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Diffstat (limited to 'os/rt/src/chschd.c')
| -rw-r--r-- | os/rt/src/chschd.c | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/os/rt/src/chschd.c b/os/rt/src/chschd.c new file mode 100644 index 000000000..615008589 --- /dev/null +++ b/os/rt/src/chschd.c @@ -0,0 +1,372 @@ +/*
+ ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
+ 2011,2012,2013 Giovanni Di Sirio.
+
+ This file is part of ChibiOS/RT.
+
+ ChibiOS/RT is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ ChibiOS/RT is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/**
+ * @file chschd.c
+ * @brief Scheduler code.
+ *
+ * @addtogroup scheduler
+ * @details This module provides the default portable scheduler code.
+ * @{
+ */
+
+#include "ch.h"
+
+/*===========================================================================*/
+/* Module local definitions. */
+/*===========================================================================*/
+
+/*===========================================================================*/
+/* Module exported variables. */
+/*===========================================================================*/
+
+/*===========================================================================*/
+/* Module local types. */
+/*===========================================================================*/
+
+/*===========================================================================*/
+/* Module local variables. */
+/*===========================================================================*/
+
+/*===========================================================================*/
+/* Module local functions. */
+/*===========================================================================*/
+
+/*===========================================================================*/
+/* Module exported functions. */
+/*===========================================================================*/
+
+/**
+ * @brief Scheduler initialization.
+ *
+ * @notapi
+ */
+void _scheduler_init(void) {
+
+ queue_init(&ch.rlist.r_queue);
+ ch.rlist.r_prio = NOPRIO;
+#if CH_CFG_USE_REGISTRY
+ ch.rlist.r_newer = ch.rlist.r_older = (thread_t *)&ch.rlist;
+#endif
+}
+
+/**
+ * @brief Inserts a thread in the Ready List.
+ * @details The thread is positioned behind all threads with higher or equal
+ * priority.
+ * @pre The thread must not be already inserted in any list through its
+ * @p p_next and @p p_prev or list corruption would occur.
+ * @post This function does not reschedule so a call to a rescheduling
+ * function must be performed before unlocking the kernel. Note that
+ * interrupt handlers always reschedule on exit so an explicit
+ * reschedule must not be performed in ISRs.
+ *
+ * @param[in] tp the thread to be made ready
+ * @return The thread pointer.
+ *
+ * @iclass
+ */
+thread_t *chSchReadyI(thread_t *tp) {
+ thread_t *cp;
+
+ chDbgCheckClassI();
+
+ /* Integrity checks.*/
+ chDbgAssert((tp->p_state != CH_STATE_READY) &&
+ (tp->p_state != CH_STATE_FINAL),
+ "invalid state");
+
+ tp->p_state = CH_STATE_READY;
+ cp = (thread_t *)&ch.rlist.r_queue;
+ do {
+ cp = cp->p_next;
+ } while (cp->p_prio >= tp->p_prio);
+ /* Insertion on p_prev.*/
+ tp->p_next = cp;
+ tp->p_prev = cp->p_prev;
+ tp->p_prev->p_next = cp->p_prev = tp;
+ return tp;
+}
+
+/**
+ * @brief Puts the current thread to sleep into the specified state.
+ * @details The thread goes into a sleeping state. The possible
+ * @ref thread_states are defined into @p threads.h.
+ *
+ * @param[in] newstate the new thread state
+ *
+ * @sclass
+ */
+void chSchGoSleepS(tstate_t newstate) {
+ thread_t *otp;
+
+ chDbgCheckClassS();
+
+ (otp = currp)->p_state = newstate;
+#if CH_CFG_TIME_QUANTUM > 0
+ /* The thread is renouncing its remaining time slices so it will have a new
+ time quantum when it will wakeup.*/
+ otp->p_preempt = CH_CFG_TIME_QUANTUM;
+#endif
+ setcurrp(queue_fifo_remove(&ch.rlist.r_queue));
+ currp->p_state = CH_STATE_CURRENT;
+ chSysSwitch(currp, otp);
+}
+
+/*
+ * Timeout wakeup callback.
+ */
+static void wakeup(void *p) {
+ thread_t *tp = (thread_t *)p;
+
+ chSysLockFromISR();
+ switch (tp->p_state) {
+ case CH_STATE_READY:
+ /* Handling the special case where the thread has been made ready by
+ another thread with higher priority.*/
+ chSysUnlockFromISR();
+ return;
+#if CH_CFG_USE_SEMAPHORES || CH_CFG_USE_QUEUES || \
+ (CH_CFG_USE_CONDVARS && CH_CFG_USE_CONDVARS_TIMEOUT)
+#if CH_CFG_USE_SEMAPHORES
+ case CH_STATE_WTSEM:
+ chSemFastSignalI((semaphore_t *)tp->p_u.wtobjp);
+ /* Falls into, intentional. */
+#endif
+#if CH_CFG_USE_QUEUES
+ case CH_STATE_WTQUEUE:
+#endif
+#if CH_CFG_USE_CONDVARS && CH_CFG_USE_CONDVARS_TIMEOUT
+ case CH_STATE_WTCOND:
+#endif
+ /* States requiring dequeuing.*/
+ queue_dequeue(tp);
+#endif
+ }
+ tp->p_u.rdymsg = RDY_TIMEOUT;
+ chSchReadyI(tp);
+ chSysUnlockFromISR();
+}
+
+/**
+ * @brief Puts the current thread to sleep into the specified state with
+ * timeout specification.
+ * @details The thread goes into a sleeping state, if it is not awakened
+ * explicitly within the specified timeout then it is forcibly
+ * awakened with a @p RDY_TIMEOUT low level message. The possible
+ * @ref thread_states are defined into @p threads.h.
+ *
+ * @param[in] newstate the new thread state
+ * @param[in] time the number of ticks before the operation timeouts, the
+ * special values are handled as follow:
+ * - @a TIME_INFINITE the thread enters an infinite sleep
+ * state, this is equivalent to invoking
+ * @p chSchGoSleepS() but, of course, less efficient.
+ * - @a TIME_IMMEDIATE this value is not allowed.
+ * .
+ * @return The wakeup message.
+ * @retval RDY_TIMEOUT if a timeout occurs.
+ *
+ * @sclass
+ */
+msg_t chSchGoSleepTimeoutS(tstate_t newstate, systime_t time) {
+
+ chDbgCheckClassS();
+
+ if (TIME_INFINITE != time) {
+ virtual_timer_t vt;
+
+ chVTDoSetI(&vt, time, wakeup, currp);
+ chSchGoSleepS(newstate);
+ if (chVTIsArmedI(&vt))
+ chVTDoResetI(&vt);
+ }
+ else
+ chSchGoSleepS(newstate);
+ return currp->p_u.rdymsg;
+}
+
+/**
+ * @brief Wakes up a thread.
+ * @details The thread is inserted into the ready list or immediately made
+ * running depending on its relative priority compared to the current
+ * thread.
+ * @pre The thread must not be already inserted in any list through its
+ * @p p_next and @p p_prev or list corruption would occur.
+ * @note It is equivalent to a @p chSchReadyI() followed by a
+ * @p chSchRescheduleS() but much more efficient.
+ * @note The function assumes that the current thread has the highest
+ * priority.
+ *
+ * @param[in] ntp the thread to be made ready
+ * @param[in] msg message to the awakened thread
+ *
+ * @sclass
+ */
+void chSchWakeupS(thread_t *ntp, msg_t msg) {
+
+ chDbgCheckClassS();
+
+ ntp->p_u.rdymsg = msg;
+ /* If the waken thread has a not-greater priority than the current
+ one then it is just inserted in the ready list else it made
+ running immediately and the invoking thread goes in the ready
+ list instead.*/
+ if (ntp->p_prio <= currp->p_prio)
+ chSchReadyI(ntp);
+ else {
+ thread_t *otp = chSchReadyI(currp);
+ setcurrp(ntp);
+ ntp->p_state = CH_STATE_CURRENT;
+ chSysSwitch(ntp, otp);
+ }
+}
+
+/**
+ * @brief Performs a reschedule if a higher priority thread is runnable.
+ * @details If a thread with a higher priority than the current thread is in
+ * the ready list then make the higher priority thread running.
+ *
+ * @sclass
+ */
+void chSchRescheduleS(void) {
+
+ chDbgCheckClassS();
+
+ if (chSchIsRescRequiredI())
+ chSchDoRescheduleAhead();
+}
+
+/**
+ * @brief Evaluates if preemption is required.
+ * @details The decision is taken by comparing the relative priorities and
+ * depending on the state of the round robin timeout counter.
+ * @note Not a user function, it is meant to be invoked by the scheduler
+ * itself or from within the port layer.
+ *
+ * @retval true if there is a thread that must go in running state
+ * immediately.
+ * @retval false if preemption is not required.
+ *
+ * @special
+ */
+bool chSchIsPreemptionRequired(void) {
+ tprio_t p1 = firstprio(&ch.rlist.r_queue);
+ tprio_t p2 = currp->p_prio;
+#if CH_CFG_TIME_QUANTUM > 0
+ /* If the running thread has not reached its time quantum, reschedule only
+ if the first thread on the ready queue has a higher priority.
+ Otherwise, if the running thread has used up its time quantum, reschedule
+ if the first thread on the ready queue has equal or higher priority.*/
+ return currp->p_preempt ? p1 > p2 : p1 >= p2;
+#else
+ /* If the round robin preemption feature is not enabled then performs a
+ simpler comparison.*/
+ return p1 > p2;
+#endif
+}
+
+/**
+ * @brief Switches to the first thread on the runnable queue.
+ * @details The current thread is positioned in the ready list behind all
+ * threads having the same priority. The thread regains its time
+ * quantum.
+ * @note Not a user function, it is meant to be invoked by the scheduler
+ * itself or from within the port layer.
+ *
+ * @special
+ */
+void chSchDoRescheduleBehind(void) {
+ thread_t *otp;
+
+ otp = currp;
+ /* Picks the first thread from the ready queue and makes it current.*/
+ setcurrp(queue_fifo_remove(&ch.rlist.r_queue));
+ currp->p_state = CH_STATE_CURRENT;
+#if CH_CFG_TIME_QUANTUM > 0
+ otp->p_preempt = CH_CFG_TIME_QUANTUM;
+#endif
+ chSchReadyI(otp);
+ chSysSwitch(currp, otp);
+}
+
+/**
+ * @brief Switches to the first thread on the runnable queue.
+ * @details The current thread is positioned in the ready list ahead of all
+ * threads having the same priority.
+ * @note Not a user function, it is meant to be invoked by the scheduler
+ * itself or from within the port layer.
+ *
+ * @special
+ */
+void chSchDoRescheduleAhead(void) {
+ thread_t *otp, *cp;
+
+ otp = currp;
+ /* Picks the first thread from the ready queue and makes it current.*/
+ setcurrp(queue_fifo_remove(&ch.rlist.r_queue));
+ currp->p_state = CH_STATE_CURRENT;
+
+ otp->p_state = CH_STATE_READY;
+ cp = (thread_t *)&ch.rlist.r_queue;
+ do {
+ cp = cp->p_next;
+ } while (cp->p_prio > otp->p_prio);
+ /* Insertion on p_prev.*/
+ otp->p_next = cp;
+ otp->p_prev = cp->p_prev;
+ otp->p_prev->p_next = cp->p_prev = otp;
+
+ chSysSwitch(currp, otp);
+}
+
+/**
+ * @brief Switches to the first thread on the runnable queue.
+ * @details The current thread is positioned in the ready list behind or
+ * ahead of all threads having the same priority depending on
+ * if it used its whole time slice.
+ * @note Not a user function, it is meant to be invoked by the scheduler
+ * itself or from within the port layer.
+ *
+ * @special
+ */
+void chSchDoReschedule(void) {
+
+#if CH_CFG_TIME_QUANTUM > 0
+ /* If CH_CFG_TIME_QUANTUM is enabled then there are two different scenarios
+ to handle on preemption: time quantum elapsed or not.*/
+ if (currp->p_preempt == 0) {
+ /* The thread consumed its time quantum so it is enqueued behind threads
+ with same priority level, however, it acquires a new time quantum.*/
+ chSchDoRescheduleBehind();
+ }
+ else {
+ /* The thread didn't consume all its time quantum so it is put ahead of
+ threads with equal priority and does not acquire a new time quantum.*/
+ chSchDoRescheduleAhead();
+ }
+#else /* !(CH_CFG_TIME_QUANTUM > 0) */
+ /* If the round-robin mechanism is disabled then the thread goes always
+ ahead of its peers.*/
+ chSchDoRescheduleAhead();
+#endif /* !(CH_CFG_TIME_QUANTUM > 0) */
+}
+
+/** @} */
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