#define	TRUE		1
#define	FALSE		0
#define	ERR		(-1)

#define	uchar		unsigned char
#define ushort		unsigned short
#define	uint		unsigned int
#define	ulong		unsigned long

#define	MAX_DEV		16
#define	MAX_SEC		1024
#define	MAX_HASH	16
#define	HASH(s)		((s)&15)

#define	USE_DEV		0xFF
#define	FRE_DEV		0xFE
#define	CHE_DEV		0

typedef struct _BP {
    struct _BP  *next;
    uchar	sum;
    uchar	dev;
    long	sec;
} SEC_PTR;

typedef struct {
    char far	*next;
    short	dev_sts;
    short	str_ent;
    short	int_ent;
    char	res[8];
} DEVHED;

typedef struct _DPB {
    uchar	DrvNum;
    uchar	UnitNum;
    short	SecLen;
    uchar	SecAlc;
    uchar	Shift;
    short	ResSec;
    uchar	FatLen;
    short	DirEnt;
    short	DatSec;
    short	MaxCls;
    uchar	FatSec;
    short	DirSta;
    DEVHED far	*DevEnt;
    uchar	MedId;
    uchar	DskCng;
    struct _DPB far *NxtDPB;
    short	CurDir;
} DPB;

typedef struct {
    short	SecLen;
    uchar	SecAlc;
    short	ResSec;
    uchar	FatLen;
    short	DirEnt;
    short	MaxSec;
    uchar	MedId;
    short	FatSec;
} BPB;

typedef struct _RH {
    uchar	len;
    uchar	unit;
    uchar	cmds;
    short	stat;
    uchar	res[8];
    uchar	md_id;
    union {
	struct {
	    short	now_sts;
	} chk;
	struct {
	    uchar far	*work;
	    BPB far	*bpb;
	} build;
	struct {
	    uchar far	*buff;
	    short	count;
	    short	sect;
	} rdwt;
	struct {
	    char	mode;
	    char	max_dev;
	    DPB far	*dpb_ptr;
	    SEC_PTR far	*lru_tbl;
	    SEC_PTR far	*use_tbl;
	} ext;
	struct {
	    ushort	psp_seg;
	} quit;
    } x;
} REQ;