TOPS-10 Monitor Calls Manual Volume 2 AA-K039D ... - Trailing-Edge

ENQ. [CALLI 151]
2 .ENQSI
Requests ownership of a resource and, if the
resource is not immediately available, causes a
software interrupt when the resource becomes
available. You can use this function when the
Programmable Software Interrupt (PSI) system is
enabled, to prevent your job from blocking while
waiting for the requests to be granted.
If all the requests in the call can be granted
immediately, this function is equivalent to
function code 0 (.ENQBL). If any of the requests
are not available, the call takes the error return
with error code 1 (ENQRU%) in the ac. In this
case, your job can continue processing until it
receives a .PCQUE software interrupt. The
interrupt control block will contain the
request-ids of the requests that are granted,
inclusively ORed into the status word. The PSI
system is described in Chapter 6.
3 .ENQMA
Modifies an existing request made by your job. If
the modification you specify in this request lS
identical to the request you made earlier, no
action is taken and the skip return is taken from
the call. If you do not have a request in any
queue, the error return is taken and the monitor
returns error code 24 (ENQNE%) in the ac. If you
specify more than one request with this function
code and the error return is taken, you must issue
the ENQC. monitor call to determine which (if
any) modification request was granted. The error
code that the monitor returns in the ac reflects
only the last error that occurred as the-result of
this call.
You can modify a request from exclusive ownership
to shared ownership, but you will receive an error
code if you attempt to modify a request from
shared to exclusive ownership if other jobs are
also sharing the resource. To modify a request
from shared to exclusive ownership when other jobs
are sharing the resource, you must first DEQ. the
request. Then, enqueue it again as an exclusive
ownership request.
SKIP RETURN
All requests in the call are granted, and the resources are locked for
your program.
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