From a67c22611aea4b643e8278fa6007da316bd06b13 Mon Sep 17 00:00:00 2001
From: Marco Costalba <mcostalba@gmail.com>
Date: Fri, 8 Aug 2014 10:59:28 +0200
Subject: [PATCH] Rework perft implementation

Unify various perft functions and move all the code
to search.cpp.

Avoid perft implementation to be splitted between
benchmark.cpp (where it has no reason to be) and
search.cpp

No functional and no speed change (tested).
---
 src/benchmark.cpp | 11 ++---------
 src/search.cpp    | 27 +++++++++++++++++----------
 src/search.h      |  2 +-
 3 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/src/benchmark.cpp b/src/benchmark.cpp
index a92a634c..3161c4ca 100644
--- a/src/benchmark.cpp
+++ b/src/benchmark.cpp
@@ -139,15 +139,8 @@ void benchmark(const Position& current, istream& is) {
       cerr << "\nPosition: " << i + 1 << '/' << fens.size() << endl;
 
       if (limitType == "perft")
-          for (MoveList<LEGAL> it(pos); *it; ++it)
-          {
-              StateInfo si;
-              pos.do_move(*it, si);
-              uint64_t cnt = limits.depth > 1 ? Search::perft(pos, (limits.depth - 1) * ONE_PLY) : 1;
-              pos.undo_move(*it);
-              cout << move_to_uci(*it, pos.is_chess960()) << ": " << cnt << endl;
-              nodes += cnt;
-          }
+          nodes += Search::perft<true>(pos, limits.depth * ONE_PLY);
+
       else
       {
           Threads.start_thinking(pos, limits, st);
diff --git a/src/search.cpp b/src/search.cpp
index 3fb1345a..8410f73b 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -152,26 +152,33 @@ void Search::init() {
 
 /// Search::perft() is our utility to verify move generation. All the leaf nodes
 /// up to the given depth are generated and counted and the sum returned.
-
-static uint64_t perft(Position& pos, Depth depth) {
+template<bool Root>
+uint64_t Search::perft(Position& pos, Depth depth) {
 
   StateInfo st;
-  uint64_t cnt = 0;
+  uint64_t cnt, nodes = 0;
   CheckInfo ci(pos);
   const bool leaf = depth == 2 * ONE_PLY;
 
   for (MoveList<LEGAL> it(pos); *it; ++it)
   {
-      pos.do_move(*it, st, ci, pos.gives_check(*it, ci));
-      cnt += leaf ? MoveList<LEGAL>(pos).size() : ::perft(pos, depth - ONE_PLY);
-      pos.undo_move(*it);
+      if (Root && depth <= ONE_PLY)
+          cnt = 1;
+      else
+      {
+          pos.do_move(*it, st, ci, pos.gives_check(*it, ci));
+          cnt = leaf ? MoveList<LEGAL>(pos).size() : perft<false>(pos, depth - ONE_PLY);
+          nodes += cnt;
+          pos.undo_move(*it);
+      }
+      if (Root)
+          sync_cout << move_to_uci(*it, pos.is_chess960()) << ": " << cnt << sync_endl;
   }
-  return cnt;
+  return nodes;
 }
 
-uint64_t Search::perft(Position& pos, Depth depth) {
-  return depth > ONE_PLY ? ::perft(pos, depth) : MoveList<LEGAL>(pos).size();
-}
+template uint64_t Search::perft<true>(Position& pos, Depth depth);
+
 
 /// Search::think() is the external interface to Stockfish's search, and is
 /// called by the main thread when the program receives the UCI 'go' command. It
diff --git a/src/search.h b/src/search.h
index 5c2dfc8a..4fe5a5b4 100644
--- a/src/search.h
+++ b/src/search.h
@@ -105,8 +105,8 @@ extern Time::point SearchTime;
 extern StateStackPtr SetupStates;
 
 extern void init();
-extern uint64_t perft(Position& pos, Depth depth);
 extern void think();
+template<bool Root> uint64_t perft(Position& pos, Depth depth);
 
 } // namespace Search
 
-- 
2.39.2