ess_getmixer
static int ess_getmixer(struct ess_info *sc, u_int port);
if (ess_getmixer(sc, 0x7a) & 0x80)
ess_setmixer(sc, 0x78, ess_getmixer(sc, 0x78) & ~0x03);
ess_setmixer(sc, 0x7a, ess_getmixer(sc, 0x7a) & ~0x80);
ess_setmixer(sc, 0x78, ess_getmixer(sc, 0x78) | 0x03);
ess_setmixer(sc, 0x78, ess_getmixer(sc, 0x78) & ~0x10);