Table of content

What is this :grey_question:

The rules of the game are explained in my original post.

20th Challenge

Challenge

Calculate crc16-EN_13757 in Rust and create a webassembly package that can be run from javascript. The motivation here is that crc is much simpler and faster in RUST.

Solution :white_check_mark: 

	mod utils;
	use wasm_bindgen::prelude::*;
	use crc16::{EN_13757, State};
	use hex::FromHexError;

	// When the `wee_alloc` feature is enabled, use `wee_alloc` as the global
	// allocator.
	#[cfg(feature = "wee_alloc")]
	#[global_allocator]
	static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;

	#[wasm_bindgen]
	extern {
	    fn alert(s: &str);
	}

	#[wasm_bindgen]
	pub fn crc16_en_13757(s: &str) -> String {
	    let a= hex::decode(&s);
	    match a {
	        Ok(_) => {format!("{:#04x}",State::<EN_13757>::calculate(&a.unwrap()))},
	        Err(_) => String::from("Error calculating CRC16, invalid input.")
	    }
	}

With a simple html the web assembly is tested. A Hex string of 50 million charcters is calculated within 800ms :astonished:

	<!DOCTYPE html>
	<html>
	  <head>
	    <meta charset="utf-8">
	    <title>hello-wasm example</title>
	  </head>
	  <body>
	    <script type="module">
	      import init, {crc16_en_13757} from "./assets/pkg/crc16_en_13757.js";
	      init()
	        .then(() => {
	          const genRanHex = size => [...Array(size)].map(() => Math.floor(Math.random() * 16).toString(16)).join('');
	          var input = genRanHex(50000000);
	          let before = Date.now();
	          var crc16=crc16_en_13757(input);
	          let after = Date.now();
	          alert(after-before);
	        });
	    </script>
	  </body>
	</html>



Result:


To see the full source see github.