RTEMS ITRON 3.0 API User's Guide
ER can_wup( INT *p_wupcnt, ID tskid );
E_OK - Normal Completion
E_ID - Invalid ID Number (tskid was invalid or could not be used)
E_NOEXS - Object does not exist (the task specified by tskid does not exist)
E_OACV - Object access violation (A tskid less than -4 was specified from a user task. This is implementation dependent.)
E_OBJ - Invalid object state (the target task is in DORMANT state)
EN_OBJNO - An object number which could not be accessed on the target node is specified.
EN_CTXID - Specified an object on another node when the system call was issued from a task in dispatch disabled state or from a task-independent portion
EN_RPAR - A value outside the range supported by the issuing node and/or transmission packet format was returned as a return parameter (a value outside supported range was returned for wupcnt)
This system call returns the wakeup request queuing count (wupcnt) for the task specified by tskid while canceling all associated wakeup requests. Specifically, it resets the wakeup request queuing count (wupcnt) to 0.
A task may specify itself by specifying tskid = TSK_SELF = 0. Note, however, that an E_ID error will result if tskid = TSK_SELF = 0 is specified when this system call is issued from a task-independent portion.
An EN_RPAR error will result if the number of bits used on the target node is larger than that used on the requesting node, and if a value not supported by the requesting node is returned for wupcnt.
This system call can be used to determine whether or not processing has ended within a certain period when a task should periodically waken up by wup_tsk and do some processing. In other words, if a task monitoring the progress of its processing issues can_wup before issuing a slp_tsk after finishing processing associated with a previous wakeup request, and if wupcnt, one of can_wup's return parameters, is equal to or greater than one, it indicates that the processing for the previous wakeup request does not complete within a required time. This allows the monitoring task to take actions against processing delays.
RTEMS ITRON 3.0 API User's Guide
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