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Revert "Extend full 3 fold detection to PvNodes"

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Marco Costalba 2013-01-28 17:24:01 +01:00
parent 483c98a69e
commit 58c9fbacc7
3 changed files with 18 additions and 14 deletions
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24
src/position.cpp
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@ -1363,31 +1363,36 @@ Value Position::compute_non_pawn_material(Color c) const {
/// Position::is_draw() tests whether the position is drawn by material,
/// repetition, or the 50 moves rule. It does not detect stalemates, this
/// must be done by the search.
template<bool CheckRepetition, bool CheckThreeFold>
template<bool SkipRepetition>
bool Position::is_draw() const {
// Draw by material?
if ( !pieces(PAWN)
&& (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMg))
return true;
// Draw by the 50 moves rule?
if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
return true;
if (CheckRepetition)
// Draw by repetition?
if (!SkipRepetition)
{
int i = 4, e = std::min(st->rule50, st->pliesFromNull), cnt;
int i = 4, e = std::min(st->rule50, st->pliesFromNull);
if (i <= e)
{
StateInfo* stp = st->previous->previous;
for (cnt = 0; i <= e; i += 2)
{
do {
stp = stp->previous->previous;
if (stp->key == st->key && (!CheckThreeFold || ++cnt >= 2))
if (stp->key == st->key)
return true;
}
i += 2;
} while (i <= e);
}
}
@ -1395,9 +1400,8 @@ bool Position::is_draw() const {
}
// Explicit template instantiations
template bool Position::is_draw<true, true>() const;
template bool Position::is_draw<true, false>() const;
template bool Position::is_draw<false,false>() const;
template bool Position::is_draw<false>() const;
template bool Position::is_draw<true>() const;
/// Position::flip() flips position with the white and black sides reversed. This

2
src/position.h
View file

@ -179,7 +179,7 @@ public:
Thread* this_thread() const;
int64_t nodes_searched() const;
void set_nodes_searched(int64_t n);
template<bool CheckRepetition, bool CheckThreeFold> bool is_draw() const;
template<bool SkipRepetition> bool is_draw() const;
// Position consistency check, for debugging
bool pos_is_ok(int* failedStep = NULL) const;

6
src/search.cpp
View file

@ -534,7 +534,7 @@ namespace {
if (!RootNode)
{
// Step 2. Check for aborted search and immediate draw
if (Signals.stop || pos.is_draw<true, PvNode>() || ss->ply > MAX_PLY)
if (Signals.stop || pos.is_draw<false>() || ss->ply > MAX_PLY)
return DrawValue[pos.side_to_move()];
// Step 3. Mate distance pruning. Even if we mate at the next move our score
@ -1109,7 +1109,7 @@ split_point_start: // At split points actual search starts from here
ss->ply = (ss-1)->ply + 1;
// Check for an instant draw or maximum ply reached
if (pos.is_draw<false, false>() || ss->ply > MAX_PLY)
if (pos.is_draw<true>() || ss->ply > MAX_PLY)
return DrawValue[pos.side_to_move()];
// Transposition table lookup. At PV nodes, we don't use the TT for
@ -1516,7 +1516,7 @@ void RootMove::extract_pv_from_tt(Position& pos) {
&& pos.is_pseudo_legal(m = tte->move()) // Local copy, TT could change
&& pos.pl_move_is_legal(m, pos.pinned_pieces())
&& ply < MAX_PLY
&& (!pos.is_draw<true, true>() || ply < 2));
&& (!pos.is_draw<false>() || ply < 2));
pv.push_back(MOVE_NONE); // Must be zero-terminating