Reformat some comments

Tests used to derive some Elo worth comments:

https://tests.stockfishchess.org/tests/view/653cf6b7cc309ae83956263a
https://tests.stockfishchess.org/tests/view/655250b7136acbc573534711
https://tests.stockfishchess.org/tests/view/65525767136acbc5735347b9
https://tests.stockfishchess.org/tests/view/65525aa1136acbc573534801

closes https://github.com/official-stockfish/Stockfish/pull/4879

No functional change

src/misc.cpp

@@ -393,8 +393,8 @@ void dbg_print() {
 }
 
 
-// Used to serialize access to std::cout to avoid multiple threads writing at
+// Used to serialize access to std::cout
-// the same time.
+// to avoid multiple threads writing at the same time.
 std::ostream& operator<<(std::ostream& os, SyncCout sc) {
 
     static std::mutex m;
@@ -558,7 +558,7 @@ void* aligned_large_pages_alloc(size_t allocSize) {
     constexpr size_t alignment = 4096;  // assumed small page size
     #endif
 
-    // round up to multiples of alignment
+    // Round up to multiples of alignment
     size_t size = ((allocSize + alignment - 1) / alignment) * alignment;
     void*  mem  = std_aligned_alloc(alignment, size);
     #if defined(MADV_HUGEPAGE)
@@ -600,7 +600,7 @@ void bindThisThread(size_t) {}
 
 #else
 
-// Retrieves logical processor information using Windows specific
+// Retrieves logical processor information using Windows-specific
 // API and returns the best node id for the thread with index idx. Original
 // code from Texel by Peter Österlund.
 static int best_node(size_t idx) {
@@ -660,8 +660,7 @@ static int best_node(size_t idx) {
             groups.push_back(n);
 
     // In case a core has more than one logical processor (we assume 2) and we
-    // have still threads to allocate, then spread them evenly across available
+    // still have threads to allocate, spread them evenly across available nodes.
-    // nodes.
     for (int t = 0; t < threads - cores; t++)
         groups.push_back(t % nodes);
 
@@ -731,7 +730,7 @@ std::string workingDirectory;  // path of the working directory
 void init([[maybe_unused]] int argc, char* argv[]) {
     std::string pathSeparator;
 
-    // extract the path+name of the executable binary
+    // Extract the path+name of the executable binary
     argv0 = argv[0];
 
 #ifdef _WIN32
@@ -747,14 +746,14 @@ void init([[maybe_unused]] int argc, char* argv[]) {
     pathSeparator = "/";
 #endif
 
-    // extract the working directory
+    // Extract the working directory
     workingDirectory = "";
     char  buff[40000];
     char* cwd = GETCWD(buff, 40000);
     if (cwd)
         workingDirectory = cwd;
 
-    // extract the binary directory path from argv0
+    // Extract the binary directory path from argv0
     binaryDirectory = argv0;
     size_t pos      = binaryDirectory.find_last_of("\\/");
     if (pos == std::string::npos)
@@ -762,7 +761,7 @@ void init([[maybe_unused]] int argc, char* argv[]) {
     else
         binaryDirectory.resize(pos + 1);
 
-    // pattern replacement: "./" at the start of path is replaced by the working directory
+    // Pattern replacement: "./" at the start of path is replaced by the working directory
     if (binaryDirectory.find("." + pathSeparator) == 0)
         binaryDirectory.replace(0, 1, workingDirectory);
 }

src/movepick.h

@@ -96,11 +96,10 @@ enum StatsType {
     Captures
 };
 
-// ButterflyHistory records how often quiet moves have been successful or
+// ButterflyHistory records how often quiet moves have been successful or unsuccessful
-// unsuccessful during the current search, and is used for reduction and move
+// during the current search, and is used for reduction and move ordering decisions.
-// ordering decisions. It uses 2 tables (one for each color) indexed by
+// It uses 2 tables (one for each color) indexed by the move's from and to squares,
-// the move's from and to squares, see www.chessprogramming.org/Butterfly_Boards
+// see www.chessprogramming.org/Butterfly_Boards (~11 elo)
-// (~11 elo)
 using ButterflyHistory = Stats<int16_t, 7183, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)>;
 
 // CounterMoveHistory stores counter moves indexed by [piece][to] of the previous

src/position.cpp

@@ -371,9 +371,8 @@ void Position::set_state() const {
 }
 
 
-// Overload to initialize the position object with
+// Overload to initialize the position object with the given endgame code string
-// the given endgame code string like "KBPKN". It is mainly a helper to
+// like "KBPKN". It's mainly a helper to get the material key out of an endgame code.
-// get the material key out of an endgame code.
 Position& Position::set(const string& code, Color c, StateInfo* si) {
 
     assert(code[0] == 'K');
@@ -472,8 +471,8 @@ void Position::update_slider_blockers(Color c) const {
 }
 
 
-// Computes a bitboard of all pieces which attack a
+// Computes a bitboard of all pieces which attack a given square.
-// given square. Slider attacks use the occupied bitboard to indicate occupancy.
+// Slider attacks use the occupied bitboard to indicate occupancy.
 Bitboard Position::attackers_to(Square s, Bitboard occupied) const {
 
     return (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN))
@@ -575,8 +574,7 @@ bool Position::pseudo_legal(const Move m) const {
     // Handle the special case of a pawn move
     if (type_of(pc) == PAWN)
     {
-        // We have already handled promotion moves, so destination
+        // We have already handled promotion moves, so destination cannot be on the 8th/1st rank
-        // cannot be on the 8th/1st rank.
         if ((Rank8BB | Rank1BB) & to)
             return false;
 
@@ -639,10 +637,9 @@ bool Position::gives_check(Move m) const {
     case PROMOTION :
         return attacks_bb(promotion_type(m), to, pieces() ^ from) & square<KING>(~sideToMove);
 
-    // En passant capture with check? We have already handled the case
+    // En passant capture with check? We have already handled the case of direct
-    // of direct checks and ordinary discovered check, so the only case we
+    // checks and ordinary discovered check, so the only case we need to handle
-    // need to handle is the unusual case of a discovered check through
+    // is the unusual case of a discovered check through the captured pawn.
-    // the captured pawn.
     case EN_PASSANT : {
         Square   capsq = make_square(file_of(to), rank_of(from));
         Bitboard b     = (pieces() ^ from ^ capsq) | to;
@@ -928,8 +925,8 @@ void Position::undo_move(Move m) {
 }
 
 
-// Helper used to do/undo a castling move. This
+// Helper used to do/undo a castling move. This is a bit
-// is a bit tricky in Chess960 where from/to squares can overlap.
+// tricky in Chess960 where from/to squares can overlap.
 template<bool Do>
 void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto) {
 
@@ -1244,8 +1241,8 @@ void Position::flip() {
 }
 
 
-// Performs some consistency checks for the
+// Performs some consistency checks for the position object
-// position object and raise an assert if something wrong is detected.
+// and raise an assert if something wrong is detected.
 // This is meant to be helpful when debugging.
 bool Position::pos_is_ok() const {
 

src/search.cpp

@@ -834,8 +834,7 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
     if (depth <= 0)
         return qsearch<PV>(pos, ss, alpha, beta);
 
-    // For cutNodes without a ttMove, we decrease depth by 2
+    // For cutNodes without a ttMove, we decrease depth by 2 if depth is high enough.
-    // if current depth >= 8.
     if (cutNode && depth >= 8 && !ttMove)
         depth -= 2;
 
@@ -1037,7 +1036,7 @@ moves_loop:  // When in check, search starts here
 
             // Note: the depth margin and singularBeta margin are known for having non-linear
             // scaling. Their values are optimized to time controls of 180+1.8 and longer
-            // so changing them requires tests at this type of time controls.
+            // so changing them requires tests at these types of time controls.
             // Recursive singular search is avoided.
             if (!rootNode && move == ttMove && !excludedMove
                 && depth >= 4 - (thisThread->completedDepth > 24) + 2 * (PvNode && tte->is_pv())
@@ -1079,7 +1078,7 @@ moves_loop:  // When in check, search starts here
                 // we do not know if the ttMove is singular or can do a multi-cut,
                 // so we reduce the ttMove in favor of other moves based on some conditions:
 
-                // If the ttMove is assumed to fail high over currnet beta (~7 Elo)
+                // If the ttMove is assumed to fail high over current beta (~7 Elo)
                 else if (ttValue >= beta)
                     extension = -2 - !PvNode;
 
@@ -1155,7 +1154,7 @@ moves_loop:  // When in check, search starts here
         if ((ss + 1)->cutoffCnt > 3)
             r++;
 
-        // Set reduction to 0 for first generated move (ttMove)
+        // Set reduction to 0 for first picked move (ttMove) (~2 Elo)
         // Nullifies all previous reduction adjustments to ttMove and leaves only history to do them
         else if (move == ttMove)
             r = 0;
@@ -1189,8 +1188,9 @@ moves_loop:  // When in check, search starts here
             {
                 // Adjust full-depth search based on LMR results - if the result
                 // was good enough search deeper, if it was bad enough search shallower.
-                const bool doDeeperSearch     = value > (bestValue + 51 + 10 * (newDepth - d));
+                const bool doDeeperSearch =
-                const bool doShallowerSearch  = value < bestValue + newDepth;
+                  value > (bestValue + 51 + 10 * (newDepth - d));             // (~1 Elo)
+                const bool doShallowerSearch = value < bestValue + newDepth;  // (~2 Elo)
 
                 newDepth += doDeeperSearch - doShallowerSearch;
 
@@ -1459,7 +1459,7 @@ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
                 bestValue = ttValue;
         }
         else
-            // In case of null move search use previous static eval with a different sign
+            // In case of null move search, use previous static eval with a different sign
             ss->staticEval = bestValue =
               (ss - 1)->currentMove != MOVE_NULL ? evaluate(pos) : -(ss - 1)->staticEval;
 

src/uci.cpp

@@ -82,8 +82,8 @@ void position(Position& pos, std::istringstream& is, StateListPtr& states) {
     }
 }
 
-// Prints the evaluation of the current position, consistent with
+// Prints the evaluation of the current position,
-// the UCI options set so far.
+// consistent with the UCI options set so far.
 void trace_eval(Position& pos) {
 
     StateListPtr states(new std::deque<StateInfo>(1));
@@ -122,9 +122,8 @@ void setoption(std::istringstream& is) {
 }
 
 
-// Called when the engine receives the "go" UCI command. The function
+// Called when the engine receives the "go" UCI command. The function sets the
-// sets the thinking time and other parameters from the input string, then starts
+// thinking time and other parameters from the input string then stars with a search
-// with a search.
 
 void go(Position& pos, std::istringstream& is, StateListPtr& states) {
 

src/uci.h

@@ -36,7 +36,7 @@ namespace UCI {
 // to the UCI centipawn result used in output. This value is derived from
 // the win_rate_model() such that Stockfish outputs an advantage of
 // "100 centipawns" for a position if the engine has a 50% probability to win
-// from this position in selfplay at fishtest LTC time control.
+// from this position in self-play at fishtest LTC time control.
 const int NormalizeToPawnValue = 328;
 
 class Option;