Audi Volkswagen MMI Becker Harman copie_scr.sh decryption

/* encryption/decryption for copie_scr.sh script used on Audi/Volkswagen MMI (Becker/Harman) */
#include <stdio.h>

unsigned int seed = 0x001be3ac;

unsigned int prng_rand() {
    unsigned int r1, r3, r0;

    r0 = seed;
    r1 = (seed >> 1) | (seed << 31);
    r3 = ((r1 >> 16) & 0xFF) + r1;
    r1 = ((r3 >> 8) & 0xFF) << 16;
    r3 -= r1;
    seed = r3;

    return r0;
}

int main(int argc, char *argv[]) {
    int c;

    prng_rand();

    c = getchar();
    while (c != EOF) {
        c ^= (prng_rand() & 0xFF);
        putchar(c);
        c = getchar();
    }
}