Java Unsigned Number Create unsignedLongToByteArray(final long value)

Description

unsigned Long To Byte Array

License

Open Source License

Declaration

public final static byte[] unsignedLongToByteArray(final long value)

Method Source Code

//package com.java2s;
/*/*from w w w  .j a  v  a 2  s .  c om*/
 * Part of the CCNx Java Library.
 *
 * Copyright (C) 2008-2012 Palo Alto Research Center, Inc.
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 * This library 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
 * Lesser General Public License for more details. You should have received
 * a copy of the GNU Lesser General Public License along with this library;
 * if not, write to the Free Software Foundation, Inc., 51 Franklin Street,
 * Fifth Floor, Boston, MA 02110-1301 USA.
 */

public class Main {
    /**
     * Convert a long value to a Big Endian byte array.  Assume
     * the long is not signed.
     *
     * This should be the equivalent of:
     *      byte [] b = BigInteger.valueOf(toBinaryTimeAsLong()).toByteArray();
     if( 0 == b[0] && b.length > 1 ) {
    byte [] bb = new byte[b.length - 1];
    System.arraycopy(b, 1, bb, 0, bb.length);
    b = bb;
     }
        
     */
    private final static byte[] _byte0 = { 0 };

    public final static byte[] unsignedLongToByteArray(final long value) {
        if (0 == value)
            return _byte0;

        if (0 <= value && value <= 0x00FF) {
            byte[] bb = new byte[1];
            bb[0] = (byte) (value & 0x00FF);
            return bb;
        }

        byte[] out = null;
        int offset = -1;
        for (int i = 7; i >= 0; --i) {
            byte b = (byte) ((value >> (i * 8)) & 0xFF);
            if (out == null && b != 0) {
                out = new byte[i + 1];
                offset = i;
            }
            if (out != null)
                out[offset - i] = b;
        }
        return out;
    }

    /**
     * Like unsignedLongToByteArray, except we specify what the first byte should be, so the
     * array is 1 byte longer than normal.  This is used by things that need a CommandMarker.
     *
     * If the value is 0, then the array will be 1 byte with only @fistByte.  The 0x00 byte
     * will not be included.
     */
    public final static byte[] unsignedLongToByteArray(final long value, final byte firstByte) {
        // A little bit of unwinding for common cases.
        // These hit a lot of the SegmentationProfile cases

        if (0 == value) {
            byte[] bb = new byte[1];
            bb[0] = firstByte;
            return bb;
        }

        if (0 <= value && value <= 0x00FF) {
            byte[] bb = new byte[2];
            bb[0] = firstByte;
            bb[1] = (byte) (value & 0x00FF);
            return bb;
        }

        if (0 <= value && value <= 0x0000FFFFL) {
            byte[] bb = new byte[3];
            bb[0] = firstByte;
            bb[1] = (byte) ((value >>> 8) & 0x00FF);
            bb[2] = (byte) (value & 0x00FF);
            return bb;
        }

        byte[] out = null;
        int offset = -1;
        for (int i = 7; i >= 0; --i) {
            byte b = (byte) ((value >> (i * 8)) & 0xFF);
            if (out == null && b != 0) {
                out = new byte[i + 2];
                offset = i;
            }
            if (out != null)
                out[offset - i + 1] = b;
        }
        out[0] = firstByte;
        return out;
    }
}

Java Unsigned Number Create unsignedLongToByteArray(final long value)

Description

License

Declaration

Method Source Code

Related