_comedi_buf_read_n_available
num_bytes = _comedi_buf_read_n_available(s);
_comedi_buf_read_n_available(s));
if (_comedi_buf_read_n_available(s) == 0 &&
_comedi_buf_read_n_available(s) == 0))
_comedi_buf_read_n_available(s) > 0)
m = _comedi_buf_read_n_available(s);
_comedi_buf_read_n_available(s) == 0)
unsigned int _comedi_buf_read_n_available(struct comedi_subdevice *s);
unsigned int nbytes = _comedi_buf_read_n_available(s);