X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=8e4fbe344e2ec576b2b434bf2021ca672062e039;hp=5662d13ad26b8fbe0a196a55fa5149f4f8bc32b3;hb=aa31f7f096adef50fe119b41d4e7834c41fec310;hpb=9742fb10fd83e82ad760e4cac5cef3d6dff670ed

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 5662d13a..8e4fbe34 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -1,7 +1,8 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2016 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -41,8 +42,9 @@ namespace {
   // 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];
@@ -57,9 +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) };
 
-  // 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) },
@@ -101,10 +100,6 @@ namespace {
     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;
@@ -181,7 +176,7 @@ namespace {
             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)];
@@ -196,9 +191,6 @@ namespace {
     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;
   }