X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=83eaf800ac480aabd64856c5d02ac3b27d8cffa5;hp=66166ce9c348f27a410ec8b7fb8eb59e9b885453;hb=aabd526f7c9cec1d1f6a8f7da738311487aa42b8;hpb=392360e73bb50fd322c544d4210cc08e7cf27eea

diff --git a/src/tt.cpp b/src/tt.cpp
index 66166ce9..83eaf800 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -1,17 +1,18 @@
 /*
-  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 Marco Costalba
 
-  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.
-  
+
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
@@ -23,6 +24,7 @@
 
 #include <cassert>
 #include <cmath>
+#include <cstring>
 
 #include "tt.h"
 
@@ -31,20 +33,13 @@
 //// Functions
 ////
 
-/// Constructor
+TranspositionTable::TranspositionTable() {
 
-TranspositionTable::TranspositionTable(unsigned mbSize) {
-
-  size = 0;
-  generation = 0;
-  writes = 0;
+  size = writes = 0;
   entries = 0;
-  set_size(mbSize);
+  generation = 0;
 }
 
-
-/// Destructor
-
 TranspositionTable::~TranspositionTable() {
 
   delete [] entries;
@@ -56,33 +51,33 @@ TranspositionTable::~TranspositionTable() {
 
 void TranspositionTable::set_size(unsigned mbSize) {
 
-  assert(mbSize >= 4 && mbSize <= 1024);
+  assert(mbSize >= 4 && mbSize <= 4096);
 
   unsigned newSize = 1024;
 
   // 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;
+  while ((2 * newSize) * 4 * (sizeof(TTEntry)) <= (mbSize << 20))
+      newSize *= 2;
+
   if (newSize != size)
   {
-    size = newSize;
-    delete [] entries;
-    entries = new TTEntry[size * 4];
-    if (!entries)
-    {
-      std::cerr << "Failed to allocate " << mbSize
-                << " MB for transposition table."
-                << std::endl;
-      exit(EXIT_FAILURE);
-    }
-    clear();
+      size = newSize;
+      delete [] entries;
+      entries = new TTEntry[size * 4];
+      if (!entries)
+      {
+          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
+/// 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?
 
@@ -94,79 +89,74 @@ 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.  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
+/// 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
 /// current search and t2 is from a previous search, or if the depth of t1
-/// is bigger than the depth of t2.
+/// is bigger than the depth of t2. A TTEntry of type VALUE_TYPE_EVAL
+/// never replaces another entry for the same position.
+
+void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m) {
 
-void TranspositionTable::store(const Position &pos, Value v, Depth d,
-                               Move m, ValueType type) {
   TTEntry *tte, *replace;
 
-  tte = replace = entries + int(pos.get_key() & (size - 1)) * 4;
-  for (int i = 0; i < 4; i++)
+  tte = replace = first_entry(posKey);
+  for (int i = 0; i < 4; i++, tte++)
   {
-    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())
-    {
-        if (m == MOVE_NONE)
-            m = (tte+i)->move();
-        
-        *(tte+i) = TTEntry(pos.get_key(), v, type, d, m, generation);
-        return;
-    }
-    if (replace->generation() == generation)
-    {
-        if ((tte+i)->generation() != generation || (tte+i)->depth() < replace->depth())
-            replace = tte+i;
-    }
-    else if ((tte+i)->generation() != generation && (tte+i)->depth() < replace->depth())
-        replace = tte+i;
+      if (!tte->key() || tte->key() == posKey) // empty or overwrite old
+      {
+          // Do not overwrite when new type is VALUE_TYPE_EVAL
+          if (tte->key() && t == VALUE_TYPE_EVAL)
+              return;
+
+          if (m == MOVE_NONE)
+              m = tte->move();
+
+          *tte = TTEntry(posKey, v, t, d, m, generation);
+          return;
+      }
+      else if (i == 0)  // replace would be a no-op in this common case
+          continue;
+
+      int c1 = (replace->generation() == generation ?  2 : 0);
+      int c2 = (tte->generation() == generation ? -2 : 0);
+      int c3 = (tte->depth() < replace->depth() ?  1 : 0);
+
+      if (c1 + c2 + c3 > 0)
+          replace = tte;
   }
-  *replace = TTEntry(pos.get_key(), v, type, d, m, generation);
+  *replace = TTEntry(posKey, v, t, d, m, generation);
   writes++;
 }
 
 
 /// TranspositionTable::retrieve looks up the current position in the
-/// transposition table, and extracts the value, value type, depth and
-/// best move if the position is found.  The return value is true if
-/// the position is found, and false if it isn't.
-
-bool TranspositionTable::retrieve(const Position &pos, Value *value,
-                                  Depth *d, Move *move,
-                                  ValueType *type) const {
-  TTEntry *tte;
-  bool found = false;
-
-  tte = entries + int(pos.get_key() & (size - 1)) * 4;
-  for (int i = 0; i < 4 && !found ; i++)
-      if ((tte+i)->key() == pos.get_key())
-      {
-          tte = tte + i;
-          found = true;
-      }
-  if (!found) {
-      *move = MOVE_NONE;
-      return false;
-  }
-  *value = tte->value();
-  *type = tte->type();
-  *d = tte->depth();
-  *move = tte->move();
-  return true;
+/// transposition table. Returns a pointer to the TTEntry or NULL
+/// if position is not found.
+
+TTEntry* TranspositionTable::retrieve(const Key posKey) const {
+
+  TTEntry *tte = first_entry(posKey);
+
+  for (int i = 0; i < 4; i++, tte++)
+      if (tte->key() == posKey)
+          return tte;
+
+  return NULL;
 }
 
 
+/// TranspositionTable::first_entry returns a pointer to the first
+/// entry of a cluster given a position.
+
+inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {
+
+  return entries + (int(posKey & (size - 1)) << 2);
+}
+
 /// TranspositionTable::new_search() is called at the beginning of every new
-/// search.  It increments the "generation" variable, which is used to
+/// search. It increments the "generation" variable, which is used to
 /// distinguish transposition table entries from previous searches from
 /// entries from the current search.
 
@@ -177,20 +167,20 @@ void TranspositionTable::new_search() {
 }
 
 
-/// 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.
+/// 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[]) {
+void TranspositionTable::insert_pv(const Position& pos, Move pv[]) {
 
-  UndoInfo u;
+  StateInfo st;
   Position p(pos);
 
   for (int i = 0; pv[i] != MOVE_NONE; i++)
   {
-    store(p, VALUE_NONE, Depth(0), pv[i], VALUE_TYPE_NONE);
-    p.do_move(pv[i], u);
+      store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i]);
+      p.do_move(pv[i], st);
   }
 }
 
@@ -199,49 +189,8 @@ void TranspositionTable::insert_pv(const Position &pos, Move pv[]) {
 /// 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() {
+int TranspositionTable::full() const {
 
   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);
-}
-
-
-/// Functions for extracting data from TTEntry objects.
-
-inline Key TTEntry::key() const {
-  return key_;
-}
-
-inline Depth TTEntry::depth() const {
-  return Depth(depth_);
-}
-
-inline Move TTEntry::move() const {
-  return Move(data & 0x7FFFF);
-}
-
-inline Value TTEntry::value() const {
-  return Value(value_);
-}
-
-inline ValueType TTEntry::type() const {
-  return ValueType((data >> 20) & 3);
-}
-
-inline int TTEntry::generation() const {
-  return (data >> 23);
-}