Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)?

From	Paul Rubin <no.email@nospam.invalid>
Newsgroups	comp.arch.embedded
Subject	Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)?
Date	2018-01-07 00:46 -0800
Organization	A noiseless patient Spider
Message-ID	<87a7xq3vkc.fsf@nightsong.com> (permalink)
References	(7 earlier) <p2jqj6$9jq$1@dont-email.me> <p2kotf$cu9$1@dont-email.me> <p2lve0$tuv$1@dont-email.me> <87vaghnndl.fsf@nightsong.com> <p2s476$cb6$1@dont-email.me>

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rickman <gnuarm.deletethisbit@gmail.com> writes:
> I can't think of any program or correctly constructed digital logic
> design that would not produce a non-deterministic FSM.

NSFM's (actually usually called NFA, non-deterministic finite automata)
are common in software.  Each NFA state potentially has multiple
outgoing edges labelled with the same symbol, and you "run" the NFA by
exploring edges and backtracking when needed.  Regexes are
straightforward to convert to NFA.  Then you can convert the NFA to a
DFA by making a separate DFA state for each subset of NFA states that
the NFA could possibly be in.  This is explained in the "dragon book"
(https://en.wikipedia.org/wiki/Dragon_Book) and other places.

> What is the point in such a distinction?

The NFA size is linear in the regex size, but it can potentially use
exponential time because of the backtracking (it usually doesn't).  The
DFA is fast but the number of states can potentially be exponential in
the regex size (it usually isn't).  Also, compiling the NFA to a DFA
takes time.  So it's a trade-off.  DFA conversion is more likely to be
worthwhile if you're scanning for the pattern a lot of times.

Thread

Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Mike Perkins <spam@spam.com> - 2017-12-10 14:56 +0000
  Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2017-12-16 11:58 -0600
    Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Ed Prochak <edprochak@gmail.com> - 2017-12-19 08:19 -0800
      Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm@gmail.com> - 2017-12-19 11:51 -0500
        Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Ed Prochak <edprochak@gmail.com> - 2018-01-02 14:58 -0800
        Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2018-01-03 06:07 -0600
          Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-03 12:59 -0500
            Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2018-01-03 17:59 -0600
              Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-04 03:33 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-04 14:31 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2018-01-04 11:56 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2018-01-04 21:46 -0600
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-04 16:46 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2018-01-04 21:47 -0600
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-06 18:55 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 00:54 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-07 13:41 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 23:32 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-10 10:33 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-10 16:29 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? upsidedown@downunder.com - 2018-01-08 08:11 +0200
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-07 23:05 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? upsidedown@downunder.com - 2018-01-08 10:06 +0200
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? David Brown <david.brown@hesbynett.no> - 2018-01-08 10:27 +0100
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-08 09:56 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-08 18:39 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-08 12:20 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-08 22:11 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? David Brown <david.brown@hesbynett.no> - 2018-01-08 22:26 +0100
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-08 22:23 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-08 14:44 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-08 23:06 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-08 10:02 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2018-01-08 17:34 -0600
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-06 22:29 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-07 00:46 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2018-01-04 21:44 -0600
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-05 09:12 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2018-01-05 21:40 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2018-01-05 21:29 -0600
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-06 09:10 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2018-01-06 16:35 -0600
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 01:04 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-06 09:17 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Les Cargill <lcargill99@comcast.com> - 2018-01-06 16:37 -0600
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 01:11 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-06 17:31 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 01:52 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-07 00:39 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 09:55 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-07 10:43 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 19:35 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-06 19:06 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-06 16:58 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-06 22:37 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-07 00:58 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-07 09:32 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Paul Rubin <no.email@nospam.invalid> - 2018-01-07 10:53 -0800
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-10 11:40 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 01:14 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-06 18:57 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 01:17 +0000
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? rickman <gnuarm.deletethisbit@gmail.com> - 2018-01-06 22:40 -0500
                Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)? Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-01-07 09:59 +0000

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