Re: KISS4691, a potentially top-ranked RNG.

From	Keith Thompson <kst-u@mib.org>
Newsgroups	sci.math, comp.lang.c, comp.lang.fortran, comp.lang.pl1, comp.lang.ada
Subject	Re: KISS4691, a potentially top-ranked RNG.
Date	2011-04-29 12:53 -0700
Organization	None to speak of
Message-ID	<lnoc3ox2a0.fsf@nuthaus.mib.org> (permalink)
References	(2 earlier) <ipbjqf$q4k$1@dont-email.me> <ipd5i2011p@news6.newsguy.com> <ipd83f$5at$1@dont-email.me> <lnsjt1w0oc.fsf@nuthaus.mib.org> <ipet84$5er$1@dont-email.me>

Cross-posted to 5 groups.

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glen herrmannsfeldt <gah@ugcs.caltech.edu> writes:
> In comp.lang.fortran Keith Thompson <kst-u@mib.org> wrote:
> (snip, I wrote)
>>> No.  You need CHAR_BIT to tell how many bits are in a char.
>>> It has been known to get to 64 on word addressed 64 bit machines.
>>> It must be at least 8, but can be more.
>  
>> Certainly CHAR_BIT *could* be 64 (or even more), but I've never heard
>> of a 64-bit system with CHAR_BIT==64.  Such an implementation would
>> have trouble dealing with octet-oriented data from other systems.
>> Some DSPs (digital signal processors) do have CHAR_BIT > 8.
>> There have been systems with, for example, 9-bit bytes, but they
>> had pretty much become obsolete by the time C was standardized.
>
> The story I remember was for a Cray machine, but I never used
> one to check on it.  I do know that there are some 64 bit
> word addressed machines, especially some from Cray.

I used to work on a Cray T90.  It had 64-bit words, and no direct
hardware access to smaller chunks of memory; to read an 8-bit byte,
you had to read the word containing it and then extract the bits
you wanted.  But the C compiler (C90, it never implemented C99)
had CHAR_BIT==8.  char was 8 bits; short, int, and long were all
64 bits.  A pointer to anything smaller than a 64-bit word stored
the byte offset in the high-order 3 bits (the address space was
much smaller than 64 bits, so the high-order bits weren't being
used for anything else).  This was all handled in software; the
compiler had to generate extra instructions to deal with byte data.

Making CHAR_BIT==64 would have made much more sense for the machine
itself in isolation, but it would have made interoperability with
other systems quite difficult.  It ran Unicos, Cray's BSDish Unix;
I'm not sure you can even implement Unix with bytes bigger than
8 bits.

It made it very slow for things like string processing, but since
it was primarily used for floating-point computations that wasn't
much of an issue.

Some older Cray vector systems ran other, non-Unix, operating systems
(COS, CTSS), but I never used any of those, and I don't know what
value their compilers used for CHAR_BIT -- if C was even supported.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Nokia
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

Thread

Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-04-28 11:14 +1000
  Re: KISS4691, a potentially top-ranked RNG. "e p chandler" <epc8@juno.com> - 2011-04-28 07:42 -0400
    Re: KISS4691, a potentially top-ranked RNG. Gib Bogle <g.bogle@auckland.ac.nz> - 2011-04-29 12:55 +1200
    Re: KISS4691, a potentially top-ranked RNG. David Bernier <david250@videotron.ca> - 2011-04-28 21:50 -0400
      Re: KISS4691, a potentially top-ranked RNG. Ian Collins <ian-news@hotmail.com> - 2011-04-29 14:09 +1200
        Re: KISS4691, a potentially top-ranked RNG. Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-04-28 23:01 -0400
          Re: KISS4691, a potentially top-ranked RNG. Ian Collins <ian-news@hotmail.com> - 2011-04-29 15:09 +1200
            Re: KISS4691, a potentially top-ranked RNG. Uno <merrilljensen@q.com> - 2011-05-08 00:34 -0700
              Re: KISS4691, a potentially top-ranked RNG. Marni Zollinger <marni@altgreendesigns.com> - 2011-05-10 23:38 -0600
          Re: KISS4691, a potentially top-ranked RNG. nmm1@cam.ac.uk - 2011-04-29 07:15 +0100
        Re: KISS4691, a potentially top-ranked RNG. David Bernier <david250@videotron.ca> - 2011-04-28 23:16 -0400
      Re: KISS4691, a potentially top-ranked RNG. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2011-04-29 02:34 +0000
        Re: KISS4691, a potentially top-ranked RNG. Uno <Uno@example.invalid> - 2011-04-29 01:04 -0600
          Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-04-30 20:48 +1000
            Re: KISS4691, a potentially top-ranked RNG. Uno <Uno@example.invalid> - 2011-05-04 19:12 -0600
        Re: KISS4691, a potentially top-ranked RNG. Keith Thompson <kst-u@mib.org> - 2011-04-29 08:13 -0700
          Re: KISS4691, a potentially top-ranked RNG. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2011-04-29 17:41 +0000
            Re: KISS4691, a potentially top-ranked RNG. Keith Thompson <kst-u@mib.org> - 2011-04-29 12:53 -0700
              Re: KISS4691, a potentially top-ranked RNG. Michael Press <rubrum@pacbell.net> - 2011-05-05 16:38 -0700
          Re: KISS4691, a potentially top-ranked RNG. Seebs <usenet-nospam@seebs.net> - 2011-04-29 22:45 +0000
          Re: KISS4691, a potentially top-ranked RNG. "Randy Brukardt" <randy@rrsoftware.com> - 2011-04-29 23:36 -0500
      Re: KISS4691, a potentially top-ranked RNG. Seebs <usenet-nospam@seebs.net> - 2011-04-29 22:43 +0000
    Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-04-29 19:43 +1000
  Re: KISS4691, a potentially top-ranked RNG. Thad Smith <ThadSmith@acm.org> - 2011-05-01 08:31 -0700
    Re: KISS4691, a potentially top-ranked RNG. Ian Collins <ian-news@hotmail.com> - 2011-05-02 07:58 +1200
      Re: KISS4691, a potentially top-ranked RNG. James Kuyper <jameskuyper@verizon.net> - 2011-05-01 20:01 -0400
        Re: KISS4691, a potentially top-ranked RNG. Ian Collins <ian-news@hotmail.com> - 2011-05-02 12:42 +1200
          Re: KISS4691, a potentially top-ranked RNG. James Kuyper <jameskuyper@verizon.net> - 2011-05-01 22:34 -0400
          Re: KISS4691, a potentially top-ranked RNG. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2011-05-02 02:50 +0000
      Re: KISS4691, a potentially top-ranked RNG. Thad Smith <ThadSmith@acm.org> - 2011-05-01 21:21 -0700
        Re: KISS4691, a potentially top-ranked RNG. nmm1@cam.ac.uk - 2011-05-02 08:31 +0100
          Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-05-23 16:52 +1000
          Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-05-23 14:18 +1000
            Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-05-23 17:20 +1000
          Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-05-23 16:52 +1000
          Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-05-23 16:52 +1000
          Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-05-23 16:53 +1000
            Re: KISS4691, a potentially top-ranked RNG. Georg Bauhaus <rm.dash-bauhaus@futureapps.de> - 2011-05-23 09:16 +0200
              Re: KISS4691, a potentially top-ranked RNG. Ilmari Karonen <usenet2@vyznev.invalid> - 2011-05-26 22:06 +0000
              Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-06-28 17:19 +1000
                Re: KISS4691, a potentially top-ranked RNG. "Vinzent Hoefler" <0439279208b62c95f1880bf0f8776eeb@t-domaingrabbing.de> - 2011-06-28 10:44 +0200
                Re: KISS4691, a potentially top-ranked RNG. Chris H <chris@phaedsys.org> - 2011-06-28 10:19 +0100
                Re: KISS4691, a potentially top-ranked RNG. Georg Bauhaus <rm.dash-bauhaus@futureapps.de> - 2011-06-28 11:14 +0200
                Re: KISS4691, a potentially top-ranked RNG. "robin" <robin51@dodo.mapson.com.au> - 2011-06-28 21:59 +1000
                Re: KISS4691, a potentially top-ranked RNG. Chris H <chris@phaedsys.org> - 2011-06-28 13:16 +0100
                Re: KISS4691, a potentially top-ranked RNG. Peter Flass <Peter_Flass@Yahoo.com> - 2011-06-28 11:44 -0400
                Re: KISS4691, a potentially top-ranked RNG. James Kuyper <jameskuyper@verizon.net> - 2011-06-28 08:33 -0400
                Re: KISS4691, a potentially top-ranked RNG. Georg Bauhaus <rm.dash-bauhaus@futureapps.de> - 2011-06-28 15:53 +0200
                Re: KISS4691, a potentially top-ranked RNG. Brian Salter-Duke <b_duke@bigpond.com.au> - 2011-06-28 22:39 +0000
                Re: KISS4691, a potentially top-ranked RNG. James Kuyper <jameskuyper@verizon.net> - 2011-06-28 08:32 -0400
                Re: KISS4691, a potentially top-ranked RNG. Chris H <chris@phaedsys.org> - 2011-06-28 14:03 +0100
                Re: KISS4691, a potentially top-ranked RNG. James Kuyper <jameskuyper@verizon.net> - 2011-06-28 10:25 -0400
                Re: KISS4691, a potentially top-ranked RNG. Chris H <chris@phaedsys.org> - 2011-06-28 16:01 +0100
                Re: KISS4691, a potentially top-ranked RNG. James Kuyper <jameskuyper@verizon.net> - 2011-06-28 20:20 -0400
                Re: KISS4691, a potentially top-ranked RNG. Michael Press <rubrum@pacbell.net> - 2011-06-29 01:38 -0700
                Re: KISS4691, a potentially top-ranked RNG. Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-28 10:04 -0600
                Re: KISS4691, a potentially top-ranked RNG. Chris H <chris@phaedsys.org> - 2011-06-28 17:36 +0100
                Re: KISS4691, a potentially top-ranked RNG. Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-28 10:51 -0600
                Re: KISS4691, a potentially top-ranked RNG. James Kuyper <jameskuyper@verizon.net> - 2011-06-28 20:27 -0400
                Re: KISS4691, a potentially top-ranked RNG. Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-28 19:00 -0600
                Re: KISS4691, a potentially top-ranked RNG. Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-06-29 19:48 +0300
                Re: KISS4691, a potentially top-ranked RNG. Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-28 10:52 -0600
                Re: KISS4691, a potentially top-ranked RNG. David Bernier <david250@videotron.ca> - 2011-06-28 13:06 -0400
                Re: Wiki "robin" <robin51@dodo.mapson.com.au> - 2011-06-29 10:00 +1000
                Re: Wiki James Kuyper <jameskuyper@verizon.net> - 2011-06-28 20:25 -0400
                Re: Wiki Ivan Shmakov <ivan@gray.siamics.net> - 2011-06-29 16:03 +0700
                Re: Wiki Chris H <chris@phaedsys.org> - 2011-06-30 13:39 +0100
                Re: Wiki Frederick Williams <freddywilliams@btinternet.com> - 2011-07-01 22:15 +0100
                Re: Wiki Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-28 18:52 -0600
                Re: Wiki James Kuyper <jameskuyper@verizon.net> - 2011-06-29 05:52 -0400
                Re: Wiki Peter Flass <Peter_Flass@Yahoo.com> - 2011-06-29 10:12 -0400
                Re: Wiki Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-29 14:29 -0600
                Re: Wiki Dr Nick <3-nospam@temporary-address.org.uk> - 2011-06-29 07:43 +0100
                Re: Wiki Peter Flass <Peter_Flass@Yahoo.com> - 2011-06-29 10:10 -0400
                Re: Wiki Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-06-29 19:42 +0300
                Re: Wiki Chris H <chris@phaedsys.org> - 2011-06-29 18:09 +0100
                Re: Wiki Dr Nick <3-nospam@temporary-address.org.uk> - 2011-06-29 18:48 +0100
                Re: Wiki Peter Flass <Peter_Flass@Yahoo.com> - 2011-06-29 09:50 -0400

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