Re: Difficulty with Brad Rodriguez' screenful

From	Andrew Haley <andrew29@littlepinkcloud.invalid>
Subject	Re: Difficulty with Brad Rodriguez' screenful
Newsgroups	comp.lang.forth
References	(6 earlier) <2013Apr2.175019@mips.complang.tuwien.ac.at> <YL6dnW-fLKgN18bMnZ2dnUVZ_tKdnZ2d@supernews.com> <2013Apr3.135744@mips.complang.tuwien.ac.at> <4-ednRv0asts1MHMnZ2dnUVZ_sadnZ2d@supernews.com> <2013Apr3.184544@mips.complang.tuwien.ac.at>
Message-ID	<L56dndFVlLOnEMHMnZ2dnUVZ_rWdnZ2d@supernews.com> (permalink)
Date	2013-04-03 15:12 -0500

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Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:
> Andrew Haley <andrew29@littlepinkcloud.invalid> writes:
> 
>>>> and for interpreted code the cost can be zero.
>>> 
>>> How does that work?
>>
>>If there's a table of pointers then you can overwrite part of the
>>table; if there's an interpreter pointer you can rewrite that when you
>>return from the handler.
> 
> That's not a non-zero cost; a table of pointers is slower than
> threaded code.

That's for the case where you already have a table of pointers.

> And if you want to patch the threaded code, you need to ensure that
> there is always a pointer to the next instruction available, which
> also has a cost, and I actually don't know how to do it.

I don't understand what you mean.

>>Synchronous signals are another matter altogether.  I see no reason
>>why those shouldn't be handled immediately.  The problem with
>>asynchronous signals is that, by their very nature, they can happen in
>>the middle of operations that you really want to be atomic.
> 
> Hmm, doing the THROW for synchronous signals from the signal handler,
> and delaying it for asynchronous ones would be an option.  But delay
> until when?

As you point out, this is ideally user-controlled, but a rule of thumb
is only to interrupt backward branches, returns, and blocking
syscalls.  Even then it's not perfect, and you may have to roll back
some changes.  It all depends on what the asychronous interrupt means:
the interrupt is not semantically related to the computation in
progress, so how can a programmer determine what should be done?

Andrew.

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Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 22:27 +0100
  Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 03:49 -0500
    Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-20 11:09 +0000
      Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 10:25 -0500
        Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-20 18:08 +0100
          Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 13:04 -0500
            Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-20 20:12 +0100
              Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-21 04:39 -0500
          Re: Difficulty with Brad Rodriguez' screenful albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-03-20 19:22 +0000
        Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-30 17:35 +0000
          Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-31 08:51 -0500
            Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-02 15:50 +0000
              Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-02 16:16 -0500
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-03 11:57 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-03 10:25 -0500
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-03 16:45 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-03 15:12 -0500
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-04 15:29 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-05 09:11 -0500
      Re: Difficulty with Brad Rodriguez' screenful Alex McDonald <blog@rivadpm.com> - 2013-03-20 10:27 -0700
  Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-20 12:03 +0000
    Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-20 18:47 +0100
      Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-30 16:40 +0000
        Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-01 02:12 +0200
          Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-01 16:58 +0000
            Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-02 04:20 +0200
              Re: Difficulty with Brad Rodriguez' screenful "Elizabeth D. Rather" <erather@forth.com> - 2013-04-01 16:39 -1000
              Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-02 14:15 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-02 21:12 +0200
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-04 13:58 +0000
            Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-02 04:17 -0500
              Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-02 15:35 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-02 16:36 -0500
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-03 04:10 +0200
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-03 04:03 -0500
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-03 21:14 +0200
          Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-03 16:13 +0000
            Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-04-03 11:54 -0500
            Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-03 22:24 +0200
              Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-04-04 11:53 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-04 18:13 +0200
              Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-04 15:53 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-04 22:11 +0200
                Re: Difficulty with Brad Rodriguez' screenful Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-04-04 21:35 +0100
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-04 23:06 +0200
                Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-04-05 10:57 +0000
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-05 14:47 +0000
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-05 14:28 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-06 03:35 +0200
                Re: Difficulty with Brad Rodriguez' screenful "Rod Pemberton" <do_not_have@notemailnotq.cpm> - 2013-04-08 23:50 -0400
                Re: Difficulty with Brad Rodriguez' screenful "Rod Pemberton" <do_not_have@notemailnotq.cpm> - 2013-04-08 23:49 -0400
                Re: Difficulty with Brad Rodriguez' screenful m.a.m.hendrix@tue.nl - 2013-04-05 02:49 -0700
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-04-05 14:55 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-05 22:05 +0200

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