# Create a loop for rights 

```mq4
int OnCalculate(...) {
    //
    // wait to pass bars until we have rights ...
    if (rates_total <= InpPeriod) {
        //
        // return not calculated ...
        return 0;
    }

    //
    // find loop count for bars manipulation ...
    int count = (prev_calculated == 0) ? rates_total - InpPeriod - 1 : rates_total - prev_calculated + 1;

    //
    // this is the main loop of calculations, for each bar index ...
    for (int i = count - 1; i >= 0; i--) {
        
    }

    //
    // return current calculated ...
    return rates_totlat;
}
```