/**

 * 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;

	}

	/** 

	 * 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;

	}

	/** 

	 * 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;

	}

}