qeq_get.cpp

00001 //////////////////////////////////////////////////////////////////////////////
00002 // Product: QF/C++
00003 // Last Updated for Version: 4.0.00
00004 // Date of the Last Update:  Apr 07, 2008
00005 //
00006 //                    Q u a n t u m     L e a P s
00007 //                    ---------------------------
00008 //                    innovating embedded systems
00009 //
00010 // Copyright (C) 2002-2008 Quantum Leaps, LLC. All rights reserved.
00011 //
00012 // This software may be distributed and modified under the terms of the GNU
00013 // General Public License version 2 (GPL) as published by the Free Software
00014 // Foundation and appearing in the file GPL.TXT included in the packaging of
00015 // this file. Please note that GPL Section 2[b] requires that all works based
00016 // on this software must also be made publicly available under the terms of
00017 // the GPL ("Copyleft").
00018 //
00019 // Alternatively, this software may be distributed and modified under the
00020 // terms of Quantum Leaps commercial licenses, which expressly supersede
00021 // the GPL and are specifically designed for licensees interested in
00022 // retaining the proprietary status of their code.
00023 //
00024 // Contact information:
00025 // Quantum Leaps Web site:  http://www.quantum-leaps.com
00026 // e-mail:                  info@quantum-leaps.com
00027 //////////////////////////////////////////////////////////////////////////////
00028 #include "qf_pkg.h"
00029 
00030 // #include "qassert.h"
00031 // Q_DEFINE_THIS_MODULE(qeq_get)
00032 
00033 /// \file
00034 /// \ingroup qf
00035 /// \brief QEQueue::get() implementation.
00036 
00037 //............................................................................
00038 QEvent const *QEQueue::get(void) {
00039     QEvent const *e;
00040     QF_INT_LOCK_KEY_
00041 
00042     QF_INT_LOCK_();
00043     if (m_frontEvt == (QEvent *)0) {                    // is the queue empty?
00044         e = (QEvent *)0;                    // no event available at this time
00045     }
00046     else {
00047         e = m_frontEvt;
00048 
00049         if (m_nFree != m_end) {          // any events in the the ring buffer?
00050             m_frontEvt = m_ring[m_tail];         // remove event from the tail
00051             if (m_tail == (QEQueueCtr)0) {           // need to wrap the tail?
00052                 m_tail = m_end;                                 // wrap around
00053             }
00054             --m_tail;
00055 
00056             ++m_nFree;               // one more free event in the ring buffer
00057 
00058             QS_BEGIN_NOLOCK_(QS_QF_EQUEUE_GET, QS::eqObj_, this)
00059                 QS_TIME_();                                       // timestamp
00060                 QS_SIG_(e->sig);                   // the signal of this event
00061                 QS_OBJ_(this);                            // this queue object
00062                 QS_U8_(e->dynamic_);    // the dynamic attributes of the event
00063                 QS_EQC_(m_nFree);                    // number of free entries
00064             QS_END_NOLOCK_()
00065         }
00066         else {
00067             m_frontEvt = (QEvent *)0;               // the queue becomes empty
00068 
00069             QS_BEGIN_NOLOCK_(QS_QF_EQUEUE_GET_LAST, QS::eqObj_, this)
00070                 QS_TIME_();                                       // timestamp
00071                 QS_SIG_(e->sig);                   // the signal of this event
00072                 QS_OBJ_(this);                            // this queue object
00073                 QS_U8_(e->dynamic_);     // the dynamic attribute of the event
00074             QS_END_NOLOCK_()
00075         }
00076     }
00077     QF_INT_UNLOCK_();
00078     return e;
00079 }