/**

 * Java RTP Library (jlibrtp)

 * Copyright (C) 2006 Arne Kepp

 * 

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 * 

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 */

package jlibrtp;

/**

 * Generic functions for converting between unsigned integers and byte[]s.

 * 

 * @author Arne Kepp

 */

public class StaticProcs {

	/**

	 * Converts an integer into an array of bytes. Primarily used for 16 bit

	 * unsigned integers, ignore the first two octets.

	 * 

	 * @param i

	 *            a 16 bit unsigned integer in an int

	 * @return byte[2] representing the integer as unsigned, most significant

	 *         bit first.

	 */

	public static byte[] uIntIntToByteWord(int i) {

		byte[] byteWord = new byte[2];

		byteWord[0] = (byte) ((i >> 8) & 0x000000FF);

		byteWord[1] = (byte) (i & 0x00FF);

		return byteWord;

	}

	public static void uIntIntToByteWord(int i, byte[] byteWord, int srcPos) {

		byteWord[0 + srcPos] = (byte) ((i >> 8) & 0x000000FF);

		byteWord[1 + srcPos] = (byte) (i & 0x00FF);

	}

	/**

	 * Converts an unsigned 32 bit integer, stored in a long, into an array of

	 * bytes.

	 * 

	 * @param j

	 *            a long

	 * @return byte[4] representing the unsigned integer, most significant bit

	 *         first.

	 */

	public static byte[] uIntLongToByteWord(long j) {

		int i = (int) j;

		byte[] byteWord = new byte[4];

		byteWord[0] = (byte) ((i >>> 24) & 0x000000FF);

		byteWord[1] = (byte) ((i >> 16) & 0x000000FF);

		byteWord[2] = (byte) ((i >> 8) & 0x000000FF);

		byteWord[3] = (byte) (i & 0x00FF);

		return byteWord;

	}

	public static void uIntLongToByteWord(long j, byte[] byteword, int srcPos) {

		int i = (int) j;

		byteword[0 + srcPos] = (byte) ((i >>> 24) & 0x000000FF);

		byteword[1 + srcPos] = (byte) ((i >> 16) & 0x000000FF);

		byteword[2 + srcPos] = (byte) ((i >> 8) & 0x000000FF);

		byteword[3 + srcPos] = (byte) (i & 0x00FF);

	}

	/**

	 * Combines two bytes (most significant bit first) into a 16 bit unsigned

	 * integer.

	 * 

	 * @param index

	 *            of most significant byte

	 * @return int with the 16 bit unsigned integer

	 */

	public static int bytesToUIntInt(byte[] bytes, int index) {

		int accum = 0;

		int i = 1;

		for (int shiftBy = 0; shiftBy < 16; shiftBy += 8) {

			accum |= ((long) (bytes[index + i] & 0xff)) << shiftBy;

			i--;

		}

		return accum;

	}

	/**

	 * Combines four bytes (most significant bit first) into a 32 bit unsigned

	 * integer.

	 * 

	 * @param bytes

	 * @param index

	 *            of most significant byte

	 * @return long with the 32 bit unsigned integer

	 */

	public static long bytesToUIntLong(byte[] bytes, int index) {

		long accum = 0;

		int i = 3;

		for (int shiftBy = 0; shiftBy < 32; shiftBy += 8) {

			accum |= ((long) (bytes[index + i] & 0xff)) << shiftBy;

			i--;

		}

		return accum;

	}

	/**

	 * Converts an arbitrary number of bytes, assumed to represent an unsigned

	 * integer, to a Java long

	 */

	/*

	 * public static long bytesToUintLong(byte[] bytes, int firstByte, int

	 * lastByte) { long accum = 0; int i = lastByte - firstByte; if(i > 7) {

	 * System.out.println(

	 * "!!!! StaticProcs.bytesToUintLong() Can't convert more than 63 bits!");

	 * return -1; } int stop = (i+1)*8;

	 * 

	 * for (int shiftBy = 0; shiftBy < stop; shiftBy += 8 ) { accum |= ( (long)(

	 * bytes[firstByte + i] & 0xff ) ) << shiftBy; i--; } return accum; }

	 */

	/**

	 * Converts an arbitrary number of bytes, assumed to represent an unsigned

	 * integer, to a Java int

	 */

	/*

	 * public static int bytesToUintInt(byte[] bytes, int firstByte, int

	 * lastByte) { int accum = 0; int i = lastByte - firstByte; if(i > 3) {

	 * System.out.println(

	 * "!!!! StaticProcs.bytesToUintLong() Can't convert more than 31 bits!");

	 * return -1; } int stop = (i+1)*8;

	 * 

	 * for (int shiftBy = 0; shiftBy < stop; shiftBy += 8 ) { accum |= ( (long)(

	 * bytes[firstByte + i] & 0xff ) ) << shiftBy; i--; } return accum; }

	 */

	/**

	 * Recreates a UNIX timestamp based on the NTP representation used in RTCP

	 * SR packets

	 * 

	 * @param ntpTs1

	 *            from RTCP SR packet

	 * @param ntpTs2

	 *            from RTCP SR packet

	 * @return the UNIX timestamp

	 */

	public static long undoNtpMess(long ntpTs1, long ntpTs2) {

		long timeVal = (ntpTs1 - 2208988800L) * 1000;

		double tmp = (1000.0 * (double) ntpTs2) / ((double) 4294967295L);

		long ms = (long) tmp;

		// System.out.println(" timeVal: " +Long.toString(timeVal)+ " ms " +

		// Long.toString(ms));

		timeVal += ms;

		return timeVal;

	}

	/**

	 * Get the bits of a byte

	 * 

	 * @param aByte

	 *            the byte you wish to convert

	 * @return a String of 1's and 0's

	 */

	public static String bitsOfByte(byte aByte) {

		int temp;

		String out = "";

		for (int i = 7; i >= 0; i--) {

			temp = (aByte >>> i);

			temp &= 0x0001;

			out += ("" + temp);

		}

		return out;

	}

	/**

	 * Get the hex representation of a byte

	 * 

	 * @param aByte

	 *            the byte you wish to convert

	 * @return a String of two chars 0-1,A-F

	 */

	public static String hexOfByte(byte aByte) {

		String out = "";

		for (int i = 0; i < 2; i++) {

			int temp = (int) aByte;

			if (temp < 0) {

				temp += 256;

			}

			if (i == 0) {

				temp = temp / 16;

			} else {

				temp = temp % 16;

			}

			if (temp > 9) {

				switch (temp) {

				case 10:

					out += "A";

					break;

				case 11:

					out += "B";

					break;

				case 12:

					out += "C";

					break;

				case 13:

					out += "D";

					break;

				case 14:

					out += "E";

					break;

				case 15:

					out += "F";

					break;

				}

			} else {

				out += Integer.toString(temp);

			}

		}

		return out;

	}

	/**

	 * Get the hex representation of a byte

	 * 

	 * @param hex

	 *            4 bytes the byte you wish to convert

	 * @return a String of two chars 0-1,A-F

	 */

	public static byte byteOfHex(byte[] hex) {

		byte retByte = 0;

		Byte tmp;

		int val = 0;

		// First 4 bits

		tmp = hex[0];

		val = tmp.intValue();

		if (val > 64) {

			// Letter

			val -= 55;

		} else {

			// Number

			val -= 48;

		}

		retByte = ((byte) (val << 4));

		// Last 4 bits

		tmp = hex[1];

		val = tmp.intValue();

		if (val > 64) {

			// Letter

			val -= 55;

		} else {

			// Number

			val -= 48;

		}

		retByte |= ((byte) val);

		return retByte;

	}

	/**

	 * Print the bits of a byte to standard out. For debugging.

	 * 

	 * @param aByte

	 *            the byte you wish to print out.

	 */

	public static void printBits(byte aByte) {

		int temp;

		for (int i = 7; i >= 0; i--) {

			temp = (aByte >>> i);

			temp &= 0x0001;

			System.out.print("" + temp);

		}

		System.out.println();

	}

	public static String bitsOfBytes(byte[] bytes) {

		String str = "";

		// Expensive, but who cares

		for (int i = 0; i < bytes.length; i++) {

			str += bitsOfByte(bytes[i]) + " ";

			if ((i + 1) % 4 == 0)

				str += "\n";

		}

		return str;

	}

}