10 years, 1 month ago.

Can we add Byte Stuffing to MODSERIAL?

A nice library, solves some issues I was having.

A feature that it would be good to include in the library is Byte Stuffing with selectable Control, and Escape char's. If enabled the defaults should match ethernet standards I think.

escape = 0x7D converts to 0x7D5D in the stream control = 0x7E converts to 0x7D5E in the stream

An extra callback could then be used on Rx to say "control char" received. Although this is already covered with the autoDetectChar it would be preferable to have a discrete callback.

A new function would be needed to "send" a control char. A method to enable and disable Stuffing on the fly would also be desirable. This would allow the port to be used in both Stuffed (cooked) and Unstuffed (raw) modes easily

I have a userland implementation, but it would really be better done between the buffer and the port.

Thanks for a great platform

Question relating to:

    int move_unstuffed(char *s, int max, char end=0x7E) {
        int counter = 0;
        char c;
        while(readable()) {
            c = getc();
            if (c == end) break;
            while ((c == 0x7D) && (counter++ < max)) { // if it is an escape char drop it and grab next char
                c=(getc());
                if ((c == 0x5D) || (c == 0x5E)) c=(c|0x20); // if a valid escaped char convert it.
                else if (counter++ < max) c=(getc()); // otherwise drop, get next char, and loop.
            }
            *(s++) = c;
            if (++counter >= max) break;
        }
        return counter;
    }