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// Copyright (C) 2018 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef HASH_H
#define HASH_H
#include <cstddef>
#include <cstdint>
#include <string>
namespace isc {
namespace util {
/// @brief Hash implementation based on Fowler-Noll-Vo hash function
///
struct Hash64 {
/// @brief Compute the hash
///
/// FNV-1a hash function
///
/// @param data data to hash
/// @param length length of data
/// @return the hash value
static uint64_t hash(const uint8_t* data, size_t length) {
uint64_t hash = FNV_offset_basis;
for (size_t i = 0; i < length; ++i) {
hash = hash ^ data[i];
hash = hash * FNV_prime;
}
return (hash);
}
/// @brief Compute the hash
///
/// FNV-1a hash function
///
/// @param str not empty string to hash
/// @return the hash value
static uint64_t hash(const std::string& str) {
return (hash(reinterpret_cast<const uint8_t*>(str.c_str()),
str.size()));
}
/// @brief Offset basis
static const uint64_t FNV_offset_basis = 14695981039346656037ull;
/// @brief Prime
static const uint64_t FNV_prime = 1099511628211ull;
};
} // end of namespace isc::util
} // end of namespace isc
#endif
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