Gert = Gertrud ... ??
f8zpublic class CRC16 {
private int intCRC16 = 0x0;
public static void main(String[] args) {
String test = "Hallo Welt";
CRC16 cc = new CRC16();
cc.update(test.getBytes());
System.out.println(cc.getCRC());
cc.reset();
}
public int update(byte b[]) {
for (int i = 0; i < b.length; i++) {
update(b[i]);
}
return intCRC16;
}
public int update(byte b) {
int intA = b;
int intB = 0;
for (int i = 7; i >= 0; i--) {
intA = intA << 1;
intB = (intA >>> 8) & 1;
if ((intCRC16 & 0x8000) != 0) {
intCRC16 = ((intCRC16 << 1) + intB) ^ 0x1021;
} else {
intCRC16 = (intCRC16 << 1) + intB;
}
intCRC16 = intCRC16 & 0xffff;
}
return intCRC16;
}
public int getCRC() {
return intCRC16;
}
public void reset() {
intCRC16 = 0;
}
} public static String Pseudo(String name) {
int xx = 0;
char[] c = name.toCharArray();
for (int i = 0; i < c.length - 1; i++) {
char c1 = c[i];
char c2 = c[i + 1];
if (c1 > c2) {
xx += c1 + c2;
} else {
xx += c1 - c2;
}
}
xx += c[c.length - 1];
xx = xx / name.length();
return String.valueOf(xx);
} public static void main(String[] args) throws IOException {
CRC24 crc = new CRC24();
byte[] bytes = "Hahaha Blablabiag".getBytes();
crc.update(bytes);
System.out.println(crc.getValue()+ " " + Arrays.toString(crc.toByteArray()));
}import java.nio.ByteBuffer;
import com.sun.org.apache.xml.internal.security.utils.Base64;
/**
* A class that can be used to compute the CRC-24 of a data stream.
*
* @author <a href="mailto:nagydani@users.sourceforge.net">Daniel A. Nagy</a>
*/
public final class CRC24 implements java.util.zip.Checksum {
final static int INIT = 0xb704ce;
final static int POLY = 0x1864cfb;
private int crc;
/**
* Creates a new CRC24 object.
*/
public CRC24() {
}
/**
* Creates a copy of a CRC24 object.
*
* @param c
* object to be copied
*/
public CRC24(CRC24 c) {
crc = c.crc;
}
/**
* Returns CRC-24 value.
*/
public long getValue() {
return crc & 0xffffff;
}
/**
* Resets CRC-24 to initial value.
*/
public void reset() {
crc = INIT;
}
/**
* Updates CRC-24 with specified byte.
*
* @param b
* the byte to update the checksum with
*/
public void update(int b) {
int i = 8;
crc ^= b << 16;
while (i-- > 0) {
crc <<= 1;
if ((crc & 0x1000000) > 0)
crc ^= POLY;
}
}
/**
* Updates CRC-24 with specified array of bytes.
*
* @param b
* the byte array to update the checksum with
* @param off
* the start offset of the data
* @param len
* the number of bytes to use for the update
*/
public void update(byte[] b, int off, int len) {
int i;
int end = off + len;
for (i = off; i < end; i++)
update(b[i]);
}
/**
* Updates CRC-24 with specified array of bytes.
*
* @param b
* the byte array to update the checksum with
*/
public void update(byte[] b) {
update(b, 0, b.length);
}
/**
* Armor Checksum
*
* @return Base64 representation prefixed by '='
*/
public String toString() {
byte[] c = { (byte) ((crc >> 16) & 0xff), (byte) ((crc >> 8) & 0xff),
(byte) (crc & 0xff) };
return "=" + Base64.encode(c);
}
/**
* Returns byte array representation of CRC-24 value
*
* @param value
* @return
*/
public byte[] toByteArray() {
ByteBuffer bb = ByteBuffer.allocate(4);
byte[] ba = bb.putInt(crc).array();
return new byte[] {ba[1], ba[2], ba[3]};
}
} public static void main(String[] args) throws IOException {
String[] namen = {"Gertrud", "Gert", "Karl", "Ina", "klaus", "tttd"};
for (String name : namen) {
printCRC(name);
}
}
public static void printCRC(String name) {
CRC24 crc = new CRC24();
byte[] bytes = name.getBytes();
crc.update(bytes);
System.out.println(crc.getValue()+ " " + Arrays.toString(crc.toByteArray()) + " " + new String(crc.toByteArray()));
}3245734 [49, -122, -90] 1†¦
8828647 [-122, -74, -25] †¶ç
9087013 [-118, -88, 37] Š¨%
1992713 [30, 104, 9] h
6217530 [94, -33, 58] ^ß:
7244855 [110, -116, 55] nŒ7naja crc24 deckt schon ne menge ab und ist um welten genauer als so händisches char nummern addieren.
bei geforderten 3 byte hat man eben nur 16.7 mio möglichkeiten. die nutzt 24er crc sauber aus.Also zwischen HEX und BCD komme ich blos auf einen Faktor von 1,6, aber trotzdem dürfte HEX in die richtige Richtung führen.
16/10 = 1,6
| Titel | Forum | Antworten | Datum | |
|---|---|---|---|---|
| F | Prüfsumme einer Klasse? | Java Basics - Anfänger-Themen | 17 | |
| B | Aufgabe Prüfsumme | Java Basics - Anfänger-Themen | 2 |
