Java Bit Count countBitsInMask(int mask)

Description

count Bits In Mask

License

Open Source License

Declaration

public static int countBitsInMask(int mask) 

Method Source Code

//package com.java2s;
/*//  w  w w.  j  a v  a 2 s .  c o m
 *    Qizx/open 4.1
 *
 * This code is the open-source version of Qizx.
 * Copyright (C) 2004-2009 Axyana Software -- All rights reserved.
 *
 * The contents of this file are subject to the Mozilla Public License 
 *  Version 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 *  WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 *  for the specific language governing rights and limitations under the
 *  License.
 *
 * The Initial Developer of the Original Code is Xavier Franc - Axyana Software.
 *
 */

public class Main {
    public static int countBitsInMask(int mask) {
        switch (mask) {
        case -1:
            return 32;
        case 0:
            return 0;
        case 1:
        case 2:
        case 4:
        case 8:
            return 1;
        case 3:
        case 5:
        case 6:
            return 2;
        case 7:
            return 3;
        default:
            int count = 0;
            for (; mask != 0;) {
                if ((mask & 1) != 0)
                    ++count;
                mask >>>= 1;
            }
            return count;
        }
    }
}

Related

1. countBits(int n)
2. countBits(int x)
3. countBits(int x)
4. countBits(long num)
5. countBits(long value)
6. countBitsNeeded(int value)
7. countBitsSet(int bitfield)