/**
* \description
* The "extended" QK scheduler performs all the steps of the regular scheduler
* QK_sched_() and additionally switches the Thread-Local Storage (TLS) and
* handles the extended context-switch.
*
* \arguments
* \arg[in] \c p priority of the next AO to schedule
*
* \note The "extended" QK scheduler needs to be called only to handle
* "asynchronous" preemption, under the assumption that neither the ISRs
* nor the QK idle loop use TLS or the co-processors requiring
* extended context switch (see [PSiCC2] Section 10.4.3).
*
* \note QK_schedExt_() must be always called with interrupts DISABLED.
*
* \note The extended scheduler might enable interrupts internally,
* but always returns with interrupts DISABLED.
*/
void QK_schedExt_(uint_fast8_t p) {
uint_fast8_t pin = QK_currPrio_; /* save the initial priority */
/* thread-local storage used? */
#ifdef QK_TLS
uint_fast8_t pprev = pin;
#endif
QActive *a;
/* extended context-switch used? */
#ifdef QK_EXT_SAVE
/* aren't we preempting the idle loop? (idle loop has prio==0) */
if (pin != (uint_fast8_t)0) {
a = QF_active_[pin]; /* the pointer to the preempted AO */
QK_EXT_SAVE(a); /* save the extended context */
}
#endif
/* loop until have ready-to-run AOs of higher priority than the initial */
do {
QEvt const *e;
a = QF_active_[p]; /* obtain the pointer to the AO */
QK_currPrio_ = p; /* this becomes the current task priority */
/* thread-local storage used? */
#ifdef QK_TLS
/* are we changing threads? */
if (p != pprev) {
QK_TLS(a); /* switch new thread-local storage */
pprev = p;
}
#endif
QS_BEGIN_NOCRIT_(QS_QK_SCHEDULE, QS_priv_.aoObjFilter, a)
QS_TIME_(); /* timestamp */
QS_U8_((uint8_t)p); /* the priority of the AO */
QS_U8_((uint8_t)pin); /* the preempted priority */
QS_END_NOCRIT_()
QF_INT_ENABLE(); /* unconditionally enable interrupts */
/* perform the run-to-completion (RTS) step...
* 1. retrieve the event from the AO's event queue, which by this
* time must be non-empty and QActive_get_() asserts it.
* 2. dispatch the event to the AO's state machine.
* 3. determine if event is garbage and collect it if so
*/
e = QActive_get_(a);
QMSM_DISPATCH(&a->super, e);
QF_gc(e);
QF_INT_DISABLE(); /* disable interrupts */
/* find new highest-priority AO ready to run... */
#if (QF_MAX_ACTIVE <= 8)
QPSet8_findMax(&QK_readySet_, p);
#else
QPSet64_findMax(&QK_readySet_, p);
#endif
/* is the new priority below the current preemption threshold? */
if (p <= pin) {
p = (uint_fast8_t)0;
}
#ifndef QK_NO_MUTEX
/* is the new priority below the mutex ceiling? */
else if (p <= QK_ceilingPrio_) {
p = (uint_fast8_t)0;
}
else {
/* empty */
}
#endif
} while (p != (uint_fast8_t)0);
QK_currPrio_ = pin; /* restore the initial priority */
#if defined(QK_TLS) || defined(QK_EXT_RESTORE)
/* aren't we preempting the idle loop? (idle loop has prio==0) */
if (pin != (uint_fast8_t)0) {
a = QF_active_[pin]; /* the pointer to the preempted AO */
/* thread-local storage used? */
#ifdef QK_TLS
QK_TLS(a); /* restore the original TLS */
#endif
/* extended context-switch used? */
#ifdef QK_EXT_RESTORE
QK_EXT_RESTORE(a); /* restore the extended context */
#endif
}
#endif
}
void QK_scheduleExt_(void) {
#else
void QK_scheduleExt_(QF_INT_KEY_TYPE intLockKey_) {
#endif
// the QK scheduler must be called at task level only
Q_REQUIRE(QK_intNest_ == (uint8_t)0);
// determine the priority of the highest-priority task ready to run
uint8_t p = QK_readySet_.findMax();
#ifdef QK_NO_MUTEX
if (p > QK_currPrio_) { // do we have a preemption?
#else // QK priority-ceiling mutexes allowed
if ((p > QK_currPrio_) && (p > QK_ceilingPrio_)) {
#endif
uint8_t pin = QK_currPrio_; // save the initial priority
QActive *a;
#ifdef QK_TLS // thread-local storage used?
uint8_t pprev = pin;
#endif
#ifdef QK_EXT_SAVE // extended context-switch used?
if (pin != (uint8_t)0) { // no extended context for the idle loop
a = QF::active_[pin]; // the pointer to the preempted AO
QK_EXT_SAVE(a); // save the extended context
}
#endif
do {
QEvent const *e;
a = QF::active_[p]; // obtain the pointer to the AO
QK_currPrio_ = p; // this becomes the current task priority
#ifdef QK_TLS // thread-local storage used?
if (p != pprev) { // are we changing threads?
QK_TLS(a); // switch new thread-local storage
pprev = p;
}
#endif
QS_BEGIN_NOLOCK_(QS_QK_SCHEDULE, QS::aoObj_, a)
QS_TIME_(); // timestamp
QS_U8_(p); // the priority of the active object
QS_U8_(pin); // the preempted priority
QS_END_NOLOCK_()
QK_INT_UNLOCK_(); // unlock the interrupts
e = a->get_(); // get the next event for this active object
a->dispatch(e); // dispatch e to the active object
QF::gc(e); // garbage collect the event, if necessary
QK_INT_LOCK_();
// determine the highest-priority AO ready to run
p = QK_readySet_.findMax();
#ifdef QK_NO_MUTEX
} while (p > pin); // is the new priority higher than initial?
#else // QK priority-ceiling mutexes allowed
} while ((p > pin) && (p > QK_ceilingPrio_));
#endif
QK_currPrio_ = pin; // restore the initial priority
#if defined(QK_TLS) || defined(QK_EXT_RESTORE)
if (pin != (uint8_t)0) { // no extended context for the idle loop
a = QF::active_[pin]; // the pointer to the preempted AO
#ifdef QK_TLS // thread-local storage used?
QK_TLS(a); // restore the original TLS
#endif
#ifdef QK_EXT_RESTORE // extended context-switch used?
QK_EXT_RESTORE(a); // restore the extended context
#endif
}
#endif
}
}
