Guardian Procedure Calls Reference Manual

Figure 4 AWAITIO[X|XL] Operation
NOTE: AWAITIOXL returns the error code directly.
How AWAITIO[X|XL] completes depends on whether the filenum parameter specifies a particular
file or any file and on what the value of timelimit is when passed with the call. The action taken
by AWAITIO[X|XL] for each combination of filenum and timelimit is summarized in Table 5.
Table 5 AWAITIO[X|XL] Action
timelimit <> 0
WAIT for any I/O completion on filenum.
timelimit = 0
CHECK for any I/O completion on filenum.
Particular File
(filenum = a file
number)
COMPLETIONCOMPLETION
File number is returned in filenum.File number is returned in filenum
Tag of completed call is returned in tag.Tag of completed call is returned in tag.
NO COMPLETIONNO COMPLETION
CCL (error 40) is returned.CCL (error 40) is returned.
File number is returned in filenum.File number returned is in filenum.
Oldest I/O operation on filenum is canceled.No I/O operation is canceled.
Tag of canceled call is returned in tag.
WAIT for any I/O completion on any open
file.
CHECK for any I/O completion on any open
file.
Any File
(filenum = -1)
COMPLETIONCOMPLETION
File number of completed call is returned in
filenum.
File number of completed call is returned in
filenum.
Tag of completed call is returned in tag.Tag of completed call is returned in tag.
NO COMPLETIONNO COMPLETION
CCL (error 40) is returned.CCL (error 40) is returned.
The value -1 is returned in filenum.The value -1 is returned in filenum.
No I/O operation is canceledNo I/O operation is canceled.
80 Guardian Procedure Calls (A-B)