From: Chris Caino <chricainogithub@gmail.com>
Date: Mon, 23 Dec 2013 19:50:28 +0000 (+0100)
Subject: Increase pawn king attack weight
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=8aa4f3fde46acc1d5a02d2b16aae5098606cfcb2

Increase pawn king attack weight

Tighter lower bound for pawn attacks so to
activate king safety in some cases like here:

6k1/2B3p1/2Pp1p2/2nPp3/2Q1P2K/P2n1qP1/R6P/1R6 w

Original patch by Chris, further simplified by
Jörg Oster.

Passed both short TC
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 30171 W: 5887 L: 5700 D: 18584

And long TC
LLR: 2.97 (-2.94,2.94) [0.00,6.00]
Total: 20706 W: 3402 L: 3204 D: 14100

bench: 7607562
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 1ee727da..72c23f19 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -434,7 +434,7 @@ Value do_evaluate(const Position& pos) {
     {
         ei.kingRing[Them] = b | shift_bb<Down>(b);
         b &= ei.attackedBy[Us][PAWN];
-        ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) / 2 : 0;
+        ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) : 0;
         ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
     }
     else