Returns the closest power-of-two number greater than or equal to x. - Java java.lang

Java examples for java.lang:double Array

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Description

Returns the closest power-of-two number greater than or equal to x.

Demo Code

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 * The Original Code is Parallel Colt.
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 * The Initial Developer of the Original Code is
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//package com.java2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        int x = 2;
        System.out.println(nextPow2(x));
    }

    /**
     * Returns the closest power-of-two number greater than or equal to x.
     * 
     * @param x
     * @return the closest power-of-two number greater than or equal to x
     */
    public static int nextPow2(int x) {
        if (x < 1)
            throw new IllegalArgumentException(
                    "x must be greater or equal 1");
        if ((x & (x - 1)) == 0) {
            return x; // x is already a power-of-two number 
        }
        x |= (x >>> 1);
        x |= (x >>> 2);
        x |= (x >>> 4);
        x |= (x >>> 8);
        x |= (x >>> 16);
        x |= (x >>> 32);
        return x + 1;
    }
}

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