Kernel Functions for Drivers                             getq(9F)



NAME
     getq - get the next message from a queue

SYNOPSIS
     #include 



     mblkt *getq(queuet *q);


INTERFACE LEVEL
     Architecture independent level 1 (DI/DKI).

PARAMETERS
     q    Pointer to the queue from which the message  is  to  be
          retrieved.


DESCRIPTION
     The getq() function is used by a service ( srv(9E))  routine
     to retrieve its enqueued messages.


     A module or driver may include a service routine to  process
     enqueued messages. Once the STREAMS scheduler calls srv() it
     must process all enqueued messages, unless prevented by flow
     control.  getq() obtains the next available message from the
     top of the queue pointed to by q. It should be called  in  a
     while  loop  that is exited only when there are no more mes-
     sages or flow control prevents further processing.


     If an attempt was made to write to the queue  while  it  was
     blocked  by flow control, getq() back-enables (restarts) the
     service routine once it falls below the low water mark.

RETURN VALUES
     If there is a message to retrieve, getq() returns a  pointer
     to  it.  If  no  message  is  queued,  getq() returns a NUL
     pointer.

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

EXAMPLES
     See dupb(9F).

SEE ALSO
     srv(9E),  bcanput(9F),  canput(9F),   dupb(9F),   putbq(9F),
     putq(9F), qenable(9F)



SunOS 5.11          Last change: 16 Jan 2006                    1






Kernel Functions for Drivers                             getq(9F)



     Writing Device Drivers


     STREAMS Programming Guide



















































SunOS 5.11          Last change: 16 Jan 2006                    2