.IX \f4WR\fP(D3DK)

NAME

WR − get a pointer to the write queue

SYNOPSIS

#include <sys/stream.h>
#include <sys/ddi.h>
queue_t ∗WR(queue_t ∗q);

ARGUMENTS

qPointer to the queue whose write queue is to be returned. 

DESCRIPTION

The WR function accepts a queue pointer as an argument and returns a pointer to the write queue of the same module. 

RETURN VALUE

The pointer to the write queue. 

LEVEL

Base or Interrupt. 

NOTES

Does not sleep. 

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

SEE ALSO

OTHERQ(D3DK), RD(D3DK)

EXAMPLE

.IX \f4WR\fP(D3DK), example

In a STREAMS open(D2DK) routine, the driver or module is passed a pointer to the read queue.  The driver or module can store a pointer to a private data structure in the q_ptr field of both the read and write queues if it needs to identify the data structures from its put(D2DK) or srv(D2DK) routines. 

 1  extern struct xxx_dev[];
    ...
 2  xxxopen(queue_t ∗q, dev_t ∗devp, int flag, int sflag, cred_t ∗crp)
 3  {
...
 3q->q_ptr = (caddr_t)&xxx_dev[getminor(∗devp)];
 4WR(q)->q_ptr = (caddr_t)&xxx_dev[getminor(∗devp)];
...
 5  }

REPLACE WITH BLANK PAGE

DDI/DKI  —  STREAMS