SVR5 and SCO OpenServer 5
datab(D4str)
datab --
STREAMS data block structure
Synopsis
#include <sys/types.h>
#include <sys/stream.h>
#include <sys/ddi.h>
Description
The datab structure describes the
data of a STREAMS message.
Usage
The actual data contained in a STREAMS message
is stored in a data buffer pointed to by this structure.
A message block structure,
msgb(D4str),
includes a member that points to a datab structure.
A data block can have more than one message block
pointing to it at one time,
so the db_ref
member keeps track
of a data block's references,
preventing it from being deallocated
until all message blocks are finished with it.
Structure definitions
The datab structure is defined as type dblk_t
and contains the following members:
uchar_t *db_base;
uchar_t *db_lim;
uchar_t db_ref;
uchar_t db_type;
Structure members
db_base
-
points to the beginning of the data buffer.
Drivers and modules should not change this member.
db_lim
-
points to one byte past the end of the data buffer.
Drivers and modules should not change this member.
db_ref
-
contains a count of the number of message blocks
sharing the data buffer.
If it is greater than 1,
drivers and modules should not change the contents
of the data buffer.
Drivers and modules should not change this member.
db_type
-
contains the message type associated with the data buffer.
This member can be changed by the driver.
If the
db_ref
member is greater than 1,
this member should not be changed.
Hardware applicability
All
Version applicability
ddi:
1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp, 8, 8mp
oddi:
1, 2, 2mp, 3, 3mp, 4, 4mp, 5, 5mp
References
free_rtn(D4str),
Intro(D7str),
msgb(D4str)
19 June 2005
© 2005 The SCO Group, Inc. All rights reserved.
OpenServer 6 and UnixWare (SVR5) HDK - June 2005