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Use key saved in state instead.

No functional change (in real games) and no speed regression.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2011-07-18 10:20:37 +02:00
parent a6fc3d6ee5
commit 3d8140a541
3 changed files with 33 additions and 45 deletions
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src/position.cpp
+21 -36
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@@ -99,7 +99,6 @@ CheckInfo::CheckInfo(const Position& pos) {
Position::Position(const Position& pos, int th) {
memcpy(this, &pos, sizeof(Position));
detach(); // Always detach() in copy c'tor to avoid surprises
threadID = th;
nodes = 0;
@@ -113,18 +112,6 @@ Position::Position(const string& fen, bool isChess960, int th) {
}
/// Position::detach() copies the content of the current state and castling
/// masks inside the position itself. This is needed when the st pointee could
/// become stale, as example because the caller is about to going out of scope.
void Position::detach() {
startState = *st;
st = &startState;
st->previous = NULL; // As a safe guard
}
/// Position::from_fen() initializes the position object with the given FEN
/// string. This function is not very robust - make sure that input FENs are
/// correct (this is assumed to be the responsibility of the GUI).
@@ -775,27 +762,16 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
/// Position::do_setup_move() makes a permanent move on the board. It should
/// be used when setting up a position on board. You can't undo the move.
void Position::do_setup_move(Move m) {
void Position::do_setup_move(Move m, StateInfo& newSt) {
assert(move_is_ok(m));
StateInfo newSt;
// Update the number of full moves after black's move
if (sideToMove == BLACK)
fullMoves++;
do_move(m, newSt);
// Reset "game ply" in case we made a non-reversible move.
// "game ply" is used for repetition detection.
if (st->rule50 == 0)
st->gamePly = 0;
// Our StateInfo newSt is about going out of scope so copy
// its content before it disappears.
detach();
assert(is_ok());
}
@@ -834,16 +810,13 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
newSt.previous = st;
st = &newSt;
// Save the current key to the history[] array, in order to be able to
// detect repetition draws.
history[st->gamePly++] = key;
// Update side to move
key ^= zobSideToMove;
// Increment the 50 moves rule draw counter. Resetting it to zero in the
// case of non-reversible moves is taken care of later.
st->rule50++;
st->gamePly++;
st->pliesFromNull++;
if (move_is_castle(m))
@@ -1369,10 +1342,6 @@ void Position::do_null_move(StateInfo& backupSt) {
backupSt.pliesFromNull = st->pliesFromNull;
st->previous = &backupSt;
// Save the current key to the history[] array, in order to be able to
// detect repetition draws.
history[st->gamePly++] = st->key;
// Update the necessary information
if (st->epSquare != SQ_NONE)
st->key ^= zobEp[st->epSquare];
@@ -1383,6 +1352,7 @@ void Position::do_null_move(StateInfo& backupSt) {
sideToMove = opposite_color(sideToMove);
st->epSquare = SQ_NONE;
st->rule50++;
st->gamePly++;
st->pliesFromNull = 0;
st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue;
@@ -1699,9 +1669,24 @@ bool Position::is_draw() const {
// Draw by repetition?
if (!SkipRepetition)
for (int i = 4, e = Min(Min(st->gamePly, st->rule50), st->pliesFromNull); i <= e; i += 2)
if (history[st->gamePly - i] == st->key)
return true;
{
int i = 4, e = Min(Min(st->gamePly, st->rule50), st->pliesFromNull);
if (i <= e)
{
StateInfo* stp = st->previous->previous;
do {
stp = stp->previous->previous;
if (stp->key == st->key)
return true;
i +=2;
} while (i <= e);
}
}
return false;
}