Merge Stats tables

Use a recursive std::array with variadic template
parameters to get rid of the last redundacy.

The first template T parameter is the base type of
the array, the W parameter is the weight applied to
the bonuses when we update values with the << operator,
the D parameter limits the range of updates (range is
[-W * D, W * D]), and the last parameters (Size and
Sizes) encode the dimensions of the array.

This allows greater flexibility because we can now tweak
the range [-W * D, W * D] for each table.

Patch removes more lines than what adds and streamlines
the Stats soup in movepick.h

Closes PR#1422 and PR#1421

No functional change.

src/search.cpp

@@ -289,7 +289,7 @@ void Thread::search() {
 
   std::memset(ss-4, 0, 7 * sizeof(Stack));
   for (int i = 4; i > 0; i--)
-     (ss-i)->contHistory = &this->contHistory[NO_PIECE][0]; // Use as sentinel
+     (ss-i)->contHistory = this->contHistory[NO_PIECE][0].get(); // Use as sentinel
 
   bestValue = delta = alpha = -VALUE_INFINITE;
   beta = VALUE_INFINITE;
@@ -550,7 +550,7 @@ namespace {
 
     (ss+1)->ply = ss->ply + 1;
     ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
-    ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
+    ss->contHistory = thisThread->contHistory[NO_PIECE][0].get();
     (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
     Square prevSq = to_sq((ss-1)->currentMove);
 
@@ -595,7 +595,7 @@ namespace {
             else if (!pos.capture_or_promotion(ttMove))
             {
                 int penalty = -stat_bonus(depth);
-                thisThread->mainHistory.update(pos.side_to_move(), ttMove, penalty);
+                thisThread->mainHistory[pos.side_to_move()][from_to(ttMove)] << penalty;
                 update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
             }
         }
@@ -715,7 +715,7 @@ namespace {
         Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
 
         ss->currentMove = MOVE_NULL;
-        ss->contHistory = &thisThread->contHistory[NO_PIECE][0];
+        ss->contHistory = thisThread->contHistory[NO_PIECE][0].get();
 
         pos.do_null_move(st);
         Value nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1)
@@ -762,7 +762,7 @@ namespace {
             if (pos.legal(move))
             {
                 ss->currentMove = move;
-                ss->contHistory = &thisThread->contHistory[pos.moved_piece(move)][to_sq(move)];
+                ss->contHistory = thisThread->contHistory[pos.moved_piece(move)][to_sq(move)].get();
 
                 assert(depth >= 5 * ONE_PLY);
 
@@ -937,7 +937,7 @@ moves_loop: // When in check, search starts from here
 
       // Update the current move (this must be done after singular extension search)
       ss->currentMove = move;
-      ss->contHistory = &thisThread->contHistory[movedPiece][to_sq(move)];
+      ss->contHistory = thisThread->contHistory[movedPiece][to_sq(move)].get();
 
       // Step 15. Make the move
       pos.do_move(move, st, givesCheck);
@@ -1401,7 +1401,7 @@ moves_loop: // When in check, search starts from here
 
     for (int i : {1, 2, 4})
         if (is_ok((ss-i)->currentMove))
-            (ss-i)->contHistory->update(pc, to, bonus);
+            (*(ss-i)->contHistory)[pc][to] << bonus;
   }
 
 
@@ -1413,14 +1413,14 @@ moves_loop: // When in check, search starts from here
       CapturePieceToHistory& captureHistory =  pos.this_thread()->captureHistory;
       Piece moved_piece = pos.moved_piece(move);
       PieceType captured = type_of(pos.piece_on(to_sq(move)));
-      captureHistory.update(moved_piece, to_sq(move), captured, bonus);
+      captureHistory[moved_piece][to_sq(move)][captured] << bonus;
 
       // Decrease all the other played capture moves
       for (int i = 0; i < captureCnt; ++i)
       {
           moved_piece = pos.moved_piece(captures[i]);
           captured = type_of(pos.piece_on(to_sq(captures[i])));
-          captureHistory.update(moved_piece, to_sq(captures[i]), captured, -bonus);
+          captureHistory[moved_piece][to_sq(captures[i])][captured] << -bonus;
       }
   }
 
@@ -1438,7 +1438,7 @@ moves_loop: // When in check, search starts from here
 
     Color us = pos.side_to_move();
     Thread* thisThread = pos.this_thread();
-    thisThread->mainHistory.update(us, move, bonus);
+    thisThread->mainHistory[us][from_to(move)] << bonus;
     update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus);
 
     if (is_ok((ss-1)->currentMove))
@@ -1450,7 +1450,7 @@ moves_loop: // When in check, search starts from here
     // Decrease all the other played quiet moves
     for (int i = 0; i < quietsCnt; ++i)
     {
-        thisThread->mainHistory.update(us, quiets[i], -bonus);
+        thisThread->mainHistory[us][from_to(quiets[i])] << -bonus;
         update_continuation_histories(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
     }
   }