[Mono-dev] some doubts on WinSerialStream

Atsushi Eno atsushieno at veritas-vos-liberabit.com
Wed Apr 22 11:12:33 EDT 2009


I have been playing with gainer (http://gainer.cc) these days.
A friend of mine wrote a pure C# controller over it,
and I of course wanted to get it working with mono.

I also have simpler test executable (testgainer.cs, attached;
compile with: gmcs testgainer.cs MnGainer/*.cs).

First I tried it on Linux but it didn't work. But I do not seem to
have working environment even with processing or flash (they are
known to work) after all, I switched to windows and mac where
I already got them working. However it didn't work neither.

I dug in depth and I have sort of fix on Win32SerialStream, as
the attached patch. However it should not be applied blindly.

Basically it tried to continue reading by GetOverlappedResult()
while it results in 0 bytes read.
The problem I experienced with gainer is that no matter how 
GetOverlappedResult() is documented as to not return results until
the operation completes when bWait flag is true,
It actually returns immediately, with 0 bytes results.

I assume that Win32 should take timeouts into GetOverlappedResult() 
results, so it may be safe to just go into infinite loop until
GetOverlappedResult() returns non-zero byte results, or win32 error.

I also assume that Timeouts class has some wrong values for
ReadXxx fields, but I have no behavioral problem because of those
values that as far as I know (it is also documented as doubtful).

The problem above might be because of these incorrect values.

Anyways with the attached patch I could get gainer working on
mono/win32. Since .NET has no problem on running those example
exe files, the problem would rather be in mono, not other sides.

Do you guys have any other ideas for attempts I should try? I guess
not many people can try the app anyways (you need gainer!).

Atsushi Eno
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