Data Structures for Drivers                             datab(9S)



NAME
     datab, dblk - STREAMS message data structure

SYNOPSIS
     #include 


INTERFACE LEVEL
     Architecture independent level 1 (DI/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 dbref member keeps track of
     a data block's references, preventing it from being  deallo-
     cated until all message blocks are finished with it.

STRUCTURE MEMBERS
       unsigned char     *dbbase;     /* first byte of buffer */
       unsigned char     *dblim;      /* last byte (]1) of buffer */
       unsigned char      dbref;      /* # of message pointers to this data */
       unsigned char      dbtype;     /* message type */



     A datab structure is defined as type dblkt.

SEE ALSO
     freertn(9S), msgb(9S)


     Writing Device Drivers


     STREAMS Programming Guide














SunOS 5.11          Last change: 24 Oct 2003                    1