Cleanup history stats

And other assorted trivia.

No functional change.

Readme.md

@@ -1,4 +1,6 @@
-### Overview      [![Build Status](https://travis-ci.org/official-stockfish/Stockfish.svg?branch=master)](https://travis-ci.org/official-stockfish/Stockfish)
+### Overview
+
+[![Build Status](https://travis-ci.org/official-stockfish/Stockfish.svg?branch=master)](https://travis-ci.org/official-stockfish/Stockfish)
 
 Stockfish is a free UCI chess engine derived from Glaurung 2.1. It is
 not a complete chess program and requires some UCI-compatible GUI

src/evaluate.cpp

@@ -171,8 +171,8 @@ namespace {
 
   // PassedFile[File] contains a bonus according to the file of a passed pawn.
   const Score PassedFile[] = {
-    S( 12,  10), S( 3,  10), S( 1, -8), S(-27, -12),
-    S(-27, -12), S( 1, -8),  S( 3, 10), S( 12,  10)
+    S( 12,  10), S( 3, 10), S( 1, -8), S(-27, -12),
+    S(-27, -12), S( 1, -8), S( 3, 10), S( 12,  10)
   };
 
   const Score ThreatenedByHangingPawn = S(40, 60);
@@ -677,20 +677,18 @@ namespace {
   // evaluate_initiative() computes the initiative correction value for the
   // position, i.e. second order bonus/malus based on the known attacking/defending
   // status of the players.
-  Score evaluate_initiative(const Position& pos, const EvalInfo& ei, const Score positional_score) {
+  Score evaluate_initiative(const Position& pos, int asymmetry, Value eg) {
 
-    int king_separation = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
-    int pawns           = pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK);
-    int asymmetry       = ei.pi->pawn_asymmetry();
+    int kingDistance = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
+    int pawns = pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK);
 
     // Compute the initiative bonus for the attacking side
-    int attacker_bonus = 8 * (pawns + asymmetry + king_separation) - 120;
+    int initiative = 8 * (pawns + asymmetry + kingDistance - 15);
 
-    // Now apply the bonus: note that we find the attacking side by extracting the sign
-    // of the endgame value of "positional_score", and that we carefully cap the bonus so
-    // that the endgame score with the correction will never be divided by more than two.
-    int eg = eg_value(positional_score);
-    int value = ((eg > 0) - (eg < 0)) * std::max(attacker_bonus, -abs(eg / 2));
+    // Now apply the bonus: note that we find the attacking side by extracting
+    // the sign of the endgame value, and that we carefully cap the bonus so
+    // that the endgame score will never be divided by more than two.
+    int value = ((eg > 0) - (eg < 0)) * std::max(initiative, -abs(eg / 2));
 
     return make_score(0, value);
   }
@@ -777,8 +775,8 @@ Value Eval::evaluate(const Position& pos) {
   if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)
       score += (evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei)) * Weights[Space];
 
-  // Evaluate initiative
-  score += evaluate_initiative(pos, ei, score);
+  // Evaluate position potential for the winning side
+  score += evaluate_initiative(pos, ei.pi->pawn_asymmetry(), eg_value(score));
 
   // Scale winning side if position is more drawish than it appears
   Color strongSide = eg_value(score) > VALUE_DRAW ? WHITE : BLACK;

src/movepick.cpp

@@ -68,8 +68,8 @@ namespace {
 /// ordering is at the current node.
 
 MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h,
-                       const CounterMovesHistoryStats& cmh, Move cm, Search::Stack* s)
-           : pos(p), history(h), counterMovesHistory(cmh), ss(s), countermove(cm), depth(d) {
+                       const CounterMovesStats& cmh, Move cm, Search::Stack* s)
+           : pos(p), history(h), counterMovesHistory(&cmh), ss(s), countermove(cm), depth(d) {
 
   assert(d > DEPTH_ZERO);
 
@@ -78,9 +78,9 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats&
   endMoves += (ttMove != MOVE_NONE);
 }
 
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h,
-                       const CounterMovesHistoryStats& cmh, Square s)
-           : pos(p), history(h), counterMovesHistory(cmh) {
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
+                       const HistoryStats& h, Square s)
+           : pos(p), history(h), counterMovesHistory(nullptr) {
 
   assert(d <= DEPTH_ZERO);
 
@@ -104,9 +104,8 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats&
   endMoves += (ttMove != MOVE_NONE);
 }
 
-MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h,
-                       const CounterMovesHistoryStats& cmh, Value th)
-           : pos(p), history(h), counterMovesHistory(cmh), threshold(th) {
+MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, Value th)
+           : pos(p), history(h), counterMovesHistory(nullptr), threshold(th) {
 
   assert(!pos.checkers());
 
@@ -141,12 +140,9 @@ void MovePicker::score<CAPTURES>() {
 template<>
 void MovePicker::score<QUIETS>() {
 
-  Square prevSq = to_sq((ss-1)->currentMove);
-  const HistoryStats& cmh = counterMovesHistory[pos.piece_on(prevSq)][prevSq];
-
   for (auto& m : *this)
       m.value =  history[pos.moved_piece(m)][to_sq(m)]
-               + cmh[pos.moved_piece(m)][to_sq(m)];
+               + (*counterMovesHistory)[pos.moved_piece(m)][to_sq(m)];
 }
 
 template<>

src/movepick.h

@@ -36,10 +36,10 @@
 /// Countermoves store the move that refute a previous one. Entries are stored
 /// using only the moving piece and destination square, hence two moves with
 /// different origin but same destination and piece will be considered identical.
-template<typename T>
+template<typename T, bool CM = false>
 struct Stats {
 
-  static const Value Max = Value(1<<28);
+  static const Value Max = Value(1 << 28);
 
   const T* operator[](Piece pc) const { return table[pc]; }
   T* operator[](Piece pc) { return table[pc]; }
@@ -51,29 +51,23 @@ struct Stats {
         table[pc][to] = m;
   }
 
-  void updateH(Piece pc, Square to, Value v) {
+  void update(Piece pc, Square to, Value v) {
 
-    if (abs(int(v)) >= 324) 
+    if (abs(int(v)) >= 324)
         return;
-    table[pc][to] -= table[pc][to] * abs(int(v)) / 324;
-    table[pc][to] += int(v) * 32;
-  }
-
-  void updateCMH(Piece pc, Square to, Value v) {
 
-    if (abs(int(v)) >= 324) 
-        return;
-    table[pc][to] -= table[pc][to] * abs(int(v)) / 512;
-    table[pc][to] += int(v) * 64;
+    table[pc][to] -= table[pc][to] * abs(int(v)) / (CM ? 512 : 324);
+    table[pc][to] += int(v) * (CM ? 64 : 32);
   }
 
 private:
   T table[PIECE_NB][SQUARE_NB];
 };
 
-typedef Stats<Value> HistoryStats;
 typedef Stats<Move> MovesStats;
-typedef Stats<HistoryStats> CounterMovesHistoryStats;
+typedef Stats<Value, false> HistoryStats;
+typedef Stats<Value,  true> CounterMovesStats;
+typedef Stats<CounterMovesStats> CounterMovesHistoryStats;
 
 
 /// MovePicker class is used to pick one pseudo legal move at a time from the
@@ -88,9 +82,9 @@ class MovePicker {
   MovePicker(const MovePicker&) = delete;
   MovePicker& operator=(const MovePicker&) = delete;
 
-  MovePicker(const Position&, Move, Depth, const HistoryStats&, const CounterMovesHistoryStats&, Square);
-  MovePicker(const Position&, Move, const HistoryStats&, const CounterMovesHistoryStats&, Value);
-  MovePicker(const Position&, Move, Depth, const HistoryStats&, const CounterMovesHistoryStats&, Move, Search::Stack*);
+  MovePicker(const Position&, Move, Depth, const HistoryStats&, Square);
+  MovePicker(const Position&, Move, const HistoryStats&, Value);
+  MovePicker(const Position&, Move, Depth, const HistoryStats&, const CounterMovesStats&, Move, Search::Stack*);
 
   Move next_move();
 
@@ -102,7 +96,7 @@ class MovePicker {
 
   const Position& pos;
   const HistoryStats& history;
-  const CounterMovesHistoryStats& counterMovesHistory;
+  const CounterMovesStats* counterMovesHistory;
   Search::Stack* ss;
   Move countermove;
   Depth depth;