45 lines
1.3 KiB
C++
45 lines
1.3 KiB
C++
/*
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* This file is part of libgim.
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*
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* libgim is free software: you can redistribute it and/or modify it under the
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* terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* libgim 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 General Public License for more
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* 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 libgim. If not, see <http://www.gnu.org/licenses/>.
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*
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* Copyright 2010 Danny Robson <danny@blubinc.net>
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*/
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#ifndef __UTIL_FLETCHER_HPP
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#define __UTIL_FLETCHER_HPP
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#include "types.hpp"
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#include <cstdint>
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#include <cstdlib>
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template <unsigned BITS, unsigned MODULUS, unsigned INITIAL_A, unsigned INITIAL_B>
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typename bits_type<BITS>::uint
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fletcher (const void *restrict _data, size_t size) {
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const uint8_t *restrict data = static_cast<const uint8_t*> (_data);
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typename bits_type<BITS>::uint A = INITIAL_A,
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B = INITIAL_B;
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for (size_t i = 0; i < size; ++i) {
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A = (A + data[i]) % MODULUS;
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B = (A + B) % MODULUS;
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}
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return (B << (BITS / 2)) | A;
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}
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#endif
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