check-ethereum-scanner/Ethereum-Renounced-Contract-Scanner/node_modules/eth-lib/src/desubits.js

Safety checks for new Ethereum tokens

const Bytes = require("./bytes");

const inis = "pbtdkgxjfvlrmnsz".split("");

const mids = "auie".split("");

const back = [inis,mids].map(chars => {
  let map = {};
  for (let i = 0; i < chars.length; ++i)
    map[chars[i]] = i;
  return map;
});

const syllableFromB64 = b64 => {
  const ini = (b64 >>> 2) & 15; 
  const mid = (b64 >>> 0) & 3;
  return inis[ini] + mids[mid];
}

const syllableToB64 = syllable => {
  const ini = back[0][syllable[0]];
  const mid = back[1][syllable[1]];
  return ini * 4 + mid;
}

const b64sFromBytes = bytes => {
  //BoooooBoooooBoooooBooooo
  //BoooooooBoooooooBooooooo
  let b64s = [], b64;
  for (let i = 0, l = Math.ceil(bytes.length * 8 / 6); i < l; ++i) {
    let j = i / 8 * 6 | 0;
    b64s.push
      ( i % 4 === 0 ?                        (bytes[j+0] /  4 | 0)
      : i % 4 === 1 ? bytes[j+0] %  4 * 16 + (bytes[j+1] / 16 | 0)
      : i % 4 === 2 ? bytes[j+0] % 16 *  4 + (bytes[j+1] / 64 | 0)
      :               bytes[j+0] % 64 *  1);
  }
  return b64s;
}

const b64sToBytes = b64s => {
  let bytes = [];
  for (let i = 0, l = Math.floor(b64s.length * 6 / 8); i < l; ++i) {
    let j = i / 6 * 8 | 0;
    bytes.push
      ( i % 3 === 0 ? b64s[j+0] % 64 *  4 + (b64s[j+1] / 16 | 0)
      : i % 3 === 1 ? b64s[j+0] % 16 * 16 + (b64s[j+1] /  4 | 0)
      :               b64s[j+0] %  4 * 64 + (b64s[j+1] /  1 | 0));
  }
  return bytes;
}

const fromBytes = bytes =>
  b64sFromBytes(Bytes.toArray(bytes)).map(syllableFromB64).join("");

const toBytes = syllables =>
  Bytes.fromArray(b64sToBytes(syllables.match(/\w\w/g).map(syllableToB64)));

module.exports = {
  fromBytes,
  toBytes
}