/*

Bonus code calculator for Race Driver 1 and 2
by Luigi Auriemma
e-mail: aluigi@autistici.org
web:    aluigi.org

pid is your ProductId

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Current Version\ProductID

The function returns your bonus code

*/

int rdbonuscode(char *pid) {
    int     tmp,
            num,
            i,
            len;

    len = strlen(pid);
    num = 0;
    for(i = 0; i < len; i++, pid++) {
        tmp = *pid % 10;

        switch((num + i) % 3) {
            case 1: tmp *= 2345; break;
            case 2: tmp *= 3456; break;
            case 3: tmp *= 4567; break;
            default: tmp *= 1234; break;
        }

        num += tmp;
    }
    return(num % 1000);
}