samestr(9f) [opensolaris man page]

SAMESTR(9F)						   Kernel Functions for Drivers 					       SAMESTR(9F)

NAME

       SAMESTR, samestr - test if next queue is in the same stream

SYNOPSIS

       #include <sys/stream.h>

       int SAMESTR(queue_t *q);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       q    Pointer to the queue.

DESCRIPTION

       The SAMESTR() function is used to see if the next queue in a stream (if it exists) is the same type as the current queue (that is, both are
       read queues or both are write queues). This function accounts for the twisted queue connections that occur in a STREAMS pipe and should	be
       used in preference to direct examination of the q_next field of queue(9S) to see if the stream continues beyond q.

RETURN VALUES

       The  SAMESTR() function returns 1 if the next queue is the same type as the current queue. It returns 0 if the next queue does not exist or
       if it is not the same type.

CONTEXT

       The SAMESTR() function can be called from user, interrupt, context.

SEE ALSO

       OTHERQ(9F)

       Writing Device Drivers

       STREAMS Programming Guide

SunOS 5.11							    16 Jan 2006 						       SAMESTR(9F)

WR(9F)							   Kernel Functions for Drivers 						    WR(9F)

NAME

       WR, wr - get pointer to the write queue for this module or driver

SYNOPSIS

       #include <sys/stream.h>
       #include <sys/ddi.h>

       queue_t *WR(queue_t *q);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       q    Pointer to the read queue whose write queue is to be returned.

DESCRIPTION

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

       CAUTION: Make sure the argument to this function is a pointer to a read queue. WR() will not check for queue type, and a system panic could
       result if the pointer is not to a read queue.

RETURN VALUES

       The pointer to the write queue.

CONTEXT

       The WR() function can be called from user, interrupt, or kernel context.

EXAMPLES

       Example 1 Using WR()

       In a STREAMS close(9E) routine, the driver or module is passed a pointer to the read queue. These usually are set to  the  address  of  the
       module-specific data structure for the minor device.

	 1   xxxclose(q, flag)
	 2	 queue_t *q;
	 3	 int flag;
	 4   {
	 5	       q->q_ptr = NULL;
	 6	   WR(q)->q_ptr = NULL;
		       . . .
	 7   }

SEE ALSO

       close(9E), OTHERQ(9F), RD(9F)

       Writing Device Drivers

       STREAMS Programming Guide

SunOS 5.11							    16 Jan 2006 							    WR(9F)