bug#43764: closed (Calc shift right broken)

[GNU bug Tracking System]

Your message dated Tue, 13 Oct 2020 11:56:50 +0200
with message-id <550C4DEF-DBAA-4175-98BC-DB484A3B89CF@acm.org>
and subject line Re: bug#43764: Calc shift right broken
has caused the debbugs.gnu.org bug report #43764,
regarding Calc shift right broken
to be marked as done.

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43764: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=43764
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--- Begin Message --- Subject: Calc shift right broken Date: Fri, 2 Oct 2020 15:28:22 +0000

Not sure whether this has to do with the other one.

I am on another machine, it is GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.20) of 2020-05-17, modified by Debian

Anyway, I do this:

2 RET

;; display in hexa

d 6 RET

;; Raise to the power 32

32 ^

;; Shitf right by 30

C-u 32 b r

;; I get 0, whereas I expected 4

I have the impression that the old bigpos bigneg lisp based big intergers have been replaced by C bigintegers, and this is the root of all these regression.

Well, just a speculation.

  V.

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#43764: Calc shift right broken
>
>
>
>
> Date: 
>
> Tue, 13 Oct 2020 11:56:50 +0200
>
>
>
>
> 9 okt. 2020 kl. 17.34 skrev Vincent Belaïche <vincent.b.1@hotmail.fr>:
>
> >       • set bit width 0 would remove the automatic clipping meaning infinite 
> > width.
>
> The previously mentioned patch implementing this has now been pushed to Emacs 
> master. Thanks again for the suggestion!
>
> I should also note the rationale for disabling left/right rotation when the 
> word size is set to zero: while it would make sense to define
>
>  (rotate-left x 1) =>
>  x≥0: (shift-left x 1)
>  x<0: (+ (shift-left x 1) 1)
>
>  (rotate-right x 1) =>
>  x≥0, x even: (shift-right x 1)
>  x<0, x odd:  (shift-right x 1),
>
> the two remaining cases of rotate right with {x≥0, x odd} or {x<0, x even} 
> cannot result in a finite integer.
>
> If someone has a better idea, or would like rotation to be implemented as a 
> partial function according to the above definition, please comment. For now the 
> bug is closed.
>
>
>
> --- End Message ---