From ac6e6f73f281458e6c5488debf4d96d7a50c8bf4 Mon Sep 17 00:00:00 2001
From: nodchip <nodchip@gmail.com>
Date: Thu, 10 Sep 2020 20:54:47 +0900
Subject: [PATCH] Added EnableTranspositionTable UCI option to enable/disable
 transposition table.

---
 src/tt.cpp        | 11 +++++++++++
 src/tt.h          |  4 ++++
 src/ucioption.cpp |  7 ++++++-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/tt.cpp b/src/tt.cpp
index 60a3a5f1..fc8ab3b1 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -28,6 +28,10 @@
 
 TranspositionTable TT; // Our global transposition table
 
+#ifdef EVAL_LEARN
+bool TranspositionTable::enable_transposition_table = true;
+#endif
+
 /// TTEntry::save() populates the TTEntry with a new node's data, possibly
 /// overwriting an old position. Update is not atomic and can be racy.
 
@@ -116,6 +120,13 @@ void TranspositionTable::clear() {
 
 TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 
+#ifdef EVAL_LEARN
+  if (!enable_transposition_table) {
+      found = false;
+      return first_entry(0);
+  }
+#endif
+
   TTEntry* const tte = first_entry(key);
   const uint16_t key16 = (uint16_t)key;  // Use the low 16 bits as key inside the cluster
 
diff --git a/src/tt.h b/src/tt.h
index fdfd6769..e83b6f3c 100644
--- a/src/tt.h
+++ b/src/tt.h
@@ -84,6 +84,10 @@ public:
     return &table[mul_hi64(key, clusterCount)].entry[0];
   }
 
+#ifdef EVAL_LEARN
+  static bool enable_transposition_table;
+#endif
+
 private:
   friend struct TTEntry;
 
diff --git a/src/ucioption.cpp b/src/ucioption.cpp
index 0e561416..b24d8d78 100644
--- a/src/ucioption.cpp
+++ b/src/ucioption.cpp
@@ -44,7 +44,10 @@ void on_use_NNUE(const Option& ) { Eval::init_NNUE(); }
 void on_eval_file(const Option& ) { Eval::init_NNUE(); }
 #ifdef EVAL_LEARN
 void on_prune_at_shallow_depth_on_pv_node(const Option& o) {
-  Search::prune_at_shallow_depth_on_pv_node = o;
+    Search::prune_at_shallow_depth_on_pv_node = o;
+}
+void on_enable_transposition_table(const Option& o) {
+    TranspositionTable::enable_transposition_table = o;
 }
 #endif
 
@@ -102,6 +105,8 @@ void init(OptionsMap& o) {
   o["EvalSaveDir"] << Option("evalsave");
   // Prune at shallow depth on PV nodes. Setting this value to true gains elo in shallow search.
   o["PruneAtShallowDepthOnPvNode"] << Option(false, on_prune_at_shallow_depth_on_pv_node);
+  // Enable transposition table.
+  o["EnableTranspositionTable"] << Option(true, on_enable_transposition_table);
 #endif
 }