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twai_sem
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Acquire semaphore resource (with time-out).
ER twai_sem (ID semid, TMO tmout);
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ID semid;
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ID number of the semaphore.
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TMO tmout;
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Specified time-out (in millisecond).
Value: Specified time-out.
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This service call acquires a resource from the semaphore specified by parameter
semid (subtracts 1 from the semaphore counter).
If no resources are acquired from the target semaphore when service call is issued this (no available resources exist), this service call does not acquire resources but queues the invoking task to the target semaphore wait queue and moves it from the RUNNING state to the WAITING state with time-out (resource acquisition wait state).
The WAITING state for a semaphore resource is cancelled in the following cases.
WAITING State for a Semaphore Resource Cancel Operation
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The resource was released to the target semaphore as a result of issuing sig_sem.
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The resource was released to the target semaphore as a result of issuing isig_sem.
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Forced release from waiting (accept rel_wai while waiting).
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Forced release from waiting (accept irel_wai while waiting).
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The time specified by tmout has elapsed.
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Note 1 Invoking tasks are queued to the target semaphore wait queue in the order defined during configuration (FIFO order or current priority order).
Note 2
TMO_FEVR is specified for wait time
tmout, processing equivalent to
wai_sem will be executed. When
TMO_POL is specified, processing equivalent to
pol_sem will be executed.
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- This service call was issued from a non-task.
- This service call was issued in the CPU locked state.
- This service call was issued in the dispatching disabled state.
- This service call was issued in the status "PSW.IPL > kernel interrupt mask level".
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Forced release from the WAITING state.
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Polling failure or specified time has elapsed.
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