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/*
* Copyright 2015 The Netty Project
*
* The Netty Project 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:
*
* 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 org.tio.utils.collection;
/**
* Math utility methods.
*
* @author netty
*/
final class MathUtil {
private MathUtil() {
}
/**
* Fast method of finding the next power of 2 greater than or equal to the supplied value.
*
* If the value is {@code <= 0} then 1 will be returned.
* This method is not suitable for {@link Integer#MIN_VALUE} or numbers greater than 2^30.
*
* @param value from which to search for next power of 2
* @return The next power of 2 or the value itself if it is a power of 2
*/
public static int findNextPositivePowerOfTwo(final int value) {
assert value > Integer.MIN_VALUE && value < 0x40000000;
return 1 << (32 - Integer.numberOfLeadingZeros(value - 1));
}
/**
* Fast method of finding the next power of 2 greater than or equal to the supplied value.
*
This method will do runtime bounds checking and call {@link #findNextPositivePowerOfTwo(int)} if within a
* valid range.
*
* @param value from which to search for next power of 2
* @return The next power of 2 or the value itself if it is a power of 2.
*
Special cases for return values are as follows:
*
* - {@code <= 0} = 1
* - {@code >= 2^30} = 2^30
*
*/
public static int safeFindNextPositivePowerOfTwo(final int value) {
return value <= 0 ? 1 : value >= 0x40000000 ? 0x40000000 : findNextPositivePowerOfTwo(value);
}
}