Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)

Chapter 9 271

Intrinsics Reference (cont)

IODONTWAIT

Passes an input buffer. Since terminals always operate

without system buffering it is not necessary for this

parameter to follow a read.

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 original request

speciﬁed halfwords, the integer represents halfwords.

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. Instead, the actual record length

is returned in the length parameter of IODONTWAIT.

cstation 16-bit unsigned integer by reference

(optional)

Not meaningful for asynchronous devices.

Condition Codes

CCE Request granted. If the functional return is not zero,

then I/O completion occurred with no errors. If the

functional return is zero, no I/O has completed.

CCG An end-of-ﬁle condition was encountered.

CCL 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.

Special Considerations

You must be running in privileged mode to specify the NOWAIT I/O

option in the FOPEN/HPFOPEN call.

Additional Discussion

See the discussion of initiating completion operations for I/O requests

in Accessing Files Programmer’s Guide. See also discussions of FOPEN,

HPFOPEN and IOWAIT in this manual.