Retire CenterBind

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 83ff4f28c1b608c3e314c8dfcef83f9ca8fcea1a..8e4fbe344e2ec576b2b434bf2021ca672062e039 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -42,8 +42,9 @@ namespace {
   // Backward pawn penalty by opposed flag
   const Score Backward[2] = { S(67, 42), S(49, 24) };
   
   // Backward pawn penalty by opposed flag
   const Score Backward[2] = { S(67, 42), S(49, 24) };
   

-  // Unsupported pawn penalty, for pawns which are neither isolated or backward
-  const Score Unsupported = S(20, 10);
+  // Unsupported pawn penalty for pawns which are neither isolated or backward,
+  // by number of pawns it supports [less than 2 / exactly 2].
+  const Score Unsupported[2] = { S(20, 10), S(25, 15) };

 
   // Connected pawn bonus by opposed, phalanx, twice supported and rank
   Score Connected[2][2][2][RANK_NB];
 
   // Connected pawn bonus by opposed, phalanx, twice supported and rank
   Score Connected[2][2][2][RANK_NB];


@@ -58,9 +59,6 @@ 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) };
 
     S( 0,  0), S( 0,  0), S(0, 0), S(0, 0),
     S(20, 20), S(40, 40), S(0, 0), S(0, 0) };
 

-  // Center bind bonus, when two pawns controls the same central square
-  const Score CenterBind = S(16, 0);
-

   // Weakness of our pawn shelter in front of the king by [distance from edge][rank]
   const Value ShelterWeakness[][RANK_NB] = {
     { V( 97), V(21), V(26), V(51), V(87), V( 89), V( 99) },
   // Weakness of our pawn shelter in front of the king by [distance from edge][rank]
   const Value ShelterWeakness[][RANK_NB] = {
     { V( 97), V(21), V(26), V(51), V(87), V( 89), V( 99) },


@@ -102,10 +100,6 @@ namespace {
     const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
     const Square Left  = (Us == WHITE ? DELTA_NW : DELTA_SE);
 
     const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
     const Square Left  = (Us == WHITE ? DELTA_NW : DELTA_SE);
 

-    const Bitboard CenterBindMask =
-      Us == WHITE ? (FileDBB | FileEBB) & (Rank5BB | Rank6BB | Rank7BB)
-                  : (FileDBB | FileEBB) & (Rank4BB | Rank3BB | Rank2BB);
-

     Bitboard b, neighbours, doubled, supported, phalanx;
     Square s;
     bool passed, isolated, opposed, backward, lever, connected;
     Bitboard b, neighbours, doubled, supported, phalanx;
     Square s;
     bool passed, isolated, opposed, backward, lever, connected;


@@ -182,7 +176,7 @@ namespace {
             score -= Backward[opposed];
 
         else if (!supported)
             score -= Backward[opposed];
 
         else if (!supported)

-            score -= Unsupported;
+            score -= Unsupported[more_than_one(neighbours & rank_bb(s + Up))];

 
         if (connected)
             score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)];
 
         if (connected)
             score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)];


@@ -197,9 +191,6 @@ namespace {
     b = e->semiopenFiles[Us] ^ 0xFF;
     e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0;
 
     b = e->semiopenFiles[Us] ^ 0xFF;
     e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0;
 

-    b = shift_bb<Right>(ourPawns) & shift_bb<Left>(ourPawns) & CenterBindMask;
-    score += CenterBind * popcount<Max15>(b);
-

     return score;
   }
 
     return score;
   }