From: Joona Kiiski <joona.kiiski@gmail.com>
Date: Thu, 21 Jan 2010 20:45:38 +0000 (+0200)
Subject: MaxGain based futility pruning for captures
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=6247f27a0548562c122f658082d31f535208d603;hp=5b2fc1e1c06d8348efb4bf45bac9c8f4916fd01c;ds=sidebyside

MaxGain based futility pruning for captures

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---

diff --git a/src/search.cpp b/src/search.cpp
index 6173a9a4..f259ab70 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1556,6 +1556,28 @@ namespace {
       // Update current move
       movesSearched[moveCount++] = ss[ply].currentMove = move;
 
+      // Futility pruning for captures
+      Color them = opposite_color(pos.side_to_move());
+
+      if (    useFutilityPruning
+          && !dangerous
+          && pos.move_is_capture(move)
+          && !pos.move_is_check(move, ci)
+          && !move_is_promotion(move)
+          && move != ttMove
+          && !move_is_ep(move)
+          && (pos.type_of_piece_on(move_to(move)) != PAWN || !pos.pawn_is_passed(them, move_to(move)))) // Do not prune passed pawn captures
+      {
+          int preFutilityValueMargin = 0;
+
+          if (newDepth >= OnePly)
+              preFutilityValueMargin = 112 * bitScanReverse32(int(newDepth) * int(newDepth) / 2);
+
+          if (ss[ply].eval + pos.endgame_value_of_piece_on(move_to(move)) + preFutilityValueMargin + ei.futilityMargin + 90 < beta)
+              continue;
+      }
+
+
       // Futility pruning
       if (    useFutilityPruning
           && !dangerous