NAME
        ElapsedTime -- returns the time elapsed since it was last called. (V40)

   SYNOPSIS
        fractionalSeconds = ElapsedTime(context);
        D0                              A0

        ULONG ElapsedTime(struct eclockval *);

   FUNCTION
        This function utilizes the timer.device/readeclock() function to get
        an accurate elapsed time value. Since the context needs to be
        established the first call to this routine will return a nonsense
        value.

        The return value for this function only allows for sixteen bits
        worth for the integer number of seconds and sixteen bits for the
        factional number of seconds.

        With sixteen bits worth of integer seconds this function can be
        used to timer an interval up to about 16 hours. If the actual time
        interval is larger this function will return this maximum value.

        The sixteen bits for fractional seconds gives a resolution of
        approximately 20 microseconds. However, it is not recomended
        to expect this function to be accurate for a time interval of
        less than 200 microseconds.

   INPUTS
        context - pointer to an eclockval structure. the first time you
                  call this function, you should initialize the structure
                  to 0s. You should then reuse the same structure for
                  subsequent calls to this function, as this is how the
                  elapsed time is calculated.

   RESULT
        fractionalSeconds - The elapsed time as a fixed point 32-bit
                            number with the point fixed in the middle.
                            That is, the upper order sixteen bits represent
                            the number of seconds elapsed. The low order
                            sixteen bit represent the fractional number of
                            seconds elapsed. This value is limited to about
                            sixteen hours. Although this value is precise
                            to nearly 20 microseconds it is only accurate to
                            within 200 microseconds.

   WARNING
        The first call to this function will return a non-sense value. Only
        rely on its result starting with the second call.

   SEE ALSO
        timer.device/readeclock()