Revert odd depths razoring

[stockfish] / src / tt.cpp

diff --git a/src/tt.cpp b/src/tt.cpp
index 268c21f896ab3c89e962ae6dde36c9001030231b..185410e6aae307c07a211364f21800973102e202 100644 (file)
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -1,13 +1,14 @@
 /*
-  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.
@@ -23,6 +24,7 @@
 
 #include <cassert>
 #include <cmath>
+#include <cstring>
 
 #include "tt.h"
 
@@ -106,29 +108,25 @@ void TranspositionTable::store(const Position &pos, Value v, Depth d,
   TTEntry *tte, *replace;
 
   tte = replace = first_entry(pos);
-  for (int i = 0; i < 4; i++)
+  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()) // overwrite old
+    if (!tte->key() || tte->key() == pos.get_key()) // empty or overwrite old
     {
         if (m == MOVE_NONE)
-            m = (tte+i)->move();
+            m = tte->move();
 
-        *(tte+i) = TTEntry(pos.get_key(), v, type, d, m, generation);
+        *tte = 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())
+    else if (i == 0)  // replace would be a no-op in this common case
         continue;
 
-    if (    replace->generation() > (tte+i)->generation()
-        || (tte+i)->depth() < replace->depth())
-        replace = tte+i;
+    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);
   writes++;
@@ -136,29 +134,19 @@ void TranspositionTable::store(const Position &pos, Value v, Depth d,
 
 
 /// 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.
+/// transposition table. Returns a pointer to the TTEntry or NULL
+/// if position is not found.
+
+const TTEntry* TranspositionTable::retrieve(const Position &pos) const {
 
-bool TranspositionTable::retrieve(const Position &pos, Value *value,
-                                  Depth *d, Move *move,
-                                  ValueType *type) const {
   TTEntry *tte = first_entry(pos);
 
-  for (int i = 0; i < 4; i++)
+  for (int i = 0; i < 4; i++, tte++)
   {
-      tte += i;
       if (tte->key() == pos.get_key())
-      {
-          *value = tte->value();
-          *type = tte->type();
-          *d = tte->depth();
-          *move = tte->move();
-          return true;
-      }
+          return tte;
   }
-  *move = MOVE_NONE;
-  return false;
+  return NULL;
 }
 
 
@@ -189,13 +177,13 @@ void TranspositionTable::new_search() {
 
 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);
+    p.do_move(pv[i], st);
   }
 }
 
@@ -219,31 +207,4 @@ 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);
-}
+  value_(int16_t(v)), depth_(int16_t(d)) {}