c
void DecodeBase64Block(uint8_t ascii[ASCII_BLOCK], uint8_t b64[B64_BLOCK]) {
    if (B64_BLOCK < 2) {
        // Handle error: b64 array too small
        return;
    }
    ascii[0] = (uint8_t) (b64[0] << 2) | (b64[1] >> 4);
    // ... rest of the function remains the same
}
