51 lines
1.2 KiB
C++
51 lines
1.2 KiB
C++
/*
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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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* Copyright 2010 Danny Robson <danny@nerdcruft.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/bits.hpp"
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#include <cstdint>
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#include <cstdlib>
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template <
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unsigned OUTPUT,
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unsigned MODULUS,
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unsigned INITIAL_A,
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unsigned INITIAL_B
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>
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typename bits_type<OUTPUT>::uint
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fletcher (const void *restrict _data,
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size_t size)
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{
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typedef typename bits_type<OUTPUT / 2>::uint temp_t;
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auto data = static_cast<const uint8_t*> (_data);
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temp_t A = INITIAL_A, 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 << (OUTPUT / 2u)) + A;
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}
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#endif
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