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76ee07f61c
Co-authored-by: Alexander Trofimov <alexander.trofimov@onlyoffice.com> Co-committed-by: Alexander Trofimov <alexander.trofimov@onlyoffice.com>
94 lines
2.7 KiB
C++
94 lines
2.7 KiB
C++
/*
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* Copyright (C) Ascensio System SIA, 2009-2026
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*
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* This program is a free software product. You can redistribute it and/or
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* modify it under the terms of the GNU Affero General Public License (AGPL)
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* version 3 as published by the Free Software Foundation, together with the
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* additional terms provided in the LICENSE file.
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*
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* This program is distributed WITHOUT ANY WARRANTY; without even the implied
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. For
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* details, see the GNU AGPL at: https://www.gnu.org/licenses/agpl-3.0.html
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*
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* You can contact Ascensio System SIA by email at info@onlyoffice.com
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* or by postal mail at 20A-6 Ernesta Birznieka-Upisha Street, Riga,
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* LV-1050, Latvia, European Union.
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*
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* The interactive user interfaces in modified versions of the Program
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* are required to display Appropriate Legal Notices in accordance with
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* Section 5 of the GNU AGPL version 3.
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*
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* No trademark rights are granted under this License.
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*
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* All non-code elements of the Product, including illustrations,
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* icon sets, and technical writing content, are licensed under the
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* Creative Commons Attribution-ShareAlike 4.0 International License:
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* https://creativecommons.org/licenses/by-sa/4.0/legalcode
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*
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* This license applies only to such non-code elements and does not
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* modify or replace the licensing terms applicable to the Program's
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* source code, which remains licensed under the GNU Affero General
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* Public License v3.
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*
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* SPDX-License-Identifier: AGPL-3.0-only
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*/
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#ifndef _ASC_COMMON_CALCULATOR_CRC32_
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#define _ASC_COMMON_CALCULATOR_CRC32_
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#include <string>
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const int g_clFilePartSize = 20 * 1024;
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class CCalculatorCRC32
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{
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public:
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CCalculatorCRC32()
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{
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m_dwMagicWord = 0xEDB88320;
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m_dwInitCrc = 0xFFFFFFFF;
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m_bInitTable = false;
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}
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public:
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unsigned int Calc(const unsigned char* pStream, unsigned int nSize)
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{
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InitCRCTable();
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unsigned int dwRes = m_dwInitCrc;
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for (unsigned int i = 0; i < nSize; i++)
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{
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dwRes = m_arCRCTable[(dwRes ^ pStream[i]) & 0xFF] ^ (dwRes >> 8);
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}
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dwRes = dwRes ^ 0xFFFFFFFF;
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return dwRes;
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}
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private:
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void InitCRCTable()
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{
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if (m_bInitTable)
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return;
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unsigned int dwTemp;
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for (int i = 0; i < 256; i++)
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{
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dwTemp = i;
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for (int j = 0; j < 8; j++)
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{
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if (0x1 == (dwTemp & 0x1))
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dwTemp = (dwTemp >> 1) ^ m_dwMagicWord;
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else
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dwTemp = dwTemp >> 1;
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}
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m_arCRCTable[i] = dwTemp;
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}
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m_bInitTable = true;
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}
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unsigned int m_dwMagicWord;
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unsigned int m_dwInitCrc;
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unsigned int m_arCRCTable[255];
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bool m_bInitTable;
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};
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#endif // _ASC_COMMON_CALCULATOR_CRC32_
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