mirror of
https://github.com/RGBCube/serenity
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85 lines
2.4 KiB
C++
85 lines
2.4 KiB
C++
/*
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* Copyright (c) 2020, the SerenityOS developers
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/Span.h>
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#include <AK/Types.h>
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#include <LibCrypto/Checksum/ChecksumFunction.h>
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namespace Crypto::Checksum {
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struct Table {
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u32 data[256];
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constexpr Table()
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: data()
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{
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for (auto i = 0; i < 256; i++) {
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u32 value = i;
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for (auto j = 0; j < 8; j++) {
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if (value & 1) {
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value = 0xEDB88320 ^ (value >> 1);
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} else {
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value = value >> 1;
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}
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}
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data[i] = value;
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}
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}
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constexpr u32 operator[](int index) const
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{
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return data[index];
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}
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};
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constexpr static auto table = Table();
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class CRC32 : public ChecksumFunction<u32> {
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public:
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CRC32() { }
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CRC32(ReadonlyBytes data)
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{
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update(data);
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}
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CRC32(u32 initial_state, ReadonlyBytes data)
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: m_state(initial_state)
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{
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update(data);
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}
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void update(ReadonlyBytes data);
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u32 digest();
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private:
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u32 m_state { ~0u };
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};
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}
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