379 lines
12 KiB
C
379 lines
12 KiB
C
/*
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ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
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2011,2012,2013 Giovanni Di Sirio.
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This file is part of ChibiOS/RT.
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ChibiOS/RT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS/RT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file chschd.c
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* @brief Scheduler code.
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*
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* @addtogroup scheduler
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* @details This module provides the default portable scheduler code,
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* scheduler functions can be individually captured by the port
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* layer in order to provide architecture optimized equivalents.
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* When a function is captured its default code is not built into
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* the OS image, the optimized version is included instead.
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* @{
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*/
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#include "ch.h"
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/**
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* @brief Ready list header.
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*/
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#if !defined(PORT_OPTIMIZED_RLIST_VAR) || defined(__DOXYGEN__)
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ReadyList rlist;
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#endif /* !defined(PORT_OPTIMIZED_RLIST_VAR) */
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/**
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* @brief Scheduler initialization.
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*
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* @notapi
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*/
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void _scheduler_init(void) {
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queue_init(&rlist.r_queue);
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rlist.r_prio = NOPRIO;
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#if CH_USE_REGISTRY
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rlist.r_newer = rlist.r_older = (Thread *)&rlist;
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#endif
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}
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/**
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* @brief Inserts a thread in the Ready List.
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* @details The thread is positioned behind all threads with higher or equal
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* priority.
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* @pre The thread must not be already inserted in any list through its
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* @p p_next and @p p_prev or list corruption would occur.
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* @post This function does not reschedule so a call to a rescheduling
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* function must be performed before unlocking the kernel. Note that
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* interrupt handlers always reschedule on exit so an explicit
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* reschedule must not be performed in ISRs.
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*
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* @param[in] tp the thread to be made ready
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* @return The thread pointer.
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*
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* @iclass
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*/
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#if !defined(PORT_OPTIMIZED_READYI) || defined(__DOXYGEN__)
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Thread *chSchReadyI(Thread *tp) {
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Thread *cp;
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chDbgCheckClassI();
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/* Integrity checks.*/
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chDbgAssert((tp->p_state != THD_STATE_READY) &&
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(tp->p_state != THD_STATE_FINAL),
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"chSchReadyI(), #1",
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"invalid state");
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tp->p_state = THD_STATE_READY;
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cp = (Thread *)&rlist.r_queue;
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do {
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cp = cp->p_next;
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} while (cp->p_prio >= tp->p_prio);
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/* Insertion on p_prev.*/
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tp->p_next = cp;
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tp->p_prev = cp->p_prev;
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tp->p_prev->p_next = cp->p_prev = tp;
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return tp;
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}
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#endif /* !defined(PORT_OPTIMIZED_READYI) */
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/**
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* @brief Puts the current thread to sleep into the specified state.
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* @details The thread goes into a sleeping state. The possible
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* @ref thread_states are defined into @p threads.h.
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*
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* @param[in] newstate the new thread state
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*
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* @sclass
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*/
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#if !defined(PORT_OPTIMIZED_GOSLEEPS) || defined(__DOXYGEN__)
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void chSchGoSleepS(tstate_t newstate) {
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Thread *otp;
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chDbgCheckClassS();
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(otp = currp)->p_state = newstate;
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#if CH_TIME_QUANTUM > 0
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/* The thread is renouncing its remaining time slices so it will have a new
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time quantum when it will wakeup.*/
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otp->p_preempt = CH_TIME_QUANTUM;
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#endif
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setcurrp(fifo_remove(&rlist.r_queue));
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currp->p_state = THD_STATE_CURRENT;
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chSysSwitch(currp, otp);
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}
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#endif /* !defined(PORT_OPTIMIZED_GOSLEEPS) */
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#if !defined(PORT_OPTIMIZED_GOSLEEPTIMEOUTS) || defined(__DOXYGEN__)
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/*
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* Timeout wakeup callback.
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*/
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static void wakeup(void *p) {
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Thread *tp = (Thread *)p;
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chSysLockFromIsr();
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switch (tp->p_state) {
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case THD_STATE_READY:
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/* Handling the special case where the thread has been made ready by
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another thread with higher priority.*/
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chSysUnlockFromIsr();
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return;
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#if CH_USE_SEMAPHORES || CH_USE_QUEUES || \
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(CH_USE_CONDVARS && CH_USE_CONDVARS_TIMEOUT)
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#if CH_USE_SEMAPHORES
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case THD_STATE_WTSEM:
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chSemFastSignalI((Semaphore *)tp->p_u.wtobjp);
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/* Falls into, intentional. */
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#endif
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#if CH_USE_QUEUES
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case THD_STATE_WTQUEUE:
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#endif
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#if CH_USE_CONDVARS && CH_USE_CONDVARS_TIMEOUT
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case THD_STATE_WTCOND:
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#endif
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/* States requiring dequeuing.*/
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dequeue(tp);
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#endif
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}
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tp->p_u.rdymsg = RDY_TIMEOUT;
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chSchReadyI(tp);
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chSysUnlockFromIsr();
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}
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/**
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* @brief Puts the current thread to sleep into the specified state with
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* timeout specification.
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* @details The thread goes into a sleeping state, if it is not awakened
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* explicitly within the specified timeout then it is forcibly
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* awakened with a @p RDY_TIMEOUT low level message. The possible
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* @ref thread_states are defined into @p threads.h.
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*
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* @param[in] newstate the new thread state
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* @param[in] time the number of ticks before the operation timeouts, the
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* special values are handled as follow:
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* - @a TIME_INFINITE the thread enters an infinite sleep
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* state, this is equivalent to invoking
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* @p chSchGoSleepS() but, of course, less efficient.
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* - @a TIME_IMMEDIATE this value is not allowed.
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* .
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* @return The wakeup message.
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* @retval RDY_TIMEOUT if a timeout occurs.
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*
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* @sclass
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*/
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msg_t chSchGoSleepTimeoutS(tstate_t newstate, systime_t time) {
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chDbgCheckClassS();
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if (TIME_INFINITE != time) {
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VirtualTimer vt;
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chVTSetI(&vt, time, wakeup, currp);
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chSchGoSleepS(newstate);
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if (chVTIsArmedI(&vt))
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chVTResetI(&vt);
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}
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else
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chSchGoSleepS(newstate);
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return currp->p_u.rdymsg;
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}
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#endif /* !defined(PORT_OPTIMIZED_GOSLEEPTIMEOUTS) */
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/**
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* @brief Wakes up a thread.
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* @details The thread is inserted into the ready list or immediately made
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* running depending on its relative priority compared to the current
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* thread.
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* @pre The thread must not be already inserted in any list through its
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* @p p_next and @p p_prev or list corruption would occur.
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* @note It is equivalent to a @p chSchReadyI() followed by a
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* @p chSchRescheduleS() but much more efficient.
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* @note The function assumes that the current thread has the highest
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* priority.
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*
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* @param[in] ntp the Thread to be made ready
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* @param[in] msg message to the awakened thread
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*
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* @sclass
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*/
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#if !defined(PORT_OPTIMIZED_WAKEUPS) || defined(__DOXYGEN__)
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void chSchWakeupS(Thread *ntp, msg_t msg) {
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chDbgCheckClassS();
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ntp->p_u.rdymsg = msg;
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/* If the waken thread has a not-greater priority than the current
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one then it is just inserted in the ready list else it made
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running immediately and the invoking thread goes in the ready
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list instead.*/
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if (ntp->p_prio <= currp->p_prio)
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chSchReadyI(ntp);
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else {
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Thread *otp = chSchReadyI(currp);
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setcurrp(ntp);
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ntp->p_state = THD_STATE_CURRENT;
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chSysSwitch(ntp, otp);
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}
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}
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#endif /* !defined(PORT_OPTIMIZED_WAKEUPS) */
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/**
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* @brief Performs a reschedule if a higher priority thread is runnable.
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* @details If a thread with a higher priority than the current thread is in
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* the ready list then make the higher priority thread running.
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*
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* @sclass
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*/
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#if !defined(PORT_OPTIMIZED_RESCHEDULES) || defined(__DOXYGEN__)
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void chSchRescheduleS(void) {
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chDbgCheckClassS();
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if (chSchIsRescRequiredI())
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chSchDoRescheduleAhead();
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}
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#endif /* !defined(PORT_OPTIMIZED_RESCHEDULES) */
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/**
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* @brief Evaluates if preemption is required.
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* @details The decision is taken by comparing the relative priorities and
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* depending on the state of the round robin timeout counter.
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* @note Not a user function, it is meant to be invoked by the scheduler
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* itself or from within the port layer.
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*
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* @retval TRUE if there is a thread that must go in running state
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* immediately.
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* @retval FALSE if preemption is not required.
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*
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* @special
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*/
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#if !defined(PORT_OPTIMIZED_ISPREEMPTIONREQUIRED) || defined(__DOXYGEN__)
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bool_t chSchIsPreemptionRequired(void) {
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tprio_t p1 = firstprio(&rlist.r_queue);
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tprio_t p2 = currp->p_prio;
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#if CH_TIME_QUANTUM > 0
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/* If the running thread has not reached its time quantum, reschedule only
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if the first thread on the ready queue has a higher priority.
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Otherwise, if the running thread has used up its time quantum, reschedule
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if the first thread on the ready queue has equal or higher priority.*/
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return currp->p_preempt ? p1 > p2 : p1 >= p2;
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#else
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/* If the round robin preemption feature is not enabled then performs a
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simpler comparison.*/
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return p1 > p2;
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#endif
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}
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#endif /* !defined(PORT_OPTIMIZED_ISPREEMPTIONREQUIRED) */
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/**
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* @brief Switches to the first thread on the runnable queue.
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* @details The current thread is positioned in the ready list behind all
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* threads having the same priority. The thread regains its time
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* quantum.
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* @note Not a user function, it is meant to be invoked by the scheduler
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* itself or from within the port layer.
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*
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* @special
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*/
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#if !defined(PORT_OPTIMIZED_DORESCHEDULEBEHIND) || defined(__DOXYGEN__)
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void chSchDoRescheduleBehind(void) {
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Thread *otp;
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otp = currp;
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/* Picks the first thread from the ready queue and makes it current.*/
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setcurrp(fifo_remove(&rlist.r_queue));
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currp->p_state = THD_STATE_CURRENT;
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#if CH_TIME_QUANTUM > 0
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otp->p_preempt = CH_TIME_QUANTUM;
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#endif
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chSchReadyI(otp);
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chSysSwitch(currp, otp);
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}
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#endif /* !defined(PORT_OPTIMIZED_DORESCHEDULEBEHIND) */
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/**
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* @brief Switches to the first thread on the runnable queue.
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* @details The current thread is positioned in the ready list ahead of all
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* threads having the same priority.
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* @note Not a user function, it is meant to be invoked by the scheduler
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* itself or from within the port layer.
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*
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* @special
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*/
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#if !defined(PORT_OPTIMIZED_DORESCHEDULEAHEAD) || defined(__DOXYGEN__)
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void chSchDoRescheduleAhead(void) {
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Thread *otp, *cp;
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otp = currp;
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/* Picks the first thread from the ready queue and makes it current.*/
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setcurrp(fifo_remove(&rlist.r_queue));
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currp->p_state = THD_STATE_CURRENT;
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otp->p_state = THD_STATE_READY;
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cp = (Thread *)&rlist.r_queue;
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do {
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cp = cp->p_next;
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} while (cp->p_prio > otp->p_prio);
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/* Insertion on p_prev.*/
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otp->p_next = cp;
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otp->p_prev = cp->p_prev;
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otp->p_prev->p_next = cp->p_prev = otp;
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chSysSwitch(currp, otp);
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}
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#endif /* !defined(PORT_OPTIMIZED_DORESCHEDULEAHEAD) */
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/**
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* @brief Switches to the first thread on the runnable queue.
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* @details The current thread is positioned in the ready list behind or
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* ahead of all threads having the same priority depending on
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* if it used its whole time slice.
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* @note Not a user function, it is meant to be invoked by the scheduler
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* itself or from within the port layer.
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*
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* @special
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*/
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#if !defined(PORT_OPTIMIZED_DORESCHEDULE) || defined(__DOXYGEN__)
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void chSchDoReschedule(void) {
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#if CH_TIME_QUANTUM > 0
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/* If CH_TIME_QUANTUM is enabled then there are two different scenarios to
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handle on preemption: time quantum elapsed or not.*/
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if (currp->p_preempt == 0) {
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/* The thread consumed its time quantum so it is enqueued behind threads
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with same priority level, however, it acquires a new time quantum.*/
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chSchDoRescheduleBehind();
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}
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else {
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/* The thread didn't consume all its time quantum so it is put ahead of
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threads with equal priority and does not acquire a new time quantum.*/
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chSchDoRescheduleAhead();
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}
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#else /* !(CH_TIME_QUANTUM > 0) */
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/* If the round-robin mechanism is disabled then the thread goes always
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ahead of its peers.*/
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chSchDoRescheduleAhead();
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#endif /* !(CH_TIME_QUANTUM > 0) */
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}
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#endif /* !defined(PORT_OPTIMIZED_DORESCHEDULE) */
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/** @} */
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