pw_rpc/java/main/dev/pigweed/pw_rpc/Ids.java

// Copyright 2021 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.

package dev.pigweed.pw_rpc;

import static java.nio.charset.StandardCharsets.UTF_8;

/** Calculates the service and method IDs. */
/* package */ class Ids {
  private static final int HASH_CONSTANT = 65599;

  private Ids() {}

  public static int calculate(byte[] string) {
    int hash = string.length;
    int coefficient = HASH_CONSTANT;

    for (byte b : string) {
      hash += coefficient * b;
      coefficient *= HASH_CONSTANT;
    }

    return hash;
  }

  public static int calculate(String string) {
    return calculate(string.getBytes(UTF_8));
  }
}