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| package com.dy.common.util;
|
|
| @SuppressWarnings("unused")
| public final class CRC16 {
|
| /*
| * 16位的CRC值是无符号两字节整数，
| * @param b 字节数组
| * @return CRC
|
| public int CRC(byte[] b) {
| int crc = 0xFFFF;
| int len = b.length;
| for (int j = 0 ; j < len; j++) {
| crc = crc ^ ((b[j] + 256) % 256) ;//转换成无符号数，因为终端实现(C语言或汇编语言)都用的是无符号数
| for (int i = 0; i < 8; i++) {
| if ((crc & 0x0001) == 0x0001) {
| crc = (crc >> 1) ^ 0xA001;
| } else {
| crc = crc >> 1;
| }
| }
| }
| return crc;
| }
| */
|
| /**
| * 16位的CRC值是无符号两字节整数，
| * @param b 字节数组
| * @param startIndex 开始下标
| * @param endIndex 截止下标
| * @return CRC
| */
| @SuppressWarnings("unused")
| public short CRC(byte[] b, int startIndex, int endIndex) {
| int crc = 0xFFFF;
| for (int j = startIndex ; j <= endIndex; j++) {
| crc = crc ^ ((b[j] + 256) % 256) ;//转换成无符号数，因为终端实现(C语言或汇编语言)都用的是无符号数
| for (int i = 0; i < 8; i++) {
| if ((crc & 0x0001) == 0x0001) {
| crc = (crc >> 1) ^ 0xA001;
| } else {
| crc = crc >> 1;
| }
| }
| }
| return (short)crc;
| }
|
|
|
| private static final int[] crc16_rev_table = new int[]
| { 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
| 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
| 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
| 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
| 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
| 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
| 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
| 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
| 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
| 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
| 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
| 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
| 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
| 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
| 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
| 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
| 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
| 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
| 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
| 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
| 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
| 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
| 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
| 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
| 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
| 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
| 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
| 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
| 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
| 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
| 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
| 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
| };
|
| /**
| * 16位的CRC值 ，查表法
| * @param bs 字节数组
| * @return CRC
| */
| @SuppressWarnings("unused")
| public int CRC_table(byte[] bs) {
| int x ;
| int crc = 0xffff;
| if(bs != null && bs.length > 0){
| for(byte b : bs){
| x = crc ^ b ;
| crc = (crc >> 8) ^ crc16_rev_table[x & 0x00FF];
| }
| }
| return crc ;
| }
|
|
| /**
| * 数据高位在低字节(数组下标小)，数据低位在高字节(数组下标大)，
| * 例如258这个数，放进四个字节数组b中：
| * b[0](低字节)=0，
| * b[1](次低字节)=0，
| * b[2](次高字节)=1(数据高位)，
| * b[3](高字节)=2(数据低位)，
| * @param c 整数
| * @return 转成的数组
| */
| public byte[] CRC2bytes(int c) {
| byte[] crc = new byte[2];
| System.arraycopy(new byte[] {(byte)(c / 256) }, 0, crc, 0, 1);
| System.arraycopy(new byte[] {(byte)(c - ((c / 256) * 256)) }, 0, crc, 1, 1);
| return crc;
| }
|
|
| }
|
|
