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Reference Semaphore Status (ref_sem, iref_sem)
Refers the status of the target semaphore. Checks the count value and existence of the wait task for the target se-
maphore.
Figure 4.12 shows example task execution control provided by the wai_sem and sig_sem service calls.
Task
Task
Task
Task
Semaphore
Counter
wai_sem
sig_sem
3
2
1
0
0
x
wai_sem
wai_sem
wai_sem
WAIT state
Figure 4.12 Task Execution Control by Semaphore