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// Copyright 2021-2023 Peter Dimov
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#ifndef BOOST_HASH_DETAIL_HASH_INTEGRAL_HPP
#define BOOST_HASH_DETAIL_HASH_INTEGRAL_HPP
#include <boost/container_hash/detail/hash_mix.hpp>
#include <type_traits>
#include <cstddef>
#include <climits>
namespace boost
{
namespace hash_detail
{
// libstdc++ doesn't provide support for __int128 in the standard traits
template<class T> struct is_integral: public std::is_integral<T>
{
};
template<class T> struct is_unsigned: public std::is_unsigned<T>
{
};
template<class T> struct make_unsigned: public std::make_unsigned<T>
{
};
#if defined(__SIZEOF_INT128__)
template<> struct is_integral<__int128_t>: public std::true_type
{
};
template<> struct is_integral<__uint128_t>: public std::true_type
{
};
template<> struct is_unsigned<__int128_t>: public std::false_type
{
};
template<> struct is_unsigned<__uint128_t>: public std::true_type
{
};
template<> struct make_unsigned<__int128_t>
{
typedef __uint128_t type;
};
template<> struct make_unsigned<__uint128_t>
{
typedef __uint128_t type;
};
#endif
template<class T,
bool bigger_than_size_t = (sizeof(T) > sizeof(std::size_t)),
bool is_unsigned = is_unsigned<T>::value,
std::size_t size_t_bits = sizeof(std::size_t) * CHAR_BIT,
std::size_t type_bits = sizeof(T) * CHAR_BIT>
struct hash_integral_impl;
template<class T, bool is_unsigned, std::size_t size_t_bits, std::size_t type_bits> struct hash_integral_impl<T, false, is_unsigned, size_t_bits, type_bits>
{
static std::size_t fn( T v )
{
return static_cast<std::size_t>( v );
}
};
template<class T, std::size_t size_t_bits, std::size_t type_bits> struct hash_integral_impl<T, true, false, size_t_bits, type_bits>
{
static std::size_t fn( T v )
{
typedef typename make_unsigned<T>::type U;
if( v >= 0 )
{
return hash_integral_impl<U>::fn( static_cast<U>( v ) );
}
else
{
return ~hash_integral_impl<U>::fn( static_cast<U>( ~static_cast<U>( v ) ) );
}
}
};
template<class T> struct hash_integral_impl<T, true, true, 32, 64>
{
static std::size_t fn( T v )
{
std::size_t seed = 0;
seed = static_cast<std::size_t>( v >> 32 ) + hash_detail::hash_mix( seed );
seed = static_cast<std::size_t>( v & 0xFFFFFFFF ) + hash_detail::hash_mix( seed );
return seed;
}
};
template<class T> struct hash_integral_impl<T, true, true, 32, 128>
{
static std::size_t fn( T v )
{
std::size_t seed = 0;
seed = static_cast<std::size_t>( v >> 96 ) + hash_detail::hash_mix( seed );
seed = static_cast<std::size_t>( v >> 64 ) + hash_detail::hash_mix( seed );
seed = static_cast<std::size_t>( v >> 32 ) + hash_detail::hash_mix( seed );
seed = static_cast<std::size_t>( v ) + hash_detail::hash_mix( seed );
return seed;
}
};
template<class T> struct hash_integral_impl<T, true, true, 64, 128>
{
static std::size_t fn( T v )
{
std::size_t seed = 0;
seed = static_cast<std::size_t>( v >> 64 ) + hash_detail::hash_mix( seed );
seed = static_cast<std::size_t>( v ) + hash_detail::hash_mix( seed );
return seed;
}
};
} // namespace hash_detail
template <typename T>
typename std::enable_if<hash_detail::is_integral<T>::value, std::size_t>::type
hash_value( T v )
{
return hash_detail::hash_integral_impl<T>::fn( v );
}
} // namespace boost
#endif // #ifndef BOOST_HASH_DETAIL_HASH_INTEGRAL_HPP
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