millisecond_count_diff

	count.u4.v = millisecond_count_diff(previous_count.u4.v)

	This function will return the difference between a previous
	millisecond count acquired through a call to millisecond_count
	and the current count.

	previous_count	previously acquired millisecond count

	This function returns status values as follows:

	1 KHz counter difference value

	This function requires the following include files:

	clib_h

	Related functions:

	millisecond_count, k15hz, clinks_now

	C/C++ usage:

	unsigned int	count;
	unsigned int	previous_count = PREVIOUS_COUNT;

	count = millisecond_count_diff(previous_count);