old threaded languages, was Re: Symbolics

From: Dwight Elvey <elvey_at_hal.com>
Date: Wed Mar 1 11:57:53 2000

John Wilson <wilson_at_dbit.dbit.com> wrote:
>
> I've never understood this. Evidently most/all of the FIG FORTHs produced
> threaded code, but I haven't found a single peep about it in the FIST
> standards
> that say it's an inherent part of the language. I've written FORTHs that did
> it both ways, very simple-minded in each case but I think it would be pretty
> easy to write a FORTH that at least pruned out most of the superfluous stack
> use (stuff that gets pushed and then popped right off) and could produce
> semi-decent machine code.

Hi
 I think that most of the FIG Forths were done that way to keep
the implementation across various platforms consistant. It surely
wasn't the fastest.
 I've done a call threaded Forth on Analog Devices' ADSP2100.
On a 2181 running at 33MHz it can sort 1000 integers in
6.8 milliseconds and that is code written in high level
Forth. I did a lot of peep-hole optimizing to keep the
top elements of the stack in registers when I could.
It also overlaped many words when compiled. Still, it wasn't
the fastest compiler. Analog Devices 'C' compiler took the
same basic source code and ran the sort a about 4 millisec.
Of course, the Forth code fit into less then 200 words of
code while the 'C' code took over 1K words. They spent a
lot more time and money on their optimizer than I did.
 If anyone out there doesn't think sorting 1000 signed integers
in 6.8 millisecs isn't fast, code it up on your PC and
see how fast it is.
Dwight
Received on Wed Mar 01 2000 - 11:57:53 GMT