Re: Looking for a garbage collection paper

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From	gah4 <gah4@u.washington.edu>
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Subject	Re: Looking for a garbage collection paper
Date	Thu, 29 Sep 2022 21:10:30 -0700 (PDT)
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On Thursday, September 29, 2022 at 10:15:49 AM UTC-7, Thomas Koenig wrote:

(snip)

>> > It also
> >> says "a single instruction". I don't think that
> >> cur_col = (cur_col + 1) mod 3
> >> can be implemented in a single instruction in common hardware.

(snip, I wrote)

> > It would seem more likely on a machine with a word size a
> > multiple of 3, with 36 bit words not so rare 50 years ago.

(snip)

> What about
>
> int a[] = {1, 2, 0};
>
> cur_col = a[cur_col];
>
> That would qualify as a single indexed load, provided cur_col
> started out with a value between 0 and 2.
> [Duh, of course that will work on any word addressed machine. -John]

A word addressed machine with an indexed load.

Or a machine with indexed load that scales for the size, like VAX.

Or a table of bytes, so the index unit is 1.

But not if index registers are different from other registers, like
(if I remember) they are on the 7090.
[Yes, the 704 series had separate index registers.  It occurs to me that
another way to do this is to use the rotate instructions the 70x and PDP-6/10
had.  Since the word is 36 bits, you rotate by 12 each time and you'll have
three bit patterns. -John]

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Looking for a garbage collection paper Spiros Bousbouras <spibou@gmail.com> - 2022-09-20 09:29 +0000
  Re: Looking for a garbage collection paper Robert Prins <robert@prino.org> - 2022-09-21 09:42 +0000
    Re: Looking for a garbage collection paper Spiros Bousbouras <spibou@gmail.com> - 2022-09-23 16:38 +0000
      Re: Looking for a garbage collection paper gah4 <gah4@u.washington.edu> - 2022-09-23 12:33 -0700
        Re: Looking for a garbage collection paper Thomas Koenig <tkoenig@netcologne.de> - 2022-09-29 13:15 -0400
          Re: Looking for a garbage collection paper gah4 <gah4@u.washington.edu> - 2022-09-29 21:10 -0700
            Re: Looking for a garbage collection paper gah4 <gah4@u.washington.edu> - 2022-09-29 23:56 -0700
  Re: Looking for a garbage collection paper drb@ihatespam.msu.edu (Dennis Boone) - 2022-09-23 19:39 +0000

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