libcruft-util/hash/bsdsum.cpp

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/*
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* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
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* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
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* Copyright 2010 Danny Robson <danny@nerdcruft.net>
*/
#include "bsdsum.hpp"
#include "../debug.hpp"
///////////////////////////////////////////////////////////////////////////////
uint16_t
util::hash::bsdsum (
const uint8_t *const restrict first,
const uint8_t *const restrict last
) {
CHECK_LE (first, last);
uint16_t accum = 0;
for (auto cursor = first; cursor != last; ++cursor) {
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accum = (accum >> 1u) | ((accum & 0x01u) << 15u);
accum += *cursor;
}
return accum;
}
///////////////////////////////////////////////////////////////////////////////
uint16_t
util::hash::bsdsum (const void *restrict data, size_t size)
{
return bsdsum (
static_cast<const uint8_t*> (data),
static_cast<const uint8_t*> (data) + size
);
}