pw_kvs/public/pw_kvs/internal/hash.h

// Copyright 2020 The Pigweed Authors
//
// 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
//
//     https://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.
#pragma once

#include <cstddef>

#include "pw_kvs/key.h"

namespace pw {
namespace kvs {
namespace internal {

// The hash function used to hash keys.
constexpr uint32_t Hash(Key string) {
  uint32_t hash = 0;
  uint32_t coefficient = 65599u;

  for (char ch : string) {
    hash += coefficient * uint32_t(ch);
    coefficient *= 65599u;
  }

  return hash;
}

}  // namespace internal
}  // namespace kvs
}  // namespace pw