502 lines
14 KiB
Java
502 lines
14 KiB
Java
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/* ====================================================================
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2002 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution,
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* if any, must include the following acknowledgment:
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* "This product includes software developed by the
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowledgment may appear in the software itself,
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* if and wherever such third-party acknowledgments normally appear.
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*
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* 4. The names "Apache" and "Apache Software Foundation" and
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* "Apache POI" must not be used to endorse or promote products
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* derived from this software without prior written permission. For
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* written permission, please contact apache@apache.org.
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*
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* 5. Products derived from this software may not be called "Apache",
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* "Apache POI", nor may "Apache" appear in their name, without
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* prior written permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*/
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package org.apache.poi.util;
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import java.io.*;
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import java.util.*;
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/**
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* a utility class for handling little-endian numbers, which the 80x86
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* world is replete with. The methods are all static, and input/output
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* is from/to byte arrays, or from InputStreams.
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*
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* @author Marc Johnson (mjohnson at apache dot org)
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* @author Andrew Oliver (acoliver at apache dot org)
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*
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*/
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public class LittleEndian
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implements LittleEndianConsts
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{
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// all methods are static, so an accessible constructor makes no
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// sense
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private LittleEndian()
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{
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}
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/**
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* get a short value from a byte array
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*
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* @param data the byte array
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* @param offset a starting offset into the byte array
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*
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* @return the short (16-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static short getShort(final byte [] data, final int offset)
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{
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return ( short ) getNumber(data, offset, SHORT_SIZE);
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}
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/**
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* get a short value from the beginning of a byte array
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*
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* @param data the byte array
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*
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* @return the short (16-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static short getShort(final byte [] data)
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{
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return getShort(data, 0);
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}
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/**
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* get an int value from a byte array
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*
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* @param data the byte array
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* @param offset a starting offset into the byte array
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*
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* @return the int (32-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static int getInt(final byte [] data, final int offset)
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{
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return ( int ) getNumber(data, offset, INT_SIZE);
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}
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/**
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* get an int value from the beginning of a byte array
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*
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* @param data the byte array
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*
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* @return the int (32-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static int getInt(final byte [] data)
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{
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return getInt(data, 0);
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}
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/**
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* get a long value from a byte array
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*
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* @param data the byte array
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* @param offset a starting offset into the byte array
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*
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* @return the long (64-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static long getLong(final byte [] data, final int offset)
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{
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return getNumber(data, offset, LONG_SIZE);
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}
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/**
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* get a long value from the beginning of a byte array
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*
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* @param data the byte array
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*
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* @return the long (64-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static long getLong(final byte [] data)
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{
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return getLong(data, 0);
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}
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/**
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* get a double value from a byte array, reads it in little endian format
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* then converts the resulting revolting IEEE 754 (curse them) floating
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* point number to a happy java double
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*
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* @param data the byte array
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* @param offset a starting offset into the byte array
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*
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* @return the double (64-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static double getDouble(final byte [] data, final int offset)
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{
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return Double.longBitsToDouble(getNumber(data, offset, DOUBLE_SIZE));
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}
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/**
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* get a double value from the beginning of a byte array
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*
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* @param data the byte array
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*
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* @return the double (64-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static double getDouble(final byte [] data)
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{
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return getDouble(data, 0);
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}
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/**
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* put a short value into a byte array
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*
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* @param data the byte array
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* @param offset a starting offset into the byte array
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* @param value the short (16-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static void putShort(final byte [] data, final int offset,
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final short value)
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{
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putNumber(data, offset, value, SHORT_SIZE);
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}
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/**
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* put a short value into beginning of a byte array
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*
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* @param data the byte array
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* @param value the short (16-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static void putShort(final byte [] data, final short value)
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{
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putShort(data, 0, value);
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}
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/**
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* put an int value into a byte array
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*
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* @param data the byte array
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* @param offset a starting offset into the byte array
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* @param value the int (32-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static void putInt(final byte [] data, final int offset,
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final int value)
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{
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putNumber(data, offset, value, INT_SIZE);
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}
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/**
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* put an int value into beginning of a byte array
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*
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* @param data the byte array
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* @param value the int (32-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static void putInt(final byte [] data, final int value)
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{
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putInt(data, 0, value);
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}
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/**
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* put a long value into a byte array
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*
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* @param data the byte array
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* @param offset a starting offset into the byte array
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* @param value the long (64-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static void putLong(final byte [] data, final int offset,
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final long value)
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{
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putNumber(data, offset, value, LONG_SIZE);
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}
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/**
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* put a long value into beginning of a byte array
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*
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* @param data the byte array
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* @param value the long (64-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static void putLong(final byte [] data, final long value)
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{
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putLong(data, 0, value);
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}
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/**
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* put a double value into a byte array
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*
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* @param data the byte array
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* @param offset a starting offset into the byte array
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* @param value the double (64-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static void putDouble(final byte [] data, final int offset,
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final double value)
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{
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putNumber(data, offset, Double.doubleToLongBits(value), DOUBLE_SIZE);
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}
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/**
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* put a double value into beginning of a byte array
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*
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* @param data the byte array
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* @param value the double (64-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static void putDouble(final byte [] data, final double value)
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{
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putDouble(data, 0, value);
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}
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/**
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* Exception to handle buffer underruns
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*
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* @author Marc Johnson (mjohnson at apache dot org)
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*/
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public static class BufferUnderrunException
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extends IOException
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{
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/**
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* simple constructor
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*/
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BufferUnderrunException()
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{
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super("buffer underrun");
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}
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}
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/**
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* get a short value from an InputStream
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*
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* @param stream the InputStream from which the short is to be
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* read
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*
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* @return the short (16-bit) value
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*
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* @exception IOException will be propagated back to the caller
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* @exception BufferUnderrunException if the stream cannot provide
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* enough bytes
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*/
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public static short readShort(final InputStream stream)
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throws IOException, BufferUnderrunException
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{
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return getShort(readFromStream(stream, SHORT_SIZE));
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}
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/**
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* get an int value from an InputStream
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*
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* @param stream the InputStream from which the int is to be read
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*
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* @return the int (32-bit) value
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*
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* @exception IOException will be propagated back to the caller
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* @exception BufferUnderrunException if the stream cannot provide
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* enough bytes
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*/
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public static int readInt(final InputStream stream)
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throws IOException, BufferUnderrunException
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{
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return getInt(readFromStream(stream, INT_SIZE));
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}
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/**
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* get a long value from an InputStream
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*
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* @param stream the InputStream from which the long is to be read
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*
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* @return the long (64-bit) value
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*
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* @exception IOException will be propagated back to the caller
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* @exception BufferUnderrunException if the stream cannot provide
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* enough bytes
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*/
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public static long readLong(final InputStream stream)
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throws IOException, BufferUnderrunException
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{
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return getLong(readFromStream(stream, LONG_SIZE));
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}
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private static final byte[] _short_buffer = new byte[ SHORT_SIZE ];
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private static final byte[] _int_buffer = new byte[ INT_SIZE ];
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private static final byte[] _long_buffer = new byte[ LONG_SIZE ];
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/**
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* Read the appropriate number of bytes from the stream and return
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* them to the caller.
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* <p>
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* It should be noted that, in an attempt to improve system
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* performance and to prevent a transient explosion of discarded
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* byte arrays to be garbage collected, static byte arrays are
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* employed for the standard cases of reading a short, an int, or
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* a long.
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* <p>
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* <b>THIS INTRODUCES A RISK FOR THREADED OPERATIONS!</b>
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* <p>
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* However, for the purposes of the POI project, this risk is
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* deemed negligible. It is, however, so noted.
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*
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* @param stream the InputStream we're reading from
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* @param size the number of bytes to read; in 99.99% of cases,
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* this will be SHORT_SIZE, INT_SIZE, or LONG_SIZE --
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* but it doesn't have to be.
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*
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* @return the byte array containing the required number of
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* bytes. The array will contain all zero's on end of
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* stream
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*
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* @exception IOException will be propagated back to the caller
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* @exception BufferUnderrunException if the stream cannot provide
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* enough bytes
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*/
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public static byte [] readFromStream(final InputStream stream,
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final int size)
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throws IOException, BufferUnderrunException
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{
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byte[] buffer = null;
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switch (size)
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{
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case SHORT_SIZE :
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buffer = _short_buffer;
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break;
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case INT_SIZE :
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buffer = _int_buffer;
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break;
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case LONG_SIZE :
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buffer = _long_buffer;
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break;
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default :
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buffer = new byte[ size ];
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break;
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}
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int count = stream.read(buffer);
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if (count == -1)
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{
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// return a zero-filled buffer
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Arrays.fill(buffer, ( byte ) 0);
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}
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else if (count != size)
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{
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throw new BufferUnderrunException();
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}
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return buffer;
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}
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private static long getNumber(final byte [] data, final int offset,
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final int size)
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{
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long result = 0;
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for (int j = offset + size - 1; j >= offset; j--)
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{
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result <<= 8;
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result |= 0xff & data[ j ];
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}
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return result;
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}
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private static void putNumber(final byte [] data, final int offset,
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final long value, final int size)
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{
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int limit = size + offset;
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long v = value;
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||
|
|
||
|
for (int j = offset; j < limit; j++)
|
||
|
{
|
||
|
data[ j ] = ( byte ) (v & 0xFF);
|
||
|
v >>= 8;
|
||
|
}
|
||
|
}
|
||
|
}
|