Process in Pipe which Processes 256 bytes at a Time

I have a c program on a Cyclone 5 that does an FFT using the connected FPGA. This program currently takes 256 bytes from stdin and then process it gives the FFT results on stdout. I run it like this from the Linux bash on the Cyclone 5. ./fpga_fft < input_s16le_audio.pcm This only evaluates the first 256 bytes. How do I do this, so that the program is continuously called with the stdin stream until all from the *.pcm file is read? Ideas: cat input_s16le_audio.pcm|xargs ./fpga_fft Somehow xargs needs to be told to process 256 bytes at the time in chronological sequential order (not parallel).