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From: jgk@osc.COM (Joe Keane)
Newsgroups: comp.arch
Subject: Re: It looks like he's at it again!
Message-ID: <3060@osc.COM>
Date: 13 Jul 90 23:08:10 GMT
References: <2328@l.cc.purdue.edu> <1990Jul10.072443.4844@cs.UAlberta.CA> <9896@celit.fps.com> <2338@l.cc.purdue.edu> <9911@celit.fps.com> <24358@estelle.udel.EDU>
Reply-To: jgk@osc.COM (Joe Keane)
Organization: Object Sciences Corp., Menlo Park, CA
Lines: 14

In article <24358@estelle.udel.EDU> new@ee.udel.edu (Darren New) writes:
>Sure.  Any inner-interpreter type of code is easiest in assembler. Things
>like Forth threading are harder to do in C than assembler because Forth
>assumes is really big on treating addresses as data and vica versa. In
>addition, it is usually only 3-6 instructions to do an inner-interpreter step
>and the more speed you can get, the better.  -- Darren

I don't see any problem with `treating addresses as data and vice versa'.
That's what casts are for.  Your C code may end up with expressions like
`*(long**)((char*)a+*(short*)b)' but it works and is even somewhat portable.

One real problem with using C for threaded interpreters is that there is no
way to make an arbitrary jump instruction.  If you could `goto' some address
expression there would be no problem.