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package org.reprap.comms.snap;
/**
*
* Represents the checksum calculation process used in SNAP which
* is an 8 bit CRC.
*
*/
public class SNAPChecksum {
/**
*
*/
byte crc;
/**
*
*/
SNAPChecksum() {
crc = 0;
}
/**
* Add data to the CRC computation
* @param data
* @return The data passed for convenience
*/
byte addData(byte data) {
byte i = (byte)(data ^ crc);
crc = 0;
if((i & 1) != 0)
crc ^= 0x5e;
if((i & 2) != 0)
crc ^= 0xbc;
if((i & 4) != 0)
crc ^= 0x61;
if((i & 8) != 0)
crc ^= 0xc2;
if((i & 0x10) != 0)
crc ^= 0x9d;
if((i & 0x20) != 0)
crc ^= 0x23;
if((i & 0x40) != 0)
crc ^= 0x46;
if((i & 0x80) != 0)
crc ^= 0x8c;
return data;
}
/**
* @return
*/
byte getResult() {
return crc;
}
}
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