From 72bb4695d1c4b7743f2141fba6b501061d1d1be9 Mon Sep 17 00:00:00 2001
From: Marco Costalba <mcostalba@gmail.com>
Date: Tue, 10 May 2016 17:50:51 +0200
Subject: [PATCH] Fix an issue with pawn ordering

A subtle one because at leat 3 leading pawns
are needed to uncover this bug.

Found by stuwph
---
 src/syzygy/tbprobe.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/syzygy/tbprobe.cpp b/src/syzygy/tbprobe.cpp
index 1af3440f..32c605c2 100644
--- a/src/syzygy/tbprobe.cpp
+++ b/src/syzygy/tbprobe.cpp
@@ -690,7 +690,7 @@ uint64_t probe_table(const Position& pos,  Entry* entry, WDLScore wdl = WDLDraw,
         idx = Pawnidx[leadPawnsCnt - 1][23 - MapToEdges[squares[0]] / 2];
 
         for (int i = 1; i < leadPawnsCnt; ++i)
-            idx += Binomial[i][MapToEdges[squares[i]]];
+            idx += Binomial[i][MapToEdges[squares[leadPawnsCnt- i]]];
 
         next = leadPawnsCnt;
         goto encode_remaining; // With pawns we have finished special treatments