CMSIS DSP - FIR decimation

Hi,

I am trying to implement FIR decimation on PDM input. Which FIR decimator function should I use? I am now trying to implement arm_fir_decimate_fast_q15 since I need to feed the output (hopefully PCM) to 10 bit DAC. But I am not sure how I get the coefficients. I would be grateful if someone has some insight to it.

Thanks.