X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=fe989e9b8f24a502f7febb083f4b6733beae5d8b;hp=d8d8243fc9570ab08b1cb7233544fabd7e8e61cf;hb=2c52147dbfdc714a0ae95982f37fc5141b225f8c;hpb=91de6b0f37516462658f6e38db430813aa9e7ed8

diff --git a/src/pawns.cpp b/src/pawns.cpp
index d8d8243f..fe989e9b 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -57,9 +57,6 @@ namespace {
     S( 0, 0), S( 0, 0), S(0, 0), S(0, 0),
     S(20,20), S(40,40), S(0, 0), S(0, 0) };
 
-  // Bonus for file distance of the two outermost pawns
-  const Score PawnsFileSpan = S(0, 15);
-
   // Unsupported pawn penalty
   const Score UnsupportedPawnPenalty = S(20, 10);
 
@@ -168,7 +165,7 @@ 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];
@@ -183,10 +180,6 @@ namespace {
     b = e->semiopenFiles[Us] ^ 0xFF;
     e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0;
 
-    // In endgame it's better to have pawns on both wings. So give a bonus according
-    // to file distance between left and right outermost pawns.
-    value += PawnsFileSpan * e->pawnSpan[Us];
-
     return value;
   }
 
@@ -194,19 +187,24 @@ namespace {
 
 namespace Pawns {
 
+/// init() initializes some tables used by evaluation. Instead of hard-coded
+/// tables, when makes sense, we prefer to calculate them with a formula to
+/// reduce independent parameters and to allow easier tuning and better insight.
+
 void init()
 {
-  const int c[RANK_NB] = {0, 6, 15, 10, 57, 75, 135, 258};
+  static const int Seed[RANK_NB] = { 0, 6, 15, 10, 57, 75, 135, 258 };
 
-  for (Rank r = RANK_2; r <= RANK_7; ++r)
-      for (int opposed = false; opposed <= true; ++opposed)
-          for (int phalanx = false; phalanx <= true; ++phalanx)
+  for (int opposed = 0; opposed <= 1; ++opposed)
+      for (int phalanx = 0; phalanx <= 1; ++phalanx)
+          for (Rank r = RANK_2; r < RANK_8; ++r)
           {
-              int bonus = c[r] + (phalanx ? (c[r + 1] - c[r]) / 2 : 0);
+              int bonus = Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0);
               Connected[opposed][phalanx][r] = make_score(bonus / 2, bonus >> opposed);
           }
 }
 
+
 /// probe() takes a position as input, computes a Entry object, and returns a
 /// pointer to it. The result is also stored in a hash table, so we don't have
 /// to recompute everything when the same pawn structure occurs again.