From 57ead90f18313949da17705a4b2a76c099c2bb55 Mon Sep 17 00:00:00 2001
From: Hisayori Noda <nodchip@gmail.com>
Date: Sat, 22 Jun 2019 00:38:24 +0900
Subject: [PATCH] Fixed a bug that the game play is invalid.

---
 src/extra/sfen_packer.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/extra/sfen_packer.cpp b/src/extra/sfen_packer.cpp
index f7c1d238..4d861a58 100644
--- a/src/extra/sfen_packer.cpp
+++ b/src/extra/sfen_packer.cpp
@@ -197,7 +197,7 @@ struct SfenPacker
 
     stream.write_n_bit(pos.state()->rule50, 6);
 
-    stream.write_n_bit(pos.game_ply(), 8);
+    stream.write_n_bit(1 + (pos.game_ply() - (pos.side_to_move() == BLACK)) / 2, 8);
 
     assert(stream.get_cursor() <= 256);
   }