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Re: Do you use FSMs or HSMs?

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Clifford Heath wrote:
> On 07/02/17 08:19, Don Y wrote:
>> On 2/6/2017 1:34 PM, Tom Gardner wrote:
>>> On 06/02/17 18:56, Don Y wrote:
>>>> On 2/6/2017 11:03 AM, Tom Gardner wrote:
>>>>>> I find that sometimes I'll sketch a FSM and then find out
>>>>>> it's just too simple or too linear. ON the flip side, I've had
>>>>>> project for
>>>>>> which
>>>>>> I'd have an extremely simple FSM documented and later it's starts
>>>>>> to get
>>>>>> elaborate and useful as new requirements emerge.
>>>>>
>>>>> Precisely.
>>>>>
>>>>> A large part of engineering is being able to
>>>>> demonstrate which part of an design implements
>>>>> each part of the specification.
>>>>>
>>>>> A good implementation of an FSM enables you
>>>>> to easily see exactly what will happen when
>>>>> any event occurs in any state. That can be very
>>>>> difficult with if-then-else clauses.
>>>>
>>>> Exactly.  IME, they are excellent for representing UI actions
>>>> along with other formal "protocols".  They allow you to verify
>>>> by inspection that all possibilities are addressed and
>>>> addressed in the manner intended -- without having to
>>>> count nesting levels of conditionals, etc.
>>>>    "Will this 'if' cover this condition in ALL states?  Or,
>>>>     does it only apply to some subset of the states, based on
>>>>     where it is syntactically anchored?"
>>>>
>>>> I'd *not* use one to implement a floating point package...
>>>
>>> Yes, but...
>>>
>>> They are very neat way of implementing parsing an ascii
>>> string and turning it into a floating point number.
>>
>> Different problem -- and one that could be "automated" with a
>> simple grammar/lex/yacc.
>
> Lex is a language for describing a regular expression,
> which it implements by turning it *into* an FSA.
>
> You don't need yacc to parse FP numbers. Such parsers
> are for handling languages that require unbounded state,
> not finite state.
>

Just to be pedantic :), it's deterministic vs. non deterministic FA.
Deterministic FA are equivalent to regular expressions. NFA
are not, and very often, NFA are what we use for program control flow.

> I'm also enthusiastic in using FSAs where appropriate,
> but a lot of problems I face require unbounded state.

This is where NFA shine - they're less formal than DFA.

> In either case, I tend not to do them long-hand - there
> are good domain-specific languages to generate the code.
>
> Clifford Heath.

-- 
Les Cargill

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Do you use FSMs or HSMs? pozz <pozzugno@gmail.com> - 2017-02-06 10:43 +0100
  Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 03:20 -0700
  Re: Do you use FSMs or HSMs? Dave Nadler <drn@nadler.com> - 2017-02-06 06:38 -0800
  Re: Do you use FSMs or HSMs? "QL" <80499@EmbeddedRelated> - 2017-02-06 08:56 -0600
    Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 12:13 -0700
    Re: Do you use FSMs or HSMs? jim.brakefield@ieee.org - 2017-02-06 16:52 -0800
      Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 18:11 -0700
      Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-06 23:32 -0600
    Re: Do you use FSMs or HSMs? pozz <pozzugno@gmail.com> - 2017-02-07 10:39 +0100
  Re: Do you use FSMs or HSMs? John Speth <johnspeth@yahoo.com> - 2017-02-06 09:17 -0800
    Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-06 18:03 +0000
      Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 11:56 -0700
        Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-06 20:34 +0000
          Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 14:19 -0700
            Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-06 22:12 +0000
              Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 15:29 -0700
              Re: Do you use FSMs or HSMs? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 12:15 -0500
                Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-08 23:52 +0000
                Re: Do you use FSMs or HSMs? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 19:59 -0500
              Re: Do you use FSMs or HSMs? Steve Watt <steve.removethis@Watt.COM> - 2017-02-17 00:30 +0000
                Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-17 00:44 +0000
            Re: Do you use FSMs or HSMs? Clifford Heath <no.spam@please.net> - 2017-02-07 10:12 +1100
              Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-06 23:36 -0600
                Re: Do you use FSMs or HSMs? George Neuner <gneuner2@comcast.net> - 2017-02-07 03:15 -0500
                Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-10 17:41 -0600
                Re: Do you use FSMs or HSMs? Clifford Heath <no.spam@please.net> - 2017-02-07 19:56 +1100
                Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-07 01:30 -0800
                Re: Do you use FSMs or HSMs? Clifford Heath <no.spam@please.net> - 2017-02-07 20:42 +1100
                Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-07 02:46 -0800
                Re: Do you use FSMs or HSMs? Clifford Heath <no.spam@please.net> - 2017-02-08 00:27 +1100
  Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-06 18:35 -0800
    Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 21:50 -0700
    Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-06 23:39 -0600
      Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-06 23:20 -0800
        Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-10 17:47 -0600
          Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-10 16:11 -0800
            Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-11 15:43 -0600
  Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-06 23:24 -0600

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