Messages in this thread | | | Date | Tue, 27 Feb 2018 06:19:05 +0100 | From | Willy Tarreau <> | Subject | Re: [PATCH 3/4] auxdisplay: charlcd: fix x/y address commands |
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On Mon, Feb 26, 2018 at 11:43:36PM +0100, Robert Abel wrote: > On 26 Feb 2018 17:49, Miguel Ojeda wrote: > > On a general note, the code seems a bit convoluted for what it does, > > specially without the comment written in the commit message :-) Isn't > > it simpler to use a tiny array in the stack and put the numbers to be > > converted instead of modifying the input sequence and dancing with > > pointers? > > That's what I felt at first, too. If we can drop the backwards > compatibility of repeated xy commands, the whole affair gets much > easier, but will unfortunately break existing use. > > Ex. ^[[Lx004y002x006; --> x6y2, because repeats of x would just > overwrite earlier values. That's what the while loop allowed in the > first place. > > I suspect the while loop to parse was just a clever way of parsing y > followed by x and x followed by y using the same code and the > overwriting behavior is actually an unaccounted-for side-effect.
Well actually I don't see a problem there at all. The principle is simply to accept any sequence assigning x or y or both. If you write x4y2x6, it simply means that you changed your mind regarding x and that the last value (6) is the one you want. Just as if you wrote "^[[Lx4;^[[y2;^[[x6;". The while loop doesn't even try to do anything clever, it simply parses everything matching x and y followed by digits. I think the only reason for having both x and y processed in the same loop was to call charlcd_gotoxy() only once for both axes.
Regards, Willy
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