qpcpp/include/qxk.hpp

//============================================================================
// QP/C++ Real-Time Embedded Framework (RTEF)
// Copyright (C) 2005 Quantum Leaps, LLC. All rights reserved.
//
// 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 version 3 (or any later version), or alternatively,
// under the terms of one of the closed source Quantum Leaps commercial
// licenses.
//
// The terms of the open source GNU General Public License version 3
// can be found at: <www.gnu.org/licenses/gpl-3.0>
//
// The terms of the closed source Quantum Leaps commercial licenses
// can be found at: <www.state-machine.com/licensing>
//
// Redistributions in source code must retain this top-level comment block.
// Plagiarizing this software to sidestep the license obligations is illegal.
//
// Contact information:
// <www.state-machine.com>
// <info@state-machine.com>
//============================================================================
//! @date Last updated on: 2021-12-23
//! @version Last updated for: @ref qpcpp_7_0_0
//!
//! @file
//! @brief QXK/C++ preemptive extended (blocking) kernel, platform-independent
//! public interface.

#ifndef QXK_HPP
#define QXK_HPP

#include "qequeue.hpp"  // QXK kernel uses the native QF event queue
#include "qmpool.hpp"   // QXK kernel uses the native QF memory pool
#include "qpset.hpp"    // QXK kernel uses the native QF priority set

//============================================================================
// QF configuration for QXK -- data members of the QActive class...

// QXK event-queue used for AOs
#define QF_EQUEUE_TYPE      QEQueue

// QXK OS-object used to store the private stack poiner for extended threads.
// (The private stack pointer is NULL for basic-threads).
//
#define QF_OS_OBJECT_TYPE   void*

// QXK thread type used to store the private Thread-Local Storage pointer.
#define QF_THREAD_TYPE      void*

//! Access Thread-Local Storage (TLS) and cast it on the given @p type_
#define QXK_TLS(type_) (static_cast<type_>(QXK_current()->m_thread))


//============================================================================
namespace QP {
    class QActive; // forward declaration
} // namespace QP

//============================================================================
extern "C" {

//! attributes of the QXK kernel
struct QXK_Attr {
    QP::QActive * volatile curr;      //!< currently executing thread
    QP::QActive * volatile next;      //!< next thread to execute
    std::uint8_t volatile actPrio;    //!< prio of the active basic thread
    std::uint8_t volatile lockPrio;   //!< lock prio (0 == no-lock)
    std::uint8_t volatile lockHolder; //!< prio of the lock holder
    std::uint8_t volatile intNest;    //!< ISR nesting level
    QP::QActive * idleThread;         //!< pointer to the idle thread
    QP::QPSet readySet;               //!< ready-set of all threads
};

//! global attributes of the QXK kernel
extern QXK_Attr QXK_attr_;

//! QXK scheduler finds the highest-priority thread ready to run
std::uint_fast8_t QXK_sched_(void) noexcept;

//! QXK activator activates the next active object. The activated AO preempts
// the currently executing AOs.
//
void QXK_activate_(void);

//! return the currently executing active-object/thread
QP::QActive *QXK_current(void) noexcept;

#ifdef QXK_ON_CONTEXT_SW

    //! QXK context switch callback (customized in BSPs for QXK)
    //!
    //! @description
    //! This callback function provides a mechanism to perform additional
    //! custom operations when QXK switches context from one thread to
    //! another.
    //!
    //! @param[in] prev   pointer to the previous thread (active object)
    //!                   (prev==0 means that @p prev was the QXK idle thread)
    //! @param[in] next   pointer to the next thread (active object)
    //!                   (next==0) means that @p next is the QXK idle thread)
    //! @attention
    //! QXK_onContextSw() is invoked with interrupts **disabled** and must also
    //! return with interrupts **disabled**.
    //!
    //! @note
    //! This callback is enabled by defining the macro #QXK_ON_CONTEXT_SW.
    //!
    //! @include qxk_oncontextsw.cpp
    //!
    void QXK_onContextSw(QP::QActive *prev, QP::QActive *next);

#endif // QXK_ON_CONTEXT_SW

} // extern "C"

//============================================================================
namespace QP {

//! The scheduler lock status
using QSchedStatus = std::uint_fast16_t;

//============================================================================
//! QXK services.
//! @description
//! This class groups together QXK services. It has only static members and
//! should not be instantiated.
//!
//! @note The QXK initialization and the QXK scheduler belong conceptually
//! to the QXK class (as static class members). However, to avoid C++
//! potential name-mangling problems in assembly language, these elements
//! are defined outside of the QXK class and outside the QP namespace with
//! the extern "C" linkage specification.
class QXK {
public:
    //! QXK selective scheduler lock
    static QSchedStatus schedLock(std::uint_fast8_t const ceiling) noexcept;

    //! QXK selective scheduler unlock
    static void schedUnlock(QSchedStatus const stat) noexcept;

    //! QXK idle callback (customized in BSPs for QXK)
    //! @description
    //! QP::QXK::onIdle() is called continously by the QXK idle loop. This
    //! callback gives the application an opportunity to enter a power-saving
    //! CPU mode, or perform some other idle processing.
    //!
    //! @note QP::QXK::onIdle() is invoked with interrupts enabled and must
    //! also return with interrupts enabled.
    //!
    //! @sa QP::QF::onIdle()
    static void onIdle(void);
};

} // namespace QP


//============================================================================
// interface used only inside QF, but not in applications

#ifdef QP_IMPL

    #ifndef QXK_ISR_CONTEXT_
        //! Internal port-specific macro that reports the execution context
        // (ISR vs. thread).
        //! @returns true if the code executes in the ISR context and false
        //! otherwise
        #define QXK_ISR_CONTEXT_() \
            (QXK_attr_.intNest != 0U)
    #endif // QXK_ISR_CONTEXT_

    // QXK-specific scheduler locking
    //! Internal macro to represent the scheduler lock status
    // that needs to be preserved to allow nesting of locks.
    //
    #define QF_SCHED_STAT_ QSchedStatus lockStat_;

    //! Internal macro for selective scheduler locking.
    #define QF_SCHED_LOCK_(prio_) do {           \
        if (QXK_ISR_CONTEXT_()) {                \
            lockStat_ = 0xFFU;                   \
        } else {                                 \
            lockStat_ = QXK::schedLock((prio_)); \
        }                                        \
    } while (false)

    //! Internal macro for selective scheduler unlocking.
    #define QF_SCHED_UNLOCK_() do {      \
        if (lockStat_ != 0xFFU) {        \
            QXK::schedUnlock(lockStat_); \
        }                                \
    } while (false)

    // QXK-specific native event queue operations...
    #define QACTIVE_EQUEUE_WAIT_(me_) \
        Q_ASSERT_ID(110, (me_)->m_eQueue.m_frontEvt != nullptr)

    #define QACTIVE_EQUEUE_SIGNAL_(me_) do {                   \
        QXK_attr_.readySet.insert(                             \
            static_cast<std::uint_fast8_t>((me_)->m_dynPrio)); \
        if (!QXK_ISR_CONTEXT_()) {                             \
            if (QXK_sched_() != 0U) {                          \
                QXK_activate_();                               \
            }                                                  \
        }                                                      \
    } while (false)

    // QXK-specific native QF event pool operations...
    #define QF_EPOOL_TYPE_  QMPool
    #define QF_EPOOL_INIT_(p_, poolSto_, poolSize_, evtSize_) \
        (p_).init((poolSto_), (poolSize_), (evtSize_))
    #define QF_EPOOL_EVENT_SIZE_(p_)  ((p_).m_blockSize)
    #define QF_EPOOL_GET_(p_, e_, m_, qs_id_) \
        ((e_) = static_cast<QEvt *>((p_).get((m_), (qs_id_))))
    #define QF_EPOOL_PUT_(p_, e_, qs_id_) ((p_).put((e_), (qs_id_)))

#endif // QP_IMPL

#endif // QXK_HPP