if the values allow it, avoid floting point math for the current speed

    if(0 == span_ms)

      span_ms=1; /* at least one millisecond MUST have passed */

    /* Calculate the average speed the last 'countindex' seconds */

    /* Calculate the average speed the last 'span_ms' milliseconds */

    {

      curl_off_t amount = data->progress.speeder[nowindex]-

        data->progress.speeder[checkindex];

      if(amount > 0xffffffff/1000)

        /* the 'amount' value is bigger than would fit in 32 bits if

           multiplied with 1000, so we use the double math for this */

        data->progress.current_speed = (curl_off_t)

      (data->progress.speeder[nowindex]-

       data->progress.speeder[checkindex])/((double)span_ms/1000);

          (amount/(span_ms/1000.0));

      else

        /* the 'amount' value is small enough to fit within 32 bits even

           when multiplied with 1000 */

        data->progress.current_speed = amount*1000/span_ms;

    }

  }

  else

    /* the first second we use the main average */