crc16-xmodem.ts

README.md (1293B)

---

 # CRC16-XMODEM
 
 <small>Generate CRC-16/XMODEM codes consistently</small>
 
 ## Why
 
 While a fairly simple task, I was implementing this throughout multiple projects
 of mine. Now if there's a bug, speed improvement to be had, or simple because
 typescript's typing system changes, I want to be able to update it in 1 location
 instead of having to fix it in every individual project.
 
 TL;DR; I'm lazy, and want a single version of the code
 
 ## Usage
 
 This package does only one thing.
 Usage is really simple:
 
 ```ts
 import { crc16, crc16b } from '@finwo/crc16-xmodem';
 
 // Note the 2 zero bytes at the end, they're useful later
 const message = Buffer.from('Hi!\0\0');
 
 // Output 12797 and <Buffer 31 fd>
 console.log(crc16(message));
 console.log(crc16b(message));
 
 // Either copy in the check code with buffer manipulation:
 const check            = crc16b(message);
 const checkableMessage = Buffer.concat([message]);
 check.copy(checkableMessage, checkableMessage.length - check.length);
 
 // Or, be lazy and just copy the crc over the zeroes directly as an uint16be
 message.writeUInt16BE(crc16(message), message.length - 2);
 
 // Now if you want to check if your message has travelled the network without errors:
 if (crc16(message) != 0) {
   throw new Error('Message got corrupted in transit');
 }
 ```