From: Rocky640 <Rocky640@users.noreply.github.com>
Date: Wed, 11 Jan 2017 07:56:38 +0000 (-0500)
Subject: StormDanger CleanUp (#964)
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=d40351243b7256a867f43741c3a53ceb781fbca1;hp=d8f683760c9eb6d2c4714ec83e717dd2143de55c

StormDanger CleanUp (#964)

Order the enum and the array the same way they appear around line 250.
Makes it much easier to follow.

Add comments in the array definition and critical rows.
Use same terminology as elsewhere in pawns.cpp

No functional change.
---

diff --git a/src/pawns.cpp b/src/pawns.cpp
index daf656c2..6c9a29d7 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -52,7 +52,8 @@ namespace {
     S(17, 16), S(33, 32), S(0, 0), S(0, 0)
   };
 
-  // Weakness of our pawn shelter in front of the king by [distance from edge][rank]
+  // Weakness of our pawn shelter in front of the king by [distance from edge][rank].
+  // RANK_1 = 0 is used for files where we have no pawns, or where our pawn is behind our king.
   const Value ShelterWeakness[][RANK_NB] = {
     { V(100), V(20), V(10), V(46), V(82), V( 86), V( 98) },
     { V(116), V( 4), V(28), V(87), V(94), V(108), V(104) },
@@ -60,25 +61,26 @@ namespace {
     { V( 75), V(12), V(43), V(59), V(90), V( 84), V(112) }
   };
 
-  // Danger of enemy pawns moving toward our king by [type][distance from edge][rank]
+  // 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 his pawn his behind our king.
   const Value StormDanger[][4][RANK_NB] = {
-    { { V( 4),  V(  73), V( 132), V(46), V(31) },
+    { { 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) },
+      { V( 0),  V(  53), V( 127), V(56), V(14) } },
+    { { V( 4),  V(  73), V( 132), V(46), V(31) },  //Unopposed
       { 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(22),  V(  45), V( 104), V(62), V( 6) },
-      { V(31),  V(  30), V(  99), V(39), V(19) },
-      { V(23),  V(  29), V(  96), V(41), V(15) },
-      { V(21),  V(  23), V( 116), V(41), V(15) } },
-    { { V( 0),  V(   0), V(  79), V(23), V( 1) },
+    { { 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(-290), V(-274), V(57), V(41) },
-      { V( 0),  V(  60), V( 144), V(39), V(13) },
-      { V( 0),  V(  65), V( 141), V(41), V(34) },
-      { V( 0),  V(  53), V( 127), V(56), V(14) } }
-
+    { { 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) },
+      { V(21),  V(  23), V( 116), V(41), V(15) } }
   };
 
   // Max bonus for king safety. Corresponds to start position with all the pawns
@@ -224,14 +226,14 @@ Entry* probe(const Position& pos) {
 
 
 /// Entry::shelter_storm() calculates shelter and storm penalties for the file
-/// the king is on, as well as the two adjacent files.
+/// the king is on, as well as the two closest files.
 
 template<Color Us>
 Value Entry::shelter_storm(const Position& pos, Square ksq) {
 
   const Color Them = (Us == WHITE ? BLACK : WHITE);
 
-  enum { NoFriendlyPawn, Unblocked, BlockedByPawn, BlockedByKing };
+  enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked };
 
   Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq));
   Bitboard ourPawns = b & pos.pieces(Us);
@@ -250,7 +252,7 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) {
       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 :
+                  rkUs   == RANK_1                                          ? Unopposed :
                   rkThem == rkUs + 1                                        ? BlockedByPawn  : Unblocked]
                  [std::min(f, FILE_H - f)][rkThem];
   }