X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=151b71f58df6ac789a87ac200b543169a6fe5c6b;hp=2979c104aac3020c3798996597b182174b03ad4b;hb=2dd24dc4e618dc7b83799890fe7e84b09b6456b4;hpb=14cf27e6f65787a1f9c8e4759ae0fcc218f37d2d

diff --git a/src/tt.cpp b/src/tt.cpp
index 2979c104..151b71f5 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -1,7 +1,8 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -17,7 +18,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <cstring>
+#include <cstring>   // For std::memset
 #include <iostream>
 
 #include "bitboard.h"
@@ -28,11 +29,11 @@ TranspositionTable TT; // Our global transposition table
 
 /// TranspositionTable::resize() sets the size of the transposition table,
 /// measured in megabytes. Transposition table consists of a power of 2 number
-/// of clusters and each cluster consists of TTClusterSize number of TTEntry.
+/// of clusters and each cluster consists of ClusterSize number of TTEntry.
 
 void TranspositionTable::resize(size_t mbSize) {
 
-  size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(TTCluster));
+  size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(Cluster));
 
   if (newClusterCount == clusterCount)
       return;
@@ -40,7 +41,7 @@ void TranspositionTable::resize(size_t mbSize) {
   clusterCount = newClusterCount;
 
   free(mem);
-  mem = calloc(clusterCount * sizeof(TTCluster) + CACHE_LINE_SIZE - 1, 1);
+  mem = calloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1, 1);
 
   if (!mem)
   {
@@ -49,7 +50,7 @@ void TranspositionTable::resize(size_t mbSize) {
       exit(EXIT_FAILURE);
   }
 
-  table = (TTCluster*)((uintptr_t(mem) + CACHE_LINE_SIZE - 1) & ~(CACHE_LINE_SIZE - 1));
+  table = (Cluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
 }
 
 
@@ -59,40 +60,58 @@ void TranspositionTable::resize(size_t mbSize) {
 
 void TranspositionTable::clear() {
 
-  std::memset(table, 0, clusterCount * sizeof(TTCluster));
+  std::memset(table, 0, clusterCount * sizeof(Cluster));
 }
 
 
-/// TranspositionTable::probe() looks up the current position in the
-/// transposition table. It returns true and a pointer to the TTEntry if
-/// the position is found. Otherwise, it returns false and a pointer to an empty or
-/// least valuable TTEntry to be replaced later. 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.
+/// TranspositionTable::probe() looks up the current position in the transposition
+/// table. It returns true and a pointer to the TTEntry if the position is found.
+/// Otherwise, it returns false and a pointer to an empty or least valuable TTEntry
+/// to be replaced later. The replace value of an entry is calculated as its depth
+/// minus 8 times its relative age. TTEntry t1 is considered more valuable than
+/// TTEntry t2 if its replace value is greater than that of t2.
 
 TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 
   TTEntry* const tte = first_entry(key);
   const uint16_t key16 = key >> 48;  // Use the high 16 bits as key inside the cluster
 
-  for (unsigned i = 0; i < TTClusterSize; ++i)
+  for (int i = 0; i < ClusterSize; ++i)
       if (!tte[i].key16 || tte[i].key16 == key16)
       {
-          if (tte[i].key16)
-              tte[i].genBound8 = uint8_t(generation | tte[i].bound()); // Refresh
+          if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)
+              tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
 
-          found = (bool)tte[i].key16;
-          return &tte[i];
+          return found = (bool)tte[i].key16, &tte[i];
       }
 
   // Find an entry to be replaced according to the replacement strategy
   TTEntry* replace = tte;
-  for (unsigned i = 1; i < TTClusterSize; ++i)
-      if (  ((  tte[i].genBound8 & 0xFC) == generation || tte[i].bound() == BOUND_EXACT)
-          - ((replace->genBound8 & 0xFC) == generation)
-          - (tte[i].depth8 < replace->depth8) < 0)
+  for (int i = 1; i < ClusterSize; ++i)
+      // Due to our packed storage format for generation and its cyclic
+      // nature we add 259 (256 is the modulus plus 3 to keep the lowest
+      // two bound bits from affecting the result) to calculate the entry
+      // age correctly even after generation8 overflows into the next cycle.
+      if (  replace->depth8 - ((259 + generation8 - replace->genBound8) & 0xFC) * 2 * ONE_PLY
+          >   tte[i].depth8 - ((259 + generation8 -   tte[i].genBound8) & 0xFC) * 2 * ONE_PLY)
           replace = &tte[i];
 
-  found = false;
-  return replace;
+  return found = false, replace;
+}
+
+
+/// Returns an approximation of the hashtable occupation during a search. The
+/// hash is x permill full, as per UCI protocol.
+
+int TranspositionTable::hashfull() const
+{
+  int cnt = 0;
+  for (int i = 0; i < 1000 / ClusterSize; i++)
+  {
+      const TTEntry* tte = &table[i].entry[0];
+      for (int j = 0; j < ClusterSize; j++)
+          if ((tte[j].genBound8 & 0xFC) == generation8)
+              cnt++;
+  }
+  return cnt;
 }