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From: philip@pescadero.Stanford.EDU (Philip Machanick)
Newsgroups: comp.arch
Subject: Re: It looks like he's at it again!
Message-ID: <1990Jul15.013016.16786@Neon.Stanford.EDU>
Date: 15 Jul 90 01:30:16 GMT
References: <37569@ucbvax.BERKELEY.EDU> <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> <3060@osc.COM>
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Reply-To: philip@pescadero.stanford.edu
Organization: Computer Science Department, Stanford University
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In article <37569@ucbvax.BERKELEY.EDU>, tve@sprite.berkeley.edu
(Thorsten von Eicken) writes:
> In article <3060@osc.COM> jgk@osc.COM (Joe Keane) writes:
> >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.
> Yep, typically the C program ends up being a hunge switch statement:
> 	loop:	switch(next_thread) {
> 		case 0: .... goto loop;
> 		case 1: .... goto loop;
> 		}
> and one hopes that a) a jump table is produced (and not a binary search
> tree) and b) the compiler doesn't dump core with some silly error when
> the number of cases reaches into the thousands...
> 
> Or can anyone suggest a better method?
If you can afford the overhead of a function call, you can use an array
of function pointers to implement a jump table.

Philip Machanick
philip@pescadero.stanford.edu