/*
* 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
*
* 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.
*/
package org.jctools_voltpatches.util;
/**
* Power of 2 utility functions.
*/
public final class Pow2 {
public static final int MAX_POW2 = 1 << 30;
private Pow2() {
}
/**
* @param value from which next positive power of two will be found.
* @return the next positive power of 2, this value if it is a power of 2. Negative values are mapped to 1.
* @throws IllegalArgumentException is value is more than MAX_POW2
*/
public static int roundToPowerOfTwo(final int value) {
if (value > MAX_POW2) {
throw new IllegalArgumentException("There is no larger power of 2 int for value:"+value+" since it exceeds 2^31.");
}
final int nextPow2 = 1 << (32 - Integer.numberOfLeadingZeros(value - 1));
return nextPow2;
}
/**
* @param value to be tested to see if it is a power of two.
* @return true if the value is a power of 2 otherwise false.
*/
public static boolean isPowerOfTwo(final int value) {
return (value & (value - 1)) == 0;
}
/**
* Align a value to the next multiple up of alignment. If the value equals an alignment multiple then it
* is returned unchanged.
*
* @param value to be aligned up.
* @param alignment to be used, must be a power of 2.
* @return the value aligned to the next boundary.
*/
public static long align(final long value, final int alignment) {
if (!isPowerOfTwo(alignment)) {
throw new IllegalArgumentException("alignment must be a power of 2:" + alignment);
}
return (value + (alignment - 1)) & ~(alignment - 1);
}
}