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/****************************************************************************
* Copyright (C) from 2009 to Present EPAM Systems.
*
* This file is part of Indigo toolkit.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
***************************************************************************/
#include <string.h>
#include "base_c/defs.h"
#include "base_cpp/crc32.h"
using namespace indigo;
CRC32 _crc; // singletone
unsigned _Reflect(unsigned ref, char ch)
{
unsigned value = 0;
// swap bits 0-7, 1-6, ...
for (int i = 1; i <= ch; i++)
{
if (ref & 1)
value |= 1 << (ch - i);
ref >>= 1;
}
return value;
}
CRC32::CRC32()
{
int i, polynom = 0x04c11db7; // used in PKZip, WinZip, and Ethernet.
for (i = 0; i < 256; i++)
{
_table[i] = _Reflect(i, 8) << 24;
for (int j = 0; j < 8; j++)
_table[i] = (_table[i] << 1) ^ (_table[i] & (1 << 31) ? polynom : 0);
_table[i] = _Reflect(_table[i], 32);
}
}
CRC32::~CRC32()
{
}
unsigned CRC32::get(const char* text)
{
unsigned code = 0xffffffff;
while (*text != 0)
{
code = (code >> 8) ^ _crc._table[(code & 0xFF) ^ ((byte)*text)];
text++;
}
return code ^ 0xffffffff;
}
unsigned CRC32::get(const char* text, int len)
{
unsigned code = 0xffffffff;
for (int i = 0; i < len; i++)
code = (code >> 8) ^ _crc._table[(code & 0xFF) ^ ((byte)text[i])];
return code ^ 0xffffffff;
}
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