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Retire undo_null_move()

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Use a templetized do_null_move() to do/undo the null move.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2011-10-29 17:49:20 +01:00
parent e896368496
commit 08abe8b4a3
3 changed files with 33 additions and 47 deletions
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73
src/position.cpp
View file

@ -1204,61 +1204,48 @@ void Position::undo_move(Move m) {
}
/// Position::do_null_move makes() a "null move": It switches the side to move
/// and updates the hash key without executing any move on the board.
/// Position::do_null_move() is used to do/undo a "null move": It flips the side
/// to move and updates the hash key without executing any move on the board.
template<bool Do>
void Position::do_null_move(StateInfo& backupSt) {
assert(!in_check());
// Back up the information necessary to undo the null move to the supplied
// StateInfo object.
// Note that differently from normal case here backupSt is actually used as
// a backup storage not as a new state to be used.
backupSt.key = st->key;
backupSt.epSquare = st->epSquare;
backupSt.value = st->value;
backupSt.previous = st->previous;
backupSt.pliesFromNull = st->pliesFromNull;
st->previous = &backupSt;
// StateInfo object. Note that differently from normal case here backupSt
// is actually used as a backup storage not as the new state. This reduces
// the number of fields to be copied.
StateInfo* src = Do ? st : &backupSt;
StateInfo* dst = Do ? &backupSt : st;
// Update the necessary information
if (st->epSquare != SQ_NONE)
st->key ^= zobEp[st->epSquare];
st->key ^= zobSideToMove;
prefetch((char*)TT.first_entry(st->key));
dst->key = src->key;
dst->epSquare = src->epSquare;
dst->value = src->value;
dst->rule50 = src->rule50;
dst->pliesFromNull = src->pliesFromNull;
sideToMove = flip(sideToMove);
st->epSquare = SQ_NONE;
st->rule50++;
st->pliesFromNull = 0;
st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
if (Do)
{
if (st->epSquare != SQ_NONE)
st->key ^= zobEp[st->epSquare];
st->key ^= zobSideToMove;
prefetch((char*)TT.first_entry(st->key));
st->epSquare = SQ_NONE;
st->rule50++;
st->pliesFromNull = 0;
st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
}
assert(pos_is_ok());
}
/// Position::undo_null_move() unmakes a "null move".
void Position::undo_null_move() {
assert(!in_check());
// Restore information from the our backup StateInfo object
StateInfo* backupSt = st->previous;
st->key = backupSt->key;
st->epSquare = backupSt->epSquare;
st->value = backupSt->value;
st->previous = backupSt->previous;
st->pliesFromNull = backupSt->pliesFromNull;
// Update the necessary information
sideToMove = flip(sideToMove);
st->rule50--;
assert(pos_is_ok());
}
// Explicit template instantiations
template void Position::do_null_move<false>(StateInfo& backupSt);
template void Position::do_null_move<true>(StateInfo& backupSt);
/// Position::see() is a static exchange evaluator: It tries to estimate the

3
src/position.h
View file

@ -166,8 +166,7 @@ public:
void do_move(Move m, StateInfo& st);
void do_move(Move m, StateInfo& st, const CheckInfo& ci, bool moveIsCheck);
void undo_move(Move m);
void do_null_move(StateInfo& st);
void undo_null_move();
template<bool Do> void do_null_move(StateInfo& st);
// Static exchange evaluation
int see(Move m) const;

4
src/search.cpp
View file

@ -870,12 +870,12 @@ namespace {
if (refinedValue - PawnValueMidgame > beta)
R++;
pos.do_null_move(st);
pos.do_null_move<true>(st);
(ss+1)->skipNullMove = true;
nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
: - search<NonPV>(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY);
(ss+1)->skipNullMove = false;
pos.undo_null_move();
pos.do_null_move<false>(st);
if (nullValue >= beta)
{