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/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtNfc module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation and
** appearing in the file LICENSE.LGPL included in the packaging of this
** file. Please review the following information to ensure the GNU Lesser
** General Public License version 2.1 requirements will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef CHECKSUM_P_H
#define CHECKSUM_P_H
// Copied from qbytearray.cpp
// Modified to initialise the crc with 0x6363 instead of 0xffff and to not invert the final result.
static const quint16 crc_tbl[16] = {
0x0000, 0x1081, 0x2102, 0x3183,
0x4204, 0x5285, 0x6306, 0x7387,
0x8408, 0x9489, 0xa50a, 0xb58b,
0xc60c, 0xd68d, 0xe70e, 0xf78f
};
quint16 qNfcChecksum(const char *data, uint len)
{
register quint16 crc = 0x6363;
uchar c;
const uchar *p = reinterpret_cast<const uchar *>(data);
while (len--) {
c = *p++;
crc = ((crc >> 4) & 0x0fff) ^ crc_tbl[((crc ^ c) & 15)];
c >>= 4;
crc = ((crc >> 4) & 0x0fff) ^ crc_tbl[((crc ^ c) & 15)];
}
return crc;
}
#endif // CHECKSUM_P_H
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