Re: Parsing timestamps?

On 6 Jul 2025 at 04:52:37 CEST, "dxf" <dxforth@gmail.com> wrote:

On 5/07/2025 6:49 pm, Anton Ertl wrote:

dxf <dxforth@gmail.com> writes:
[8 stack items on the FP stack]

Puzzling because of a thread here not long ago in which scientific users
appear to suggest the opposite.  Such concerns have apparently been around
a long time:
 
https://groups.google.com/g/comp.lang.forth/c/CApt6AiFkxo/m/wwZmc_Tr1PcJ

 
I have read through the thread.  It's unclear to me which scientific
users you have in mind.  My impression is that 8 stack items was
deemed sufficient by many, and preferable (on 387) for efficiency
reasons.

 
AFAICS both Skip Carter (proponent) and Julian Noble were suggesting the
6 level minimum were inadequate.  A similar sentiment was expressed here
only several months ago.  AFAIK all major forths supporting x87 hardware
offer software stack options.
 

Certainly, of the two points this thread is about, there was a
Forth200x proposal for standardizing a separate FP stack, and this
proposal was accepted.  There was no proposal for increasing the
minimum size of the FP stack; Forth-2012 still says:
 
|The size of a floating-point stack shall be at least 6 items.

 
Only because nothing further was heard.  What became of the review
Elizabeth announced I've no idea.
 

One interesting aspect is that VFX 5.x finally includes an FP package
by default, and it started by including an SSE2-based FP package which
supports a deep FP stack.  However, MPE received customer complaints
about the lower number of significant digits in SSE2 (binary64)
vs. 387 (80-bit FP values), so they switched the default to the
387-based FP package that only has 8 FP stack items.  Apparently no
MPE customer complains about that limitation.
...

 
AFAIK x87 hardware stack was always MPE's main and best supported FP
package.  As for SSE2 it wouldn't exist if industry didn't consider
double-precision adequate.  My impression of MPE's SSE2 implementation
is that it's 'a work in progress'.  The basic precision is there but
transcendentals appear to be limited to single-precision.  That'd be
the reason I'd stick with MPE's x87 package.  Other reason is it's now
quite difficult and error-prone to switch FP packages as it involves
rebuilding the system.  The old scheme was simpler and idiot-proof.

You do not have to rebuild the system to switch. Just read the manual.

"The old scheme was simpler and idiot-proof." Yes, that's why we
did it that way, but a certain "guru" who only does testing kept
moaning. If people would prefer us to go back to the old scheme,
VFX 6 still has time for changes. The whole idea that compiling
one file is improper is very non-Forth, or even anti-Forth.

I may be getting grumpier as I get older.

Stephen
--
Stephen Pelc, stephen@vfxforth.com
Wodni & Pelc GmbH
Vienna, Austria
Tel: +44 (0)7803 903612, +34 649 662 974
http://www.vfxforth.com/downloads/VfxCommunity/
  free VFX Forth downloads