px_digital_out
#define PX_DIGITAL_OUT chip->px_digital_out
chip->px_digital_out = chip->bx_digital_out = 6;
chip->px_digital_out = chip->bx_digital_out = 8;
return init_engine(substream, hw_params, px_digital_out(chip) +
char px_digital_out, px_analog_in, px_digital_in, px_num;