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Re: New Vax - future directions :-)

On 2021-07-06 18:34, Paul Koning wrote:

On Jul 6, 2021, at 10:42 AM, Mouse <mouse%Rodents-Montreal.ORG@localhost> wrote:

So I'd say [EMUL/EMULU] definitely have value.  However, it's a fair
point that it might be hard to get compilers to make use of it.

Perhaps.  But it can be used under the hood by large-number support
routines, either libc "word×word->doubleword" or large integer
arithmetic such as is used by modern crypto.  Even if there are only
two EMULU instructions in an executable, they can still make a
significant difference.

As is the case for so much of the stuff in the VAX.  It's good for
people writing in assembler, but difficult to make use of by

Well, modern compilers, because they attempt to be multi-target.  Build
a VAX-target compiler, with no care for non-VAX targets, and it becomes

GCC certainly can handle single * single -> double operations, that's a standard pattern in the back end support machinery.  PDP11 and VAX both use it, as do 28 other targets GCC knows about.

Cool. I didn't know GCC could understand and make use of such an oddity.

You don't have any modern language that want to deal with the upper
part anyway.

Only antique languages (like Lisp) with bignum support, or fringe
applications like cryptography.

I don't think Python 3 is an antique language, and it uses bignum arithmetic for all its integer arithmetic.  Python 2 do so optionally.  And cryptography is about as far from a fringe application as you can get.

I think it's called "irony" or "sarcasm" or something... ;-)


Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt%softjar.se@localhost             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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