2.9BSD/usr/man/man5/types.5

.TH TYPES 5
.UC
.SH NAME
types \- primitive system data types
.SH SYNOPSIS
.B #include <sys/types.h>
.SH DESCRIPTION
The data types defined in the include file
are used in UNIX system code;
some data of these types are accessible to user code:
.PP
.ta \w'typedef 'u +\w'unsigned\ short\ 'u +\w'label_t[7]\ \ 'u
.nf
typedef	char	bool_t;		/* Boolean */
typedef	char *     	caddr_t;  	/* virtual core address */
typedef	unsigned short	comp_t;		/* "floating pt": 3 bits base 8 exp, 13 bits fraction */
typedef	long       	daddr_t;  	/* disk address */
typedef	short        	dev_t;    	/* device code */
typedef	unsigned short	ino_t;     	/* i-node number */
#ifdef	MENLO_KOV
typedef	short	label_t[7];	/* regs 2-7 and __ovno */
#else
typedef	short        	label_t[6]; 	/* program status */
#endif
typedef unsigned	memaddr;	/* core or swap address */
typedef	long       	off_t;    	/* offset in file */
typedef	struct {short r[1];}*	physadr;
typedef unsigned	size_t;		/* size of process segments */
typedef	long       	time_t;   	/* a time */
typedef	long	ubadr_t;	/* UNIBUS address */
typedef	unsigned short	u_short;
typedef	short	void;

	/* selectors and constructor for device code */
#define	major(x)  	(short)(((unsigned)(x)>>8))
#define	minor(x)  	(short)((x)&0377)
#define	makedev(x,y)	(dev_t)((x)<<8|(y))
.fi
.PP
The form
.I daddr\_t
is used for disk addresses except in an
i-node on disk, see
.IR filsys (5).
Times are encoded in seconds since 00:00:00 GMT, January 1, 1970.
The major and minor parts of a device code
specify kind and unit number of a device
and are installation-dependent.
Offsets
.RI ( off\_t )
are measured in bytes from the beginning of a file.
The
.I label\_t
variables are used to save the processor state
while another process is running.
.SH SEE ALSO
adb(1), lseek(2), time(2), filsys(5)