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Initiates completion operations for a nowait I/O request.
Syntax
fnum := IO[DONT]WAIT ( [filenum] [,target] [,tcount] [,cstation] )
Parameters
- fnum (returned function value)
- 16-bit integer. The socket/VC socket descriptor for which an I/O
request has completed. Zero indicates no completion. If there are any
nowait file access requests outstanding, and if the
filenum parameter is zero, the returned function value
may be an actual file number.
- filenum (input)
- 16-bit integer, by value. The call/VC socket descriptor
indicating the socket or connection (that is, call or VC socket) for
which the nowait I/O request was issued. If omitted, or if the value is
zero, any nowait NetIPC or file request issued by the calling process
may be completed by this intrinsic call.
- target
- Array of 16-bit values, by reference. Not used by NetIPC.
- tcount (output)
- 16-bit integer, by reference. Returns the amount of data received
after a nowait IPCRECV call. The actual data will be in the
IPCRECV data parameter.
- station (output)
- 16-bit integer (unsigned), by reference. Bit one is returned on
if the completed request was a send, off if it was a receive. All other
bits will be off.
Description
Either IOWAIT or IODONTWAIT is needed to complete a NetIPC
nowait send or receive request. IOWAIT waits until a request can be
completed; IODONTWAIT checks to see if a request can be completed and
then immediately returns control to the calling process.
If a nowait IPCSEND, IPCRECVCN, or IPCRECV request
is issued, the data and flags parameters (if specified) must exist when
IOWAIT or IODONTWAIT is called. In other words, these
parameters must be global to both the IPC intrinsic that initiates the request
and the IO[DONT]WAIT that attempts to complete the I/O.
All parameters are optional (option variable). In general, the condition codes
returned by IOWAIT/IODONTWAIT for socket I/O have the following
meanings:
- CCE — Succeeded.
- CCL — Failed.
- CCG — The operation succeeded but a noncritical error occurred
(for example, the flags parameter was out of bounds).
IOWAIT and IODONTWAIT can be called in split stack mode.
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