X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Ftt.cpp;h=f598e3bf1318d4a57e7368d5e9b18a284f86e56b;hb=8e71ee7ec6c1634af5d17f8ba43049f85ef42c53;hp=956184a92576089b14ced36fdd57285babaa944a;hpb=6f6f59ea6a066eac291eac5ad0369cd2e0daf739;p=stockfish

diff --git a/src/tt.cpp b/src/tt.cpp
index 956184a9..f598e3bf 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -24,8 +24,8 @@
 
 #include <cassert>
 #include <cstring>
+#include <iostream>
 
-#include "evaluate.h"
 #include "tt.h"
 
 // The main transposition table
@@ -55,30 +55,33 @@ void TranspositionTable::set_size(size_t mbSize) {
 
   size_t newSize = 1024;
 
-  // We store a cluster of ClusterSize number of TTEntry for each position
-  // and newSize is the maximum number of storable positions.
-  while ((2 * newSize) * sizeof(TTCluster) <= (mbSize << 20))
+  // Transposition table consists of clusters and each cluster consists
+  // of ClusterSize number of TTEntries. Each non-empty entry contains
+  // information of exactly one position and newSize is the number of
+  // clusters we are going to allocate.
+  while (2ULL * newSize * sizeof(TTCluster) <= (mbSize << 20))
       newSize *= 2;
 
-  if (newSize != size)
+  if (newSize == size)
+      return;
+
+  size = newSize;
+  delete [] entries;
+  entries = new (std::nothrow) TTCluster[size];
+  if (!entries)
   {
-      size = newSize;
-      delete [] entries;
-      entries = new TTCluster[size];
-      if (!entries)
-      {
-          std::cerr << "Failed to allocate " << mbSize
-                    << " MB for transposition table." << std::endl;
-          Application::exit_with_failure();
-      }
+      std::cerr << "Failed to allocate " << mbSize
+                << " MB for transposition table." << std::endl;
+      exit(EXIT_FAILURE);
   }
+  clear();
 }
 
 
 /// TranspositionTable::clear overwrites the entire transposition table
 /// with zeroes. It is called whenever the table is resized, or when the
 /// user asks the program to clear the table (from the UCI interface).
-/// Perhaps we should also clear it when the "ucinewgame" command is recieved?
+/// Perhaps we should also clear it when the "ucinewgame" command is received?
 
 void TranspositionTable::clear() {
 
@@ -86,15 +89,15 @@ void TranspositionTable::clear() {
 }
 
 
-/// TranspositionTable::store writes a new entry containing a position,
-/// a value, a value type, a search depth, and a best move to the
-/// transposition table. Transposition table is organized in clusters of
-/// four TTEntry objects, and when a new entry is written, it replaces
-/// the least valuable of the four entries in a cluster. A TTEntry t1 is
-/// considered to be more valuable than a TTEntry t2 if t1 is from the
+/// TranspositionTable::store writes a new entry containing position key and
+/// valuable information of current position.
+/// The Lowest order bits of position key are used to decide on which cluster
+/// the position will be placed.
+/// When a new entry is written and there are no empty entries available in cluster,
+/// it replaces the least valuable of entries.
+/// A TTEntry t1 is considered to be more valuable than a TTEntry t2 if t1 is from the
 /// current search and t2 is from a previous search, or if the depth of t1
-/// is bigger than the depth of t2. A TTEntry of type VALUE_TYPE_EVAL
-/// never replaces another entry for the same position.
+/// is bigger than the depth of t2.
 
 void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m, Value statV, Value kingD) {
 
@@ -105,9 +108,9 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d,
   tte = replace = first_entry(posKey);
   for (int i = 0; i < ClusterSize; i++, tte++)
   {
-      if (!tte->key() || tte->key() == posKey32) // empty or overwrite old
+      if (!tte->key() || tte->key() == posKey32) // Empty or overwrite old
       {
-          // Preserve any exsisting ttMove
+          // Preserve any existing ttMove
           if (m == MOVE_NONE)
               m = tte->move();
 
@@ -115,7 +118,8 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d,
           return;
       }
 
-      if (i == 0)  // replace would be a no-op in this common case
+      // Replacing first entry is default and already set before entering for-loop
+      if (i == 0)
           continue;
 
       c1 = (replace->generation() == generation ?  2 : 0);