/* READ_RAW     - Read raw encoded number */
/* READ_NUM     - Read decoded number */
/* WRITE_NUM    - Write encoded number */
/* WRITE_HEADER - Write the static header used for all stored numbers */
#define READ_RAW(x) ((x) & 0x3FFFF)
#define READ_NUM(x) ((int)(READ_RAW(x) - 0x1ffff))
#define WRITE_NUM(n, x) ((n) = (((n) & 0xfffc0000) | ((unsigned int)(x + 0x1ffff) & 0x3ffff)))
#define WRITE_HEADER(n) ((n) &= 0x3FFFFFF | 0x50000000)

/* An array used for the encryption... somehow */
unsigned int someArray[] = {
    0b00010000010101011011011110011110,
    0b11001111000001101101100010100010,
    0b01011001101011111111111000111000,
    0b10111111001010100100101111101110,
    0b10100101111011101101100010100000,
    0b00010011110101111111111000111100,
    0b00100101101110100100101111100110,
    0b01100010000101101101100010110000,
    0b00000010010011111111111000011100,
    0b10000010001100100100101110100110,
    0b00111010100000110110111110101110,
    0b01001010001010010010011110111110,
    0b11011000100011011011011110011110,
    0b01001101010010010010000001000000,
    0b11100100101101111111011100011110,
    0b00100100011110100101100110100010,
    0b11001100101100110100101110100110,
    0b11000111111100010110111110101110,
    0b10001100100001010010011110111110,
    0b01001100000110000000000000000000,
    0b01110000001110000000000000000000,
    0b00001110011000000000000000000000,
    0b01010110101001011011011110011110,
    0b10100000111111101101100010100010,
    0b01111100001001111111111000111000,
    0b01100111111001111111110001110001,
    0b10101110100100000000000000000000,
    0b01100010100110000000000000000000,
    0b10010010100010000000000000000000,
    0b00101001101000000000000000000000,
    0b10010100011000000000000000000000,
    0b01001000011100000000000000000000,
};

/* Encrypts numbers by the key */
unsigned int encryptFormattedNumber(unsigned int num, int key)
{
    unsigned int result = 0, mask = 1;
    num = READ_RAW(num ^ (-0x2751 * key));

    for (int bit = 0; bit < 32; bit++) {
        int temp = mask;
        if (!(__popcnt((READ_RAW(num) | 0x10000000) & someArray[bit]) & 1))
            temp = 0;

        result |= temp;
        mask <<= 1;
    }

    return result;
}

/* Decrypts numbers by key */
unsigned int decryptFormattedNumber(unsigned int num, int key)
{
  unsigned int partialDec1 = num ^ (0x1F3D8AF * key);
  unsigned int rotl = _rotl(num, 7);
  unsigned int rotr = _rotr(num, 3);
  unsigned int partialDec2 = (rotl ^ rotr);

  return (partialDec1 ^ partialDec2);
}

/* Example usage function */
void example() {
  unsigned int numToStore = 50;
  unsigned int key = 20;

  unsigned int dataToEncrypt = 0;
  WRITE_HEADER(dataToEncrypt);
  WRITE_NUM(dataToEncrypt, numToStore);

  unsigned int encrypted = encryptFormattedNumber(dataToEncrypt, key);
  unsigned int decryptedDirty = decryptFormattedNumber(encrypted, key);
  unsigned int decryptedClean = decryptedDirty & ~0x3FC0000; /* Clean excess bits */
               WRITE_HEADER(decryptedClean); /* Correct header */

  assert(READ_NUM(dataToEncrypt) == READ_NUM(decryptedClean));
}

| 31           26 | 25        18 | 17                0 |
| Header (static) |    Excess    | Bias encoded number |
|     010100      |   00000000   |  000000000000000000 |