HP 3000 Manuals HP 3000 Manuals
IOWAIT
NM and CM callable.
Initiates completion operations for an I/O request.
Syntax
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| |
| I16 I16V UDS I16 U16 |
| fnum:=IOWAIT(filenum,buffer,length,cstation);|
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Functional Return
fnum 16-bit signed integer (assigned functional return)
The file number for which the completion occurred.
If no completion occurred, zero is returned.
Parameters
filenum 16-bit signed integer by value (required)
The file number for which there is a pending I/O
request. If you specify 0, the IOWAIT intrinsic
waits for the first I/O completion.
buffer user-defined structure (optional)
Passes an input buffer. This buffer must be large
enough to contain the input record. It should be
the same buffer specified in the original I/O
request if that was a read request. This allows
for proper recognition of EOF where applicable.
The buffer parameter is required if not in
priviledged mode, or the buffer parameter can be
ommitted if the GETPRIVMODE intrinsic is called
first.
length 16-bit signed integer by reference (optional)
Returns the length of the received or transmitted
record. If the original request specified a byte
count, the integer represents bytes; if the request
specified half words, the integer represents half
words. This parameter is pertinent only if the
original I/O request was a read request. The FREAD
intrinsic always returns zero as its functional
return if you specify nowait I/O. In this case, the
actual record length is returned in the length
parameter of IOWAIT.
cstation 16-bit unsigned integer by reference (optional)
Returns the number of the calling station when
completed (used for distributed systems).
(ASC) Not used for asynchronous devices.
Operation Notes
The IOWAIT intrinsic initiates completion operations for an I/O request.
If you opened a file with the nowait I/O mode aoption of the
FOPEN/HPFOPEN intrinsic (aoption bit (4:1) = 1), calls to either the
IOWAIT or IODONTWAIT intrinsic must follow all read and write requests.
This intrinsic initiates completion operations for the associated I/O
request, including data transfer into your buffer area if necessary.
The IOWAIT intrinsic call must precede any subsequent I/O request against
the file. Within this restriction, you can delay the IOWAIT intrinsic
call as long as desired to allow effective I/O and processing overlap.
Condition Codes
CCE (2) Request granted. I/O completion occurred with no
errors.
CCG (0) An end-of-file was encountered.
CCL (1) Request denied. Normal I/O completion did not
occur, because there were no I/O requests pending,
a parameter error occurred, or an abnormal I/O
completion occurred.
Related Information
Intrinsics None
Commands None
Manuals Interprocess Communication Programmer's Guide
(32650-90019)