From: Marco Costalba <mcostalba@gmail.com>
Date: Sun, 3 Feb 2013 08:01:55 +0000 (+0100)
Subject: Correctly score enpassant captures
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=5f58db8c9971d8709093ca3c97cecdc99c61303e

Correctly score enpassant captures

Surprisingly this rare case was not considered
when scoring a capture.

Also take in account that in the promotion case
we gain a new piece (typically a queen) but we
lose the promoting pawn.

These small issues were present since Glaurung times!

Found while browsing DiscoCheck sources

bench: 5400063
---

diff --git a/src/movepick.cpp b/src/movepick.cpp
index e6b16cc4..4cf45ad3 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -168,7 +168,10 @@ void MovePicker::score_captures() {
                  - type_of(pos.piece_moved(m));
 
       if (type_of(m) == PROMOTION)
-          it->score += PieceValue[MG][promotion_type(m)];
+          it->score += PieceValue[MG][promotion_type(m)] - PieceValue[MG][PAWN];
+
+      else if (type_of(m) == ENPASSANT)
+          it->score += PieceValue[MG][PAWN];
   }
 }