Re: Request for source code review of simple Ising model

From	James Kuyper <jameskuyper@verizon.net>
Newsgroups	comp.lang.c
Subject	Re: Request for source code review of simple Ising model
Date	2014-04-17 16:34 -0400
Organization	Self
Message-ID	<53503AC2.5040208@verizon.net> (permalink)
References	(8 earlier) <87vbu8a2n8.fsf@panda.goosenet.in> <lna9bk6lxm.fsf@nuthaus.mib.org> <lip739$i4h$1@speranza.aioe.org> <53502AD2.2050506@verizon.net> <qpW3v.8524$vM2.5585@fx18.am4>

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On 04/17/2014 04:00 PM, BartC wrote:
> "James Kuyper" <jameskuyper@verizon.net> wrote in message 
> news:53502AD2.2050506@verizon.net...
> 
>> I believe that one possibility allowed by C90 was an integer type with
>> one or more padding bits. Such a padding bit could be either a mark
>> parity bit, or an odd parity bit - either of those options would
>> prohibit 0 from being represented by all-bits-zero.
> 
> These are parity bits accessible from software? The ones I've come across 
> were dealt with in hardware and wouldn't impact on using all-bits-zero for 
> any values. They would in fact be completely transparent.

Completely transparent bits don't count as padding bits for the purposes
of the C standard. Padding bits can always be made visible by accessing
the memory as if it were an array of unsigned char. The fact that those
bits are padding bits means that they would be invisible (unless they
give the object a trap representation) when viewing that same memory
using an lvalue of the integer type for which they constitute padding
bits. It would be up to the implementation to make sure a) that the
padding bits are actually invisible and b) that they get set to valid
values when code with defined behavior is used to write the values to
memory.

Please do NOT ask me to provide real-world examples. I'm just trying to
give an example of something that was allowed by C90, but not by C99.
I'm fairly certain that the committee would not have changed the
standard to disallow such an implementation, if they had been aware of
any significant number of real-world implementations where something
like that was actually being done. If nobody was doing anything like
that, there's probably no good motivation for doing anything like that -
so for the same reason, please don't ask me to provide such a motivation.

Thread

Request for source code review of simple Ising model Udyant Wig <udyant@panda.goosenet.in> - 2014-04-10 23:38 +0530
  Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-10 13:30 -0700
    Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-12 00:34 +0530
      Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-11 12:25 -0700
      Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-16 01:12 +0530
        Re: Request for source code review of simple Ising model Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-04-16 01:33 +0100
          Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-16 17:57 +0530
            Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-16 06:00 -0700
            Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-16 10:58 -0400
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-16 09:07 -0700
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-16 12:22 -0400
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-16 10:38 -0700
                Re: Request for source code review of simple Ising model Kaz Kylheku <kaz@kylheku.com> - 2014-04-16 19:37 +0000
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-17 12:00 +0530
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-17 09:32 +0000
                Re: Request for source code review of simple Ising model "BartC" <bc@freeuk.com> - 2014-04-17 12:24 +0100
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 08:16 -0700
                Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-17 04:41 -0700
                Re: Request for source code review of simple Ising model Les Cargill <lcargill99@comcast.com> - 2014-04-17 07:49 -0500
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 08:00 -0700
                Re: Request for source code review of simple Ising model Kaz Kylheku <kaz@kylheku.com> - 2014-04-17 15:06 +0000
                Re: Request for source code review of simple Ising model Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-18 21:04 -0700
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-17 18:38 +0000
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-17 15:26 -0400
                Re: Request for source code review of simple Ising model "BartC" <bc@freeuk.com> - 2014-04-17 21:00 +0100
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-17 16:34 -0400
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-18 04:31 +0000
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 14:05 -0700
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 17:06 -0700
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-18 04:54 +0000
                Re: Request for source code review of simple Ising model Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-18 11:51 -0700
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-17 11:42 +0530
            Re: Request for source code review of simple Ising model Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-04-16 16:54 +0100
              Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-16 15:22 -0700
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-17 13:03 +0530
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 08:44 -0700
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-17 12:12 -0400
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 12:38 +0530
                Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-18 03:11 -0700
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 12:32 +0530
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-18 10:05 -0400
        Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-16 07:10 +0000
        Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-17 13:10 -0400
          Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 18:24 +0530
            Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-18 09:52 -0400
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 20:04 +0530
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-18 11:00 -0400
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 01:49 +0530
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-19 21:20 +0000
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 11:11 +0530
                Re: Request for source code review of simple Ising model Richard Damon <Richard@Damon-Family.org> - 2014-04-20 09:06 -0400
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-20 10:50 -0400
                Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-21 09:14 -0700
              Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-19 05:43 +0000
            Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 19:47 +0530
            Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 01:21 +0530
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-20 14:24 -0700
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 10:40 +0530
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 12:29 +0530
          Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-18 08:36 -0700
            Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-18 13:40 -0400
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-18 11:14 -0700
              Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-18 13:55 -0700
            Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-19 01:25 +0530
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-19 01:44 +0530
              Re: Request for source code review of simple Ising model Kaz Kylheku <kaz@kylheku.com> - 2014-04-18 20:24 +0000
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-18 13:36 -0700
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-19 20:18 +0530
              Re: Request for source code review of simple Ising model Richard <rgrdev_@gmail.com> - 2014-04-19 14:55 +0100
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 02:10 +0530
            Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-19 05:40 +0000
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-19 14:39 -0700
                Re: Request for source code review of simple Ising model Ian Collins <ian-news@hotmail.com> - 2014-04-20 10:44 +1200
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-19 17:11 -0700
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 11:24 +0530
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-19 17:19 -0700
                Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-20 10:10 +0000
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-20 14:21 -0700
                Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-20 22:18 +0000
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-20 19:27 -0700
                Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-21 12:38 +0000
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 18:12 +0530
                Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-21 13:13 +0000
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 19:46 +0530
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-21 09:06 -0700
                Re: Request for source code review of simple Ising model jacob navia <jacob@spamsink.net> - 2014-04-21 00:26 +0200
        Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 01:15 +0530
        Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 11:46 +0530

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