需要帮助纠正用Javascript（node.js）编写的CRC-ITU检查方法中的问题
我们正在尝试在Javascript上编写GPS设备侦听器 这样做时，我们无法为CRC-ITU错误检查开发正确的脚本。从协议文件生成crc代码的说明如下 终端或服务器可以使用检查码来区分 接收到的信息是否错误。防止错误 在数据传输过程中发生，将根据数据添加错误检查 误操作，从而提高系统的安全性和效率 系统。校验码由CRC-ITU校验方法生成。 协议结构中的数据检查代码，来自 信息序列号的数据包长度（包括“数据包 “长度”和“信息序列号”）是CRC-ITU的值。华润 当计算接收到的信息时出错，接收器 将忽略并丢弃数据包 我们参考了协议文档中给出的C代码示例-需要帮助纠正用Javascript（node.js）编写的CRC-ITU检查方法中的问题,javascript,node.js,gps,crc,Javascript,Node.js,Gps,Crc,我们正在尝试在Javascript上编写GPS设备侦听器 这样做时，我们无法为CRC-ITU错误检查开发正确的脚本。从协议文件生成crc代码的说明如下 终端或服务器可以使用检查码来区分 接收到的信息是否错误。防止错误 在数据传输过程中发生，将根据数据添加错误检查 误操作，从而提高系统的安全性和效率 系统。校验码由CRC-ITU校验方法生成。 协议结构中的数据检查代码，来自 信息序列号的数据包长度（包括“数据包 “长度”和“信息序列号”）是CRC-ITU的值。华润 当计算接收到的信息时出错，接收器
// calculate the 16-bit CRC of data with predetermined length.
U16 GetCrc16(const U8* pData, int nLength)
{
U16 fcs = 0xffff; // initialization
while(nLength>0)
{
fcs = (fcs >> 8) ^ crctab16[(fcs ^ *pData) & 0xff];
nLength--;
pData++;
}
return ~fcs; // negated
}
Incoming data string comes in following format
Example of data packet sent by the terminal 78 78 0D 01 01 23 45 67 89 01 23 45 00 01 8C DD 0D 0A
Explanation
Start Bit - 0x78 0x78
Length - 0x0D
Protocol - 0x01
Terminal ID - 0x01 0x23 0x45 0x67 0x89 0x01 0x23 0x45
Serial No - 0x00 0x01
Error - 0x8C 0xDD
Stop Bit - 0x0D 0x0A
var net = require('net');
net.createServer(function(socket)
{
socket.setEncoding('hex');
// New client connection event
socket.on('connect', function(data)
// Incoming data event
socket.on('data', function(data)
{
console.log("Client said: " + data); // server log
data_p = data.substring(4,28);
err_code = crc16(data_p);
console.log("error: " + err_code);
});
// Disconnect event
socket.on('end', function()
{
//Log it to the server output
console.log("someone left us." + socket.remoteAddress);
});
}).listen(3006);
console.log("TCP ECHO SERVER STARTED ON 3006");
function crc16(buf)
{
var crcTable =
[
0X0000, 0X1189, 0X2312, 0X329B, 0X4624, 0X57AD, 0X6536, 0X74BF, 0X8C48, 0X9DC1, 0XAF5A,
0XBED3, 0XCA6C, 0XDBE5, 0XE97E, 0XF8F7, 0X1081, 0X0108, 0X3393, 0X221A, 0X56A5, 0X472C,
0X75B7, 0X643E, 0X9CC9, 0X8D40, 0XBFDB, 0XAE52, 0XDAED, 0XCB64, 0XF9FF, 0XE876, 0X2102,
0X308B, 0X0210, 0X1399, 0X6726, 0X76AF, 0X4434, 0X55BD, 0XAD4A, 0XBCC3, 0X8E58, 0X9FD1,
0XEB6E, 0XFAE7, 0XC87C, 0XD9F5, 0X3183, 0X200A, 0X1291, 0X0318, 0X77A7, 0X662E, 0X54B5,
0X453C, 0XBDCB, 0XAC42, 0X9ED9, 0X8F50, 0XFBEF, 0XEA66, 0XD8FD, 0XC974, 0X4204, 0X538D,
0X6116, 0X709F, 0X0420, 0X15A9, 0X2732, 0X36BB, 0XCE4C, 0XDFC5, 0XED5E, 0XFCD7, 0X8868,
0X99E1, 0XAB7A, 0XBAF3, 0X5285, 0X430C, 0X7197, 0X601E, 0X14A1, 0X0528, 0X37B3, 0X263A,
0XDECD, 0XCF44, 0XFDDF, 0XEC56, 0X98E9, 0X8960, 0XBBFB, 0XAA72, 0X6306, 0X728F, 0X4014,
0X519D, 0X2522, 0X34AB, 0X0630, 0X17B9, 0XEF4E, 0XFEC7, 0XCC5C, 0XDDD5, 0XA96A, 0XB8E3,
0X8A78, 0X9BF1, 0X7387, 0X620E, 0X5095, 0X411C, 0X35A3, 0X242A, 0X16B1, 0X0738, 0XFFCF,
0XEE46, 0XDCDD, 0XCD54, 0XB9EB, 0XA862, 0X9AF9, 0X8B70, 0X8408, 0X9581, 0XA71A, 0XB693,
0XC22C, 0XD3A5, 0XE13E, 0XF0B7, 0X0840, 0X19C9, 0X2B52, 0X3ADB, 0X4E64, 0X5FED, 0X6D76,
0X7CFF, 0X9489, 0X8500, 0XB79B, 0XA612, 0XD2AD, 0XC324, 0XF1BF, 0XE036, 0X18C1, 0X0948,
0X3BD3, 0X2A5A, 0X5EE5, 0X4F6C, 0X7DF7, 0X6C7E, 0XA50A, 0XB483, 0X8618, 0X9791, 0XE32E,
0XF2A7, 0XC03C, 0XD1B5, 0X2942, 0X38CB, 0X0A50, 0X1BD9, 0X6F66, 0X7EEF, 0X4C74, 0X5DFD,
0XB58B, 0XA402, 0X9699, 0X8710, 0XF3AF, 0XE226, 0XD0BD, 0XC134, 0X39C3, 0X284A, 0X1AD1,
0X0B58, 0X7FE7, 0X6E6E, 0X5CF5, 0X4D7C, 0XC60C, 0XD785, 0XE51E, 0XF497, 0X8028, 0X91A1,
0XA33A, 0XB2B3, 0X4A44, 0X5BCD, 0X6956, 0X78DF, 0X0C60, 0X1DE9, 0X2F72, 0X3EFB, 0XD68D,
0XC704, 0XF59F, 0XE416, 0X90A9, 0X8120, 0XB3BB, 0XA232, 0X5AC5, 0X4B4C, 0X79D7, 0X685E,
0X1CE1, 0X0D68, 0X3FF3, 0X2E7A, 0XE70E, 0XF687, 0XC41C, 0XD595, 0XA12A, 0XB0A3, 0X8238,
0X93B1, 0X6B46, 0X7ACF, 0X4854, 0X59DD, 0X2D62, 0X3CEB, 0X0E70, 0X1FF9, 0XF78F, 0XE606,
0XD49D, 0XC514, 0XB1AB, 0XA022, 0X92B9, 0X8330, 0X7BC7, 0X6A4E, 0X58D5, 0X495C, 0X3DE3,
0X2C6A, 0X1EF1, 0X0F78
];
crcX = parseInt("FFFF",16);
cr1 = parseInt("FF",16);
cr2 = parseInt("FFFF",16);
i = 0;
while(i < buf.length)
{
str = buf.substring(i,i+4);
console.log("str "+str);
str_hex = parseInt(str,16);
j = (crcX ^ str_hex) & cr1;
crcX = (crcX >> 8) ^ crcTable[j] ;
i = i + 4;
}
crcX = ~crcX;
console.log("crcX - " + crcX.toString(16));
return crcX;
}
非常感谢。原始代码中的
~crcX=crcX^0xffffcrcX=~crcX另外，您的
buf.子字符串（i，i+4）i=i+4i+2npmcrcccrc itunpm install crc-itu
var crc16 = require('crc-itu').crc16;
var crcInHex = crc16('0d0103588990501766460026', 'hex').toString(16);
console.log(crcInHex); // will print 7bf9
crc16（数据）。toString（16）=>crcstart data crc end
-------------------------------------------
7878 0d0103588990501766460026 7bf9 0d0a
7878 0d010358899050176646002a b195 0d0a
7878 0d010358899050176646002b a01c 0d0a
var net = require('net');
var HOST = '192.168.1.151';
var PORT = 5023;
function protocall_decorder(data,sbit,plength,protono,ebit){
// Login data
if(plength.toString('hex') == '0d') {
var ret = crc16Ccitt(data.slice(2,14));
var err_code = ret;
console.log(err_code.toString(16));
plength = new Buffer('05','hex');
var res = sbit + plength + protono + data.slice(12,14) + err_code.toString(16) + ebit;
data = "device_imei: " + parseInt(data.slice(4,12).toString('hex'));
console.log(data);
res = new Buffer(res)
var dataArr = {response:res, type:"login", data:data};
}
/*
// Location data
else if(plength == '1F') {
var res = '787805' + ***** + data.slice(60,64) + data.slice(24,28) +'D9DC' + '0D0A';
dataArr = data.substring(2);
}
// Alarm data
else if(plength == '25') {
dataArr = data.substring(2);
}
// Heart Beat
else if(plength == '08') {
dataArr = data.substring(2);
}
// Undefined data length
*/
else {
var dataArr = {response:"error", data:plength};
}
return dataArr;
}
// The sock object the callback function receives UNIQUE for each connection
net.createServer(function(sock) {
// We have a connection - a socket object is assigned to the connection automatically
console.log('CONNECTED: ' + sock.remoteAddress +':'+ sock.remotePort);
// Add a 'data' event handler to this instance of socket
sock.on('data', function(data) {
console.log('DATA ' + sock.remoteAddress + ': ' + data);
// Write the data back to the socket, the client will receive it as data from the server
//////////////// MySQL | Begin ////////////////////
var mysql = require('mysql');
var con = mysql.createConnection({
host : 'localhost',
user : 'root',
password : 'lahirutm',
database : 'gt06n'
});
con.connect();
var sbit = data.slice(0,2);
var plength = data.slice(2,3);
var protono = data.slice(3,4);
var ebit = data.slice(-2)
if(sbit.toString('hex') == '7878') {
var res = protocall_decorder(data,sbit,plength,protono,ebit);
if(res['response'] != 'error') {
sock.write(res['response']);
var response = res['response'];
}
}
else {
console.log('Undefined protocol data');
}
console.log(response); // Write data to socket
var message = {start_bit: sbit, packet_length: plength, proto_no: protono, serial:'*', end_bit: ebit};
var query = con.query('INSERT INTO incoming_data SET ?', message,
//var message = {data: data}
//var query = con.query('INSERT INTO row_data SET ?', message,
function(err, result) {
// Neat!
});
console.log(query.sql);
var message = {data: data}
var query = con.query('INSERT INTO row_data SET ?', message,
function(err, result) {
// Neat!
});
console.log(query.sql);
con.end();
/////////////// MySQL | Begin ////////////////
});
// Add a 'close' event handler to this instance of socket
sock.on('close', function(data) {
console.log('CLOSED: ' + sock.remoteAddress +' '+ sock.remotePort);
});
}).listen(PORT, HOST);
console.log('Server listening on ' + HOST +':'+ PORT);
/**
* CRC functions
*/
var crc16CcittTableReverse = [
0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E,
0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876,
0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD,
0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5,
0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C,
0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974,
0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB,
0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3,
0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A,
0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72,
0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9,
0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1,
0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738,
0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70,
0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7,
0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF,
0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036,
0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E,
0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5,
0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD,
0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134,
0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C,
0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3,
0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB,
0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232,
0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A,
0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1,
0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9,
0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330,
0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78
];
var crc16CcittStart = 0xFFFF;
var crc16CcittXorout = 0xFFFF;
function crc16Reflected(buf, crc_in, table) {
var crc16 = crc_in;
for (i = 0; i < buf.length; i++) {
crc16 = table[(crc16 ^ buf[i]) & 0xff] ^ (crc16 >> 8);
}
return crc16 & 0xFFFF;
}
function crc16Ccitt(buf) {
return crc16Reflected(buf, crc16CcittStart, crc16CcittTableReverse) ^ crc16CcittXorout;
}
var net=require（'net'）；
var HOST='192.168.1.151'；
var端口=5023；
函数protocall_decorder（数据、sbit、充压、protono、ebit）{
//登录数据
if（正压涡轮串（'hex'）='0d'）{
var-ret=crc16Ccitt（数据切片（2,14））；
var err_code=ret；
console.log（err_code.toString（16））；
正压=新缓冲器（'05'，'hex'）；
var res=sbit+plength+protono+data.slice（12,14）+错误代码toString（16）+息税前利润；
data=“device_imei:”+parseInt（data.slice（4,12）.toString（'hex'）；
控制台日志（数据）；
res=新缓冲区（res）
var dataArr={响应：res，类型：“login”，数据：data}；
}
/*
//位置数据
否则如果（正压='1F'）{
var res='787805'+******+data.slice（60,64）+data.slice（24,28）+'D9DC'+'0D0A'；
dataArr=数据子串（2）；
}
//报警数据
否则如果（正压='25'）{
dataArr=数据子串（2）；
}
//心跳
否则如果（正压='08'）{
dataArr=数据子串（2）；
}
//未定义的数据长度
*/
否则{
var dataArr={响应：“错误”，数据：plength}；
}
返回数据arr；
}
//回调函数接收的sock对象对于每个连接都是唯一的
net.createServer（函数（sock）{
//我们有一个连接-一个套接字对象被自动分配给该连接
log（'CONNECTED:'+sock.remoteAddress+'：'+sock.remotePort）；
//将“数据”事件处理程序添加到此套接字实例
sock.on（'data'，函数（data）{
log（'DATA'+sock.remoteAddress+'：'+DATA）；
//将数据写回套接字，客户端将从服务器接收数据
////////////////MySQL |开始////////////////////
var mysql=require（'mysql'）；
var con=mysql.createConnection({
主机：“localhost”，
用户：'根'，
密码：“lahirutm”，
数据库：“gt06n”
});
con.connect（）；
var sbit=数据切片（0,2）；
var plength=数据切片（2,3）；
var protono=data.slice（3,4）；
var息税前利润=数据切片（-2）
如果（sbit.toString（'hex'）=='7878'）{
var res=协议调用（数据、sbit、正压、协议编号、息税前利润）；
如果（res['response']！='error'）{
sock.write（res['response']）；
var响应=res[‘响应’]；
}
}
否则{
log（“未定义的协议数据”）；
}
console.log（response）；//将数据写入套接字
var消息={起始位：sbit，数据包长度：正整数，协议号：协议号，序列号：'*'，结束位：ebit}；
var query=con.query（'插入到传入的_数据集中？'，消息，
//var message={data:data}
//var query=con.query（'INSERT INTO row_data SET？'），消息，
函数（错误、结果）{
//干净利落！
});
log（query.sql）；
var message={data:data}
var query=con.query（'INSERT INTO row_data SET？'），消息，
函数（错误、结果）{
//干净利落！
});
log（query.sql）；
con.end（）；
///////////////MySQL |开始////////////////
});
//将“关闭”事件处理程序添加到此套接字实例
sock.on（'close'，函数（数据）{
console.log（'CLOSED:'+sock.remoteAddress+'+sock.remotePort）；
});
}).侦听（端口、主机）；
log（'在'+HOST+'上侦听的服务器：'+PORT）；
/**
*CRC函数
*/
变量crc16CcittTableReverse=[
0x0000、0x1189、0x2312、0x329B、0x4624、0x57AD、0x6536、0x74BF、，
0x8C48、0x9DC1、0xAF5A、0xBED3、0xCA6C、0xDBE5、0xE97E、0xF8F7、，
0x1081、0x0108、0x3393、0x221A、0x56A5、0x472C、0x75B7、0x643E、，
0x9CC9、0x8D40、0xBFDB、0xAE52、0xDAED、0xCB64、0xF9FF、0xE876、，
0x2102、0x308B、0x0210、0x1399、0x6726、0x76AF、0x4434、0x55BD、，
0xAD4A、0xBCC3、0x8E58、0x9FD1、0xEB6E、0xFAE7、0xC87C、0xD9F5、，
0x3183、0x200A、0x1291、0x0318、0x77A7、0x662E、0x54B5、0x453C、，
0xBDCB、0xAC42、0x9ED9、0x8F50、0xFBEF、0xEA66、0xD8FD、0xC974、，
0x4204、0x538D、0x6116、0x709F、0x0420、0x15A9、0x2732、0x36BB、，
0xCE4C、0xDFC5、0xED5E、0xFCD7、0x8868、0x99E1、0xAB7A、0xBAF3、，
0x5285、0x430C、0x7197、0x601E、0x14A1、0x0528、0x37B3、0x263A、，
0xDECD、0xCF44、0xFDDF、0xEC56、0x98E9、0x8960、0xBBFB、0xAA72、，
0x6306、0x728F、0x4014、0x519D、0x2522、0x34AB、0x0630、0x17B9、，
0
var net = require('net');
var HOST = '192.168.1.151';
var PORT = 5023;
function protocall_decorder(data,sbit,plength,protono,ebit){
// Login data
if(plength.toString('hex') == '0d') {
var ret = crc16Ccitt(data.slice(2,14));
var err_code = ret;
console.log(err_code.toString(16));
plength = new Buffer('05','hex');
var res = sbit + plength + protono + data.slice(12,14) + err_code.toString(16) + ebit;
data = "device_imei: " + parseInt(data.slice(4,12).toString('hex'));
console.log(data);
res = new Buffer(res)
var dataArr = {response:res, type:"login", data:data};
}
/*
// Location data
else if(plength == '1F') {
var res = '787805' + ***** + data.slice(60,64) + data.slice(24,28) +'D9DC' + '0D0A';
dataArr = data.substring(2);
}
// Alarm data
else if(plength == '25') {
dataArr = data.substring(2);
}
// Heart Beat
else if(plength == '08') {
dataArr = data.substring(2);
}
// Undefined data length
*/
else {
var dataArr = {response:"error", data:plength};
}
return dataArr;
}
// The sock object the callback function receives UNIQUE for each connection
net.createServer(function(sock) {
// We have a connection - a socket object is assigned to the connection automatically
console.log('CONNECTED: ' + sock.remoteAddress +':'+ sock.remotePort);
// Add a 'data' event handler to this instance of socket
sock.on('data', function(data) {
console.log('DATA ' + sock.remoteAddress + ': ' + data);
// Write the data back to the socket, the client will receive it as data from the server
//////////////// MySQL | Begin ////////////////////
var mysql = require('mysql');
var con = mysql.createConnection({
host : 'localhost',
user : 'root',
password : 'lahirutm',
database : 'gt06n'
});
con.connect();
var sbit = data.slice(0,2);
var plength = data.slice(2,3);
var protono = data.slice(3,4);
var ebit = data.slice(-2)
if(sbit.toString('hex') == '7878') {
var res = protocall_decorder(data,sbit,plength,protono,ebit);
if(res['response'] != 'error') {
sock.write(res['response']);
var response = res['response'];
}
}
else {
console.log('Undefined protocol data');
}
console.log(response); // Write data to socket
var message = {start_bit: sbit, packet_length: plength, proto_no: protono, serial:'*', end_bit: ebit};
var query = con.query('INSERT INTO incoming_data SET ?', message,
//var message = {data: data}
//var query = con.query('INSERT INTO row_data SET ?', message,
function(err, result) {
// Neat!
});
console.log(query.sql);
var message = {data: data}
var query = con.query('INSERT INTO row_data SET ?', message,
function(err, result) {
// Neat!
});
console.log(query.sql);
con.end();
/////////////// MySQL | Begin ////////////////
});
// Add a 'close' event handler to this instance of socket
sock.on('close', function(data) {
console.log('CLOSED: ' + sock.remoteAddress +' '+ sock.remotePort);
});
}).listen(PORT, HOST);
console.log('Server listening on ' + HOST +':'+ PORT);
/**
* CRC functions
*/
var crc16CcittTableReverse = [
0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E,
0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876,
0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD,
0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5,
0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C,
0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974,
0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB,
0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3,
0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A,
0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72,
0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9,
0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1,
0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738,
0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70,
0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7,
0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF,
0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036,
0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E,
0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5,
0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD,
0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134,
0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C,
0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3,
0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB,
0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232,
0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A,
0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1,
0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9,
0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330,
0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78
];
var crc16CcittStart = 0xFFFF;
var crc16CcittXorout = 0xFFFF;
function crc16Reflected(buf, crc_in, table) {
var crc16 = crc_in;
for (i = 0; i < buf.length; i++) {
crc16 = table[(crc16 ^ buf[i]) & 0xff] ^ (crc16 >> 8);
}
return crc16 & 0xFFFF;
}
function crc16Ccitt(buf) {
return crc16Reflected(buf, crc16CcittStart, crc16CcittTableReverse) ^ crc16CcittXorout;
}
public static void main(String[] args) {
String sample_string ="78 78 0D 01 01 23 45 67 89 01 23 45 00 01 8C DD 0D
0A";
String[] data_packet = packet.split(" ");
String[] pdata = Arrays.copyOfRange(data_packet, 2, data_packet.length - 4);
//pdata will be from "packet-length" to "Information Serial Nummber"
//discarding "start-bit" from start and "Error-check" and "Stop Bit" from end
//actual pdata[]={0D,01,01,23,45,67,89,01,23,45,00,01};
String error_code = crc16(pdata);
System.out.println("================>Error_code:" + error_code);
}
public String crc16(String[] pdata) {
int[] crcTable
= {
0X0000, 0X1189, 0X2312, 0X329B, 0X4624, 0X57AD, 0X6536, 0X74BF, 0X8C48, 0X9DC1, 0XAF5A,
0XBED3, 0XCA6C, 0XDBE5, 0XE97E, 0XF8F7, 0X1081, 0X0108, 0X3393, 0X221A, 0X56A5, 0X472C,
0X75B7, 0X643E, 0X9CC9, 0X8D40, 0XBFDB, 0XAE52, 0XDAED, 0XCB64, 0XF9FF, 0XE876, 0X2102,
0X308B, 0X0210, 0X1399, 0X6726, 0X76AF, 0X4434, 0X55BD, 0XAD4A, 0XBCC3, 0X8E58, 0X9FD1,
0XEB6E, 0XFAE7, 0XC87C, 0XD9F5, 0X3183, 0X200A, 0X1291, 0X0318, 0X77A7, 0X662E, 0X54B5,
0X453C, 0XBDCB, 0XAC42, 0X9ED9, 0X8F50, 0XFBEF, 0XEA66, 0XD8FD, 0XC974, 0X4204, 0X538D,
0X6116, 0X709F, 0X0420, 0X15A9, 0X2732, 0X36BB, 0XCE4C, 0XDFC5, 0XED5E, 0XFCD7, 0X8868,
0X99E1, 0XAB7A, 0XBAF3, 0X5285, 0X430C, 0X7197, 0X601E, 0X14A1, 0X0528, 0X37B3, 0X263A,
0XDECD, 0XCF44, 0XFDDF, 0XEC56, 0X98E9, 0X8960, 0XBBFB, 0XAA72, 0X6306, 0X728F, 0X4014,
0X519D, 0X2522, 0X34AB, 0X0630, 0X17B9, 0XEF4E, 0XFEC7, 0XCC5C, 0XDDD5, 0XA96A, 0XB8E3,
0X8A78, 0X9BF1, 0X7387, 0X620E, 0X5095, 0X411C, 0X35A3, 0X242A, 0X16B1, 0X0738, 0XFFCF,
0XEE46, 0XDCDD, 0XCD54, 0XB9EB, 0XA862, 0X9AF9, 0X8B70, 0X8408, 0X9581, 0XA71A, 0XB693,
0XC22C, 0XD3A5, 0XE13E, 0XF0B7, 0X0840, 0X19C9, 0X2B52, 0X3ADB, 0X4E64, 0X5FED, 0X6D76,
0X7CFF, 0X9489, 0X8500, 0XB79B, 0XA612, 0XD2AD, 0XC324, 0XF1BF, 0XE036, 0X18C1, 0X0948,
0X3BD3, 0X2A5A, 0X5EE5, 0X4F6C, 0X7DF7, 0X6C7E, 0XA50A, 0XB483, 0X8618, 0X9791, 0XE32E,
0XF2A7, 0XC03C, 0XD1B5, 0X2942, 0X38CB, 0X0A50, 0X1BD9, 0X6F66, 0X7EEF, 0X4C74, 0X5DFD,
0XB58B, 0XA402, 0X9699, 0X8710, 0XF3AF, 0XE226, 0XD0BD, 0XC134, 0X39C3, 0X284A, 0X1AD1,
0X0B58, 0X7FE7, 0X6E6E, 0X5CF5, 0X4D7C, 0XC60C, 0XD785, 0XE51E, 0XF497, 0X8028, 0X91A1,
0XA33A, 0XB2B3, 0X4A44, 0X5BCD, 0X6956, 0X78DF, 0X0C60, 0X1DE9, 0X2F72, 0X3EFB, 0XD68D,
0XC704, 0XF59F, 0XE416, 0X90A9, 0X8120, 0XB3BB, 0XA232, 0X5AC5, 0X4B4C, 0X79D7, 0X685E,
0X1CE1, 0X0D68, 0X3FF3, 0X2E7A, 0XE70E, 0XF687, 0XC41C, 0XD595, 0XA12A, 0XB0A3, 0X8238,
0X93B1, 0X6B46, 0X7ACF, 0X4854, 0X59DD, 0X2D62, 0X3CEB, 0X0E70, 0X1FF9, 0XF78F, 0XE606,
0XD49D, 0XC514, 0XB1AB, 0XA022, 0X92B9, 0X8330, 0X7BC7, 0X6A4E, 0X58D5, 0X495C, 0X3DE3,
0X2C6A, 0X1EF1, 0X0F78
};
int crcX = 0xFFFF;
int cr1 = 0xFF;
int cr2 = 0xFFFF;
int i = 0;
int j;
while (i < pdata.length) {
String str = pdata[i];
int str_hex = Integer.parseInt(str, 16);
j = (crcX ^ str_hex) & cr1;
crcX = (crcX >> 8) ^ crcTable[j];
i++;
}