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	/*
	* reserved comment block
	* DO NOT REMOVE OR ALTER!
	*/
	/*
	* 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.sun.org.apache.xerces.internal.impl.io;

	import java.io.IOException;
	import java.io.InputStream;
	import java.io.Reader;
	import java.util.Locale;

	import com.sun.org.apache.xerces.internal.impl.msg.XMLMessageFormatter;
	import com.sun.org.apache.xerces.internal.util.MessageFormatter;

	/**
	* <p>
	* A UTF-16 reader. Can also be used for UCS-2 (i.e. ISO-10646-UCS-2).</p>
	*
	* @xerces.internal
	*
	* @author Michael Glavassevich, IBM
	*
	* @version $Id: UTF16Reader.java 718095 2008-11-16 20:00:14Z mrglavas $
	*/
	public final class UTF16Reader
	extends Reader {

	//
	// Constants
	//
	/**
	* Default byte buffer size (4096).
	*/
	public static final int DEFAULT_BUFFER_SIZE = 4096;

	//
	// Data
	//
	/**
	* Input stream.
	*/
	protected final InputStream fInputStream;

	/**
	* Byte buffer.
	*/
	protected final byte[] fBuffer;

	/**
	* Endianness.
	*/
	protected final boolean fIsBigEndian;

	// message formatter; used to produce localized exception messages
	private final MessageFormatter fFormatter;

	// Locale to use for messages
	private final Locale fLocale;

	//
	// Constructors
	//
	/**
	* Constructs a UTF-16 reader from the specified input stream using the
	* default buffer size. Primarily for testing.
	*
	* @param inputStream The input stream.
	* @param isBigEndian The byte order.
	*/
	public UTF16Reader(InputStream inputStream, boolean isBigEndian) {
	this(inputStream, DEFAULT_BUFFER_SIZE, isBigEndian,
	new XMLMessageFormatter(), Locale.getDefault());
	} // <init>(InputStream, boolean)

	/**
	* Constructs a UTF-16 reader from the specified input stream using the
	* default buffer size and the given MessageFormatter.
	*
	* @param inputStream The input stream.
	* @param isBigEndian The byte order.
	*/
	public UTF16Reader(InputStream inputStream, boolean isBigEndian,
	MessageFormatter messageFormatter, Locale locale) {
	this(inputStream, DEFAULT_BUFFER_SIZE, isBigEndian, messageFormatter, locale);
	} // <init>(InputStream, boolean, MessageFormatter, Locale)

	/**
	* Constructs a UTF-16 reader from the specified input stream and buffer
	* size and given MessageFormatter.
	*
	* @param inputStream The input stream.
	* @param size The initial buffer size.
	* @param isBigEndian The byte order.
	* @param messageFormatter Given MessageFormatter
	* @param locale Locale to use for messages
	*/
	public UTF16Reader(InputStream inputStream, int size, boolean isBigEndian,
	MessageFormatter messageFormatter, Locale locale) {
	this(inputStream, new byte[size], isBigEndian, messageFormatter, locale);
	} // <init>(InputStream, int, boolean, MessageFormatter, Locale)

	/**
	* Constructs a UTF-16 reader from the specified input stream, buffer and
	* MessageFormatter.
	*
	* @param inputStream The input stream.
	* @param buffer The byte buffer.
	* @param isBigEndian The byte order.
	* @param messageFormatter Given MessageFormatter
	* @param locale Locale to use for messages
	*/
	public UTF16Reader(InputStream inputStream, byte[] buffer, boolean isBigEndian,
	MessageFormatter messageFormatter, Locale locale) {
	fInputStream = inputStream;
	fBuffer = buffer;
	fIsBigEndian = isBigEndian;
	fFormatter = messageFormatter;
	fLocale = locale;
	} // <init>(InputStream, byte[], boolean, MessageFormatter, Locale)

	//
	// Reader methods
	//
	/**
	* Read a single character. This method will block until a character is
	* available, an I/O error occurs, or the end of the stream is reached.
	*
	* <p>
	* Subclasses that intend to support efficient single-character input should
	* override this method.
	*
	* @return The character read, as an integer in the range 0 to 65535
	* (<tt>0x00-0xffff</tt>), or -1 if the end of the stream has been reached
	*
	* @exception IOException If an I/O error occurs
	*/
	public int read() throws IOException {
	final int b0 = fInputStream.read();
	if (b0 == -1) {
	return -1;
	}
	final int b1 = fInputStream.read();
	if (b1 == -1) {
	expectedTwoBytes();
	}
	// UTF-16BE
	if (fIsBigEndian) {
	return (b0 << 8) \| b1;
	}
	// UTF-16LE
	return (b1 << 8) \| b0;
	} // read():int

	/**
	* Read characters into a portion of an array. This method will block until
	* some input is available, an I/O error occurs, or the end of the stream is
	* reached.
	*
	* @param ch Destination buffer
	* @param offset Offset at which to start storing characters
	* @param length Maximum number of characters to read
	*
	* @return The number of characters read, or -1 if the end of the stream has
	* been reached
	*
	* @exception IOException If an I/O error occurs
	*/
	public int read(char ch[], int offset, int length) throws IOException {
	int byteLength = length << 1;
	if (byteLength > fBuffer.length) {
	byteLength = fBuffer.length;
	}
	int byteCount = fInputStream.read(fBuffer, 0, byteLength);
	if (byteCount == -1) {
	return -1;
	}
	// If an odd number of bytes were read, we still need to read one more.
	if ((byteCount & 1) != 0) {
	int b = fInputStream.read();
	if (b == -1) {
	expectedTwoBytes();
	}
	fBuffer[byteCount++] = (byte) b;
	}
	final int charCount = byteCount >> 1;
	if (fIsBigEndian) {
	processBE(ch, offset, charCount);
	} else {
	processLE(ch, offset, charCount);
	}
	return charCount;
	} // read(char[],int,int)

	/**
	* Skip characters. This method will block until some characters are
	* available, an I/O error occurs, or the end of the stream is reached.
	*
	* @param n The number of characters to skip
	*
	* @return The number of characters actually skipped
	*
	* @exception IOException If an I/O error occurs
	*/
	public long skip(long n) throws IOException {
	long bytesSkipped = fInputStream.skip(n << 1);
	if ((bytesSkipped & 1) != 0) {
	int b = fInputStream.read();
	if (b == -1) {
	expectedTwoBytes();
	}
	++bytesSkipped;
	}
	return bytesSkipped >> 1;
	} // skip(long):long

	/**
	* Tell whether this stream is ready to be read.
	*
	* @return True if the next read() is guaranteed not to block for input,
	* false otherwise. Note that returning false does not guarantee that the
	* next read will block.
	*
	* @exception IOException If an I/O error occurs
	*/
	public boolean ready() throws IOException {
	return false;
	} // ready()

	/**
	* Tell whether this stream supports the mark() operation.
	*/
	public boolean markSupported() {
	return false;
	} // markSupported()

	/**
	* Mark the present position in the stream. Subsequent calls to reset() will
	* attempt to reposition the stream to this point. Not all character-input
	* streams support the mark() operation.
	*
	* @param readAheadLimit Limit on the number of characters that may be read
	* while still preserving the mark. After reading this many characters,
	* attempting to reset the stream may fail.
	*
	* @exception IOException If the stream does not support mark(), or if some
	* other I/O error occurs
	*/
	public void mark(int readAheadLimit) throws IOException {
	throw new IOException(fFormatter.formatMessage(fLocale, "OperationNotSupported", new Object[]{"mark()", "UTF-16"}));
	} // mark(int)

	/**
	* Reset the stream. If the stream has been marked, then attempt to
	* reposition it at the mark. If the stream has not been marked, then
	* attempt to reset it in some way appropriate to the particular stream, for
	* example by repositioning it to its starting point. Not all
	* character-input streams support the reset() operation, and some support
	* reset() without supporting mark().
	*
	* @exception IOException If the stream has not been marked, or if the mark
	* has been invalidated, or if the stream does not support reset(), or if
	* some other I/O error occurs
	*/
	public void reset() throws IOException {
	} // reset()

	/**
	* Close the stream. Once a stream has been closed, further read(), ready(),
	* mark(), or reset() invocations will throw an IOException. Closing a
	* previously-closed stream, however, has no effect.
	*
	* @exception IOException If an I/O error occurs
	*/
	public void close() throws IOException {
	fInputStream.close();
	} // close()

	//
	// Private methods
	//
	/**
	* Decodes UTF-16BE *
	*/
	private void processBE(final char ch[], int offset, final int count) {
	int curPos = 0;
	for (int i = 0; i < count; ++i) {
	final int b0 = fBuffer[curPos++] & 0xff;
	final int b1 = fBuffer[curPos++] & 0xff;
	ch[offset++] = (char) ((b0 << 8) \| b1);
	}
	} // processBE(char[],int,int)

	/**
	* Decodes UTF-16LE *
	*/
	private void processLE(final char ch[], int offset, final int count) {
	int curPos = 0;
	for (int i = 0; i < count; ++i) {
	final int b0 = fBuffer[curPos++] & 0xff;
	final int b1 = fBuffer[curPos++] & 0xff;
	ch[offset++] = (char) ((b1 << 8) \| b0);
	}
	} // processLE(char[],int,int)

	/**
	* Throws an exception for expected byte.
	*/
	private void expectedTwoBytes()
	throws MalformedByteSequenceException {
	throw new MalformedByteSequenceException(fFormatter,
	fLocale,
	XMLMessageFormatter.XML_DOMAIN,
	"ExpectedByte",
	new Object[]{"2", "2"});
	} // expectedTwoBytes()

	} // class UTF16Reader

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