MAC address generator

#define RANDOM(x) (rand()%x)
#define MAC_ADDR_LENGTH 6

void macGen() {
    uint8_t HEXCHAR[256];
    uint8_t MACAddr[MAC_ADDR_LENGTH];
    for (int j = 0; j < 256; j ++) {
        HEXCHAR[j] = j;
    }

    srand(getpid());
    for(int i = 0;i < MAC_ADDR_LENGTH; i++) {
        int n = RANDOM(255);
        MACAddr[i] = HEXCHAR[n];
    }
}