CRC-CCITT 標準CRC16(1021) 算法校驗類

package org.david.tools.util;

/**
 * @File_Name CRCUtil.java
 * @Author David.Lee
 * @Date 2018年2月9日 下午2:26:38
 * @Copyright 2018 www.zhihu.com/people/david.lee9 Inc. All rights reserved.
 * @Description CRC-CCITT 算法校驗類
 */
public class CRCUtil {
    /*
     * CCITT標準CRC16(1021)餘數表 CRC16-CCITT ISO HDLC, ITU X.25, x16+x12+x5+1 多項式
     * 高位在先時生成多項式 Gm=0x11021 低位在先時生成多項式，Gm=0x8408 本例採用高位在先
     */
    private static int crc16_ccitt_table[] = { 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 0x8108, 0x9129, 0xa14a,
            0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, 0x9339, 0x8318, 0xb37b,
            0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485, 0xa56a, 0xb54b, 0x8528,
            0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, 0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, 0xb75b, 0xa77a, 0x9719,
            0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823, 0xc9cc, 0xd9ed, 0xe98e,
            0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, 0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, 0xdbfd, 0xcbdc, 0xfbbf,
            0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, 0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, 0xedae, 0xfd8f, 0xcdec,
            0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49, 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70, 0xff9f, 0xefbe, 0xdfdd,
            0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, 0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f, 0x1080, 0x00a1, 0x30c2,
            0x20e3, 0x5004, 0x4025, 0x7046, 0x6067, 0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, 0x02b1, 0x1290, 0x22f3,
            0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, 0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, 0x34e2, 0x24c3, 0x14a0,
            0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c, 0x26d3, 0x36f2, 0x0691,
            0x16b0, 0x6657, 0x7676, 0x4615, 0x5634, 0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, 0x5844, 0x4865, 0x7806,
            0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3, 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, 0x4a75, 0x5a54, 0x6a37,
            0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 0x7c26, 0x6c07, 0x5c64,
            0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, 0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 0x6e17, 0x7e36, 0x4e55,
            0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0 };


    /**
     *
     * @param reg_init CRC校驗時初值
     * @param message 校驗值
     * @return
     */
    private static int do_crc(int reg_init, byte[] message) {
        int crc_reg = reg_init;
        for (int i = 0; i < message.length; i++) {
            crc_reg = (crc_reg >> 8) ^ crc16_ccitt_table[(crc_reg ^ message[i]) & 0xff];
        }
        return crc_reg;
    }

    /**
     * 根據數據生成CRC校驗碼
     *
     * @param message
     *            byte數據
     *
     * @return int 返校驗碼
     */
    private static int do_crc(byte[] message) {
        // 計算CRC校驗時初值從0x0000開始。
        int crc_reg = 0x0000;
        return do_crc(crc_reg, message);
    }
    /**
     * db44檢驗方法
     *
     * @param message 消息內容
     * @param crc 檢驗碼值
     * @return
     */
    private static boolean do_crc(byte[] message,byte[] crc) {
        // 計算CRC校驗時初值從0x0000開始。
        int crc_reg = 0x0000;
        int crc_value = (crc[0]&0xff)*256+(crc[1]&0xff);
        return crc_value ==do_crc(crc_reg, message);
    }
    /**
     * 供db44結構代碼使用,數組後兩位爲CRC-校驗碼值
     * @param messages
     * @return
     */
    public static boolean do_crc_db44(byte[] messages) {
        // 計算CRC校驗時初值從0x0000開始。
        byte[] messageArray = new byte[messages.length-2];
        byte[] crcArray = new byte[2];
        System.arraycopy(messages, 0, messageArray, 0, messageArray.length);
        System.arraycopy(messages, messages.length-2, crcArray, 0, 2);
        return do_crc(messageArray, crcArray);
    }

    /**
     * use
     * @param bytes
     * @return
     */
    public static int CRC_XModem(byte[] bytes){
        int crc = 0x00;          // initial value
        int polynomial = 0x1021;
        for (int index = 0 ; index< bytes.length; index++) {
            byte b = bytes[index];
            for (int i = 0; i < 8; i++) {
                boolean bit = ((b   >> (7-i) & 1) == 1);
                boolean c15 = ((crc >> 15    & 1) == 1);
                crc <<= 1;
                if (c15 ^ bit) crc ^= polynomial;
            }
        }
        crc &= 0xffff;
        return crc;
    }

    public static void main(String[] args) {
        // 一個db44測試樣本數據
        byte p[] = {15,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,68,31,32,0,1,2};
        String hex = "0805140001000200114571251005457125100508FFFFFFFFFFFF";

        int crc = do_crc(ByteUtils.hexStringToByteArray(hex)); // 計算前兩位的CRC碼
        // 65336
        System.out.println(crc+"====="
                +Integer.toHexString(crc)+"=========="
                +CRC_XModem(ByteUtils.hexStringToByteArray(hex))
        +"======"+Integer.toHexString(CRC_XModem(ByteUtils.hexStringToByteArray(hex))));

    }

}