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wai_flg
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Wait for eventflag (waiting forever).
ER wai_flg (ID flgid, FLGPTN waiptn, MODE wfmode, FLGPTN *p_flgptn);
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ID flgid;
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ID number of the eventflag.
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FLGPTN waiptn;
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MODE wfmode;
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FLGPTN *p_flgptn;
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Bit pattern causing a task to be released from waiting.
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This service call checks whether the bit pattern specified by parameter waiptn and the bit pattern that satisfies the required condition specified by parameter wfmode are set to the eventflag specified by parameter flgid.
If a bit pattern that satisfies the required condition has been set for the target eventflag, the bit pattern of the target eventflag is stored in the area specified by parameter p_flgptn.
If the bit pattern of the target eventflag does not satisfy the required condition when this service call is issued, the invoking task is queued to the target eventflag wait queue.
As a result, the invoking task is unlinked from the ready queue and is moved from the RUNNING state to the WAITING state (WAITING state for an eventflag).
The WAITING state for an eventflag is cancelled in the following cases.
WAITING State for an Eventflag Cancel Operation
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A bit pattern that satisfies the required condition was set to the target eventflag as a result of issuing set_flg.
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A bit pattern that satisfies the required condition was set to the target eventflag as a result of issuing iset_flg.
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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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Forced release from waiting (accept del_flg while waiting).
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The following shows the specification format of required condition
wfmode.
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wfmode ==
TWF_ANDW
Checks whether all of the bits to which 1 is set by parameter
waiptn are set as the target eventflag.
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wfmode ==
TWF_ORW
Checks which bit, among bits to which 1 is set by parameter
waiptn, is set as the target eventflag.
Note 1 With the RI600PX, whether to enable queuing of multiple tasks to the event flag wait queue is defined at eventflag creation. If this service call is issued for the event flag (
TA_WSGL attribute) to which a wait task is queued, therefore, "E_ILUSE" is returned regardless of whether the required condition is immediately satisfied.
TA_WSGL: Only one task is allowed to be in the WAITING state for the eventflag.
TA_WMUL: Multiple tasks are allowed to be in the WAITING state for the eventflag.
Note 2 Invoking tasks are queued to the target event flag (
TA_WMUL attribute) wait queue in the order specified at creating the eventflag (FIFO order or current priority order).
However, when the
TA_CLR attribute is not specified, the wait queue is managed in the FIFO order even if the priority order is specified. This behavior falls outside
mITRON4.0 specification.
Note 3 The RI600PX performs bit pattern clear processing (0 setting) when the required condition of the target eventflag (
TA_CLR attribute) is satisfied.
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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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- Stack pointer points out of user stack for invoking task.
- The operand-write access to the area indicated by p_flgptn has not been permitted to the invoking task.
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Illegal use of service call.
- There is already a task waiting for an eventflag with the TA_WSGL attribute.
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- The eventflag specified by flgid does not exist.
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Forced release from the WAITING state.
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