Working of processor loadable down counter

Hi all,

i am verifying the 16-bit pulse counter which interfaced with
processor.

I want to know the working of down counter where its values are
0x0_0000 to 0X3_FFFF

If am set the time base for 10 us and loaded counter with 1 ms and
toggling the input pulse_din0 signal at 200 ns than i can calculate
the number of counts (actual time / time base) = 1 ms/10 us = 1000
counts...which is loaded into the register CNT_P4P_PC0 which is
loadable by the processor so now the value in this reg is 0x000003E8,

1.Now my question is if it decrements to 0 and PC_0 (which is a result
counter ) incmrements by 1 and the value is laoded to this counter. if
CNT_P4P_PC0 is not decrements or not equals to 0x0000 than what will
be the value in both the registers?

2. second question is how to verify this requirement: The CNT_P4P_PC0
shall be a processor loadable down counter with a range of a minimum
of 100 ns to a maximum of 1.3 s.

please give me some clear steps..it will be a great sharing of
knowledge

Sreeniv