Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (C)
Guardian Procedure Calls Reference Manual—522629-013
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CONTROL Procedure
operation input
INT:value
is a value that defines an operation to be performed (see Table 3-4
and Table 3-5
for a list of operation numbers).
param input
INT:value
is the value of an operation being performed (see Table 3-4
and Table 3-5).
tag input
INT(32):value
applies to nowait I/O only. The
tag parameter is a value you define uniquely
identifying the operation associated with this CONTROL call.
Condition Code Settings
< (CCL) indicates that an error occurred (call FILE_GETINFO_ or FILEINFO).
= (CCE) indicates that the CONTROL was successful.
> (CCG) for magnetic tape, indicates that the end of file (EOF) was encountered
while spacing records; for a process file, this setting indicates that the
process is not accepting process CONTROL messages. When device
handlers do not allow the operation, file-system error 2 returns.
Note. The system stores the tag value until the I/O operation completes. It then returns the
tag information to the program in the tag parameter of the call to AWAITIO, thus indicating
that the operation finished.