Memory.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.taobao.common.ziputil;

import java.nio.ByteOrder;

public final class Memory {
    private Memory() { }

    public static int peekInt(byte[] src, int offset, ByteOrder order) {
        if (order == ByteOrder.BIG_ENDIAN) {
            return (((src[offset++] & 0xff) << 24)
                    | ((src[offset++] & 0xff) << 16)
                    | ((src[offset++] & 0xff) <<  8)
                    | ((src[offset  ] & 0xff) <<  0));
        } else {
            return (((src[offset++] & 0xff) <<  0)
                    | ((src[offset++] & 0xff) <<  8)
                    | ((src[offset++] & 0xff) << 16)
                    | ((src[offset  ] & 0xff) << 24));
        }
    }
    public static long peekLong(byte[] src, int offset, ByteOrder order) {
        if (order == ByteOrder.BIG_ENDIAN) {
            int h = ((src[offset++] & 0xff) << 24)
                    | ((src[offset++] & 0xff) << 16)
                    | ((src[offset++] & 0xff) <<  8)
                    | ((src[offset++] & 0xff) <<  0);
            int l = ((src[offset++] & 0xff) << 24)
                    | ((src[offset++] & 0xff) << 16)
                    | ((src[offset++] & 0xff) <<  8)
                    | ((src[offset  ] & 0xff) <<  0);
            return (((long) h) << 32L) | ((long) l) & 0xffffffffL;
        } else {
            int l = ((src[offset++] & 0xff) <<  0)
                    | ((src[offset++] & 0xff) <<  8)
                    | ((src[offset++] & 0xff) << 16)
                    | ((src[offset++] & 0xff) << 24);
            int h = ((src[offset++] & 0xff) <<  0)
                    | ((src[offset++] & 0xff) <<  8)
                    | ((src[offset++] & 0xff) << 16)
                    | ((src[offset  ] & 0xff) << 24);
            return (((long) h) << 32L) | ((long) l) & 0xffffffffL;
        }
    }
    public static short peekShort(byte[] src, int offset, ByteOrder order) {
        if (order == ByteOrder.BIG_ENDIAN) {
            return (short) ((src[offset] << 8) | (src[offset + 1] & 0xff));
        } else {
            return (short) ((src[offset + 1] << 8) | (src[offset] & 0xff));
        }
    }
    public static void pokeInt(byte[] dst, int offset, int value, ByteOrder order) {
        if (order == ByteOrder.BIG_ENDIAN) {
            dst[offset++] = (byte) ((value >> 24) & 0xff);
            dst[offset++] = (byte) ((value >> 16) & 0xff);
            dst[offset++] = (byte) ((value >>  8) & 0xff);
            dst[offset  ] = (byte) ((value >>  0) & 0xff);
        } else {
            dst[offset++] = (byte) ((value >>  0) & 0xff);
            dst[offset++] = (byte) ((value >>  8) & 0xff);
            dst[offset++] = (byte) ((value >> 16) & 0xff);
            dst[offset  ] = (byte) ((value >> 24) & 0xff);
        }
    }
    public static void pokeLong(byte[] dst, int offset, long value, ByteOrder order) {
        if (order == ByteOrder.BIG_ENDIAN) {
            int i = (int) (value >> 32);
            dst[offset++] = (byte) ((i >> 24) & 0xff);
            dst[offset++] = (byte) ((i >> 16) & 0xff);
            dst[offset++] = (byte) ((i >>  8) & 0xff);
            dst[offset++] = (byte) ((i >>  0) & 0xff);
            i = (int) value;
            dst[offset++] = (byte) ((i >> 24) & 0xff);
            dst[offset++] = (byte) ((i >> 16) & 0xff);
            dst[offset++] = (byte) ((i >>  8) & 0xff);
            dst[offset  ] = (byte) ((i >>  0) & 0xff);
        } else {
            int i = (int) value;
            dst[offset++] = (byte) ((i >>  0) & 0xff);
            dst[offset++] = (byte) ((i >>  8) & 0xff);
            dst[offset++] = (byte) ((i >> 16) & 0xff);
            dst[offset++] = (byte) ((i >> 24) & 0xff);
            i = (int) (value >> 32);
            dst[offset++] = (byte) ((i >>  0) & 0xff);
            dst[offset++] = (byte) ((i >>  8) & 0xff);
            dst[offset++] = (byte) ((i >> 16) & 0xff);
            dst[offset  ] = (byte) ((i >> 24) & 0xff);
        }
    }
    public static void pokeShort(byte[] dst, int offset, short value, ByteOrder order) {
        if (order == ByteOrder.BIG_ENDIAN) {
            dst[offset++] = (byte) ((value >> 8) & 0xff);
            dst[offset  ] = (byte) ((value >> 0) & 0xff);
        } else {
            dst[offset++] = (byte) ((value >> 0) & 0xff);
            dst[offset  ] = (byte) ((value >> 8) & 0xff);
        }
    }
}