Java BitSet Convert bitSet2byte(BitSet b)

Description

converts a BitSet into a binary field used in pack routines This method will set bits 0 (and 65) if there's a secondary (and tertiary) bitmap (i.e., if the bitmap length is > 64 (and > 128))

License

Open Source License

Parameter

Parameter	Description
b	- the BitSet

Return

binary representation

Declaration

public static byte[] bitSet2byte(BitSet b)

Method Source Code

//package com.java2s;
/*//from   w w w .  j  a v a  2  s . c  o  m
 * jPOS Project [http://jpos.org]
 * Copyright (C) 2000-2019 jPOS Software SRL
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.util.*;

public class Main {
    /**
     * converts a BitSet into a binary field
     * used in pack routines
     *
     * This method will set bits 0 (and 65) if there's a secondary (and tertiary) bitmap
     * (i.e., if the bitmap length is > 64 (and > 128))
     *
     * @param b - the BitSet
     * @return binary representation
     */
    public static byte[] bitSet2byte(BitSet b) {
        int len = b.length() + 62 >> 6 << 6; // +62 because we don't use bit 0 in the BitSet
        byte[] d = new byte[len >> 3];
        for (int i = 0; i < len; i++)
            if (b.get(i + 1)) // +1 because we don't use bit 0 of the BitSet
                d[i >> 3] |= 0x80 >> i % 8;
        if (len > 64)
            d[0] |= 0x80;
        if (len > 128)
            d[8] |= 0x80;
        return d;
    }

    /**
     * converts a BitSet into a binary field
     * used in pack routines
     *
     * This method will set bits 0 (and 65) if there's a secondary (and tertiary) bitmap
     * (i.e., if the bitmap length is > 64 (and > 128))
     *
     * @param b - the BitSet
     * @param bytes - number of bytes to return
     * @return binary representation
     */
    public static byte[] bitSet2byte(BitSet b, int bytes) {
        int len = bytes * 8;

        byte[] d = new byte[bytes];
        for (int i = 0; i < len; i++)
            if (b.get(i + 1)) // +1 because we don't use bit 0 of the BitSet
                d[i >> 3] |= 0x80 >> i % 8;
        //TODO: review why 2nd & 3rd bit map flags are set here??? 
        if (len > 64)
            d[0] |= 0x80;
        if (len > 128)
            d[8] |= 0x80;
        return d;
    }
}