Re: [Boost-users] finite state filters controlled ...

Subject: Re: [Boost-users] finite state filters controlled ...
From: Nat Goodspeed (nat_at_[hidden])
Date: 2014-02-18 18:33:44

On Tue, Feb 18, 2014 at 4:18 PM, raespi <raespi_at_[hidden]> wrote:

> Boost hi .. I'm using the finite state filter component in the iostreams
> library to create a state machine that can easily help me process incoming
> data streams from various medical sensors.
>
> 1- Constant datastream with no variation in datagrams.  Solution: use finite
> state filters as they come, works ok !
> 2- Variable datastreams with constant size in datagrams. Solution: use
> finite state filters with a transition table that can interpret anything and
> choosing in the processing function the right way to go, not very clean, but
> works !!
> 3- Variable datastreams with variable sizes.  Solution: trying to change the
> finite state filter on the go, currently doesn't work.  I noticed that when
> bytes are inserted into the state machine these don't get processed until a
> certain buffer size is met internally, resulting in a behaviour where data
> gets analyzed long after it has been inserted.  I saw that the flush()
> function for the iostream that contains de state machine suffices when
> called before inserting a new character with a line such as:
>
> io::flush<io::filtering_ostream> ( this->data );
>
> but the problem is that the only mechanism that can determine when a whole
> package has been received and one can change state machines to analyze a new
> state lies within the state machine itself (in the processing functions), I
> can't issue a flush() from within a state machine since it won't execute
> until a specific buffer size is met.
>
> Any ideas on how to go around this matter ??

Disclaimer: I haven't used the state machine filter for iostreams, so
I can't answer the problem as stated.

However, you might consider using a coroutine to process your incoming
data? The coroutine could make dynamic decisions (using normal C++
control structures) about what to do with each new chunk of received
data.