qs_blk.cpp

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// Product: QS/C++
// Last Updated for Version: 4.4.00
// Date of the Last Update:  Mar 28, 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 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 2 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:
// Quantum Leaps Web sites: http://www.quantum-leaps.com
//                          http://www.state-machine.com
// e-mail:                  info@quantum-leaps.com
#include "qs_pkg.h"


QP_BEGIN_

//............................................................................
// get up to *pn bytes of contiguous memory
uint8_t const *QS::getBlock(uint16_t * const pNbytes) {
    uint8_t *block;
    if (QS_used_ == static_cast<QSCtr>(0)) {
        *pNbytes = static_cast<uint16_t>(0);
        block = static_cast<uint8_t *>(0);     // no bytes to return right now
    }
    else {
        QSCtr n = static_cast<QSCtr>(QS_end_ - QS_tail_);
        if (n > QS_used_) {
            n = QS_used_;
        }
        if (n > static_cast<QSCtr>(*pNbytes)) {
            n = static_cast<QSCtr>(*pNbytes);
        }
        *pNbytes = static_cast<uint16_t>(n);
        QS_used_ = static_cast<QSCtr>(QS_used_ - n);
        QSCtr t  = QS_tail_;
        QS_tail_ = static_cast<QSCtr>(QS_tail_ + n);
        if (QS_tail_ == QS_end_) {
            QS_tail_ = static_cast<QSCtr>(0);
        }
        block = &QS_PTR_AT_(t);
    }
    return block;
}

QP_END_