X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;ds=sidebyside;f=src%2Ftt.cpp;h=a7042f9ef2b9c56a83cb987f30345eda5e0604d6;hb=88c3670edf26d094678eeef3a2ed1eeffaf344d4;hp=09a74d2d5936273b1a97d25358dd7c45ae63e5f4;hpb=b76c04c0975326d3274d7d7fb6df4edef7a040b5;p=stockfish

diff --git a/src/tt.cpp b/src/tt.cpp
index 09a74d2d..a7042f9e 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -20,6 +20,7 @@
 #include <cstring>
 #include <iostream>
 
+#include "bitboard.h"
 #include "tt.h"
 
 TranspositionTable TT; // Our global transposition table
@@ -37,18 +38,13 @@ TranspositionTable::~TranspositionTable() {
 
 
 /// TranspositionTable::set_size() sets the size of the transposition table,
-/// measured in megabytes.
+/// measured in megabytes. Transposition table consists of a power of 2 number of
+/// TTCluster and each cluster consists of ClusterSize number of TTEntries. Each
+/// non-empty entry contains information of exactly one position.
 
 void TranspositionTable::set_size(size_t mbSize) {
 
-  size_t newSize = 1024;
-
-  // 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;
+  size_t newSize = 1ULL << msb((mbSize << 20) / sizeof(TTCluster));
 
   if (newSize == size)
       return;
@@ -56,13 +52,15 @@ void TranspositionTable::set_size(size_t mbSize) {
   size = newSize;
   delete [] entries;
   entries = new (std::nothrow) TTCluster[size];
+
   if (!entries)
   {
       std::cerr << "Failed to allocate " << mbSize
                 << "MB for transposition table." << std::endl;
       exit(EXIT_FAILURE);
   }
-  clear();
+
+  clear(); // Operator new is not guaranteed to initialize memory to zero
 }
 
 
@@ -84,23 +82,23 @@ void TranspositionTable::clear() {
 /// 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.
 
-void TranspositionTable::store(const Key posKey, Value v, Bound t, Depth d, Move m, Value statV, Value kingD) {
+void TranspositionTable::store(const Key key, Value v, Bound t, Depth d, Move m, Value statV, Value kingD) {
 
   int c1, c2, c3;
   TTEntry *tte, *replace;
-  uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key inside the cluster
+  uint32_t key32 = key >> 32; // Use the high 32 bits as key inside the cluster
 
-  tte = replace = first_entry(posKey);
+  tte = replace = first_entry(key);
 
   for (int i = 0; i < ClusterSize; i++, tte++)
   {
-      if (!tte->key() || tte->key() == posKey32) // Empty or overwrite old
+      if (!tte->key() || tte->key() == key32) // Empty or overwrite old
       {
           // Preserve any existing ttMove
           if (m == MOVE_NONE)
               m = tte->move();
 
-          tte->save(posKey32, v, t, d, m, generation, statV, kingD);
+          tte->save(key32, v, t, d, m, generation, statV, kingD);
           return;
       }
 
@@ -112,7 +110,7 @@ void TranspositionTable::store(const Key posKey, Value v, Bound t, Depth d, Move
       if (c1 + c2 + c3 > 0)
           replace = tte;
   }
-  replace->save(posKey32, v, t, d, m, generation, statV, kingD);
+  replace->save(key32, v, t, d, m, generation, statV, kingD);
 }
 
 
@@ -120,13 +118,13 @@ void TranspositionTable::store(const Key posKey, Value v, Bound t, Depth d, Move
 /// transposition table. Returns a pointer to the TTEntry or NULL if
 /// position is not found.
 
-TTEntry* TranspositionTable::probe(const Key posKey) const {
+TTEntry* TranspositionTable::probe(const Key key) const {
 
-  uint32_t posKey32 = posKey >> 32;
-  TTEntry* tte = first_entry(posKey);
+  TTEntry* tte = first_entry(key);
+  uint32_t key32 = key >> 32;
 
   for (int i = 0; i < ClusterSize; i++, tte++)
-      if (tte->key() == posKey32)
+      if (tte->key() == key32)
           return tte;
 
   return NULL;