qk_mutex.c

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/*****************************************************************************
* Product: QK/C
* Last Updated for Version: 4.4.00
* Date of the Last Update:  Jan 04, 2012
*
*                    Q u a n t u m     L e a P s
*                    ---------------------------
*                    innovating embedded systems
*
* Copyright (C) 2002-2012 Quantum Leaps, LLC. All rights reserved.
*
* This software may be distributed and modified under the terms of the GNU
* General Public License version 2 (GPL) as published by the Free Software
* Foundation and appearing in the file GPL.TXT included in the packaging of
* this file. Please note that GPL Section 2[b] requires that all works based
* on this software must also be made publicly available under the terms of
* the GPL ("Copyleft").
*
* Alternatively, this software may be distributed and modified under the
* terms of Quantum Leaps commercial licenses, which expressly supersede
* the GPL and are specifically designed for licensees interested in
* retaining the proprietary status of their code.
*
* Contact information:
* Quantum Leaps Web site:  http://www.quantum-leaps.com
* e-mail:                  info@quantum-leaps.com
*****************************************************************************/
#include "qk_pkg.h"
/*#include "qassert.h"*/

/*Q_DEFINE_THIS_MODULE("qk_mutex")*/

#ifdef QK_NO_MUTEX
    #error "qk_mutex.c included in the build when QK_NO_MUTEX defined"
#endif

/* package-scope objects ---------------------------------------------------*/
uint8_t QK_ceilingPrio_;                     /* ceiling priority of a mutex */

/*..........................................................................*/
QMutex QK_mutexLock(uint8_t prioCeiling) {
    uint8_t mutex;
    QF_CRIT_STAT_
    QF_CRIT_ENTRY_();
    mutex = QK_ceilingPrio_;  /* the original QK priority ceiling to return */
    if (QK_ceilingPrio_ < prioCeiling) {
        QK_ceilingPrio_ = prioCeiling;     /* raise the QK priority ceiling */
    }

    QS_BEGIN_NOCRIT_(QS_QK_MUTEX_LOCK, (void *)0, (void *)0)
        QS_TIME_();                                            /* timestamp */
        QS_U8_(mutex);                             /* the original priority */
        QS_U8_(QK_ceilingPrio_);            /* the current priority ceiling */
    QS_END_NOCRIT_()

    QF_CRIT_EXIT_();
    return mutex;
}
/*..........................................................................*/
void QK_mutexUnlock(QMutex mutex) {
    QF_CRIT_STAT_
    QF_CRIT_ENTRY_();

    QS_BEGIN_NOCRIT_(QS_QK_MUTEX_UNLOCK, (void *)0, (void *)0)
        QS_TIME_();                                            /* timestamp */
        QS_U8_(mutex);                             /* the original priority */
        QS_U8_(QK_ceilingPrio_);            /* the current priority ceiling */
    QS_END_NOCRIT_()

    if (QK_ceilingPrio_ > mutex) {
        QK_ceilingPrio_ = mutex;      /* restore the saved priority ceiling */
        mutex = QK_schedPrio_();          /* reuse 'mutex' to hold priority */
        if (mutex != (uint8_t)0) {
            QK_sched_(mutex);
        }
    }
    QF_CRIT_EXIT_();
}