ess_get_dsp_status
u_char ess_get_dsp_status(struct ess_softc *);
return (ess_get_dsp_status(sc) & ESS_DSP_READ_READY) ? 1 : 0;
return (ess_get_dsp_status(sc) & ESS_DSP_WRITE_BUSY) ? 0 : 1;