SVR5 and SCO OpenServer 5

datamsg(D3str)

datamsg -- test whether a message is a data message

Synopsis

   #include <sys/types.h>
   #include <sys/stream.h>
   #include <sys/ddi.h>
   
   int datamsg(uchar_t type);

Description

The datamsg function tests the type of message to determine if it is a data message type: M_DATA(D7str), M_DELAY(D7str), M_PROTO(D7str), or M_PCPROTO(D7str).

Arguments

type: The type of message to be tested.

Return values

datamsg returns 1 if the message is a data message and 0 if the message is any other type.

Usage

The db_type field of the datab structure contains the message type. This field may be accessed through the message block using mp->b_datap->db_type.

Context

Base or Interrupt.

Synchronization constraints

Does not block.

Driver-defined basic locks, read/write locks, and sleep locks may be held across calls to this function.

Examples

The put(D2str) routine enqueues all data messages for handling by the srv(D2str) service routine. All non-data messages are handled in the put routine.

    1  xxxput(q, mp)
    2	queue_t *q;
    3	mblk_t *mp;
    4  {
    5	if (datamsg(mp->b_datap->db_type)) {
    6		putq(q, mp);
    7		return;
    8	}
    9	switch (mp->b_datap->db_type) {
   10	case M_FLUSH:
   	...
   11	}
   12  }

Hardware applicability

All

Version applicability

ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp, 7.1, 7.1mp, 8, 8mp
oddi: 1, 2, 2mp, 3, 3mp, 4, 4mp, 5, 5mp, 6, 6mp

Differences between versions

In ODDI version 3 and later versions, datamsg is implemented as a macro. The syntax is the same.

References

allocb(D3str), datab(D4str), Intro(D7str), msgb(D4str)