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	/*
	* Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.management.counter.perf;

	import sun.management.counter.*;
	import java.nio.*;
	import java.io.UnsupportedEncodingException;

	class PerfDataEntry {
	private class EntryFieldOffset {
	private final static int SIZEOF_BYTE = 1;
	private final static int SIZEOF_INT = 4;
	private final static int SIZEOF_LONG = 8;

	private final static int ENTRY_LENGTH_SIZE = SIZEOF_INT;
	private final static int NAME_OFFSET_SIZE = SIZEOF_INT;
	private final static int VECTOR_LENGTH_SIZE = SIZEOF_INT;
	private final static int DATA_TYPE_SIZE = SIZEOF_BYTE;
	private final static int FLAGS_SIZE = SIZEOF_BYTE;
	private final static int DATA_UNIT_SIZE = SIZEOF_BYTE;
	private final static int DATA_VAR_SIZE = SIZEOF_BYTE;
	private final static int DATA_OFFSET_SIZE = SIZEOF_INT;

	final static int ENTRY_LENGTH = 0;
	final static int NAME_OFFSET = ENTRY_LENGTH + ENTRY_LENGTH_SIZE;
	final static int VECTOR_LENGTH = NAME_OFFSET + NAME_OFFSET_SIZE;;
	final static int DATA_TYPE = VECTOR_LENGTH + VECTOR_LENGTH_SIZE;
	final static int FLAGS = DATA_TYPE + DATA_TYPE_SIZE;
	final static int DATA_UNIT = FLAGS + FLAGS_SIZE;
	final static int DATA_VAR = DATA_UNIT + DATA_UNIT_SIZE;
	final static int DATA_OFFSET = DATA_VAR + DATA_VAR_SIZE;
	}

	private String name;
	private int entryStart;
	private int entryLength;
	private int vectorLength;
	private PerfDataType dataType;
	private int flags;
	private Units unit;
	private Variability variability;
	private int dataOffset;
	private int dataSize;
	private ByteBuffer data;

	PerfDataEntry(ByteBuffer b) {
	entryStart = b.position();
	entryLength = b.getInt();

	// check for valid entry length
	if (entryLength <= 0 \|\| entryLength > b.limit()) {
	throw new InstrumentationException("Invalid entry length: " +
	" entryLength = " + entryLength);
	}
	// check if last entry occurs before the eof.
	if ((entryStart + entryLength) > b.limit()) {
	throw new InstrumentationException("Entry extends beyond end of buffer: " +
	" entryStart = " + entryStart +
	" entryLength = " + entryLength +
	" buffer limit = " + b.limit());
	}

	b.position(entryStart + EntryFieldOffset.NAME_OFFSET);
	int nameOffset = b.getInt();

	if ((entryStart + nameOffset) > b.limit()) {
	throw new InstrumentationException("Invalid name offset: " +
	" entryStart = " + entryStart +
	" nameOffset = " + nameOffset +
	" buffer limit = " + b.limit());
	}


	b.position(entryStart + EntryFieldOffset.VECTOR_LENGTH);
	vectorLength = b.getInt();

	b.position(entryStart + EntryFieldOffset.DATA_TYPE);
	dataType = PerfDataType.toPerfDataType(b.get());

	b.position(entryStart + EntryFieldOffset.FLAGS);
	flags = b.get();

	b.position(entryStart + EntryFieldOffset.DATA_UNIT);
	unit = Units.toUnits(b.get());

	b.position(entryStart + EntryFieldOffset.DATA_VAR);
	variability = Variability.toVariability(b.get());

	b.position(entryStart + EntryFieldOffset.DATA_OFFSET);
	dataOffset = b.getInt();

	// read in the perfData item name, casting bytes to chars. skip the
	// null terminator
	b.position(entryStart + nameOffset);
	// calculate the length of the name
	int nameLength = 0;
	byte c;
	for (; (c = b.get()) != (byte)0; nameLength++);

	byte[] symbolBytes = new byte[nameLength];
	b.position(entryStart + nameOffset);
	for (int i = 0; i < nameLength; i++) {
	symbolBytes[i] = b.get();
	}

	// convert name into a String
	try {
	name = new String(symbolBytes, "UTF-8");
	}
	catch (UnsupportedEncodingException e) {
	// should not reach here
	// "UTF-8" is always a known encoding
	throw new InternalError(e.getMessage(), e);
	}

	if (variability == Variability.INVALID) {
	throw new InstrumentationException("Invalid variability attribute:" +
	" name = " + name);
	}
	if (unit == Units.INVALID) {
	throw new InstrumentationException("Invalid units attribute: " +
	" name = " + name);
	}

	if (vectorLength > 0) {
	dataSize = vectorLength * dataType.size();
	} else {
	dataSize = dataType.size();
	}

	// check if data beyond the eof.
	if ((entryStart + dataOffset + dataSize) > b.limit()) {
	throw new InstrumentationException("Data extends beyond end of buffer: " +
	" entryStart = " + entryStart +
	" dataOffset = " + dataOffset+
	" dataSize = " + dataSize +
	" buffer limit = " + b.limit());
	}
	// Construct a ByteBuffer for the data
	b.position(entryStart + dataOffset);
	data = b.slice();
	data.order(b.order());
	data.limit(dataSize);
	}


	public int size() {
	return entryLength;
	}

	public String name() {
	return name;
	}

	public PerfDataType type() {
	return dataType;
	}

	public Units units() {
	return unit;
	}

	public int flags() {
	return flags;
	}

	/**
	* Returns the number of elements in the data.
	*/
	public int vectorLength() {
	return vectorLength;
	}

	public Variability variability() {
	return variability;
	}

	public ByteBuffer byteData() {
	data.position(0);
	assert data.remaining() == vectorLength();
	return data.duplicate();
	}

	public LongBuffer longData() {
	LongBuffer lb = data.asLongBuffer();
	return lb;
	}
	}

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