rd(9f) [osx man page]

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

NAME

       RD, rd - get pointer to the read queue

SYNOPSIS

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

       queue_t *RD(queue_t *q);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

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

DESCRIPTION

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

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

RETURN VALUES

       The pointer to the read queue.

CONTEXT

       RD() can be called from user or interrupt context.

EXAMPLES

       Example 1: Function page reference

       See the qreply(9F) function page for an example of RD().

SEE ALSO

       qreply(9F), WR(9F)

       Writing Device Drivers

        STREAMS Programming Guide

SunOS 5.10                                                          15 Nov 1991                                                             RD(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

       WR() can be called from user or interrupt 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 5.10                                                          15 Nov 1991                                                             WR(9F)