snd_c2unit
udcmask |= snd_c2unit(cunit);
udcmask &= ~snd_c2unit(cunit);
udcmask &= ~snd_c2unit(cunit);
udcmask |= snd_c2unit(cunit);
#define PCMMKMINOR(u, d, sub) (snd_u2unit(u) | snd_c2unit(sub) | snd_d2unit(d))
#define snd_mkunit(u, d, c) (snd_u2unit(u) | snd_d2unit(d) | snd_c2unit(c))