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Data Structures for Driversmsgb(9S)


NAME

 msgb - 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 5.9Go To TopLast Changed 11 Apr 1991

 
      
      
Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.