node-crc16
v2.0.7
A native node addon to calcalate and verify CRC16 values, adopted by MODBUS agreement.
0/weekUpdated 3 years agoMITUnpacked: 178.3 KB
Published by imnemo
npm install node-crc16
Node CRC16 - (中文版README)
[MODBUS][1] is an application-layer messaging protocol, positioned at level 7 of the OSI model. It provides client/server communication between devices connected on different types of buses or networks.The
CRC(Cyclic Redundancy Check) part in protocol, such as [MODBUS over serial line]2, and [Modbus-RTU]3, adopt the same one algorithm.node-crc16 implement the c++ version of this algorithm by table look-up, and also provide a node native addon and a nodejs version wrapper.
This module has been well unit tested and documented.
Versions
If your version of node.js is lower than v8.x.x, please use the latest v1.x.x of this module, or you should select v2.x.x, which uses NAPI to implement native addon gracefully and compatibly.
Usage
Tips: the most intuitive decription about this module is the comment in src and the code in unit test :).
$3
npm install node-crc16$3
checkSumaccept three params, the first two params (input, [encoding]) construct a Buffer``
javascript
crc16.checkSum('utf8 string', 'utf8')
`
default is hex
javascript
var sum = crc16.checkSum('a031ffb7');
sum.should.equal('726d');
`
the third param is ，which type is Object
+ set the format of the returned sum
* default is hex，two bytes BigEndian hex string, 726d
* , two unsigned char number of the returned sum，[114, 109]
* ，one unsigned short number of the returned sum，29293
* ，Buffer type of the returned sum，
javascript
var sum = crc16.checkSum('a031ffb7', {retType: 'array'});
sum.should.eql([114, 109]);
`
$3
Params of is same as checkSum, the first two params are used to constructe a Buffer which contains the sum to be verified.
`javascript
var stream = 'a031ffb7',
sum = '726d';
var isValid = crc16.verifySum(stream + sum);
isValid.should.equal(true);
`Contribution
$3
sh
fork and clone the code to your local env
git clone git@github.com:imnemo/crc16.git
cd crc16
`$3
├── lib //CRC16 algorithm implemention in c++
├── util //Util functions
├── src //Node Native Addon
├── test //JS unit testing
├── test_cpp //C++ unit testing
├── index.js //Main entry of NodeJS module
$3
$3
The implemention of checking and verifing algorithm in c++ is standalone in ./lib/crc16.cc. If you want to modify it, please write suitable unittest cases. You can reference Catch, and then run:
`bash
make test
`
> Make sure all the unit testing case is passed after you modify.$3
or ./node_modules/.bin/mocha --reporter spec$3
#### use benchmark.js
bash
>>> npm run benchmark> node-crc16@1.0.0 benchmark /Users/nemo/code/imnemo/crc16
> node benchmark/benchmark.js
CEC16#checkSum x 905,071 ops/sec ±2.00% (83 runs sampled)
CRC16#verifySum x 1,540,940 ops/sec ±19.92% (65 runs sampled)
Fastest is CRC16#verifySum
`#### use nanobench
bash
>>> npm run nanobench> node-crc16@1.0.0 nanobench /Users/nemo/code/imnemo/crc16
> node benchmark/nanobench.js
NANOBENCH version 2
> /Users/nemo/.nvm/versions/node/v8.1.2/bin/node benchmark/nanobench.js
CRC16#checkSum 2,000,000 times
ok ~3.17 s (3 s + 166422442 ns)CRC16#verifySum 2,000,000 times
ok ~2.85 s (2 s + 848059820 ns)all benchmarks completed
ok ~6.01 s (6 s + 14482262 ns)
`$3
You can pull a request when you complete all steps above.
TODO
- [x] Add JS code lint
- [x] Add changelog
- [x] Add JS unit test
- [x] Add JS unit test code covarage
- [x] Add C++ unit test
- [x] Add CI
- [x] Add performance test
- [x] Refactor node native addon part with NAPI
- [x] Add - [ ] Add global module supported to provide a cli tool
- [ ] Add donate entry
---
twitter: @imoncoding
Welcome to subscribe my wechat!
[1]: http://modbus.org/specs.php
[2]: https://www.honeywellprocess.com/library/support/Public/Documents/51-52-25-66.pdf
[3]: http://modbus.org/docs/Modbus_over_serial_line_V1_02.pdf
License
