Fpga halfband filter

Dear everyone:
In the FPGA code of halfband_decim,v of USRP1, it has a input
strobe_in, which indates a new data comes. Strobe_in is determined by
the decimation rate. For example if we decimate by 6 we write to the
register FR_DECIM_RATE 6/2-1=2 and strobe_in comes high every 3 clocks.
My question is that if I want to use halfband filter only to get a
decimation of 2 (for other purpose of my FPGA project, not used in
USRP), how should I set strobe_in? I noticed that whether I set it equal
to the clock or set it equal to 1, the strobe_out always comes high
every two clocks and data_out is different. So can you tell me how I
should set strobe_in? Besides my data are 8 bits wide, is it proper to
pad 0 to my data to reach 16 bits wide?

Best regards