Use more continuation histories.

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 71332e506dfcc28a50cc24bf03ef4f5da864a00d..a1834ab99b303387f505cd4011ee2f1cc4a25026 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -918,7 +918,7 @@ moves_loop: // When in check, search starts here
         return probCutBeta;
 
     const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
-                                          nullptr                   , (ss-4)->continuationHistory,
+                                         (ss-3)->continuationHistory, (ss-4)->continuationHistory,
                                           nullptr                   , (ss-6)->continuationHistory };
 
     Move countermove = prevSq != SQ_NONE ? thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] : MOVE_NONE;
@@ -1511,7 +1511,7 @@ moves_loop: // When in check, search starts here
     }
 
     const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
-                                          nullptr                   , (ss-4)->continuationHistory,
+                                         (ss-3)->continuationHistory, (ss-4)->continuationHistory,
                                           nullptr                   , (ss-6)->continuationHistory };
 
     // Initialize a MovePicker object for the current position, and prepare
@@ -1768,13 +1768,13 @@ moves_loop: // When in check, search starts here
 
   void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
 
-    for (int i : {1, 2, 4, 6})
+    for (int i : {1, 2, 3, 4, 6})
     {
         // Only update the first 2 continuation histories if we are in check
         if (ss->inCheck && i > 2)
             break;
         if (is_ok((ss-i)->currentMove))
-            (*(ss-i)->continuationHistory)[pc][to] << bonus;
+            (*(ss-i)->continuationHistory)[pc][to] << bonus / (1 + 3 * (i == 3));
     }
   }