freebsd man page for datab

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  ref-
       erences, 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

SunOS 5.10							    24 Oct 2003 							 datab(9S)