X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.h;h=9f18997406fe63c24dcb06eb9a0a136749d7e9a5;hb=d0e87104aa782176735442e1f6668f91014f07eb;hp=f210f5387fcb222bb8a0728e4a9e413a2a7b583b;hpb=b0658f09b93185e2b43d4b2d6f0daa30c36ebcc2;p=stockfish

diff --git a/src/movepick.h b/src/movepick.h
index f210f538..9f189974 100644
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -32,7 +32,10 @@
 
 namespace Stockfish {
 
-constexpr int PAWN_HISTORY_SIZE = 512;
+constexpr int PAWN_HISTORY_SIZE = 512;  // has to be a power of 2
+
+static_assert((PAWN_HISTORY_SIZE & (PAWN_HISTORY_SIZE - 1)) == 0,
+              "PAWN_HISTORY_SIZE has to be a power of 2");
 
 inline int pawn_structure(const Position& pos) { return pos.pawn_key() & (PAWN_HISTORY_SIZE - 1); }
 
@@ -116,7 +119,7 @@ using PieceToHistory = Stats<int16_t, 29952, PIECE_NB, SQUARE_NB>;
 // (~63 elo)
 using ContinuationHistory = Stats<PieceToHistory, NOT_USED, PIECE_NB, SQUARE_NB>;
 
-// PawnStructureHistory is addressed by the pawn structure and a move's [piece][to]
+// PawnHistory is addressed by the pawn structure and a move's [piece][to]
 using PawnHistory = Stats<int16_t, 8192, PAWN_HISTORY_SIZE, PIECE_NB, SQUARE_NB>;
 
 // MovePicker class is used to pick one pseudo-legal move at a time from the
@@ -141,7 +144,7 @@ class MovePicker {
                const ButterflyHistory*,
                const CapturePieceToHistory*,
                const PieceToHistory**,
-               const PawnHistory&,
+               const PawnHistory*,
                Move,
                const Move*);
     MovePicker(const Position&,
@@ -150,9 +153,9 @@ class MovePicker {
                const ButterflyHistory*,
                const CapturePieceToHistory*,
                const PieceToHistory**,
-               const PawnHistory&,
+               const PawnHistory*,
                Square);
-    MovePicker(const Position&, Move, Value, const CapturePieceToHistory*, const PawnHistory&);
+    MovePicker(const Position&, Move, Value, const CapturePieceToHistory*);
     Move next_move(bool skipQuiets = false);
 
    private:
@@ -167,7 +170,7 @@ class MovePicker {
     const ButterflyHistory*      mainHistory;
     const CapturePieceToHistory* captureHistory;
     const PieceToHistory**       continuationHistory;
-    const PawnHistory&           pawnHistory;
+    const PawnHistory*           pawnHistory;
     Move                         ttMove;
     ExtMove                      refutations[3], *cur, *endMoves, *endBadCaptures;
     int                          stage;