CyberChef/src/core/operations/FromBCD.mjs

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/**
* @author n1474335 [n1474335@gmail.com]
* @copyright Crown Copyright 2017
* @license Apache-2.0
*/
import Operation from "../Operation";
import Utils from "../Utils";
import OperationError from "../errors/OperationError";
import {ENCODING_SCHEME, ENCODING_LOOKUP, FORMAT} from "../lib/BCD";
import BigNumber from "bignumber.js";
/**
* From BCD operation
*/
class FromBCD extends Operation {
/**
* FromBCD constructor
*/
constructor() {
super();
this.name = "From BCD";
this.module = "Default";
this.description = "Binary-Coded Decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. Special bit patterns are sometimes used for a sign.";
this.infoURL = "https://wikipedia.org/wiki/Binary-coded_decimal";
this.inputType = "string";
this.outputType = "BigNumber";
this.args = [
{
"name": "Scheme",
"type": "option",
"value": ENCODING_SCHEME
},
{
"name": "Packed",
"type": "boolean",
"value": true
},
{
"name": "Signed",
"type": "boolean",
"value": false
},
{
"name": "Input format",
"type": "option",
"value": FORMAT
}
];
this.patterns = [
{
match: "^(?:\\d{4} ){3,}\\d{4}$",
flags: "",
args: ["8 4 2 1", true, false, "Nibbles"]
},
];
}
/**
* @param {string} input
* @param {Object[]} args
* @returns {BigNumber}
*/
run(input, args) {
const encoding = ENCODING_LOOKUP[args[0]],
packed = args[1],
signed = args[2],
inputFormat = args[3],
nibbles = [];
let output = "",
byteArray;
// Normalise the input
switch (inputFormat) {
case "Nibbles":
case "Bytes":
input = input.replace(/\s/g, "");
for (let i = 0; i < input.length; i += 4) {
nibbles.push(parseInt(input.substr(i, 4), 2));
}
break;
case "Raw":
default:
byteArray = Utils.strToByteArray(input);
byteArray.forEach(b => {
nibbles.push(b >>> 4);
nibbles.push(b & 15);
});
break;
}
if (!packed) {
// Discard each high nibble
for (let i = 0; i < nibbles.length; i++) {
nibbles.splice(i, 1);
}
}
if (signed) {
const sign = nibbles.pop();
if (sign === 13 ||
sign === 11) {
// Negative
output += "-";
}
}
nibbles.forEach(n => {
if (isNaN(n)) throw new OperationError("Invalid input");
const val = encoding.indexOf(n);
if (val < 0) throw new OperationError(`Value ${Utils.bin(n, 4)} is not in the encoding scheme`);
output += val.toString();
});
return new BigNumber(output);
}
}
export default FromBCD;