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/*
* Copyright (c) 2007 innoSysTec (R) GmbH, Germany. All rights reserved.
* Original author: Edmund Wagner
* Creation date: 29.05.2007
*
* Source: $HeadURL$
* Last changed: $LastChangedDate$
*
* the unrar licence applies to all junrar source and binary distributions
* you are not allowed to use this source to re-create the RAR compression algorithm
*
* Here some html entities which can be used for escaping javadoc tags:
* "&": "&" or "&"
* "<": "<" or "<"
* ">": ">" or ">"
* "@": "@"
*/
package org.fox.ttcomics2.junrar.crc;
public class RarCRC {
private final static int crcTab[];
static {
crcTab = new int[256];
for (int i = 0; i < 256; i++) {
int c = i;
for (int j = 0; j < 8; j++) {
if ((c & 1) != 0) {
c >>>= 1;
c ^= 0xEDB88320;
} else {
c >>>= 1;
}
}
crcTab[i] = c;
}
}
private RarCRC() {
}
public static int checkCrc(int startCrc, byte[] data, int offset,
int count) {
int size = Math.min(data.length - offset, count);
// #if defined(LITTLE_ENDIAN) && defined(PRESENT_INT32) &&
// defined(ALLOW_NOT_ALIGNED_INT)
/*
for (int i = 0; (0 < size) && i < data.length - 8
&& ((data[i + 8] & 7) != 0); i++) {
startCrc = crcTab[(short) (startCrc ^ data[i]) & 0x00FF] ^ (startCrc >>> 8);
size--;
}
for (int i = 0; size >= 8; i += 8) {
startCrc ^= data[i + 0] << 24;
startCrc ^= data[i + 1] << 16;
startCrc ^= data[i + 2] << 8;
startCrc ^= data[i + 3];
startCrc = crcTab[(short) startCrc & 0x00FF] ^ (startCrc >>> 8);
startCrc = crcTab[(short) startCrc & 0x00FF] ^ (startCrc >>> 8);
startCrc = crcTab[(short) startCrc & 0x00FF] ^ (startCrc >>> 8);
startCrc = crcTab[(short) startCrc & 0x00FF] ^ (startCrc >>> 8);
startCrc ^= data[i + 4] << 24;
startCrc ^= data[i + 5] << 16;
startCrc ^= data[i + 6] << 8;
startCrc ^= data[i + 7];
startCrc = crcTab[(short) startCrc & 0x00FF] ^ (startCrc >>> 8);
startCrc = crcTab[(short) startCrc & 0x00FF] ^ (startCrc >>> 8);
startCrc = crcTab[(short) startCrc & 0x00FF] ^ (startCrc >>> 8);
startCrc = crcTab[(short) startCrc & 0x00FF] ^ (startCrc >>> 8);
size -= 8;
}*/
for (int i = 0; i < size; i++) {
/*
// (byte)(StartCRC^Data[I])
int pos = 0; // pos=0x00000000
pos |= startCrc; // pos=ffffffff
pos ^= data[i]; // data[0]=0x73=115dec --> pos=140
System.out.println(Integer.toHexString(pos));
// Only last 8 bit because CRCtab has length 256
pos = pos & 0x000000FF;
System.out.println("pos:"+pos);
//startCrc >>>= 8;
//StartCRC>>8
int temp =0;
temp|=startCrc;
temp >>>= 8;
System.out.println("temp:"+Integer.toHexString(temp));
startCrc = (crcTab[pos]^temp);
System.out.println("--"+Integer.toHexString(startCrc));*/
startCrc = (crcTab[(startCrc ^
(int) data[offset + i]) & 0xff] ^ (startCrc >>> 8));
//System.out.println(Integer.toHexString(startCrc));
// Original code:
//StartCRC=CRCTab[(byte)(StartCRC^Data[I])]^(StartCRC>>8);
}
return (startCrc);
}
public static short checkOldCrc(short startCrc, byte[] data, int count) {
int n = Math.min(data.length, count);
for (int i = 0; i < n; i++) {
startCrc = (short) ((short) (startCrc + (short) (data[i] & 0x00ff)) & -1);
startCrc = (short) (((startCrc << 1) | (startCrc >>> 15)) & -1);
}
return (startCrc);
}
// public static void main(String[] args)
// {
// RarCRC rc = new RarCRC();
// //byte[] data = { 0x72, 0x21, 0x1A, 0x07, 0x00};
//
// byte[] data = {0x73 ,0x00 ,0x00 ,0x0D ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00};
//
// int crc = 0x90CF;
//
//
// int result = rc.checkCrc(0xFFFFffff, data,0,data.length);
// System.out.println("3: "+Integer.toHexString(~result&0xffff));
//
// }
}
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