Re: Text on FSM

From	Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups	comp.arch.embedded
Subject	Re: Text on FSM
Date	2023-03-14 18:49 +0200
Organization	Tidorum Ltd
Message-ID	<k7bmsmFhvrbU1@mid.individual.net> (permalink)
References	(2 earlier) <rr5m0i5dh7buhchacl4tnplmtf4h39vrr5@4ax.com> <99eae897-178b-4760-bc71-61ba49b76b44n@googlegroups.com> <tunfr9$3qkp8$1@dont-email.me> <tunj1u$3rca5$2@dont-email.me> <tuq1ra$84eb$1@dont-email.me>

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On 2023-03-14 16:54, pozz wrote:
> Il 13/03/2023 17:29, Don Y ha scritto:
>> On 3/13/2023 8:35 AM, pozz wrote:
>>> I think the complexity of a FSM is not only related to the number if 
>>> states, but also to the transitions/inputs.
>>
>> Of course.  A 0..99 counter can have oodles of states... but the 
>> interactions
>> between them are trivial to the point of being boring.
>>
>> Interconnectedness is the source of *all* complexity.  E.g., the more
>> modules your code interacts with, the more complex the code is likely 
>> to be!
>>
>>> It's much simpler to detect errors on a diagram instead on a cryptic 
>>> list of switch/case instructions.
>>
>> That depends on the problem and how expressive (and intuitive!) the
>> drawing.
> 
> A good diagram is always much more expressive than a good code, for 
> developers and for non-developers.

In my experience, diagrams that describe all the details of the code, as 
would be required for generating the code from the diagram, are usually 
much too complex to comprehend easily ("visually"). They tend to be 
mazes where one can perhaps trace out some significant paths with a 
careful finger, unless too many lines cross at one point.

To get a good, visually graspable diagram, IME one must almost always 
simplify and elide details. And then such diagrams are very good entry 
points into the code, if one has to read the code to get a complete 
understanding.

I remember one case where the SW for the central computer of a satellite 
was generated from state-and-message diagrams by an automatic 
"model-based design" tool. In graphical form, the diagrams covered 
numerous A4 pages and each page had several cryptically labelled 
inter-page links for messages coming from other pages and going to other 
pages. It was very difficult to get any kind of overall understanding of 
the SW.

I admit that there are some domains -- for example, servo-control 
systems -- where it is possible to generate significant amounts of code 
from readable diagrams, eg. SIMULINK diagrams. But I don't think it 
works well for most code in embedded systems.

Thread

Text on FSM jmariano <jmariano65@gmail.com> - 2023-03-09 14:17 -0800
  Re: Text on FSM Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-09 16:52 -0800
  Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-09 19:11 -0700
    Re: Text on FSM Bill Davy <Bill@XchelSys.co.uk> - 2023-03-10 08:37 +0000
      Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-10 03:50 -0700
  Re: Text on FSM pozz <pozzugno@gmail.com> - 2023-03-10 09:54 +0100
    Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-10 04:17 -0700
    Re: Text on FSM Robert Roland <fake@ddress.no> - 2023-03-10 12:48 +0100
      Re: Text on FSM Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-10 07:20 -0800
        Re: Text on FSM pozz <pozzugno@gmail.com> - 2023-03-13 16:35 +0100
          Re: Text on FSM StateMachineCOM <statemachineguru@gmail.com> - 2023-03-13 08:55 -0700
            Re: Text on FSM pozz <pozzugno@gmail.com> - 2023-03-14 15:44 +0100
          Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-13 09:29 -0700
            Re: Text on FSM pozz <pozzugno@gmail.com> - 2023-03-14 15:54 +0100
              Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-14 08:39 -0700
              Re: Text on FSM Niklas Holsti <niklas.holsti@tidorum.invalid> - 2023-03-14 18:49 +0200
      Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-10 09:39 -0700
        Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-10 10:02 -0700
        Re: Text on FSM Ed Prochak <edprochak@gmail.com> - 2023-03-10 10:10 -0800
          Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-10 12:10 -0700
            Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-10 12:49 -0700
            Re: Text on FSM Ed Prochak <edprochak@gmail.com> - 2023-03-10 14:02 -0800
              Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-11 06:01 -0700
                Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-11 06:17 -0700
  Re: Text on FSM StateMachineCOM <statemachineguru@gmail.com> - 2023-03-10 07:54 -0800
  Re: Text on FSM jmariano <jmariano65@gmail.com> - 2023-03-10 09:51 -0800
    Re: Text on FSM Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-10 11:27 -0800
    Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-10 12:46 -0700
    Re: Text on FSM Ed Prochak <edprochak@gmail.com> - 2023-03-10 13:11 -0800
    Re: Text on FSM Gerhard Hoffmann <dk4xp@arcor.de> - 2023-03-13 21:20 +0100
      Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-13 15:41 -0700
        Re: Text on FSM George Neuner <gneuner2@comcast.net> - 2023-03-13 23:07 -0400
          Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-13 22:59 -0700
            Re: Text on FSM George Neuner <gneuner2@comcast.net> - 2023-03-14 21:29 -0400
              Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-14 19:40 -0700
                Re: Text on FSM George Neuner <gneuner2@comcast.net> - 2023-03-22 16:37 -0400
                Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-22 18:15 -0700
                Re: Text on FSM George Neuner <gneuner2@comcast.net> - 2023-03-26 00:45 -0400
                Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-26 03:35 -0700
                Re: Text on FSM George Neuner <gneuner2@comcast.net> - 2023-03-27 02:32 -0400
                Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-27 01:16 -0700
                Re: Text on FSM George Neuner <gneuner2@comcast.net> - 2023-03-28 15:25 -0400
                Re: Text on FSM Don Y <blockedofcourse@foo.invalid> - 2023-03-28 16:56 -0700
                Re: Text on FSM Clifford Heath <no.spam@please.net> - 2023-03-27 16:18 +1100
                Re: Text on FSM George Neuner <gneuner2@comcast.net> - 2023-03-28 11:17 -0400
                Re: Text on FSM Clifford Heath <no.spam@please.net> - 2023-03-29 09:00 +1100
                Re: Text on FSM George Neuner <gneuner2@comcast.net> - 2023-03-28 21:27 -0400
                Re: Text on FSM Clifford Heath <no.spam@please.net> - 2023-03-30 08:33 +1100
                Re: Text on FSM Richard Damon <Richard@Damon-Family.org> - 2023-03-28 21:31 -0400
  Re: Text on FSM George Neuner <gneuner2@comcast.net> - 2023-03-10 16:49 -0500

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