set a specific amount of bits on the left side to a value - Java java.lang

Java examples for java.lang:byte Array Bit Operation

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Description

set a specific amount of bits on the left side to a value

Demo Code

/*******************************************************************************
 * Copyright 2015 SPECURE GmbH//ww  w.  java 2 s.co  m
 *
 * 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 com.java2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        byte b = 2;
        int bitlen = 2;
        int value = 2;
        System.out.println(setLeftBitsValue(b, bitlen, value));
    }

    /**
     * set a specific amount of bits on the left side to a value
     * @param b the byte
     * @param bitlen the amount of bits on the right side
     * @param value the new value
     * @return
     */
    public static byte setLeftBitsValue(byte b, int bitlen, int value) {
        final int bitmask = ~((0xff >> (8 - bitlen)) << (8 - bitlen));
        final int valueBitmask = ~((0xff >> bitlen) << bitlen);
        final byte r = (byte) ((b & bitmask) | (byte) (value & valueBitmask) << (8 - bitlen));
        return r;
    }
}

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