X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=380c334291e3b79a0d30dfd74c37ffb0e41616de;hp=e20eed9fe1f2da39cacebcc70347d520b2bc54e9;hb=86f04dbcc08e52864c1136d713996e3a0c8d2610;hpb=aa242d2f84eaf2307f34d5356079125eaf5ff26a

diff --git a/src/search.cpp b/src/search.cpp
index e20eed9f..380c3342 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -174,9 +174,9 @@ void Search::init() {
 }
 
 
-/// Search::reset() clears all search memory, to obtain reproducible search results
+/// Search::clear() resets to zero search state, to obtain reproducible results
 
-void Search::reset () {
+void Search::clear() {
 
   TT.clear();
   CounterMovesHistory.clear();
@@ -216,7 +216,7 @@ uint64_t Search::perft(Position& pos, Depth depth) {
   return nodes;
 }
 
-template uint64_t Search::perft<true>(Position& pos, Depth depth);
+template uint64_t Search::perft<true>(Position&, Depth);
 
 
 /// MainThread::think() is called by the main thread when the program receives
@@ -344,7 +344,7 @@ void MainThread::think() {
 
 void Thread::search(bool isMainThread) {
 
-  Stack* ss = stack + 2; // To allow referencing (ss-2) and (ss+2)
+  Stack stack[MAX_PLY+4], *ss = stack+2; // To allow referencing (ss-2) and (ss+2)
   Value bestValue, alpha, beta, delta;
   Move easyMove = MOVE_NONE;
 
@@ -577,7 +577,7 @@ namespace {
     {
         // Step 2. Check for aborted search and immediate draw
         if (Signals.stop.load(std::memory_order_relaxed) || pos.is_draw() || ss->ply >= MAX_PLY)
-            return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos) 
+            return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos)
                                                   : DrawValue[pos.side_to_move()];
 
         // Step 3. Mate distance pruning. Even if we mate at the next move our score
@@ -836,7 +836,7 @@ moves_loop: // When in check search starts from here
 
       if (RootNode && thisThread == Threads.main())
       {
-          Signals.firstRootMove = moveCount == 1;
+          Signals.firstRootMove = (moveCount == 1);
 
           if (Time.elapsed() > 3000)
               sync_cout << "info depth " << depth / ONE_PLY
@@ -1095,7 +1095,7 @@ moves_loop: // When in check search starts from here
              && is_ok((ss - 1)->currentMove)
              && is_ok((ss - 2)->currentMove))
     {
-        Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY -1);
+        Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1);
         Square prevPrevSq = to_sq((ss - 2)->currentMove);
         CounterMovesStats& prevCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
         prevCmh.update(pos.piece_on(prevSq), prevSq, bonus);
@@ -1359,8 +1359,8 @@ moves_loop: // When in check search starts from here
   }
 
 
-  // update_stats() updates killers, history, countermove history and
-  // countermoves stats for a quiet best move.
+  // update_stats() updates killers, history, countermove and countermove
+  // history when a new quiet best move is found.
 
   void update_stats(const Position& pos, Stack* ss, Move move,
                     Depth depth, Move* quiets, int quietsCnt) {
@@ -1371,7 +1371,7 @@ moves_loop: // When in check search starts from here
         ss->killers[0] = move;
     }
 
-    Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY -1);
+    Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY) + depth / ONE_PLY - 1);
 
     Square prevSq = to_sq((ss-1)->currentMove);
     CounterMovesStats& cmh = CounterMovesHistory[pos.piece_on(prevSq)][prevSq];
@@ -1394,14 +1394,14 @@ moves_loop: // When in check search starts from here
             cmh.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
     }
 
-    // Extra penalty for TT move in previous ply when it gets refuted
+    // Extra penalty for a quiet TT move in previous ply when it gets refuted
     if (   (ss-1)->moveCount == 1
         && !pos.captured_piece_type()
         && is_ok((ss-2)->currentMove))
     {
         Square prevPrevSq = to_sq((ss-2)->currentMove);
         CounterMovesStats& prevCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
-        prevCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * ((depth + 1) / ONE_PLY));
+        prevCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * (depth + 1) / ONE_PLY);
     }
   }
 
@@ -1411,23 +1411,23 @@ moves_loop: // When in check search starts from here
 
   Move Skill::pick_best(size_t multiPV) {
 
-    // PRNG sequence should be non-deterministic, so we seed it with the time at init
     const Search::RootMoveVector& rootMoves = Threads.main()->rootMoves;
-    static PRNG rng(now());
+    static PRNG rng(now()); // PRNG sequence should be non-deterministic
 
     // RootMoves are already sorted by score in descending order
-    int variance = std::min(rootMoves[0].score - rootMoves[multiPV - 1].score, PawnValueMg);
+    Value topScore = rootMoves[0].score;
+    int delta = std::min(topScore - rootMoves[multiPV - 1].score, PawnValueMg);
     int weakness = 120 - 2 * level;
     int maxScore = -VALUE_INFINITE;
 
-    // Choose best move. For each move score we add two terms both dependent on
+    // Choose best move. For each move score we add two terms, both dependent on
     // weakness. One deterministic and bigger for weaker levels, and one random,
     // then we choose the move with the resulting highest score.
     for (size_t i = 0; i < multiPV; ++i)
     {
         // This is our magic formula
-        int push = (  weakness * int(rootMoves[0].score - rootMoves[i].score)
-                    + variance * (rng.rand<unsigned>() % weakness)) / 128;
+        int push = (  weakness * int(topScore - rootMoves[i].score)
+                    + delta * (rng.rand<unsigned>() % weakness)) / 128;
 
         if (rootMoves[i].score + push > maxScore)
         {
@@ -1435,6 +1435,7 @@ moves_loop: // When in check search starts from here
             best = rootMoves[i].pv[0];
         }
     }
+
     return best;
   }
 
@@ -1512,7 +1513,8 @@ void RootMove::insert_pv_in_tt(Position& pos) {
       TTEntry* tte = TT.probe(pos.key(), ttHit);
 
       if (!ttHit || tte->move() != m) // Don't overwrite correct entries
-          tte->save(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, m, VALUE_NONE, TT.generation());
+          tte->save(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE,
+                    m, VALUE_NONE, TT.generation());
 
       pos.do_move(m, *st++, pos.gives_check(m, CheckInfo(pos)));
   }
@@ -1522,10 +1524,10 @@ void RootMove::insert_pv_in_tt(Position& pos) {
 }
 
 
-/// RootMove::extract_ponder_from_tt() is called in case we have no ponder move before
-/// exiting the search, for instance in case we stop the search during a fail high at
-/// root. We try hard to have a ponder move to return to the GUI, otherwise in case of
-/// 'ponder on' we have nothing to think on.
+/// RootMove::extract_ponder_from_tt() is called in case we have no ponder move
+/// before exiting the search, for instance in case we stop the search during a
+/// fail high at root. We try hard to have a ponder move to return to the GUI,
+/// otherwise in case of 'ponder on' we have nothing to think on.
 
 bool RootMove::extract_ponder_from_tt(Position& pos)
 {
@@ -1549,11 +1551,11 @@ bool RootMove::extract_ponder_from_tt(Position& pos)
 }
 
 
-/// check_time() is called by the timer thread when the timer triggers. It is
-/// used to print debug info and, more importantly, to detect when we are out of
+/// TimerThread::check_time() is called by when the timer triggers. It is used
+/// to print debug info and, more importantly, to detect when we are out of
 /// available time and thus stop the search.
 
-void check_time() {
+void TimerThread::check_time() {
 
   static TimePoint lastInfoTime = now();
   int elapsed = Time.elapsed();