X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=fc0bdfb47c1c96f1738c8403795640fbf13056f8;hp=1959693258c3d8e0e6dbad995103ed0ee766cbe2;hb=7ae3c05795e79c9bd945607cdcfb08198f4c4b45;hpb=a230dc14045691667ffce46619de60497edceb88

diff --git a/src/tt.cpp b/src/tt.cpp
index 19596932..f5b72ba8 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -1,13 +1,15 @@
 /*
-  Glaurung, a UCI chess playing engine.
-  Copyright (C) 2004-2008 Tord Romstad
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
-  Glaurung is free software: you can redistribute it and/or modify
+  Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
-  Glaurung is distributed in the hope that it will be useful,
+  Stockfish is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
@@ -16,201 +18,100 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include <cstring>   // For std::memset
+#include <iostream>
 
-////
-//// Includes
-////
-
-#include <cassert>
-#include <cmath>
-
+#include "bitboard.h"
 #include "tt.h"
 
+TranspositionTable TT; // Our global transposition table
 
-////
-//// Functions
-////
-
-/// Constructor
-
-TranspositionTable::TranspositionTable(unsigned mbSize) {
-
-  size = 0;
-  generation = 0;
-  writes = 0;
-  entries = 0;
-  set_size(mbSize);
-}
-
-
-/// Destructor
 
-TranspositionTable::~TranspositionTable() {
-
-  delete [] entries;
-}
+/// 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 ClusterSize number of TTEntry.
 
+void TranspositionTable::resize(size_t mbSize) {
 
-/// TranspositionTable::set_size sets the size of the transposition table,
-/// measured in megabytes.
+  size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(Cluster));
 
-void TranspositionTable::set_size(unsigned mbSize) {
+  if (newClusterCount == clusterCount)
+      return;
 
-  assert(mbSize >= 4 && mbSize <= 1024);
+  clusterCount = newClusterCount;
 
-  unsigned newSize = 1024;
+  free(mem);
+  mem = calloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1, 1);
 
-  // We store a cluster of 4 TTEntry for each position and newSize is
-  // the maximum number of storable positions
-  for ( ; newSize * 4 * (sizeof(TTEntry)) <= (mbSize << 20); newSize *= 2);
-  newSize /= 2;
-  if (newSize != size)
+  if (!mem)
   {
-    size = newSize;
-    delete [] entries;
-    entries = new TTEntry[size * 4];
-    if (!entries)
-    {
       std::cerr << "Failed to allocate " << mbSize
-                << " MB for transposition table."
-                << std::endl;
+                << "MB for transposition table." << std::endl;
       exit(EXIT_FAILURE);
-    }
-    clear();
   }
+
+  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
+/// TranspositionTable::clear() overwrites the entire transposition table
+/// 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).
-/// Perhaps we should also clear it when the "ucinewgame" command is recieved?
 
 void TranspositionTable::clear() {
 
-  memset(entries, 0, size * 4 * sizeof(TTEntry));
-}
-
-
-/// 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.  The 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
-/// 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 Position &pos, Value v, Depth d,
-                               Move m, ValueType type) {
-  TTEntry *tte, *replace;
-
-  tte = replace = first_entry(pos);
-  for (int i = 0; i < 4; i++)
-  {
-    if (!(tte+i)->key()) // still empty
-    {
-        *(tte+i) = TTEntry(pos.get_key(), v, type, d, m, generation);
-        writes++;
-        return;
-    }
-    if ((tte+i)->key() == pos.get_key()) // overwrite old
-    {
-        if (m == MOVE_NONE)
-            m = (tte+i)->move();
-
-        *(tte+i) = TTEntry(pos.get_key(), v, type, d, m, generation);
-        return;
-    }
-    if (   i == 0  // already is (replace == tte+i), common case
-        || replace->generation() < (tte+i)->generation())
-        continue;
-
-    if (    replace->generation() > (tte+i)->generation()
-        || (tte+i)->depth() < replace->depth())
-        replace = tte+i;
-  }
-  *replace = TTEntry(pos.get_key(), v, type, d, m, generation);
-  writes++;
+  std::memset(table, 0, clusterCount * sizeof(Cluster));
 }
 
 
-/// TranspositionTable::retrieve looks up the current position in the
-/// transposition table. Returns a pointer to the TTEntry or NULL
-/// if position is not found.
-
-const TTEntry* TranspositionTable::retrieve(const Position &pos) const {
-
-  TTEntry *tte = first_entry(pos);
+/// 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.
 
-  for (int i = 0; i < 4; i++)
-  {
-      tte += i;
-      if (tte->key() == pos.get_key())
-          return tte;
-  }
-  return NULL;
-}
-
-
-/// TranspositionTable::first_entry returns a pointer to the first
-/// entry of a cluster given a position.
+TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 
-inline TTEntry* TranspositionTable::first_entry(const Position &pos) const {
+  TTEntry* const tte = first_entry(key);
+  const uint16_t key16 = key >> 48;  // Use the high 16 bits as key inside the cluster
 
-  return entries + (int(pos.get_key() & (size - 1)) << 2);
-}
+  for (int i = 0; i < ClusterSize; ++i)
+      if (!tte[i].key16 || tte[i].key16 == key16)
+      {
+          if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)
+              tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
 
-/// TranspositionTable::new_search() is called at the beginning of every new
-/// search.  It increments the "generation" variable, which is used to
-/// distinguish transposition table entries from previous searches from
-/// entries from the current search.
+          return found = (bool)tte[i].key16, &tte[i];
+      }
 
-void TranspositionTable::new_search() {
+  // 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];
 
-  generation++;
-  writes = 0;
+  return found = false, replace;
 }
 
 
-/// TranspositionTable::insert_pv() is called at the end of a search
-/// iteration, and inserts the PV back into the PV.  This makes sure the
-/// old PV moves are searched first, even if the old TT entries have been
-/// overwritten.
-
-void TranspositionTable::insert_pv(const Position &pos, Move pv[]) {
+/// TranspositionTable::hashfull() returns an approximation of the hashtable
+/// occupation during a search. The hash is x permill full, as per UCI protocol.
 
-  UndoInfo u;
-  Position p(pos);
+int TranspositionTable::hashfull() const {
 
-  for (int i = 0; pv[i] != MOVE_NONE; i++)
+  int cnt = 0;
+  for (int i = 0; i < 1000 / ClusterSize; i++)
   {
-    store(p, VALUE_NONE, Depth(0), pv[i], VALUE_TYPE_NONE);
-    p.do_move(pv[i], u);
+      const TTEntry* tte = &table[i].entry[0];
+      for (int j = 0; j < ClusterSize; j++)
+          if ((tte[j].genBound8 & 0xFC) == generation8)
+              cnt++;
   }
+  return cnt;
 }
-
-
-/// TranspositionTable::full() returns the permill of all transposition table
-/// entries which have received at least one write during the current search.
-/// It is used to display the "info hashfull ..." information in UCI.
-
-int TranspositionTable::full() {
-
-  double N = double(size) * 4.0;
-  return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N))));
-}
-
-
-/// Constructors
-
-TTEntry::TTEntry() {
-}
-
-TTEntry::TTEntry(Key k, Value v, ValueType t, Depth d, Move m,
-                 int generation) :
-  key_ (k), data((m & 0x7FFFF) | (t << 20) | (generation << 23)),
-  value_(v), depth_(int16_t(d)) {}
-
-
-