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78 lines
2.0 KiB
C++
78 lines
2.0 KiB
C++
/***************************************************************************
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*
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* Project _____ __ ____ _ _
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* ( _ ) /__\ (_ _)_| |_ _| |_
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* )(_)( /(__)\ )( (_ _)(_ _)
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* (_____)(__)(__)(__) |_| |_|
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*
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*
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* Copyright 2018-present, Leonid Stryzhevskyi, <lganzzzo@gmail.com>
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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***************************************************************************/
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#include "CRC.hpp"
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namespace oatpp { namespace algorithm {
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const p_word32 CRC32::TABLE_04C11DB7 = generateTable(0x04C11DB7);
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v_word32 CRC32::bitReverse(v_word32 poly) {
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v_word32 result = 0;
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for(v_int32 i = 0; i < 32; i ++) {
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if((poly & (1 << i)) > 0) {
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result |= 1 << (31 - i);
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}
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}
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return result;
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}
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p_word32 CRC32::generateTable(v_word32 poly) {
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p_word32 result = new v_word32[256];
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v_word32 polyReverse = bitReverse(poly);
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v_word32 value;
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for(v_int32 i = 0; i < 256; i++) {
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value = i;
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for (v_int32 bit = 0; bit < 8; bit++) {
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if (value & 1) {
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value = (value >> 1) ^ polyReverse;
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} else {
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value = (value >> 1);
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}
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}
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result[i] = value;
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}
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return result;
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}
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v_word32 CRC32::calc(const void *buffer, v_int32 size, v_word32 crc, v_word32 initValue, v_word32 xorOut, p_word32 table) {
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p_word8 data = (p_word8) buffer;
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crc = crc ^ initValue;
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for(v_int32 i = 0; i < size; i++) {
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crc = table[(crc & 0xFF) ^ data[i]] ^ (crc >> 8);
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}
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return crc ^ xorOut;
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}
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}}
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