From 60bc30275decbb00aa26af8dc14ad6cb167eaa82 Mon Sep 17 00:00:00 2001
From: Marco Costalba <mcostalba@gmail.com>
Date: Mon, 5 Oct 2009 12:00:35 +0100
Subject: [PATCH] Small code reformat in TranspositionTable::extract_pv()

In particular don't use an array of StateInfo, this
avoids a possible overflow and is in any case redundant.

Also pass as argument the pv[] array size to avoid a second
possible overflow on this one.

Fix suggested by Joona.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---
 src/search.cpp |  2 +-
 src/tt.cpp     | 33 ++++++++++++++++-----------------
 src/tt.h       |  2 +-
 3 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/src/search.cpp b/src/search.cpp
index 08b2c006..32934393 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -947,7 +947,7 @@ namespace {
             // Update PV
             rml.set_move_score(i, value);
             update_pv(ss, 0);
-            TT.extract_pv(pos, ss[0].pv);
+            TT.extract_pv(pos, ss[0].pv, PLY_MAX);
             rml.set_move_pv(i, ss[0].pv);
 
             if (MultiPV == 1)
diff --git a/src/tt.cpp b/src/tt.cpp
index 9f0e21fd..5e1dfe17 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -220,27 +220,26 @@ void TranspositionTable::insert_pv(const Position& pos, Move pv[]) {
 /// will often get single-move PVs when the search stops while failing high,
 /// and a single-move PV means that we don't have a ponder move.
 
-void TranspositionTable::extract_pv(const Position& pos, Move pv[]) {
+void TranspositionTable::extract_pv(const Position& pos, Move pv[], int pvSize) {
 
-  int ply;
-  Position p(pos);
-  StateInfo st[100];
-
-  for (ply = 0; pv[ply] != MOVE_NONE; ply++)
-      p.do_move(pv[ply], st[ply]);
-
-  bool stop;
   const TTEntry* tte;
-  for (stop = false, tte = retrieve(p.get_key());
-       tte && tte->move() != MOVE_NONE && !stop;
-       tte = retrieve(p.get_key()), ply++)
+  StateInfo st;
+  Position p(pos);
+  int ply = 0;
+
+  // Update position to the end of current PV
+  while (pv[ply] != MOVE_NONE)
+      p.do_move(pv[ply++], st);
+
+  // Try to add moves from TT until possible
+  while (   (tte = retrieve(p.get_key())) != NULL
+         && tte->move() != MOVE_NONE
+         && move_is_legal(p, tte->move())
+         && (!p.is_draw() || ply < 2)
+         && ply < pvSize)
   {
-      if (!move_is_legal(p, tte->move()))
-          break;
       pv[ply] = tte->move();
-      p.do_move(pv[ply], st[ply]);
-      for (int j = 0; j < ply; j++)
-          if (st[j].key == p.get_key()) stop = true;
+      p.do_move(pv[ply++], st);
   }
   pv[ply] = MOVE_NONE;
 }
diff --git a/src/tt.h b/src/tt.h
index 2c989dac..bff17498 100644
--- a/src/tt.h
+++ b/src/tt.h
@@ -102,7 +102,7 @@ public:
   void prefetch(const Key posKey) const;
   void new_search();
   void insert_pv(const Position& pos, Move pv[]);
-  void extract_pv(const Position& pos, Move pv[]);
+  void extract_pv(const Position& pos, Move pv[], int pvSize);
   int full() const;
 
 private:
-- 
2.39.2