Data Structures for Drivers                              msgb(9S)



NAME
     msgb, mblk - STREAMS message block structure

SYNOPSIS
     #include 


INTERFACE LEVEL
     Architecture independent level 1 (DI/DKI)

DESCRIPTION
     A STREAMS message is made up of one or more message  blocks,
     referenced  by a pointer to a msgb structure. The bnext and
     bprev pointers are used to  link  messages  together  on  a
     QUEUE.  The   bcont  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     *bnext;    /* next message on queue */
       struct msgb     *bprev;    /* previous message on queue */
       struct msgb     *bcont;    /* next message block */
       unsigned char   *brptr;    /* 1st unread data byte of buffer */
       unsigned char   *bwptr;    /* 1st unwritten data byte of buffer */
       struct datab    *bdatap;   /* pointer to data block */
       unsigned char   bband;     /* message priority  */
       unsigned short  bflag;     /* 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 mblkt.

SEE ALSO
     datab(9S)


     Writing Device Drivers





SunOS 5.11          Last change: 11 Apr 1991                    1






Data Structures for Drivers                              msgb(9S)



     STREAMS Programming Guide






















































SunOS 5.11          Last change: 11 Apr 1991                    2