#include <iostream>
#include <cstring>

using namespace std;

int main()
{
    unsigned int protocolID = 0x2709021983;
    unsigned int crcHash = 0x9c95fbd6;
    char payload[] = "j123456789abcdefghijklm";

    unsigned char packet[sizeof(payload) + 8];
    packet[0] = (unsigned char) (protocolID >> 24);
    packet[1] = (unsigned char) ((protocolID >> 16) & 0xFF);
    packet[2] = (unsigned char) ((protocolID >> 8) & 0xFF);
    packet[3] = (unsigned char) ((protocolID) & 0xFF);

    packet[4] = (unsigned char) (crcHash >> 24);
    packet[5] = (unsigned char) ((crcHash >> 16) & 0xFF);
    packet[6] = (unsigned char) ((crcHash >> 8) & 0xFF);
    packet[7] = (unsigned char) ((crcHash) & 0xFF);

    memcpy(&packet[8], payload, sizeof(payload));

    cout << packet << "\n" << sizeof(packet) << "\n";

    char crc[4];

    crc[0] = packet[4];
    crc[1] = packet[5];
    crc[2] = packet[6];
    crc[3] = packet[7];

    unsigned int crcNew = (unsigned int) crc;

    cout << crcNew;
}