pSOSystem System Calls - Read

pSOS+ System Calls ev_receive
See Also
2. The ev_receive() call captures only the events that the caller selects. It
captures each selected event once. If a pending event does not match a selected
event, the pending event remains pending. Also, if a pending event was sent
after an earlier event was used to match a selected event, the pending event
remains pending. Consider the following example sequence:
a. Task P has pending events 1 and 2.
b. With EV_ALL set, P calls ev_receive() for events 1, 3, and 8. Pending
event 1 is cleared.
c. Task A sends events 1 and 8 to P.
d. Event 1 is made pending. Event 8 is used to match the wanted event.
e. Task B sends events 2, 3, and 5 to P. Event 2 has no effect because event 2
is already pending. Event 5 is unwanted and made pending. Event 3 is used
to match a wanted event. The event condition is met, so P becomes ready to
run.
f. Events 1, 2, and 5 are left pending.
g. Events 1, 3, and 8 are returned in events_r.
Multiprocessor Considerations
None. The actions performed by ev_receive() take place only on the local node
(whether or not events come from other nodes).
Callable From
■ Task
ev_send
pSOSystem System Calls 1-29
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