typedef struct Audio Audio;struct Audio {	Audio *next;	char *name;	void *ctlr;	void *mixer;	void (*attach)(Audio *);	long (*read)(Audio *, void *, long, vlong);	long (*write)(Audio *, void *, long, vlong);	long (*volread)(Audio *, void *, long, vlong);	long (*volwrite)(Audio *, void *, long, vlong);	void (*close)(Audio *);	long (*ctl)(Audio *, void *, long, vlong);	long (*status)(Audio *, void *, long, vlong);	long (*buffered)(Audio *);	int ctlrno;}; void addaudiocard(char *name, int (*probefn)(Audio *));void ac97mixreset(Audio *, void (*wr)(Audio*,int,ushort), ushort (*rr)(Audio*,int));int ac97hardrate(Audio *adev, int rate);