newgrf_roadstop.cpp

void TriggerRoadStopRandomisation(Station *st, TileIndex tile, RoadStopRandomTrigger trigger, CargoID cargo_type)
{
	if (GetTileType(tile) != MP_STATION) return;
	if (st == nullptr) st = Station::GetByTile(tile);

	SetBit(st->waiting_triggers, trigger);
  // omitted
	RoadStopResolverObject object(rss, BaseStation::GetByTile(tile), tile, road_rti, 0);
	
	uint32 reseed = object.GetReseedSum();
	if (reseed != 0) {
		reseed >>= 16;

		/* Set individual tile random bits */
		st->random_bits &= ~reseed;
		st->random_bits |= Random() & reseed;

		SetStationTileRandomBits(tile, st->random_bits);

		MarkTileDirtyByTile(tile);
	}
}