用 APDU 和 Boolean 重写函数

Question

I need some help

I need that this function return a boolean if while is executed or no.

Could you help me?

Answer 1

Let us rewrite that APDU example from the API because it is clearly broken. It will generate a separate request to receiveBytes when it is not required.

public boolean receiveIncomingFNEL(APDU apdu) {
    byte[] buf = apdu.getBuffer();

    short bytesRead = apdu.setIncomingAndReceive();
    // NOTE: we must always call setIncomingAndReceive() first
    short offsetCdata = apdu.getOffsetCdata();
    short bytesLeft = apdu.getIncomingLength() - bytesRead;
    boolean receiveBytesRequired = true;
    while (true) {
        // --- do something with the bytes in buf, offsetCdata and bytesRead here
        if (bytesLeft <= 0) {
             receiveBytesRequired = false;
             break;
        }
        bytesRead = apdu.receiveBytes(offsetCdata);
        bytesLeft -= bytesRead;
    }
    // --- do other stuff
    return receiveBytesRequired;
}

The if & break statements in the while() loop are a bit weird, but that's the only way that I could think of to have one place handling the data in the APDU buffer and one part where receiveBytes() is called. This is because setIncomingAndReceive() includes a receiveBytes() within the call (ideas to create a normal while loop welcome).