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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:
 *
 * 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 io.netty.util.internal;

/**
 * Math utility methods.
 */
public 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); } /** * Determine if the requested {@code index} and {@code length} will fit within {@code capacity}. * @param index The starting index. * @param length The length which will be utilized (starting from {@code index}). * @param capacity The capacity that {@code index + length} is allowed to be within. * @return {@code true} if the requested {@code index} and {@code length} will fit within {@code capacity}. * {@code false} if this would result in an index out of bounds exception. */ public static boolean isOutOfBounds(int index, int length, int capacity) { return (index | length | (index + length) | (capacity - (index + length))) < 0; } /** * Compares two {@code int} values. * * @param x the first {@code int} to compare * @param y the second {@code int} to compare * @return the value {@code 0} if {@code x == y}; * {@code -1} if {@code x < y}; and * {@code 1} if {@code x > y} */ public static int compare(final int x, final int y) { // do not subtract for comparison, it could overflow return x < y ? -1 : (x > y ? 1 : 0); } /** * Compare two {@code long} values. * @param x the first {@code long} to compare. * @param y the second {@code long} to compare. * @return *
    *
  • 0 if {@code x == y}
  • *
  • {@code > 0} if {@code x > y}
  • *
  • {@code < 0} if {@code x < y}
  • *
*/ public static int compare(long x, long y) { return (x < y) ? -1 : (x > y) ? 1 : 0; } }




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