dblk(9s) [sunos man page]

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)

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

NAME

       msgb, mblk - STREAMS message block structure

SYNOPSIS

       #include <sys/stream.h>

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI)

DESCRIPTION

       A  STREAMS  message  is made up of one or more message blocks, referenced by a pointer to a msgb structure. The b_next and  b_prev pointers
       are used to link messages together on a QUEUE. The  b_cont pointer links message blocks together when a message consists of more  than  one
       block.

       Each   msgb  structure also includes a pointer to a  datab(9S) structure, the data block (which contains pointers to the actual data of the
       message), and the type of the message.

STRUCTURE MEMBERS

       struct msgb     *b_next; 	  /* next message on queue */
       struct msgb     *b_prev; 	  /* previous message on queue */
       struct msgb     *b_cont; 	  /* next message block */
       unsigned char   *b_rptr; 	  /* 1st unread data byte of buffer */
       unsigned char   *b_wptr; 	  /* 1st unwritten data byte of buffer */
       struct datab    *b_datap;	  /* pointer to data block */
       unsigned char   b_band;		  /* message priority  */
       unsigned short  b_flag;		  /* used by stream head  */

       Valid flags are as follows:

       MSGMARK	       Last byte of message is marked.

       MSGDELIM        Message is delimited.

       The msgb structure is defined as type mblk_t.

SEE ALSO

       datab(9S)

       Writing Device Drivers

       STREAMS Programming Guide

SunOS 5.10							    11 Apr 1991 							  msgb(9S)