Java ByteBuffer Shift leftShift(final ByteBuffer buffer, int shift)

Description

left Shift

License

Apache License

Declaration

public static ByteBuffer leftShift(final ByteBuffer buffer, int shift) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.util.Arrays;

public class Main {
    private static final byte BYTE_LENGTH = 8;

    public static ByteBuffer leftShift(final ByteBuffer buffer, int shift) {
        final BigInteger bigInt = new BigInteger(buffer.array());
        final byte[] shiftedBytes = bigInt.shiftLeft(shift).and(allOnes((buffer.remaining()) * BYTE_LENGTH))
                .toByteArray();/*from  w  ww .j av  a 2 s  . co m*/
        final int resultLength = buffer.capacity();
        final int sourceOffset = resultLength >= shiftedBytes.length ? 0 : 1;
        final int destinationOffset = resultLength - shiftedBytes.length > 0 ? resultLength - shiftedBytes.length
                : 0;
        Arrays.fill(buffer.array(), (byte) 0);
        System.arraycopy(shiftedBytes, sourceOffset, buffer.array(), destinationOffset,
                shiftedBytes.length - sourceOffset);
        return buffer;
    }

    private static BigInteger allOnes(final int length) {
        return BigInteger.ZERO.setBit(length).subtract(BigInteger.ONE);
    }
}

Related

1. shift(ByteBuffer buffer, int distance)