zad 02,03 #37

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s426159 wants to merge 14 commits from s426159/DALGLI0:master into master
3 changed files with 85 additions and 1 deletions
Showing only changes of commit 140e6a4606 - Show all commits

13
03-rozwiazanie.js Normal file
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@ -0,0 +1,13 @@
const crc = require("./crc.js");
let message = process.argv[3];
let flag = process.argv[2];
switch (flag) {
case '-e':
console.log(crc.encode(message));
break;
case '-d':
break;
default:
throw "incorect flag"
}

64
crc.js Normal file
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@ -0,0 +1,64 @@
let Polynomial = require('./polynomial.js');
const to_bytes_ascii = a => a.charCodeAt(0);
const from_bytes_ascii = a => String.fromCharCode(a);
const to_bin = a => {
var result = "";
for (var i = 0; i < a.length; i++) {
var bin = a[i].charCodeAt().toString(2);
result += Array(8 - bin.length + 1).join("0") + bin;
}
return result;
}
const to_ascii = a => {
a = a.join('');
return String.fromCharCode(parseInt(a, 2));;
}
const fcs = m => {
bits = m.map(to_bin); //message in binary
bits = bits.join('').split('').reverse(); //reverse binary decoded message
let M = new Polynomial.Class(2, bits);
let L = new Polynomial.Class(2, new Array(16).fill(1));
let X = new Polynomial.Class(2, [0, 1]);
let X16 = Polynomial.power(X, 16);
let G = new Polynomial.Class(2, [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1]); //jako ze można to od razu wymnożyć
let fcs = Polynomial.multiply(X16, M);
fcs = Polynomial.add(fcs,
Polynomial.multiply(
Polynomial.power(X, m.length * 8),
L
)
)
fcs = Polynomial.divide(fcs, G);
for (let i = 0; i < 16 - fcs.coefficients.length; i++) fcs.coefficients.push(0);
fcs.coefficients.reverse();
return fcs.coefficients;
}
function encode(m) {
m = m.split('');
let res = fcs(m);
let f1 = [];
let f2 = [];
for (let i = 0; i < res.length; i++) {
if (i < 8) {
f1.push(res[i]);
} else {
f2.push(res[i]);
}
}
f1 = to_ascii(f1);
f2 = to_ascii(f2);
m.push(f1);
m.push(f2);
return m;
}
exports.encode = encode;

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@ -2,7 +2,14 @@ class Polynomial {
constructor(mod, coefArray) {
this.mod = mod;
this.degree = (coefArray.length - 1);
this.coefficients = coefArray;
this.coefficients = Array.from(coefArray); //zeby nie przekazywać referencji
this.normalize();
}
normalize() {
while (this.coefficients && this.coefficients[this.coefficients.length - 1] == 0) {
this.coefficients.pop();
}
}
}