common/include/ceiling_power_of_2.hpp

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *
 *   http://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.
 */

#ifndef CEILING_POWER_OF_2_HPP_
#define CEILING_POWER_OF_2_HPP_

#include <cstdint>

namespace datasketches {

// compute the next highest power of 2 of 32-bit n
// taken from https://graphics.stanford.edu/~seander/bithacks.html
static inline uint32_t ceiling_power_of_2(uint32_t n) {
  --n;
  n |= n >> 1;
  n |= n >> 2;
  n |= n >> 4;
  n |= n >> 8;
  n |= n >> 16;
  return ++n;
}

} /* namespace datasketches */

#endif // CEILING_POWER_OF_2_HPP_