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Backup some mor einfo in do_null_move()

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Faster undo_null_move()

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2009-05-21 09:54:48 +02:00
parent 5603e25a7f
commit 595c7d75a2
1 changed files with 7 additions and 9 deletions
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16
src/position.cpp
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@ -1413,11 +1413,13 @@ void Position::do_null_move(StateInfo& backupSt) {
assert(!is_check());
// Back up the information necessary to undo the null move to the supplied
// StateInfo object. In the case of a null move, the only thing we need to
// remember is the en passant square.
// 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.epSquare = st->epSquare;
backupSt.key = st->key;
backupSt.mgValue = st->mgValue;
backupSt.egValue = st->egValue;
backupSt.previous = st->previous;
st->previous = &backupSt;
@ -1451,19 +1453,15 @@ void Position::undo_null_move() {
// Restore information from the our backup StateInfo object
st->epSquare = st->previous->epSquare;
st->key = st->previous->key;
st->mgValue = st->previous->mgValue;
st->egValue = st->previous->egValue;
st->previous = st->previous->previous;
if (st->epSquare != SQ_NONE)
st->key ^= zobEp[st->epSquare];
// Update the necessary information
sideToMove = opposite_color(sideToMove);
st->rule50--;
gamePly--;
st->key ^= zobSideToMove;
st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
assert(is_ok());
}