/* 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.activiti.engine.impl.util;
/**
* Util class for manipulating bit-flag in ints.
*
* Currently, only 8-bits are supporten, but can be extended to use all
* 31 bits in the integer (1st of 32 bits is used for sign).
*
* @author Frederik Heremans
*/
public class BitMaskUtil {
// First 8 masks as constant to prevent having to math.pow() every time a bit needs flippin'.
private static final int FLAG_BIT_1 = 1; // 000...00000001
private static final int FLAG_BIT_2 = 2; // 000...00000010
private static final int FLAG_BIT_3 = 4; // 000...00000100
private static final int FLAG_BIT_4 = 8; // 000...00001000
private static final int FLAG_BIT_5 = 16; // 000...00010000
private static final int FLAG_BIT_6 = 32; // 000...00100000
private static final int FLAG_BIT_7 = 64; // 000...01000000
private static final int FLAG_BIT_8 = 128; // 000...10000000
private static int[] MASKS = {FLAG_BIT_1, FLAG_BIT_2, FLAG_BIT_3, FLAG_BIT_4, FLAG_BIT_5, FLAG_BIT_6, FLAG_BIT_7, FLAG_BIT_8};
/**
* Set bit to '1' in the given int.
* @param current integer value
* @param bitNumber number of the bit to set to '1' (right first bit starting at 1).
*/
public static int setBitOn(int value, int bitNumber) {
if(bitNumber <= 0 && bitNumber > 8) {
throw new IllegalArgumentException("Only bits 1 htrough 8 are supported");
}
// To turn on, OR with the correct mask
return value | MASKS[bitNumber - 1];
}
/**
* Set bit to '0' in the given int.
* @param current integer value
* @param bitNumber number of the bit to set to '0' (right first bit starting at 1).
*/
public static int setBitOff(int value, int bitNumber) {
if(bitNumber <= 0 && bitNumber > 8) {
throw new IllegalArgumentException("Only bits 1 htrough 8 are supported");
}
// To turn on, OR with the correct mask
return value &~MASKS[bitNumber - 1];
}
/**
* Check if the bit is set to '1'
* @param value integer to check bit
* @param number of bit to check (right first bit starting at 1)
*/
public static boolean isBitOn(int value, int bitNumber) {
if(bitNumber <= 0 && bitNumber > 8) {
throw new IllegalArgumentException("Only bits 1 htrough 8 are supported");
}
return ((value & MASKS[bitNumber - 1]) == MASKS[bitNumber - 1]);
}
/**
* Set bit to '0' or '1' in the given int.
* @param current integer value
* @param bitNumber number of the bit to set to '0' or '1' (right first bit starting at 1).
* @param bitValue if true, bit set to '1'. If false, '0'.
*/
public static int setBit(int value, int bitNumber, boolean bitValue)
{
if(bitValue) {
return setBitOn(value, bitNumber);
} else {
return setBitOff(value, bitNumber);
}
}
}