如何用java实现CRC8验证算法

如何用java实现CRC8验证算法

package com.dalsemi.onewire.utils;


public class CRC8
{

//--------
//-------- Variables
//--------


private static byte dscrc_table [];


static
{

//Translated from the assembly code in iButton Standards, page 129.
dscrc_table = new byte [256];

int acc;
int crc;

for (int i = 0; i < 256; i++)
{
acc = i;
crc = 0;

for (int j = 0; j < 8; j++)
{
if (((acc ^ crc) & 0x01) == 0x01)
{
crc = ((crc ^ 0x18) >> 1) | 0x80;
}
else
crc = crc >> 1;

acc = acc >> 1;
}

dscrc_table [i] = ( byte ) crc;
}
}

//--------
//-------- Constructor
//--------


private CRC8 ()
{
}

//--------
//-------- Methods
//--------


public static int compute (int dataToCRC, int seed)
{
return (dscrc_table [(seed ^ dataToCRC) & 0x0FF] & 0x0FF);
}


public static int compute (int dataToCRC)
{
return (dscrc_table [dataToCRC & 0x0FF] & 0x0FF);
}


public static int compute (byte dataToCrc [])
{
return compute(dataToCrc, 0, dataToCrc.length);
}


public static int compute (byte dataToCrc [], int off, int len)
{
return compute(dataToCrc, off, len, 0);
}


public static int compute (byte dataToCrc [], int off, int len, int seed)
{

// loop to do the crc on each data element
int CRC8 = seed;

for (int i = 0; i < len; i++)
CRC8 = dscrc_table [(CRC8 ^ dataToCrc [i + off]) & 0x0FF];

return (CRC8 & 0x0FF);
}


public static int compute (byte dataToCrc [], int seed)
{
return compute(dataToCrc, 0, dataToCrc.length, seed);
}
}追问seed参数的作用是什么？