qk.cpp

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//============================================================================
// QP/C++ Real-Time Event Framework (RTEF)
//
// Copyright (C) 2005 Quantum Leaps, LLC. All rights reserved.
//
//                    Q u a n t u m  L e a P s
//                    ------------------------
//                    Modern Embedded Software
//
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-QL-commercial
//
// This software is dual-licensed under the terms of the open-source GNU
// General Public License (GPL) or under the terms of one of the closed-
// source Quantum Leaps commercial licenses.
//
// Redistributions in source code must retain this top-level comment block.
// Plagiarizing this software to sidestep the license obligations is illegal.
//
// NOTE:
// The GPL does NOT permit the incorporation of this code into proprietary
// programs. Please contact Quantum Leaps for commercial licensing options,
// which expressly supersede the GPL and are designed explicitly for
// closed-source distribution.
//
// Quantum Leaps contact information:
// <www.state-machine.com/licensing>
// <info@state-machine.com>
//============================================================================
#define QP_IMPL             // this is QP implementation
#include "qp_port.hpp"      // QP port
#include "qp_pkg.hpp"       // QP package-scope interface
#include "qsafe.h"          // QP Functional Safety (FuSa) Subsystem
#ifdef Q_SPY                // QS software tracing enabled?
    #include "qs_port.hpp"  // QS port
    #include "qs_pkg.hpp"   // QS facilities for pre-defined trace records
#else
    #include "qs_dummy.hpp" // disable the QS software tracing
#endif // Q_SPY
 
// protection against including this source file in a wrong project
#ifndef QK_HPP_
    #error Source file included in a project NOT based on the QK kernel
#endif // QK_HPP_
 
// unnamed namespace for local definitions with internal linkage
namespace {
Q_DEFINE_THIS_MODULE("qk")
} // unnamed namespace
 
//============================================================================
namespace QP {
 
QK QK::priv_;
 
//............................................................................
QK::QK() noexcept
 :  readySet(),
    actPrio(0U),
    nextPrio(0U),
    actThre(0U),
    lockCeil(0U),
    intNest(0U)
{}
//............................................................................
QSchedStatus QK::schedLock(std::uint8_t const ceiling) noexcept {
    QF_CRIT_STAT
    QF_CRIT_ENTRY();
 
    // scheduler should never be locked inside an ISR
    Q_REQUIRE_INCRIT(100, !QK_ISR_CONTEXT_());
 
    QSchedStatus stat = 0xFFU; // assume scheduler NOT locked
    if (ceiling > priv_.lockCeil) { // increasing the lock ceiling?
        QS_BEGIN_PRE(QS_SCHED_LOCK, priv_.actPrio)
            QS_TIME_PRE();   // timestamp
            // the previous lock ceiling & new lock ceiling
            QS_2U8_PRE(priv_.lockCeil, ceiling);
        QS_END_PRE()
 
        // previous status of the lock
        stat = static_cast<QSchedStatus>(priv_.lockCeil);
 
        // new status of the lock
        priv_.lockCeil = static_cast<std::uint8_t>(ceiling);
    }
    QF_CRIT_EXIT();
 
    return stat; // return the status to be saved in a stack variable
}
 
//............................................................................
void QK::schedUnlock(QSchedStatus const prevCeil) noexcept {
    // has the scheduler been actually locked by the last QK::schedLock()?
    if (prevCeil != 0xFFU) {
        QF_CRIT_STAT
        QF_CRIT_ENTRY();
 
        // scheduler should never be unlocked inside an ISR
        Q_REQUIRE_INCRIT(200, !QK_ISR_CONTEXT_());
 
        // the current lock-ceiling must be higher than the previous ceiling
        Q_REQUIRE_INCRIT(220, priv_.lockCeil > prevCeil);
 
        QS_BEGIN_PRE(QS_SCHED_UNLOCK, priv_.actPrio)
            QS_TIME_PRE(); // timestamp
            // current lock ceiling (old), previous lock ceiling (new)
            QS_2U8_PRE(priv_.lockCeil,
                       static_cast<std::uint8_t>(prevCeil));
        QS_END_PRE()
 
        // restore the previous lock ceiling
        priv_.lockCeil = prevCeil;
 
        // find if any AOs should be run after unlocking the scheduler
        if (sched_() != 0U) { // preemption needed?
            activate_(); // activate any unlocked AOs
        }
 
        QF_CRIT_EXIT();
    }
}
 
//............................................................................
std::uint_fast8_t QK::sched_() noexcept {
    // NOTE: this function is entered with interrupts DISABLED
 
    std::uint8_t p = 0U; // assume NO activation needed
    if (priv_.readySet.notEmpty()) {
        // find the highest-prio AO with non-empty event queue
        p = static_cast<std::uint8_t>(priv_.readySet.findMax());
 
        // is the AO's prio. below the active preemption-threshold?
        if (p <= priv_.actThre) {
            p = 0U; // no activation needed
        }
        else {
            // is the AO's prio. below the lock-ceiling?
            if (p <= priv_.lockCeil) {
                p = 0U; // no activation needed
            }
            else {
                priv_.nextPrio = p; // next AO to run
            }
        }
    }
 
    return p; // the next priority or 0
}
 
//............................................................................
std::uint_fast8_t QK::sched_act_(
    QActive const * const act,
    std::uint_fast8_t const pthre_in) noexcept
{
    // NOTE: this function is entered with interrupts DISABLED
 
    std::uint8_t p = act->m_prio;
    if (act->m_eQueue.isEmpty()) { // empty queue?
        priv_.readySet.remove(p);
    }
 
    if (priv_.readySet.isEmpty()) { // no AOs ready to run?
        p = 0U; // no activation needed
    }
    else {
        // find new highest-prio AO ready to run...
        p = static_cast<std::uint8_t>(priv_.readySet.findMax());
        // NOTE: p is guaranteed to be <= QF_MAX_ACTIVE
 
        // is the new prio. below the initial preemption-threshold?
        if (p <= pthre_in) {
            p = 0U; // no activation needed
        }
        else {
            // is the AO's prio. below the lock preemption-threshold?
            if (p <= priv_.lockCeil) {
                p = 0U; // no activation needed
            }
        }
    }
 
    return p;
}
 
//............................................................................
void QK::activate_() {
    // NOTE: this function is entered with interrupts DISABLED
 
    std::uint8_t const prio_in = priv_.actPrio; // save initial prio.
    std::uint8_t p = priv_.nextPrio; // next prio to run
 
 
    // the activated AO's prio must be in range and cannot be 0 (idle thread)
    Q_REQUIRE_INCRIT(520, (0U < p) && (p <= QF_MAX_ACTIVE));
 
    // the initial prio. must be lower than the activated AO's prio.
    Q_REQUIRE_INCRIT(530, prio_in < p);
 
#if (defined QF_ON_CONTEXT_SW) || (defined Q_SPY)
    std::uint8_t pprev = prio_in;
#endif // QF_ON_CONTEXT_SW || Q_SPY
 
    priv_.nextPrio = 0U; // clear for the next time
 
    std::uint8_t pthre_in = 0U; // assume preempting the idle thread
    if (prio_in > 0U) { // preempting a regular thread (NOT the idle thread)?
        QActive const * const a = QActive_registry_[prio_in];
 
        // the AO must be registered at prio. prio_in
        Q_ASSERT_INCRIT(540, a != nullptr);
 
        pthre_in = a->m_pthre;
    }
 
    // loop until no more ready-to-run AOs of higher pthre than the initial
    do  {
        QActive * const a = QActive_registry_[p];
 
        // the AO must be registered at prio. p
        Q_ASSERT_INCRIT(570, a != nullptr);
        std::uint8_t const pthre = a->m_pthre;
 
        // set new active prio. and preemption-threshold
        priv_.actPrio = p;
        priv_.actThre = pthre;
 
#if (defined QF_ON_CONTEXT_SW) || (defined Q_SPY)
        if (p != pprev) { // changing threads?
 
            QS_BEGIN_PRE(QS_SCHED_NEXT, p)
                QS_TIME_PRE();     // timestamp
                QS_2U8_PRE(p, pprev);
            QS_END_PRE()
 
#ifdef QF_ON_CONTEXT_SW
            QF_onContextSw(QActive_registry_[pprev], a);
#endif // QF_ON_CONTEXT_SW
 
            pprev = p; // update previous prio.
        }
#endif // QF_ON_CONTEXT_SW || Q_SPY
 
        QF_INT_ENABLE(); // unconditionally enable interrupts
 
        QEvt const * const e = a->get_(); // queue not empty
        a->dispatch(e, p); // dispatch event (virtual call)
#if (QF_MAX_EPOOL > 0U)
        QF::gc(e); // check if the event is garbage, and collect it if so
#endif
 
        // determine the next highest-prio. AO ready to run...
        QF_INT_DISABLE(); // unconditionally disable interrupts
 
        // schedule next AO
        p = static_cast<std::uint8_t>(sched_act_(a, pthre_in));
 
    } while (p != 0U);
 
    // restore the active prio. and preemption-threshold
    priv_.actPrio = prio_in;
    priv_.actThre = pthre_in;
 
#if (defined QF_ON_CONTEXT_SW) || (defined Q_SPY)
    if (prio_in != 0U) { // resuming an active object?
        QS_BEGIN_PRE(QS_SCHED_NEXT, prio_in)
            QS_TIME_PRE();     // timestamp
            // prio. of the resumed AO, previous prio.
            QS_2U8_PRE(prio_in, pprev);
        QS_END_PRE()
 
#ifdef QF_ON_CONTEXT_SW
        QF_onContextSw(QActive_registry_[pprev],
                       QActive_registry_[prio_in]);
#endif // QF_ON_CONTEXT_SW
    }
    else {  // resuming prio.==0 --> idle
        QS_BEGIN_PRE(QS_SCHED_IDLE, pprev)
            QS_TIME_PRE();     // timestamp
            QS_U8_PRE(pprev);  // previous prio.
        QS_END_PRE()
 
#ifdef QF_ON_CONTEXT_SW
        QF_onContextSw(QActive_registry_[pprev], nullptr);
#endif // QF_ON_CONTEXT_SW
    }
 
#endif // QF_ON_CONTEXT_SW || Q_SPY
}
 
//----------------------------------------------------------------------------
namespace QF {
 
//............................................................................
void init() {
    // setup the QK scheduler as initially locked and not running
    QK::priv_.lockCeil = (QF_MAX_ACTIVE + 1U); // scheduler locked
 
#ifdef QK_INIT
    QK_INIT(); // port-specific initialization of the QK kernel
#endif
}
//............................................................................
void stop() {
    onCleanup(); // application-specific cleanup callback
    // nothing else to do for the preemptive QK kernel
}
//............................................................................
int_t run() {
    QF_INT_DISABLE();
#ifdef Q_SPY
    // produce the QS_QF_RUN trace record
    QS::beginRec_(static_cast<std::uint_fast8_t>(QS_QF_RUN));
    QS::endRec_();
#endif // Q_SPY
 
#ifdef QK_START
    QK_START(); // port-specific startup of the QK kernel
#endif
 
    QK::priv_.lockCeil = 0U; // unlock the QK scheduler
 
#ifdef QF_ON_CONTEXT_SW
    // officially switch to the idle context
    QF_onContextSw(nullptr, QActive_registry_[QK::priv_.nextPrio]);
#endif
 
    // activate AOs to process events posted so far
    if (QK::sched_() != 0U) {
        QK::activate_();
    }
 
    QF_INT_ENABLE();
 
    onStartup(); // app. callback: configure and enable interrupts
 
    for (;;) { // QK idle loop...
        QK::onIdle(); // application-specific QK idle callback
    }
}
 
} // namespace QF
 
//............................................................................
void QActive::start(
    QPrioSpec const prioSpec,
    QEvtPtr * const qSto,
    std::uint_fast16_t const qLen,
    void * const stkSto,
    std::uint_fast16_t const stkSize,
    void const * const par)
{
    Q_UNUSED_PAR(stkSto);  // not needed in QK
    Q_UNUSED_PAR(stkSize); // not needed in QK
 
    QF_CRIT_STAT
    QF_CRIT_ENTRY();
 
    // stack storage must NOT be provided for an AO (QK does not need it)
    Q_REQUIRE_INCRIT(910, stkSto == nullptr);
 
    QF_CRIT_EXIT();
 
    m_prio  = static_cast<std::uint8_t>(prioSpec & 0xFFU); // prio. of the AO
    m_pthre = static_cast<std::uint8_t>(prioSpec >> 8U);   // preemption-thre.
    register_(); // register this AO with the framework
 
    m_eQueue.init(qSto, qLen); // init the built-in queue
 
    // top-most initial tran. (virtual call)
    this->init(par, m_prio);
    QS_FLUSH(); // flush the trace buffer to the host
 
    // see if this AO needs to be scheduled if QK is already running
    QF_CRIT_ENTRY();
    if (QK::sched_() != 0U) { // activation needed?
        QK::activate_();
    }
    QF_CRIT_EXIT();
}
 
} // namespace QP