littleendian.java

这是一款基于PlaceLab软件开发的导航系统中间件的客户端程序.

/* 
$Id: LittleEndian.java,v 1.2 2004/08/27 02:03:19 jameshoward Exp $ 

this is from apache poi version 1.5.1 
*/
/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache POI" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache POI", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.poi.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;

/**
 * a utility class for handling little-endian numbers, which the 80x86
 * world is replete with. The methods are all static, and input/output
 * is from/to byte arrays, or from InputStreams.
 *
 * 
 * 
 *
 */

public class LittleEndian
        implements LittleEndianConsts
{

    // all methods are static, so an accessible constructor makes no
    // sense
    private LittleEndian()
    {
    }

    /**
     * get a short value from a byte array
     *
     * @param data the byte array
     * @param offset a starting offset into the byte array
     *
     * @return the short (16-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static short getShort(final byte[] data, final int offset)
    {
        return (short) getNumber(data, offset, SHORT_SIZE);
    }

    /**
     * get a short array from a byte array.
     */
    public static short[] getSimpleShortArray(final byte[] data, final int offset, final int size)
    {
        short[] results = new short[size];
        for (int i = 0; i < size; i++)
        {
            results[i] = getShort(data, offset + 2 + (i * 2));
        }
        return results;
    }
    /**
     * get a short array from a byte array.  The short array is assumed
     * to start with a word describing the length of the array.
     */
    public static short[] getShortArray(final byte[] data, final int offset)
    {
        int size = (short) getNumber(data, offset, SHORT_SIZE);
        short[] results = getSimpleShortArray(data, offset, size);
        return results;
    }

    /**
     * get a short value from the beginning of a byte array
     *
     * @param data the byte array
     *
     * @return the short (16-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static short getShort(final byte[] data)
    {
        return getShort(data, 0);
    }

    /**
     * get an int value from a byte array
     *
     * @param data the byte array
     * @param offset a starting offset into the byte array
     *
     * @return the int (32-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static int getInt(final byte[] data, final int offset)
    {
        return (int) getNumber(data, offset, INT_SIZE);
    }

    /**
     * get an int value from the beginning of a byte array
     *
     * @param data the byte array
     *
     * @return the int (32-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static int getInt(final byte[] data)
    {
        return getInt(data, 0);
    }

    /**
     * get a long value from a byte array
     *
     * @param data the byte array
     * @param offset a starting offset into the byte array
     *
     * @return the long (64-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static long getLong(final byte[] data, final int offset)
    {
        return getNumber(data, offset, LONG_SIZE);
    }

    /**
     * get a long value from the beginning of a byte array
     *
     * @param data the byte array
     *
     * @return the long (64-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static long getLong(final byte[] data)
    {
        return getLong(data, 0);
    }

    /**
     * get a double value from a byte array, reads it in little endian format
     * then converts the resulting revolting IEEE 754 (curse them) floating
     * point number to a happy java double
     *
     * @param data the byte array
     * @param offset a starting offset into the byte array
     *
     * @return the double (64-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static double getDouble(final byte[] data, final int offset)
    {
        return Double.longBitsToDouble(getNumber(data, offset, DOUBLE_SIZE));
    }

    /**
     * get a double value from the beginning of a byte array
     *
     * @param data the byte array
     *
     * @return the double (64-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static double getDouble(final byte[] data)
    {
        return getDouble(data, 0);
    }

    /**
     * put a short value into a byte array
     *
     * @param data the byte array
     * @param offset a starting offset into the byte array
     * @param value the short (16-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */
    public static void putShort(final byte[] data, final int offset,
                                final short value)
    {
        putNumber(data, offset, value, SHORT_SIZE);
    }

    /**
     * put an unsigned short value into a byte array
     *
     * @param data the byte array
     * @param offset a starting offset into the byte array
     * @param value the short (16-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */
    public static void putUShort(final byte[] data, final int offset,
                                final int value)
    {
        putNumber(data, offset, value, SHORT_SIZE);
    }

    /**
     * put a array of shorts into a byte array
     *
     * @param data the byte array
     * @param offset a starting offset into the byte array
     * @param value the short array
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */
    public static void putShortArray(final byte[] data, final int offset, final short[] value)
    {
        putNumber(data, offset, value.length, SHORT_SIZE);
        for (int i = 0; i < value.length; i++)
        {
            putNumber(data, offset + 2 + (i * 2), value[i], SHORT_SIZE);
        }
    }

    /**
     * put a short value into beginning of a byte array
     *
     * @param data the byte array
     * @param value the short (16-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static void putShort(final byte[] data, final short value)
    {
        putShort(data, 0, value);
    }

    /**
     * put an int value into a byte array
     *
     * @param data the byte array
     * @param offset a starting offset into the byte array
     * @param value the int (32-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */

    public static void putInt(final byte[] data, final int offset,
                              final int value)
    {
        putNumber(data, offset, value, INT_SIZE);
    }

    /**
     * put an int value into beginning of a byte array