Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > comp.lang.c > #162607

Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ?

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ?
Date 2021-09-03 19:45 +0100
Organization A noiseless patient Spider
Message-ID <87r1e5sdkl.fsf@bsb.me.uk> (permalink)
References (12 earlier) <b269912f-21e1-4c16-9bb1-efcd6954453en@googlegroups.com> <sgtdf2$g6v$1@dont-email.me> <90a43fde-5b57-48a6-ac61-c11b16f1425an@googlegroups.com> <871r65ttr3.fsf@bsb.me.uk> <sgtp10$a22$2@dont-email.me>

Show all headers | View raw


I replied to an email from you instead of the public post.  Please don't
mail copies of posts...

James Kuyper <jameskuyper@alumni.caltech.edu> writes:

> On 9/3/21 2:10 PM, Ben Bacarisse wrote:
>> "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> writes:
> ...
>>> On a platform such as the one I've described, with no hardware support for
>>> access to any piece of memory smaller than 16 bits, and a compiler which
>>> chooses to set CHAR_BIT == 8, the following function:
>>>
>>>       void add_3a(unsigned char *p) { *p += 3; }
>>>
>>> Would have to be compiled into machine code which does something
>>> similar to:
>>>
>>>     struct _byteptr {
>>>         int *addr
>>>         int offset;
>>>     };
>> 
>> I used (as was tangentially involved in the implementation of) C on a
>> machine that had 16 bit words and only word addressing.  The choice made
>> there was to use the bottom bit to select between the two halves of the
>> word addressed by the pointer (shifted right by 1).
>
> If I understand you correctly, that's a workable approach so long as you
> have no more than 32768 words of addressable memory.

Yes.  It was a per-process limit.  The machine had more than that in total.

> However, as such,
> it's not an example of an implementation where sizeof(void*) > sizeof(int*).

Yes.  I was only showing another approach to implementing byte
addresses.

-- 
Ben.

Back to comp.lang.c | Previous | NextPrevious in thread | Next in thread | Find similar | Unroll thread


Thread

Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Lynn McGuire <lynnmcguire5@gmail.com> - 2021-08-30 21:59 -0500
  Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-08-30 21:53 -0700
    Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-08-30 21:59 -0700
  Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bo Persson <bo@bo-persson.se> - 2021-08-31 09:01 +0200
    Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Lynn McGuire <lynnmcguire5@gmail.com> - 2021-08-31 23:46 -0500
      Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? David Brown <david.brown@hesbynett.no> - 2021-09-01 08:19 +0200
      Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? scott@slp53.sl.home (Scott Lurndal) - 2021-09-01 15:32 +0000
        Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-01 19:20 +0200
          Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? David Brown <david.brown@hesbynett.no> - 2021-09-01 19:44 +0200
            Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Lynn McGuire <lynnmcguire5@gmail.com> - 2021-09-01 13:17 -0500
              Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? David Brown <david.brown@hesbynett.no> - 2021-09-01 20:32 +0200
              Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? scott@slp53.sl.home (Scott Lurndal) - 2021-09-01 19:00 +0000
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Lynn McGuire <lynnmcguire5@gmail.com> - 2021-09-01 15:06 -0500
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? scott@slp53.sl.home (Scott Lurndal) - 2021-09-01 20:14 +0000
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Michael S <already5chosen@yahoo.com> - 2021-09-01 14:04 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? scott@slp53.sl.home (Scott Lurndal) - 2021-09-01 23:44 +0000
            Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-01 20:37 +0200
              Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-01 12:43 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-02 05:37 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-02 11:28 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-03 07:10 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-03 06:59 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-03 17:02 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Manfred <noname@add.invalid> - 2021-09-03 19:33 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-03 19:47 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? scott@slp53.sl.home (Scott Lurndal) - 2021-09-03 17:54 +0000
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bart <bc@freeuk.com> - 2021-09-03 20:54 +0100
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? scott@slp53.sl.home (Scott Lurndal) - 2021-09-03 20:52 +0000
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-04 12:36 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-03 10:49 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-09-03 19:10 +0100
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-09-03 14:20 -0400
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-09-03 19:45 +0100
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-09-03 16:35 -0400
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? David Brown <david.brown@hesbynett.no> - 2021-09-04 13:12 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-04 09:11 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-04 11:27 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-05 04:25 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-06 16:10 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-08 19:44 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-08 11:45 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-09 19:09 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-09 10:51 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-10 10:31 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-10 10:41 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-14 04:14 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-14 07:45 -0700
            Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bart <bc@freeuk.com> - 2021-09-01 20:34 +0100
              Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-09-01 13:02 -0700
              Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? scott@slp53.sl.home (Scott Lurndal) - 2021-09-01 20:18 +0000
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Michael S <already5chosen@yahoo.com> - 2021-09-01 14:07 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bart <bc@freeuk.com> - 2021-09-01 22:18 +0100
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-09-01 18:23 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? David Brown <david.brown@hesbynett.no> - 2021-09-02 13:35 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-09-02 05:24 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2021-09-02 14:56 -0600
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Vir Campestris <vir.campestris@invalid.invalid> - 2021-09-07 21:12 +0100
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-09-07 22:19 -0400
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Vir Campestris <vir.campestris@invalid.invalid> - 2021-09-12 21:23 +0100
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Michael S <already5chosen@yahoo.com> - 2021-09-09 08:36 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Lynn McGuire <lynnmcguire5@gmail.com> - 2021-09-01 17:46 -0500
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-09-01 16:53 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Lynn McGuire <lynnmcguire5@gmail.com> - 2021-09-02 17:11 -0500
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-09-01 16:59 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-09-01 17:01 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bart <bc@freeuk.com> - 2021-09-02 01:29 +0100
              Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? David Brown <david.brown@hesbynett.no> - 2021-09-02 13:29 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bart <bc@freeuk.com> - 2021-09-02 14:19 +0100
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-09-02 17:10 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Michael S <already5chosen@yahoo.com> - 2021-09-02 07:28 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? David Brown <david.brown@hesbynett.no> - 2021-09-02 21:07 +0200
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Michael S <already5chosen@yahoo.com> - 2021-09-02 13:05 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-09-02 17:18 -0700
                Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Bart <bc@freeuk.com> - 2021-09-03 01:25 +0100
  Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Mark Bluemel <mark.bluemel@gmail.com> - 2021-09-01 03:30 -0700
    Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Mark Bluemel <mark.bluemel@gmail.com> - 2021-09-01 03:36 -0700
    Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Lynn McGuire <lynnmcguire5@gmail.com> - 2021-09-01 12:49 -0500
      Re: Examples of current platforms/architectures where sizeof(void*) > sizeof(int*) ? Mark Bluemel <mark.bluemel@gmail.com> - 2021-09-01 14:30 -0700

csiph-web