enum {	Maxtrack		= 200,	Ntrack		= Maxtrack+1,	BScdrom		= 2048,	BScdda		= 2352,	BScdxa		= 2336,	BSmax		= 2352,	Nalloc		= 12*BScdda,	DictBlock	= 1, 	TypeDA		= 0,		/* Direct Access */	TypeSA		= 1,		/* Sequential Access */	TypeWO		= 4,		/* Worm */	TypeCD		= 5,		/* CD-ROM */	TypeMO		= 7,		/* rewriteable Magneto-Optical */	TypeMC		= 8,		/* Medium Changer */ 	TypeNone	= 0,	TypeAudio,	TypeAwritable,	TypeData,	TypeDwritable,	TypeDisk,	TypeBlank, 	Cwrite = 1<<0,	Ccdda = 1<<1, 	Nblock = 12,}; typedef struct Buf Buf;typedef struct Drive Drive;typedef struct Track Track;typedef struct Otrack Otrack;typedef struct Dev Dev;typedef struct Msf Msf;	/* minute, second, frame */ struct Msf {	int m;	int s;	int f;}; struct Track{	/* initialized while obtaining the toc (gettoc) */	vlong	size;		/* total size in bytes */	long	bs;		/* block size in bytes */	ulong	beg;		/* beginning block number */	ulong	end;		/* ending block number */	int	type;	Msf	mbeg;	Msf	mend;  	/* initialized by fs */	char	name[32];	int	mode;	int	mtime;}; struct DTrack{	uchar	name[32];	uchar	beg[4];	uchar	end[4];	uchar	size[8];	uchar	magic[4];}; struct Otrack{	Track *track;	Drive *drive;	int nchange;	int omode;	Buf *buf; 	int nref;	/* kept by file server */}; struct Dev{	Otrack* (*openrd)(Drive *d, int trackno);	Otrack* (*create)(Drive *d, int bs);	long (*read)(Otrack *t, void *v, long n, long off);	long (*write)(Otrack *t, void *v, long n);	void (*close)(Otrack *t);	int (*gettoc)(Drive*);	int (*fixate)(Drive *d);	char* (*ctl)(Drive *d, int argc, char **argv);	char* (*setspeed)(Drive *d, int r, int w);}; struct Drive{	QLock;	Scsi; 	int	type;	int	nopen;	int	firsttrack;	int	ntrack;	int	nchange;	int	changetime;	int	nameok;	int	writeok;	Track	track[Ntrack];	ulong	cap;	uchar	blkbuf[BScdda];	int	maxreadspeed;	int	maxwritespeed;	int	readspeed;	int	writespeed;	Dev; 	void *aux;	/* kept by driver */}; struct Buf{	uchar *data;	/* buffer */	long off;		/* data[0] at offset off in file */	int bs;		/* block size */	long ndata;	/* no. valid bytes in data */	int nblock;	/* total buffer size in blocks */	int	omode;	/* OREAD, OWRITE */	long	(*fn)(Buf*, void*, long, long);	/* read, write */ 	/* used only by client */	Otrack *otrack;}; extern int	vflag;