QP/C: qeq_get.c Source File

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00001 /*****************************************************************************
00002 * Product: QF/C
00003 * Last Updated for Version: 4.4.00
00004 * Date of the Last Update:  Jan 14, 2012
00005 *
00006 *                    Q u a n t u m     L e a P s
00007 *                    ---------------------------
00008 *                    innovating embedded systems
00009 *
00010 * Copyright (C) 2002-2012 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 /* #include "qassert.h" */
00030 
00031 /* Q_DEFINE_THIS_MODULE("qeq_get") */
00032 
00040 /*..........................................................................*/
00041 QEvent const *QEQueue_get(QEQueue *me) {
00042     QEvent const *e;
00043     QF_CRIT_STAT_
00044     QF_CRIT_ENTRY_();
00045     if (me->frontEvt == (QEvent *)0) {               /* is the queue empty? */
00046         e = (QEvent *)0;                 /* no event available at this time */
00047     }
00048     else {                                        /* the queue is not empty */
00049         e = me->frontEvt;
00050 
00051         if (me->nFree != me->end) {       /* any events in the ring buffer? */
00052             me->frontEvt = QF_PTR_AT_(me->ring, me->tail); /* get from tail */
00053             if (me->tail == (QEQueueCtr)0) {      /* need to wrap the tail? */
00054                 me->tail = me->end;                          /* wrap around */
00055             }
00056             --me->tail;
00057 
00058             ++me->nFree;          /* one more free event in the ring buffer */
00059 
00060             QS_BEGIN_NOCRIT_(QS_QF_EQUEUE_GET, QS_eqObj_, me)
00061                 QS_TIME_();                                    /* timestamp */
00062                 QS_SIG_(e->sig);                /* the signal of this event */
00063                 QS_OBJ_(me);                           /* this queue object */
00064                 QS_U8_(QF_EVT_POOL_ID_(e));     /* the pool Id of the event */
00065                 QS_U8_(QF_EVT_REF_CTR_(e));   /* the ref count of the event */
00066                 QS_EQC_(me->nFree);               /* number of free entries */
00067             QS_END_NOCRIT_()
00068         }
00069         else {
00070             me->frontEvt = (QEvent *)0;              /* queue becomes empty */
00071 
00072             QS_BEGIN_NOCRIT_(QS_QF_EQUEUE_GET_LAST, QS_eqObj_, me)
00073                 QS_TIME_();                                    /* timestamp */
00074                 QS_SIG_(e->sig);                /* the signal of this event */
00075                 QS_OBJ_(me);                           /* this queue object */
00076                 QS_U8_(QF_EVT_POOL_ID_(e));     /* the pool Id of the event */
00077                 QS_U8_(QF_EVT_REF_CTR_(e));   /* the ref count of the event */
00078             QS_END_NOCRIT_()
00079         }
00080     }
00081     QF_CRIT_EXIT_();
00082     return e;
00083 }