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Fix an off-by-one bug in extract_pv()

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In case we reach ply == PLY_MAX we exit the function
writing

pv[PLY_MAX] = MOVE_NONE;

And because SearchStack is defined as:

struct SearchStack {
  Move pv[PLY_MAX];
  Move currentMove;
  .....

We end up with the unwanted assignment

SearchStack.currentMove = MOVE_NONE;

Fortunatly this is harmless because currentMove is not used where
extarct_pv() is called. But neverthless this is a bug that
needs to be fixed.

Thanks to Uri Blass for spotting out this.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-10-09 10:04:55 +01:00
parent d892063cd3
commit 06a5b602dc
3 changed files with 4 additions and 4 deletions
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4
src/tt.cpp
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@@ -220,7 +220,7 @@ 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[], int pvSize) {
void TranspositionTable::extract_pv(const Position& pos, Move pv[], const int PLY_MAX) {
const TTEntry* tte;
StateInfo st;
@@ -236,7 +236,7 @@ void TranspositionTable::extract_pv(const Position& pos, Move pv[], int pvSize)
&& tte->move() != MOVE_NONE
&& move_is_legal(p, tte->move())
&& (!p.is_draw() || ply < 2)
&& ply < pvSize)
&& ply < PLY_MAX)
{
pv[ply] = tte->move();
p.do_move(pv[ply++], st);