/*
Copyright (C) 1997-2001 Id Software, Inc.

This program 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 2
of the License, or (at your option) any later version.

This program 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.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

// Created on 25.01.2004 by RST.
// $Id: CRC.java,v 1.1 2004-07-09 06:50:49 hzi Exp $
package jake2.qcommon;

import jake2.util.Vargs;

public class CRC
{

	public final static short CRC_INIT_VALUE= (short) 0xffff;
	public final static short CRC_XOR_VALUE= (short) 0x0000;

	private static int crctable[]=
		{
			0x0000,
			0x1021,
			0x2042,
			0x3063,
			0x4084,
			0x50a5,
			0x60c6,
			0x70e7,
			0x8108,
			0x9129,
			0xa14a,
			0xb16b,
			0xc18c,
			0xd1ad,
			0xe1ce,
			0xf1ef,
			0x1231,
			0x0210,
			0x3273,
			0x2252,
			0x52b5,
			0x4294,
			0x72f7,
			0x62d6,
			0x9339,
			0x8318,
			0xb37b,
			0xa35a,
			0xd3bd,
			0xc39c,
			0xf3ff,
			0xe3de,
			0x2462,
			0x3443,
			0x0420,
			0x1401,
			0x64e6,
			0x74c7,
			0x44a4,
			0x5485,
			0xa56a,
			0xb54b,
			0x8528,
			0x9509,
			0xe5ee,
			0xf5cf,
			0xc5ac,
			0xd58d,
			0x3653,
			0x2672,
			0x1611,
			0x0630,
			0x76d7,
			0x66f6,
			0x5695,
			0x46b4,
			0xb75b,
			0xa77a,
			0x9719,
			0x8738,
			0xf7df,
			0xe7fe,
			0xd79d,
			0xc7bc,
			0x48c4,
			0x58e5,
			0x6886,
			0x78a7,
			0x0840,
			0x1861,
			0x2802,
			0x3823,
			0xc9cc,
			0xd9ed,
			0xe98e,
			0xf9af,
			0x8948,
			0x9969,
			0xa90a,
			0xb92b,
			0x5af5,
			0x4ad4,
			0x7ab7,
			0x6a96,
			0x1a71,
			0x0a50,
			0x3a33,
			0x2a12,
			0xdbfd,
			0xcbdc,
			0xfbbf,
			0xeb9e,
			0x9b79,
			0x8b58,
			0xbb3b,
			0xab1a,
			0x6ca6,
			0x7c87,
			0x4ce4,
			0x5cc5,
			0x2c22,
			0x3c03,
			0x0c60,
			0x1c41,
			0xedae,
			0xfd8f,
			0xcdec,
			0xddcd,
			0xad2a,
			0xbd0b,
			0x8d68,
			0x9d49,
			0x7e97,
			0x6eb6,
			0x5ed5,
			0x4ef4,
			0x3e13,
			0x2e32,
			0x1e51,
			0x0e70,
			0xff9f,
			0xefbe,
			0xdfdd,
			0xcffc,
			0xbf1b,
			0xaf3a,
			0x9f59,
			0x8f78,
			0x9188,
			0x81a9,
			0xb1ca,
			0xa1eb,
			0xd10c,
			0xc12d,
			0xf14e,
			0xe16f,
			0x1080,
			0x00a1,
			0x30c2,
			0x20e3,
			0x5004,
			0x4025,
			0x7046,
			0x6067,
			0x83b9,
			0x9398,
			0xa3fb,
			0xb3da,
			0xc33d,
			0xd31c,
			0xe37f,
			0xf35e,
			0x02b1,
			0x1290,
			0x22f3,
			0x32d2,
			0x4235,
			0x5214,
			0x6277,
			0x7256,
			0xb5ea,
			0xa5cb,
			0x95a8,
			0x8589,
			0xf56e,
			0xe54f,
			0xd52c,
			0xc50d,
			0x34e2,
			0x24c3,
			0x14a0,
			0x0481,
			0x7466,
			0x6447,
			0x5424,
			0x4405,
			0xa7db,
			0xb7fa,
			0x8799,
			0x97b8,
			0xe75f,
			0xf77e,
			0xc71d,
			0xd73c,
			0x26d3,
			0x36f2,
			0x0691,
			0x16b0,
			0x6657,
			0x7676,
			0x4615,
			0x5634,
			0xd94c,
			0xc96d,
			0xf90e,
			0xe92f,
			0x99c8,
			0x89e9,
			0xb98a,
			0xa9ab,
			0x5844,
			0x4865,
			0x7806,
			0x6827,
			0x18c0,
			0x08e1,
			0x3882,
			0x28a3,
			0xcb7d,
			0xdb5c,
			0xeb3f,
			0xfb1e,
			0x8bf9,
			0x9bd8,
			0xabbb,
			0xbb9a,
			0x4a75,
			0x5a54,
			0x6a37,
			0x7a16,
			0x0af1,
			0x1ad0,
			0x2ab3,
			0x3a92,
			0xfd2e,
			0xed0f,
			0xdd6c,
			0xcd4d,
			0xbdaa,
			0xad8b,
			0x9de8,
			0x8dc9,
			0x7c26,
			0x6c07,
			0x5c64,
			0x4c45,
			0x3ca2,
			0x2c83,
			0x1ce0,
			0x0cc1,
			0xef1f,
			0xff3e,
			0xcf5d,
			0xdf7c,
			0xaf9b,
			0xbfba,
			0x8fd9,
			0x9ff8,
			0x6e17,
			0x7e36,
			0x4e55,
			0x5e74,
			0x2e93,
			0x3eb2,
			0x0ed1,
			0x1ef0 };

	static short CRC_Block(byte start[], int count)
	{
		short crc= CRC_INIT_VALUE;

		int ndx= 0;

		while (count-- > 0)
			crc= (short) ((crc << 8) ^ crctable[0xff & ((crc >> 8) ^ start[ndx++])]);

		return crc;
	}

	public static void main(String[] args)
	{
		byte data[]=
			{
				(byte) 0x71,
				(byte) 0xa9,
				(byte) 0x05,
				(byte) 0xce,
				(byte) 0x8d,
				(byte) 0x75,
				(byte) 0x28,
				(byte) 0xc8,
				(byte) 0xba,
				(byte) 0x97,
				
				(byte) 0x45,
				(byte) 0xe9,
				(byte) 0x8a,
				(byte) 0xe0,
				(byte) 0x37,
				(byte) 0xbd,
				(byte) 0x6c,
				(byte) 0x6d,
				(byte) 0x67,
				(byte) 0x4a, 
				(byte) 0x21 };
				System.out.println("crc:" + (CRC_Block(data, 21) & 0xffff));
				System.out.println("----");
				for (int n=0; n < 5; n++)
					System.out.println("seq:" + (Com.BlockSequenceCRCByte( data,0, 21,n*10) & 0xff));
				
	}
	
/* c test:
 * 
 * D:\Rene\gamesrc\quake2-3.21\qcommon>crc
 * crc=-12353
 * ----
 * seq:215
 * seq:252
 * seq:164
 * seq:202
 * seq:201
 * 
int main()
{
	byte data[21] = 
	{	
				  0x71,
				  0xa9,
				  0x05,
				  0xce,
				  0x8d,
				  0x75,
				  0x28,
				  0xc8,
				  0xba,
				  0x97,
				
				  0x45,
				  0xe9,
				  0x8a,
				  0xe0,
				  0x37,
				  0xbd,
				  0x6c,
				  0x6d,
				  0x67,
				  0x4a, 0x21 };
	int n=0;

	printf("crc=%d\n", (short) CRC_Block(&data, 21));

	printf("----\n");
	for (n=0; n < 5; n++)
		printf("seq:%d\n", COM_BlockSequenceCRCByte( &data,21, n*10) );
} 
 */	
	
}