57 lines
1.6 KiB
C++
57 lines
1.6 KiB
C++
// MassBuilderSaveTool
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// Copyright (C) 2021-2024 Guillaume Jacquemin
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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#include "Crc32.h"
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namespace mbst { namespace Utilities {
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std::uint32_t
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crc32(std::uint32_t initial, Containers::ArrayView<const void> data) {
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static const auto table = []{
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std::uint32_t polynomial = 0xEDB88320u;
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Containers::StaticArray<256, std::uint32_t> temp{ValueInit};
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for(std::uint32_t i = 0; i < 256; i++) {
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std::uint32_t c = i;
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for(std::size_t j = 0; j < 8; j++) {
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if(c & 1) {
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c = polynomial ^ (c >> 1);
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}
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else {
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c >>= 1;
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}
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}
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temp[i] = c;
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}
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return temp;
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}();
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std::uint32_t c = initial ^ 0xFFFFFFFF;
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auto u = Containers::arrayCast<const std::uint8_t>(data);
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for(std::size_t i = 0; i < data.size(); ++i) {
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c = table[(c ^ u[i]) & 0xFF] ^ (c >> 8);
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}
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return c ^ 0xFFFFFFFF;
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}
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}}
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