Convert Paxton

convertPaxton.js

const convertPaxton = (uid) => {
  if (!uid) uid = "11223344"
  const type = 3;
  let result = 0n;
  let dec = 0n;
  // For each digit in 11223344
  uid.split('').forEach(
    (digit, index) => {
      dec = (getParity(BigInt(digit)) << 4n) + BigInt(digit); // getParity does some funky shit and returns the new BigInt.
      // 4n is Numeric 4 but represented in a way that it can iterate with BitWise operators
      // Attempting to represent this as Numeric 4 yields error TypeError: Cannot mix BigInt and other types, use explicit conversions
      // But essentially here it's just an Numeric value of 4.
      result = (result << 5n) + BigInt(dec);

      // if it's the 6th item in 11223344 (so "3") then the result is the result with a left shift of 2.
      if (index == 5) {
        result = result << 2n;
      }
    }
  );
  // The result is a Math operator of the result left shifted by 22 then added to 412.... and then added to 3.
  result = (result << 22n) + 4128768n + BigInt(type);
  // each page value is a substring of this result
  const page4 = result.toString(16).substr(0, 8);
  const page5 = result.toString(16).substr(8, 16);
  console.log(page4, page5);
}

const getParity = (n) => {
  return ~(((BigInt(n) * BigInt("0x0101010101010101")) & BigInt("0x8040201008040201")) % BigInt("0x1FF")) & 1n;
  // ~ is a bitwise operator - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operator
  // & 1n the bitwise AND operator - This operator expects two numbers and retuns a number.
  // In case they are not numbers, they are cast to numbers.
  // % is a modulo which is similar to 14/5 = 4 as 4 is the left over after dividing wholes.
}

// Get the ID from the command line input IE node convertPaxton.js 11223344
const id = process.argv[2];
convertPaxton(id);