CDT91 crc

crc8.java

import com.google.common.io.BaseEncoding;

public class CRC8 {
    private static byte[] CRC_TABLE = new byte[256];
    static {
        init();
    }

    static void init() {
        byte temp = 0;
        for (short i = 0; i < 256; i++) {
            temp = (byte) i;
            for (byte j = 0; j < 8; j++) {
                if ((temp & 0x80) != 0) {
                    temp = (byte) (temp << 1);
                    temp = (byte) (temp ^ 0x7);
                } else {
                    temp = (byte) (temp << 1);
                }
            }
            CRC_TABLE[i] = temp;
        }
    }

    /**
     * 获取CRC校验码（算式是0x107）
     * 
     * @param data
     *            需要计算校验的数组
     * @param startIndex
     *            开始校验位
     * @param length
     *            进行校验的字节总长度
     * @return CRC8校验
     */
    public static byte crc(byte[] data, int startIndex, int length) {
        byte returnValue = 0;
        int index = 0;
        for (int i = startIndex; i < startIndex + length; i++) {
            returnValue = (byte) (returnValue ^ data[i]);
            index = returnValue;
            if (returnValue < 0) {
                index = (returnValue & 0xff);
            }
            returnValue = CRC_TABLE[index];
        }
        returnValue = (byte) (returnValue ^ 0xff);
        return (byte) returnValue;
    }

    /**
     * 获取CRC校验码（算式是0x107）
     * 
     * @param data
     *            需要计算校验的数组
     * @return CRC8校验
     */
    public static byte crc(byte[] data) {
        return crc(data, 0, data.length);
    }

    public static void main(String[] args) {
        byte[] decode = BaseEncoding.base16().withSeparator(" ", 2).decode("01 C8 00 9C FF");
        byte crc = crc(decode);
        System.out.println(BaseEncoding.base16().withSeparator(" ", 2).encode(decode)
                           + " "
                           + Integer.toHexString(0x00ff & crc));
    }
}

EB 90 EB 90 EB 90 71 61 02 01 01 84 00 FC 2F FF 7F BD 01 00 80 9C FF 78
EB 90 EB 90 EB 90 71 C2 02 01 01 41 00 FF 07 9C 0F 08 01 C8 00 64 00 26
EB 90 EB 90 EB 90 71 B3 02 01 01 65 00 FF 0F C4 09 EF 01 C8 00 9C FF 69