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72 lines
1.9 KiB
C++
72 lines
1.9 KiB
C++
/*******************************************************************************
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COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2012.
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COPYRIGHT(C) KRZYSZTOF DABROWSKI 1999, 2000.
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COPYRIGHT(C) ElysiuM deeZine 1999, 2000.
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Based on implementation by Finn Yannick Jacobs.
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This file is part of LibMaxsi.
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LibMaxsi is free software: you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License as published by the Free
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Software Foundation, either version 3 of the License, or (at your option)
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any later version.
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LibMaxsi is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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details.
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You should have received a copy of the GNU Lesser General Public License
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along with LibMaxsi. If not, see <http://www.gnu.org/licenses/>.
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crc32.cpp
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Calculates a CRC32 Checksum of binary data.
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*******************************************************************************/
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#include <libmaxsi/platform.h>
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#include <libmaxsi/crc32.h>
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namespace Maxsi {
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namespace CRC32 {
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void GenerateTable(uint32_t tabel[256])
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{
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uint32_t poly = 0xEDB88320U;
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for ( uint32_t i = 0; i < 256; i++ )
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{
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uint32_t crc = i;
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for ( uint32_t j = 8; 0 < j; j-- )
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{
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if ( crc & 1 ) { crc = (crc >> 1) ^ poly; }
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else { crc >>= 1; }
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}
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tabel[i] = crc;
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}
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}
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uint32_t Continue(uint32_t tabel[256], uint32_t crc, uint8_t* block,
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size_t size)
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{
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for ( size_t i = 0; i < size; i++ )
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{
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crc = ((crc >> 8) & 0x00FFFFFF) ^ tabel[(crc ^ *block++) & 0xFF];
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}
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return crc;
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}
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uint32_t Finish(uint32_t crc)
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{
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return crc ^ 0xFFFFFFFF;
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}
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uint32_t Hash(uint8_t* block, size_t size)
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{
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uint32_t tabel[256];
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GenerateTable(tabel);
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return Finish(Continue(tabel, START_SEED, block, size));
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}
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} // namespace CRC32
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} // namespace Maxsi
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