Small clean-ups

- Comment for Countemove pruning -> Continuation history
- Fix comment in input_slice.h
- Shorter lines in Makefile
- Comment for scale factor
- Fix comment for pinners in see_ge()
- Change Thread.id() signature to size_t
- Trailing space in reprosearch.sh
- Add Douglas Matos Gomes to the AUTHORS file
- Introduce comment for undo_null_move()
- Use Stockfish coding style for export_net()
- Change date in AUTHORS file

closes https://github.com/official-stockfish/Stockfish/pull/3416

No functional change

AUTHORS

@@ -1,4 +1,4 @@
-# List of authors for Stockfish, as of March 31, 2021
+# List of authors for Stockfish, as of May 17, 2021
 
 # Founders of the Stockfish project and fishtest infrastructure
 Tord Romstad (romstad)
@@ -52,6 +52,7 @@ Dieter Dobbelaere (ddobbelaere)
 DiscanX
 Dominik Schlösser (domschl)
 double-beep
+Douglas Matos Gomes (dsmsgms)
 Eduardo Cáceres (eduherminio)
 Eelco de Groot (KingDefender)
 Elvin Liu (solarlight2)

src/Makefile

@@ -96,8 +96,7 @@ endif
 ifeq ($(ARCH), $(filter $(ARCH), \
                  x86-64-vnni512 x86-64-vnni256 x86-64-avx512 x86-64-bmi2 x86-64-avx2 \
                  x86-64-sse41-popcnt x86-64-modern x86-64-ssse3 x86-64-sse3-popcnt \
-                 x86-64 x86-32-sse41-popcnt x86-32-sse2 x86-32 ppc-64 ppc-32 \
-                 e2k \
+                 x86-64 x86-32-sse41-popcnt x86-32-sse2 x86-32 ppc-64 ppc-32 e2k \
                  armv7 armv7-neon armv8 apple-silicon general-64 general-32))
    SUPPORTED_ARCH=true
 else
@@ -840,8 +839,7 @@ config-sanity: net
 	@test "$(optimize)" = "yes" || test "$(optimize)" = "no"
 	@test "$(SUPPORTED_ARCH)" = "true"
 	@test "$(arch)" = "any" || test "$(arch)" = "x86_64" || test "$(arch)" = "i386" || \
-	 test "$(arch)" = "ppc64" || test "$(arch)" = "ppc" || \
-	 test "$(arch)" = "e2k" || \
+	 test "$(arch)" = "ppc64" || test "$(arch)" = "ppc" || test "$(arch)" = "e2k" || \
 	 test "$(arch)" = "armv7" || test "$(arch)" = "armv8" || test "$(arch)" = "arm64"
 	@test "$(bits)" = "32" || test "$(bits)" = "64"
 	@test "$(prefetch)" = "yes" || test "$(prefetch)" = "no"

src/evaluate.cpp

@@ -114,24 +114,28 @@ namespace Eval {
         }
   }
 
+  /// NNUE::export_net() exports the currently loaded network to a file
   void NNUE::export_net(const std::optional<std::string>& filename) {
     std::string actualFilename;
-    if (filename.has_value()) {
-      actualFilename = filename.value();
-    } else {
-      if (eval_file_loaded != EvalFileDefaultName) {
-        sync_cout << "Failed to export a net. A non-embedded net can only be saved if the filename is specified." << sync_endl;
-        return;
-      }
-      actualFilename = EvalFileDefaultName;
+
+    if (filename.has_value())
+        actualFilename = filename.value();
+    else 
+    {
+        if (eval_file_loaded != EvalFileDefaultName)
+        {
+             sync_cout << "Failed to export a net. A non-embedded net can only be saved if the filename is specified." << sync_endl;
+             return;
+        }
+        actualFilename = EvalFileDefaultName;
     }
 
     ofstream stream(actualFilename, std::ios_base::binary);
-    if (save_eval(stream)) {
+
+    if (save_eval(stream))
         sync_cout << "Network saved successfully to " << actualFilename << "." << sync_endl;
-    } else {
+    else
         sync_cout << "Failed to export a net." << sync_endl;
-    }
   }
 
   /// NNUE::verify() verifies that the last net used was loaded successfully
@@ -927,7 +931,7 @@ namespace {
     Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
     int sf = me->scale_factor(pos, strongSide);
 
-    // If scale factor is not already specific, scale down via general heuristics
+    // If scale factor is not already specific, scale up/down via general heuristics
     if (sf == SCALE_FACTOR_NORMAL)
     {
         if (pos.opposite_bishops())

src/nnue/layers/input_slice.h

@@ -53,7 +53,7 @@ class InputSlice {
     return true;
   }
 
-  // Read network parameters
+  // Write network parameters
   bool write_parameters(std::ostream& /*stream*/) const {
     return true;
   }

src/position.cpp

@@ -988,7 +988,7 @@ void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Squ
 }
 
 
-/// Position::do(undo)_null_move() is used to do(undo) a "null move": it flips
+/// Position::do_null_move() is used to do a "null move": it flips
 /// the side to move without executing any move on the board.
 
 void Position::do_null_move(StateInfo& newSt) {
@@ -1027,6 +1027,9 @@ void Position::do_null_move(StateInfo& newSt) {
   assert(pos_is_ok());
 }
 
+
+/// Position::undo_null_move() must be used to undo a "null move"
+
 void Position::undo_null_move() {
 
   assert(!checkers());
@@ -1092,8 +1095,8 @@ bool Position::see_ge(Move m, Value threshold) const {
       if (!(stmAttackers = attackers & pieces(stm)))
           break;
 
-      // Don't allow pinned pieces to attack (except the king) as long as
-      // there are pinners on their original square.
+      // Don't allow pinned pieces to attack as long as there are
+      // pinners on their original square.
       if (pinners(~stm) & occupied)
           stmAttackers &= ~blockers_for_king(stm);
 

src/search.cpp

@@ -862,7 +862,6 @@ namespace {
              && ttValue != VALUE_NONE
              && ttValue < probCutBeta))
     {
-
         assert(probCutBeta < VALUE_INFINITE);
 
         MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory);
@@ -1025,7 +1024,7 @@ moves_loop: // When in check, search starts from here
           }
           else
           {
-              // Countermoves based pruning (~20 Elo)
+              // Continuation history based pruning (~20 Elo)
               if (   lmrDepth < 4
                   && (*contHist[0])[movedPiece][to_sq(move)] < CounterMovePruneThreshold
                   && (*contHist[1])[movedPiece][to_sq(move)] < CounterMovePruneThreshold)
@@ -1528,7 +1527,7 @@ moves_loop: // When in check, search starts from here
                                                                 [pos.moved_piece(move)]
                                                                 [to_sq(move)];
 
-      // CounterMove based pruning
+      // Continuation history based pruning
       if (  !captureOrPromotion
           && bestValue > VALUE_TB_LOSS_IN_MAX_PLY
           && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold

src/thread.h

@@ -55,7 +55,7 @@ public:
   void idle_loop();
   void start_searching();
   void wait_for_search_finished();
-  int id() const { return idx; }
+  size_t id() const { return idx; }
 
   Pawns::Table pawnsTable;
   Material::Table materialTable;

tests/reprosearch.sh

@@ -10,7 +10,7 @@ trap 'error ${LINENO}' ERR
 
 echo "reprosearch testing started"
 
-# repeat two short games, separated by ucinewgame. 
+# repeat two short games, separated by ucinewgame.
 # with go nodes $nodes they should result in exactly
 # the same node count for each iteration.
 cat << EOF > repeat.exp