/*
	This file is part of Fennix Kernel.

	Fennix Kernel is free software: you can redistribute it and/or
	modify it under the terms of the GNU General Public License as
	published by the Free Software Foundation, either version 3 of
	the License, or (at your option) any later version.

	Fennix Kernel is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with Fennix Kernel. If not, see <https://www.gnu.org/licenses/>.
*/

#ifndef __FENNIX_KERNEL_STD_FUNCTIONAL_H__
#define __FENNIX_KERNEL_STD_FUNCTIONAL_H__

#include <types.h>
#include <assert.h>

namespace std
{
	template <typename Key>
	struct hash
	{
		size_t operator()(const Key &key) const
		{
			static_assert(sizeof(size_t) == sizeof(uint64_t)); // size_t and uint64_t must have the same size
			const uint64_t fnv_offset_basis = 14695981039346656037ull;
			const uint64_t fnv_prime = 1099511628211ull;

			const uint8_t *data = reinterpret_cast<const uint8_t *>(&key);
			const size_t size = sizeof(Key);
			uint64_t ret = fnv_offset_basis;

			for (size_t i = 0; i < size; ++i)
			{
				ret ^= static_cast<uint64_t>(data[i]);
				ret *= fnv_prime;
			}

			return static_cast<size_t>(ret);
		}
	};
}

#endif // !__FENNIX_KERNEL_STD_FUNCTIONAL_H__