DATAB(9S) Data Structures for Drivers DATAB(9S)

NAME

datab, dblk - STREAMS message data structure

SYNOPSIS

#include <sys/stream.h>

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

DESCRIPTION

The datab structure describes the data of a STREAMS message. The
actual data contained in a STREAMS message is stored in a data buffer
pointed to by this structure. A msgb (message block) structure
includes a field that points to a datab structure.


Because a data block can have more than one message block pointing to
it at one time, the db_ref member keeps track of a data block's
references, preventing it from being deallocated until all message
blocks are finished with it.

STRUCTURE MEMBERS

unsigned char *db_base; /* first byte of buffer */
unsigned char *db_lim; /* last byte (+1) of buffer */
unsigned char db_ref; /* # of message pointers to this data */
unsigned char db_type; /* message type */


A datab structure is defined as type dblk_t.

SEE ALSO

free_rtn(9S), msgb(9S)


Writing Device Drivers


STREAMS Programming Guide

October 24, 2003 DATAB(9S)