/// @file
/// @brief QXK/C++ preemptive extended (blocking) kernel, platform-independent
/// public interface.
/// @ingroup qxk
/// @cond
///***************************************************************************
/// Last updated for version 5.9.4
/// Last updated on  2017-07-06
///
///                    Q u a n t u m     L e a P s
///                    ---------------------------
///                    innovating embedded systems
///
/// Copyright (C) Quantum Leaps, LLC. All rights reserved.
///
/// This program is open source 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.
///
/// Alternatively, this program may be distributed and modified under the
/// terms of Quantum Leaps commercial licenses, which expressly supersede
/// the GNU General Public License and are specifically designed for
/// licensees interested in retaining the proprietary status of their code.
///
/// This program 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/>.
///
/// Contact information:
/// https://state-machine.com
/// mailto:info@state-machine.com
///***************************************************************************
/// @endcond

#ifndef qxk_h
#define qxk_h

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

//****************************************************************************
// QF configuration for QXK: data members of the ::QMActive class...

//! This macro defines the type of the event queue used for the AOs
/// @description
/// QXK uses the native QF event queue QEQueue.
///
#define QF_EQUEUE_TYPE      QEQueue

//! Private OS-object attribute of active objects in QXK
///
/// @description
/// QXK uses this member to store the private stack poiner for the thread.
/// (The private stack pointer is NULL for AO-threads).///
///
#define QF_OS_OBJECT_TYPE   void*

//! OS-dependent representation of the private thread
/// @description
/// QXK uses this member 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 *curr;  //!< currently executing thread
    QP::QActive *next;  //!< next thread to execute
    uint_fast8_t volatile actPrio;    //!< prio of the active basic thread
    uint_fast8_t volatile lockPrio;   //!< lock prio (0 == no-lock)
    uint_fast8_t volatile lockHolder; //!< prio of the lock holder
#ifndef QXK_ISR_CONTEXT_
    uint_fast8_t volatile intNest;    //!< ISR nesting level
#endif // QXK_ISR_CONTEXT_
    QP::QPSet readySet; //!< ready-set of basic- and extended-threads
};

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

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

//! 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);

} // extern "C"

//****************************************************************************
namespace QP {

//****************************************************************************
//! 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 initialization
    /// @description
    /// QP::QXK::init() must be called from the application before
    /// QP::QF::run() to initialize the stack for the QXK idle thread.
    static void init(void * const idleStkSto,
                     uint_fast16_t const idleStkSize);

    //! 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);

    //! get the current QXK version number string of the form X.Y.Z
    static char_t const *getVersion(void) {
        return versionStr;
    }
};

//****************************************************************************
//! Priority Ceiling Mutex the QXK preemptive kernel
class QXMutex {
public:

    //! initialize the QXK priority-ceiling mutex
    void init(uint_fast8_t const prio);

    //! lock the QXK priority-ceiling mutex
    void lock(void);

    //! unlock the QXK priority-ceiling mutex
    void unlock(void);

private:
    uint_fast8_t m_lockPrio;   //!< lock prio (priority ceiling)
    uint_fast8_t m_prevPrio;   //!< previoius lock prio
    uint_fast8_t m_prevHolder; //!< priority of the thread holding the lock

    friend class QF;
};

} // 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 != static_cast<uint_fast8_t>(0))
    #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_ QXMutex schedLock_;

    //! Internal macro for selective scheduler locking.
    #define QF_SCHED_LOCK_(prio_) do { \
        if (QXK_ISR_CONTEXT_()) { \
            schedLock_.m_lockPrio = static_cast<uint_fast8_t>(0); \
        } else { \
            schedLock_.init((prio_)); \
            schedLock_.lock(); \
        } \
    } while (false)

    //! Internal macro for selective scheduler unlocking.
    #define QF_SCHED_UNLOCK_() do { \
        if (schedLock_.m_lockPrio != static_cast<uint_fast8_t>(0)) { \
            schedLock_.unlock(); \
        } \
    } while (false)

    // QXK-specific native event queue operations...
    #define QACTIVE_EQUEUE_WAIT_(me_) \
        Q_ASSERT_ID(110, (me_)->m_eQueue.m_frontEvt != static_cast<QEvt *>(0))

    #define QACTIVE_EQUEUE_SIGNAL_(me_) do { \
        QXK_attr_.readySet.insert((me_)->m_prio); \
        if (!QXK_ISR_CONTEXT_()) { \
            if (QXK_sched_() != static_cast<uint_fast8_t>(0)) { \
                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_) \
        static_cast<uint_fast16_t>((p_).getBlockSize())
    #define QF_EPOOL_GET_(p_, e_, m_) \
        ((e_) = static_cast<QEvt *>((p_).get((m_))))
    #define QF_EPOOL_PUT_(p_, e_) ((p_).put(e_))

#endif // QP_IMPL

#endif // qxk_h
