X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=3c43e12ce58cb17e5bc376feda94b60ab468430e;hp=248cbad96d930baebe75d7bae3536145a69ccd1a;hb=ace8e951d70c2986a0af83effcc0d2b2312d29e3;hpb=ccd823a4ffd2ed3e60cb03ab49a841742bae1994

diff --git a/src/tt.cpp b/src/tt.cpp
index 248cbad9..3c43e12c 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"
@@ -28,13 +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(uint64_t mbSize) {
+void TranspositionTable::resize(size_t mbSize) {
 
-  assert(msb((mbSize * 1024 * 1024) / sizeof(TTCluster)) < 32);
-
-  uint32_t newClusterCount = 1 << msb((mbSize * 1024 * 1024) / sizeof(TTCluster));
+  size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(Cluster));
 
   if (newClusterCount == clusterCount)
       return;
@@ -42,7 +41,7 @@ void TranspositionTable::resize(uint64_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)
   {
@@ -51,72 +50,68 @@ void TranspositionTable::resize(uint64_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));
 }
 
 
 /// TranspositionTable::clear() overwrites the entire transposition table
-/// with zeroes. It is called whenever the table is resized, or when the
+/// with zeros. It is called whenever the table is resized, or when the
 /// user asks the program to clear the table (from the UCI interface).
 
 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. Returns a pointer to the TTEntry or NULL if
-/// position is not found.
+/// 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.
 
-const TTEntry* TranspositionTable::probe(const Key key) const {
+TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 
-  TTEntry* tte = first_entry(key);
-  uint16_t key16 = key >> 48;
+  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, ++tte)
-      if (tte->key16 == key16)
+  for (int i = 0; i < ClusterSize; ++i)
+      if (!tte[i].key16 || tte[i].key16 == key16)
       {
-          tte->genBound8 = generation | tte->bound(); // Refresh
-          return tte;
+          if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)
+              tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
+
+          return found = (bool)tte[i].key16, &tte[i];
       }
 
-  return NULL;
+  // Find an entry to be replaced according to the replacement strategy
+  TTEntry* replace = tte;
+  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
+          >   tte[i].depth8 - ((259 + generation8 -   tte[i].genBound8) & 0xFC) * 2)
+          replace = &tte[i];
+
+  return found = false, replace;
 }
 
 
-/// 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 in which cluster the position will be placed.
-/// When a new entry is written and there are no empty entries available in the
-/// cluster, it replaces the least valuable of the 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.
-
-void TranspositionTable::store(const Key key, Value v, Bound b, Depth d, Move m, Value statV) {
-
-  TTEntry *tte, *replace;
-  uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
-
-  tte = replace = first_entry(key);
+/// Returns an approximation of the hashtable occupation during a search. The
+/// hash is x permill full, as per UCI protocol.
 
-  for (unsigned i = 0; i < TTClusterSize; ++i, ++tte)
+int TranspositionTable::hashfull() const
+{
+  int cnt = 0;
+  for (int i = 0; i < 1000 / ClusterSize; i++)
   {
-      if (!tte->key16 || tte->key16 == key16) // Empty or overwrite old
-      {
-          if (!m)
-              m = tte->move(); // Preserve any existing ttMove
-
-          replace = tte;
-          break;
-      }
-
-      // Implement replace strategy
-      if (  ((    tte->genBound8 & 0xFC) == generation || tte->bound() == BOUND_EXACT)
-          - ((replace->genBound8 & 0xFC) == generation)
-          - (tte->depth8 < replace->depth8) < 0)
-          replace = tte;
+      const TTEntry* tte = &table[i].entry[0];
+      for (int j = 0; j < ClusterSize; j++)
+          if ((tte[j].genBound8 & 0xFC) == generation8)
+              cnt++;
   }
-
-  replace->save(key16, v, b, d, m, generation, statV);
+  return cnt;
 }