Re: Best tools for writing an assembler?

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From	Hans-Peter Diettrich <DrDiettrich1@aol.com>
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Subject	Re: Best tools for writing an assembler?
Date	Tue, 25 Feb 2014 04:23:40 +0100
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glen herrmannsfeldt schrieb:

> There are some interesting cases where the instruction choice (and
> length) depends on the size of an address, which (in the case of a
> forward reference) depends on the instruction length.  If you can
> avoid that, it is pretty easy.
>
> -- glen
> [Variable length instructions aren't that hard.  You start by assuming
> everything will be the long form, then iterate over the code a few
> times shrinking what you can.  That isn't always perfectly optimal
> (which is known to be NP complete), but it's pretty close. -John]

Hmm, I'd start with the *shortest* encoding, and extend whatever doesn't
fit afterwards. This avoids "deadlocks", resulting from kind of circular
references. Indeed harder is reordering parts of the code, in order to
reduce the number of long references - kind of "travelling salesman"
problem?

DoDi

Thread

Best tools for writing an assembler? tpphysik@gmail.com - 2014-02-18 16:04 -0800
  Re: Best tools for writing an assembler? "C. Bergström" <cbergstrom@pathscale.com> - 2014-02-19 11:14 +0700
  Re: Best tools for writing an assembler? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-02-19 04:25 +0000
  Re: Best tools for writing an assembler? Ivan Godard <ivan@ootbcomp.com> - 2014-02-18 23:23 -0800
    Re: Best tools for writing an assembler? Robert A Duff <bobduff@TheWorld.com> - 2014-02-19 18:20 -0500
      Re: Best tools for writing an assembler? Sébastien Fricker <sebastien.fricker@gmail.com> - 2014-02-21 12:00 +0100
      Re: Best tools for writing an assembler? "BartC" <bc@freeuk.com> - 2014-02-22 00:28 +0000
      Re: Best tools for writing an assembler? noitalmost <noitalmost@cox.net> - 2014-02-23 11:22 -0500
        Re: Best tools for writing an assembler? Sébastien Fricker <sebastien.fricker@gmail.com> - 2014-02-24 07:32 +0100
          Re: Best tools for writing an assembler? Louis Krupp <lkrupp@pssw.com> - 2014-02-24 15:39 -0700
          Re: Best tools for writing an assembler? Ivan Godard <ivan@ootbcomp.com> - 2014-02-24 15:04 -0800
            Re: Best tools for writing an assembler? rpw3@rpw3.org (Rob Warnock) - 2014-02-25 13:00 +0000
          Re: Best tools for writing an assembler? Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2014-02-25 04:09 +0100
        Re: Best tools for writing an assembler? "James Harris" <james.harris.1@gmail.com> - 2014-02-24 23:18 +0000
        Re: Best tools for writing an assembler? noitalmost <noitalmost@cox.net> - 2014-02-27 18:11 -0500
          Re: Best tools for writing an assembler? George Neuner <gneuner2@comcast.net> - 2014-03-01 13:09 -0500
            Re: Best tools for writing an assembler? federation2005@netzero.com - 2014-03-26 17:57 -0700
              Re: Best tools for writing an assembler? federation2005@netzero.com - 2014-04-13 12:24 -0700
  Re: Best tools for writing an assembler? Sébastien Fricker <sebastien.fricker@gmail.com> - 2014-02-19 09:59 +0100
    Re: Best tools for writing an assembler? Robert A Duff <bobduff@shell01.TheWorld.com> - 2014-02-19 18:27 -0500
  Re: Best tools for writing an assembler? Patrik Túri <tpphysik@gmail.com> - 2014-02-20 17:15 -0800
    Re: Best tools for writing an assembler? Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2014-02-21 12:09 +0100
      Re: Best tools for writing an assembler? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-02-24 20:42 +0000
        Re: Best tools for writing an assembler? Ivan Godard <ivan@ootbcomp.com> - 2014-02-24 15:13 -0800
        Re: Best tools for writing an assembler? hu47121@usenet.kitty.sub.org (Hannah) - 2014-02-25 00:43 +0000
          Re: Best tools for writing an assembler? Walter Banks <walter@bytecraft.com> - 2014-02-27 14:14 -0500
        Re: Best tools for writing an assembler? Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2014-02-25 04:23 +0100
    Re: Best tools for writing an assembler? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-02-24 20:35 +0000

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