libcruft-util/hash/fletcher.cpp
Danny Robson 34788756d2 build: don't use './' as an include prefix
GCC produces ODR error when including paths of the form './foo' and
'foo' in the same binary. Rather than managing duplication we just
universally pick the absolute form over the relative form.
2017-11-22 16:49:37 +11:00

90 lines
2.3 KiB
C++

/*
* 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
*
* 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.
*
* Copyright 2010 Danny Robson <danny@nerdcruft.net>
*/
#include "fletcher.hpp"
#include "../debug.hpp"
using util::hash::fletcher;
///////////////////////////////////////////////////////////////////////////////
template <typename T>
fletcher<T>::fletcher (part_t _modulus, part_t _a, part_t _b):
m_modulus { _modulus },
m_initial { _a, _b },
m_state { m_initial }
{ ; }
//-----------------------------------------------------------------------------
template <typename T>
void
fletcher<T>::reset (void)
{
m_state = m_initial;
}
///////////////////////////////////////////////////////////////////////////////
template <typename T>
void
fletcher<T>::update (const void *restrict data, size_t size) noexcept
{
CHECK (data);
auto first = static_cast<const uint8_t *restrict> (data);
update (first, first + size);
}
//-----------------------------------------------------------------------------
template <typename T>
void
fletcher<T>::update (const uint8_t *restrict first, const uint8_t *restrict last) noexcept
{
CHECK (first);
CHECK (last);
CHECK_LE (first, last);
for (auto cursor = first; cursor < last; ++cursor) {
m_state.a = (m_state.a + *cursor ) % m_modulus;
m_state.b = (m_state.a + m_state.b) % m_modulus;
}
}
//-----------------------------------------------------------------------------
template <typename T>
void
fletcher<T>::finish (void)
{ ; }
///////////////////////////////////////////////////////////////////////////////
template <typename T>
typename fletcher<T>::digest_t
fletcher<T>::digest (void) const
{
return (m_state.b << (sizeof (part_t) * 8)) + m_state.a;
}
///////////////////////////////////////////////////////////////////////////////
template class util::hash::fletcher<uint32_t>;