const string StartPositionFEN = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
// Keep track of position keys along the setup moves (from start position to the
- // position just before to start searching). This is needed by draw detection.
- std::vector<StateInfo> SetupState(200, StateInfo());
+ // position just before to start searching). This is needed by draw detection
+ // where, due to 50 moves rule, we need to ckeck at most 100 plies back.
+ StateInfo StateRingBuf[102], *SetupState = StateRingBuf;
// UCIParser is a class for parsing UCI input. The class
// is actually a string stream built on a given input string.
}
else return;
- SetupState.clear();
-
// Parse move list (if any)
while (up >> token && (m = move_from_uci(pos, token)) != MOVE_NONE)
{
- SetupState.push_back(StateInfo());
- pos.do_move(m, SetupState.back());
+ pos.do_move(m, *SetupState);
+
+ // Increment pointer to StateRingBuf circular buffer
+ if (++SetupState - StateRingBuf >= 102)
+ SetupState = StateRingBuf;
}
}