) {}
 
   if (relative_rank(Us, ksq) > RANK_4)
-      return make_score(0, -16 * minKPdistance[Us]);
+      return make_score(0, -16 * minKingPawnDistance[Us]);
 
   Value bonus = shelter_storm<Us>(pos, ksq);
 
@@ -286,7 +300,7 @@ Score Entry::do_king_safety(const Position& pos, Square ksq) {
   if (pos.can_castle(MakeCastling<Us, QUEEN_SIDE>::right))
       bonus = std::max(bonus, shelter_storm<Us>(pos, relative_square(Us, SQ_C1)));
 
-  return make_score(bonus, -16 * minKPdistance[Us]);
+  return make_score(bonus, -16 * minKingPawnDistance[Us]);
 }
 
 // Explicit template instantiation