qpcpp/qf/source/qa_lifo.cpp
Quantum Leaps 6e9dc8bb13 5.3.0
2014-04-21 21:48:04 -04:00

122 lines
4.3 KiB
C++

/// \file
/// \brief QP::QActive::postLIFO_() definition.
/// \ingroup qf
/// \cond
///***************************************************************************
/// Product: QF/C++
/// Last updated for version 5.3.0
/// Last updated on 2014-04-08
///
/// Q u a n t u m L e a P s
/// ---------------------------
/// innovating embedded systems
///
/// Copyright (C) Quantum Leaps, www.state-machine.com.
///
/// 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:
/// Web: www.state-machine.com
/// Email: info@state-machine.com
///***************************************************************************
/// \endcond
#define QP_IMPL // this is QP implementation
#include "qf_port.h" // QF port
#include "qf_pkg.h"
#ifdef Q_SPY // QS software tracing enabled?
#include "qs_port.h" // include QS port
#else
#include "qs_dummy.h" // disable the QS software tracing
#endif // Q_SPY
#include "qassert.h"
namespace QP {
Q_DEFINE_THIS_MODULE("qa_lifo")
/// \note
/// This source file is only included in the QF library when the native
/// QF active object queue is used (instead of a message queue of an RTOS).
//****************************************************************************
/// \description
/// posts an event to the event queue of the active object using the
/// Last-In-First-Out (LIFO) policy.
///
/// \note The LIFO policy should be used only for self-posting and with
/// caution because it alters order of events in the queue.
///
/// \arguments
/// \arg[in] \c e pointer to the event to post to the queue
///
/// \sa QActive_post_()
///
void QActive::postLIFO(QEvt const * const e) {
QF_CRIT_STAT_
QF_CRIT_ENTRY_();
QEQueueCtr nFree = m_eQueue.m_nFree;// tmp to avoid UB for volatile access
// the queue must be able to accept the event (cannot overflow)
Q_ASSERT_ID(110, nFree != static_cast<QEQueueCtr>(0));
QS_BEGIN_NOCRIT_(QS_QF_ACTIVE_POST_LIFO, QS::priv_.aoObjFilter, this)
QS_TIME_(); // timestamp
QS_SIG_(e->sig); // the signal of this event
QS_OBJ_(this); // this active object
QS_2U8_(e->poolId_, e->refCtr_); // pool Id & refCtr of the evt
QS_EQC_(nFree); // number of free entries
QS_EQC_(m_eQueue.m_nMin); // min number of free entries
QS_END_NOCRIT_()
// is it a dynamic event?
if (e->poolId_ != u8_0) {
QF_EVT_REF_CTR_INC_(e); // increment the reference counter
}
--nFree; // one free entry just used up
m_eQueue.m_nFree = nFree; // update the volatile
if (m_eQueue.m_nMin > nFree) {
m_eQueue.m_nMin = nFree; // update minimum so far
}
QEvt const *frontEvt = m_eQueue.m_frontEvt;// read volatile into temporary
m_eQueue.m_frontEvt = e; // deliver the event directly to the front
// was the queue empty?
if (frontEvt == null_evt) {
QACTIVE_EQUEUE_SIGNAL_(this); // signal the event queue
}
// queue is not empty, leave event in the ring-buffer
else {
++m_eQueue.m_tail;
if (m_eQueue.m_tail == m_eQueue.m_end) { // need to wrap the tail?
m_eQueue.m_tail = static_cast<QEQueueCtr>(0); // wrap around
}
QF_PTR_AT_(m_eQueue.m_ring, m_eQueue.m_tail) = frontEvt;
}
QF_CRIT_EXIT_();
}
} // namespace QP