//******************************************************************************
//
// File:    Packing.java
// Package: edu.rit.util
// Unit:    Class edu.rit.util.Packing
//
// This Java source file is copyright (C) 2012 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ 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 for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************

package edu.rit.util;

/**
 * Class Packing provides static methods for packing and unpacking arrays of
 * bytes into and out of integers, long integers, and arrays thereof.
 * <P>
 * <I>Note:</I> The operations in class Packing are not multiple thread safe.
 *
 * @author  Alan Kaminsky
 * @version 26-Mar-2012
 */
public class Packing
	{

// Prevent construction.

	private Packing()
		{
		}

// Exported operations.

	/**
	 * Pack bytes from the given array into an integer in little-endian order.
	 *
	 * @param  src     Source array of bytes to pack.
	 * @param  srcPos  Index of first byte to pack.
	 *
	 * @return  Elements <TT>src[srcPos]</TT> through <TT>src[srcPos+3]</TT>
	 *          packed into an integer in little-endian order.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if packing would cause accessing array
	 *     elements out of bounds.
	 */
	public static int packIntLittleEndian
		(byte[] src,
		 int srcPos)
		{
		if (srcPos + 4 > src.length) throw new IndexOutOfBoundsException();
		int rv = 0;
		for (int i = 0; i <= 3; ++ i)
			rv |= (src[srcPos+i] & 0xFF) << (i*8);
		return rv;
		}

	/**
	 * Pack bytes from the given array into an integer in big-endian order.
	 *
	 * @param  src     Source array of bytes to pack.
	 * @param  srcPos  Index of first byte to pack.
	 *
	 * @return  Elements <TT>src[srcPos]</TT> through <TT>src[srcPos+3]</TT>
	 *          packed into an integer in big-endian order.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if packing would cause accessing array
	 *     elements out of bounds.
	 */
	public static int packIntBigEndian
		(byte[] src,
		 int srcPos)
		{
		if (srcPos + 4 > src.length) throw new IndexOutOfBoundsException();
		int rv = 0;
		for (int i = 0; i <= 3; ++ i)
			rv |= (src[srcPos+i] & 0xFF) << ((3 - i)*8);
		return rv;
		}

	/**
	 * Pack bytes from the given array into the given array of integers in
	 * little-endian order. Elements <TT>src[srcPos]</TT> through
	 * <TT>src[srcPos+4*len-1]</TT> are packed into <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+len-1]</TT>.
	 *
	 * @param  src     Source array of bytes to pack.
	 * @param  srcPos  Index of first byte to pack.
	 * @param  dst     Destination array of packed integers.
	 * @param  dstPos  Index of first packed integer.
	 * @param  len     Number of integers (not bytes!) to pack.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null. Thrown if
	 *     <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if packing would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void packIntLittleEndian
		(byte[] src,
		 int srcPos,
		 int[] dst,
		 int dstPos,
		 int len)
		{
		if (srcPos + 4*len > src.length) throw new IndexOutOfBoundsException();
		if (dstPos + len > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i < len; ++ i)
			dst[dstPos+i] = packIntLittleEndian (src, srcPos + 4*i);
		}

	/**
	 * Pack bytes from the given array into the given array of integers in
	 * big-endian order. Elements <TT>src[srcPos]</TT> through
	 * <TT>src[srcPos+4*len-1]</TT> are packed into <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+len-1]</TT>.
	 *
	 * @param  src     Source array of bytes to pack.
	 * @param  srcPos  Index of first byte to pack.
	 * @param  dst     Destination array of packed integers.
	 * @param  dstPos  Index of first packed integer.
	 * @param  len     Number of integers (not bytes!) to pack.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null. Thrown if
	 *     <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if packing would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void packIntBigEndian
		(byte[] src,
		 int srcPos,
		 int[] dst,
		 int dstPos,
		 int len)
		{
		if (srcPos + 4*len > src.length) throw new IndexOutOfBoundsException();
		if (dstPos + len > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i < len; ++ i)
			dst[dstPos+i] = packIntBigEndian (src, srcPos + 4*i);
		}

	/**
	 * Pack bytes from the given array into a long integer in little-endian
	 * order.
	 *
	 * @param  src     Source array of bytes to pack.
	 * @param  srcPos  Index of first byte to pack.
	 *
	 * @return  Elements <TT>src[srcPos]</TT> through <TT>src[srcPos+7]</TT>
	 *          packed into a long integer in little-endian order.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if packing would cause accessing array
	 *     elements out of bounds.
	 */
	public static long packLongLittleEndian
		(byte[] src,
		 int srcPos)
		{
		if (srcPos + 8 > src.length) throw new IndexOutOfBoundsException();
		long rv = 0L;
		for (int i = 0; i <= 7; ++ i)
			rv |= (src[srcPos+i] & 0xFFL) << (i*8);
		return rv;
		}

	/**
	 * Pack bytes from the given array into a long integer in big-endian order.
	 *
	 * @param  src     Source array of bytes to pack.
	 * @param  srcPos  Index of first byte to pack.
	 *
	 * @return  Elements <TT>src[srcPos]</TT> through <TT>src[srcPos+7]</TT>
	 *          packed into a long integer in big-endian order.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if packing would cause accessing array
	 *     elements out of bounds.
	 */
	public static long packLongBigEndian
		(byte[] src,
		 int srcPos)
		{
		if (srcPos + 8 > src.length) throw new IndexOutOfBoundsException();
		long rv = 0L;
		for (int i = 0; i <= 7; ++ i)
			rv |= (src[srcPos+i] & 0xFFL) << ((7 - i)*8);
		return rv;
		}

	/**
	 * Pack bytes from the given array into the given array of long integers in
	 * little-endian order. Elements <TT>src[srcPos]</TT> through
	 * <TT>src[srcPos+8*len-1]</TT> are packed into <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+len-1]</TT>.
	 *
	 * @param  src     Source array of bytes to pack.
	 * @param  srcPos  Index of first byte to pack.
	 * @param  dst     Destination array of packed long integers.
	 * @param  dstPos  Index of first packed long integer.
	 * @param  len     Number of long integers (not bytes!) to pack.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null. Thrown if
	 *     <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if packing would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void packLongLittleEndian
		(byte[] src,
		 int srcPos,
		 long[] dst,
		 int dstPos,
		 int len)
		{
		if (srcPos + 8*len > src.length) throw new IndexOutOfBoundsException();
		if (dstPos + len > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i < len; ++ i)
			dst[dstPos+i] = packLongLittleEndian (src, srcPos + 8*i);
		}

	/**
	 * Pack bytes from the given array into the given array of long integers in
	 * big-endian order. Elements <TT>src[srcPos]</TT> through
	 * <TT>src[srcPos+8*len-1]</TT> are packed into <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+len-1]</TT>.
	 *
	 * @param  src     Source array of bytes to pack.
	 * @param  srcPos  Index of first byte to pack.
	 * @param  dst     Destination array of packed long integers.
	 * @param  dstPos  Index of first packed long integer.
	 * @param  len     Number of long integers (not bytes!) to pack.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null. Thrown if
	 *     <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if packing would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void packLongBigEndian
		(byte[] src,
		 int srcPos,
		 long[] dst,
		 int dstPos,
		 int len)
		{
		if (srcPos + 8*len > src.length) throw new IndexOutOfBoundsException();
		if (dstPos + len > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i < len; ++ i)
			dst[dstPos+i] = packLongBigEndian (src, srcPos + 8*i);
		}

	/**
	 * Unpack the given integer into the given array of bytes in little-endian
	 * order. The integer is unpacked into elements <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+3]</TT>.
	 *
	 * @param  src     Source integer to unpack.
	 * @param  dst     Destination array to receive unpacked bytes.
	 * @param  dstPos  Index of first unpacked byte.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if unpacking would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void unpackIntLittleEndian
		(int src,
		 byte[] dst,
		 int dstPos)
		{
		if (dstPos + 4 > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i <= 3; ++ i)
			dst[dstPos+i] = (byte)(src >> (i*8));
		}

	/**
	 * Unpack the given integer into the given array of bytes in big-endian
	 * order. The integer is unpacked into elements <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+3]</TT>.
	 *
	 * @param  src     Source integer to unpack.
	 * @param  dst     Destination array to receive unpacked bytes.
	 * @param  dstPos  Index of first unpacked byte.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if unpacking would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void unpackIntBigEndian
		(int src,
		 byte[] dst,
		 int dstPos)
		{
		if (dstPos + 4 > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i <= 3; ++ i)
			dst[dstPos+i] = (byte)(src >> ((3 - i)*8));
		}

	/**
	 * Unpack integers from the given array into the given array of bytes in
	 * little-endian order. Elements <TT>src[srcPos]</TT> through
	 * <TT>src[srcPos+len-1]</TT> are unpacked into <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+4*len-1]</TT>.
	 *
	 * @param  src     Source array of integers to unpack.
	 * @param  srcPos  Index of first integer to unpack.
	 * @param  dst     Destination array to receive unpacked bytes.
	 * @param  dstPos  Index of first unpacked byte.
	 * @param  len     Number of integers (not bytes!) to unpack.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null. Thrown if
	 *     <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if unpacking would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void unpackIntLittleEndian
		(int[] src,
		 int srcPos,
		 byte[] dst,
		 int dstPos,
		 int len)
		{
		if (srcPos + len > src.length) throw new IndexOutOfBoundsException();
		if (dstPos + 4*len > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i < len; ++ i)
			unpackIntLittleEndian (src[srcPos+i], dst, dstPos + 4*i);
		}

	/**
	 * Unpack integers from the given array into the given array of bytes in
	 * big-endian order. Elements <TT>src[srcPos]</TT> through
	 * <TT>src[srcPos+len-1]</TT> are unpacked into <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+4*len-1]</TT>.
	 *
	 * @param  src     Source array of integers to unpack.
	 * @param  srcPos  Index of first integer to unpack.
	 * @param  dst     Destination array to receive unpacked bytes.
	 * @param  dstPos  Index of first unpacked byte.
	 * @param  len     Number of integers (not bytes!) to unpack.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null. Thrown if
	 *     <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if unpacking would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void unpackIntBigEndian
		(int[] src,
		 int srcPos,
		 byte[] dst,
		 int dstPos,
		 int len)
		{
		if (srcPos + len > src.length) throw new IndexOutOfBoundsException();
		if (dstPos + 4*len > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i < len; ++ i)
			unpackIntBigEndian (src[srcPos+i], dst, dstPos + 4*i);
		}

	/**
	 * Unpack the given long integer into the given array of bytes in
	 * little-endian order. The long integer is unpacked into elements
	 * <TT>dst[dstPos]</TT> through <TT>dst[dstPos+7]</TT>.
	 *
	 * @param  src     Source long integer to unpack.
	 * @param  dst     Destination array to receive unpacked bytes.
	 * @param  dstPos  Index of first unpacked byte.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if unpacking would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void unpackLongLittleEndian
		(long src,
		 byte[] dst,
		 int dstPos)
		{
		if (dstPos + 8 > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i <= 7; ++ i)
			{
			dst[dstPos+i] = (byte)(src >> (i*8));
			}
		}

	/**
	 * Unpack the given long integer into the given array of bytes in big-endian
	 * order. The long integer is unpacked into elements <TT>dst[dstPos]</TT>
	 * through <TT>dst[dstPos+3]</TT>.
	 *
	 * @param  src     Source long integer to unpack.
	 * @param  dst     Destination array to receive unpacked bytes.
	 * @param  dstPos  Index of first unpacked byte.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if unpacking would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void unpackLongBigEndian
		(long src,
		 byte[] dst,
		 int dstPos)
		{
		if (dstPos + 8 > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i <= 7; ++ i)
			{
			dst[dstPos+i] = (byte)(src >> ((7 - i)*8));
			}
		}

	/**
	 * Unpack long integers from the given array into the given array of bytes
	 * in little-endian order. Elements <TT>src[srcPos]</TT> through
	 * <TT>src[srcPos+len-1]</TT> are unpacked into <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+8*len-1]</TT>.
	 *
	 * @param  src     Source array of long integers to unpack.
	 * @param  srcPos  Index of first long integer to unpack.
	 * @param  dst     Destination array to receive unpacked bytes.
	 * @param  dstPos  Index of first unpacked byte.
	 * @param  len     Number of integers (not bytes!) to unpack.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null. Thrown if
	 *     <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if unpacking would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void unpackLongLittleEndian
		(long[] src,
		 int srcPos,
		 byte[] dst,
		 int dstPos,
		 int len)
		{
		if (srcPos + len > src.length) throw new IndexOutOfBoundsException();
		if (dstPos + 8*len > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i < len; ++ i)
			unpackLongLittleEndian (src[srcPos+i], dst, dstPos + 8*i);
		}

	/**
	 * Unpack long integers from the given array into the given array of bytes
	 * in big-endian order. Elements <TT>src[srcPos]</TT> through
	 * <TT>src[srcPos+len-1]</TT> are unpacked into <TT>dst[dstPos]</TT> through
	 * <TT>dst[dstPos+8*len-1]</TT>.
	 *
	 * @param  src     Source array of long integers to unpack.
	 * @param  srcPos  Index of first long integer to unpack.
	 * @param  dst     Destination array to receive unpacked bytes.
	 * @param  dstPos  Index of first unpacked byte.
	 * @param  len     Number of integers (not bytes!) to unpack.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>src</TT> is null. Thrown if
	 *     <TT>dst</TT> is null.
	 * @exception  IndexOutOfBoundsException
	 *     (unchecked exception) Thrown if unpacking would cause accessing array
	 *     elements out of bounds; in this case <TT>dst</TT> is not altered.
	 */
	public static void unpackLongBigEndian
		(long[] src,
		 int srcPos,
		 byte[] dst,
		 int dstPos,
		 int len)
		{
		if (srcPos + len > src.length) throw new IndexOutOfBoundsException();
		if (dstPos + 8*len > dst.length) throw new IndexOutOfBoundsException();
		for (int i = 0; i < len; ++ i)
			unpackLongBigEndian (src[srcPos+i], dst, dstPos + 8*i);
		}

	}