package com.fastbee.common.utils.gateway;
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import com.fastbee.common.utils.gateway.protocol.ByteUtils;
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public class CRC16Utils {
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//ff
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private static int CRC_FF = 0x000000ff;
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//01
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private static int CRC_01 = 0x00000001;
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//04
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private static final int LENGTH_04 = 4;
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//16进制
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private static final int OXFF = 0xff;
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/**
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* 低位在前，高位在后
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*
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* @param bytes
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* @return
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*/
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public static String getCRC(byte[] bytes) {
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return getCRC(bytes, true);
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}
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/**
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* @param bytes
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* @param lb 是否低位在前, 高位在后
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* @return
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*/
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public static String getCRC(byte[] bytes, boolean lb) {
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int CRC = 0x0000ffff;
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int POLYNOMIAL = 0x0000a001;
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int i, j;
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for (i = 0; i < bytes.length; i++) {
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CRC ^= ((int) bytes[i] & 0x000000ff);
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for (j = 0; j < 8; j++) {
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if ((CRC & 0x00000001) != 0) {
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CRC >>= 1;
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CRC ^= POLYNOMIAL;
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} else {
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CRC >>= 1;
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}
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}
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}
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//结果转换为16进制
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String result = Integer.toHexString(CRC).toUpperCase();
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if (result.length() != 4) {
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StringBuffer sb = new StringBuffer("0000");
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result = sb.replace(4 - result.length(), 4, result).toString();
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}
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if (lb) { // 低位在前, 高位在后
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result = result.substring(2, 4) + result.substring(0, 2);
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}
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return result;
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}
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/**
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* 计算CRC校验和
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*
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* @param bytes
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* @return 返回 byte[]
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*/
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public static byte[] getCrc16Byte(byte[] bytes) {
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//寄存器全为1
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int CRC_16 = 0x0000ffff;
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// 多项式校验值
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int POLYNOMIAL = 0x0000a001;
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for (byte aByte : bytes) {
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CRC_16 ^= ((int) aByte & CRC_FF);
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for (int j = 0; j < 8; j++) {
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if ((CRC_16 & CRC_01) != 0) {
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CRC_16 >>= 1;
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CRC_16 ^= POLYNOMIAL;
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} else {
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CRC_16 >>= 1;
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}
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}
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}
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// 低8位 ，高8位
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return new byte[]{(byte) (CRC_16 & OXFF), (byte) (CRC_16 >> 8 & OXFF)};
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}
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public static byte[] CRC(byte[] source) {
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source[2] = (byte) ((int) source[2] * 2);
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byte[] result = new byte[source.length + 2];
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byte[] crc16Byte = CRC16Utils.getCrc16Byte(source);
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System.arraycopy(source, 0, result, 0, source.length);
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System.arraycopy(crc16Byte, 0, result, result.length - 2, 2);
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return result;
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}
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public static byte CRC8(byte[] buffer) {
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int crci = 0xFF; //起始字节FF
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for (int j = 0; j < buffer.length; j++) {
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crci ^= buffer[j] & 0xFF;
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for (int i = 0; i < 8; i++) {
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if ((crci & 1) != 0) {
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crci >>= 1;
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crci ^= 0xB8; //多项式当中的那个啥的，不同多项式不一样
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} else {
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crci >>= 1;
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}
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}
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}
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return (byte) crci;
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}
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public static void main(String[] args)throws Exception {
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String hex = "01000002";
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byte[] bytes = ByteUtils.hexToByte(hex);
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String crc = getCRC(bytes);
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System.out.println(crc);
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String crc8 = "680868333701120008C100";
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byte[] byte8 = ByteUtils.hexToByte(crc8);
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int b = CRC8(byte8);
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System.out.println((int) b);
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}
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}
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