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Re: Arduino / compilers on uC

From David Brown <david.brown@hesbynett.no>
Newsgroups sci.electronics.design
Subject Re: Arduino / compilers on uC
Date 2017-02-13 16:49 +0100
Organization A noiseless patient Spider
Message-ID <o7ske5$9su$1@dont-email.me> (permalink)
References (5 earlier) <48fmA.157015$6N1.154146@fx09.am4> <fbe16b9e-6b68-44fd-a42a-025b2b55c232@googlegroups.com> <Wh0nA.89206$8K.21381@fx46.am4> <o7shtm$9o$1@dont-email.me> <WhkoA.440018$sc6.92372@fx25.am4>

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On 13/02/17 16:29, Tom Gardner wrote:
> On 13/02/17 15:06, David Brown wrote:
>> On 09/02/17 16:55, Tom Gardner wrote:
>>> On 09/02/17 13:42, dagmargoodboat@yahoo.com wrote:
>>>> On Tuesday, February 7, 2017 at 3:00:05 AM UTC-5, Tom Gardner wrote:
>>>>> On 07/02/17 04:14, dagmargoodboat@yahoo.com wrote:
>>>>>> On Monday, February 6, 2017 at 10:08:19 PM UTC-5, Clifford Heath
>>>>>> wrote:
>>>>>
>>>>>> You're not understanding--I'm fully aware that I can go so far as to
>>>>>> embed
>>>>>> assembly if I choose.
>>>>>>
>>>>>> The fact that the compiler is jumping though hoops to map virtual
>>>>>> pin numbers
>>>>>> to physical ports and pins is exactly my point: it's solving
>>>>>> problems that
>>>>>> a human programmer wouldn't have to.  I'd just read-modify-write the
>>>>>> port
>>>>>> with the appropriate mask.
>>>>>>
>>>>>> BUT, what the naive users have and use, is layers and layers
>>>>>> abstracted from
>>>>>> the hardware doing the actual work.
>>>>>
>>>>> That's a major objective of libraries and
>>>>> environments in general.
>>>>
>>>> To an extent, true. More often my aim in using a pre-written
>>>> function is
>>>> to avoid repeating the work, not avoiding understanding the task.
>>>>
>>>> 'C' was conceived as a portable assembly language, so it's bizarre and
>>>> ironic that this portable 'assembly' doesn't guarantee the size of its
>>>> basic variables--that's one of the most basic elements of
>>>> assembly-level
>>>> programming.
>>>
>>> Porting C code has /always/ been very difficult, and required
>>> arcane knowledge and extreme care; start by considering
>>> "porting" from twos complement to ones complement machines.
>>
>> No, porting C code is not necessarily difficult.  C makes it quite clear
>> what behaviour is full specified by the C standards, what is
>> implementation-specified (i.e., different compiler implementations can
>> do things in different ways, but they have to tell you their choices in
>> their documentation), and what is undefined (i.e., the standards make no
>> comment on what happens).
>>
>> If your code relies only on standards specified behaviour, and you use
>> conforming compilers, "porting" is just a matter of re-compiling.
>>
>> If your code relies on implementation-defined behaviour, then porting is
>> a matter of checking that the new compiler fits your requirements.
>>
>> If your code relies on undefined behaviour, you should fix the code
>> before you even think about porting.
>>
>> Now, it is certainly the case that a good deal of code relies on
>> implementation-dependent behaviour.  And much of that does so in a /bad/
>> way (such as making assumptions about the size of an "int"), making code
>> porting difficult, rather than in a /good/ way (such as using
>> implementation-dependent sized integer types).  That is a problem with
>> the way C code is written, rather than a problem with C itself - and C99
>> included useful changes to make it easier to write good portable code.
> 
> While true, that argument has always struck me as unhelpfully
> splitting hairs.

If you write code that assumes it is safe to store a pointer in an int,
then you will have more problems porting it than if you store your
pointer in an intptr_t.  If you write code that assumes an int is
32-bits, then you will have more problems than if you use an int32_t (or
your own home-made equivalent type pre-C99 - then you only need to
change one definition in your code).

> 
> Gurus are different, of course, but are in limited supply.
> 
> 
>>> But from the late 80s onwards it has been unsuccessfully
>>> straddling two stools: that of a general purpose high level
>>> language for applications and also for low-level near-the-silicon
>>> "system/firmware" code. Consider that multithreading behaviour
>>> is (was?) explicitly left undefined or implementation dependent,
>>> but POSIX thread implementations relied on that behaviour.
>>
>> C has been, and continues to be, remarkably successful for such an
>> "unsuccessful" language.
> 
> Strawman argument: I've never said C is "unsuccessful", and
> I didn't above.

Fair enough.  You said it "has been unsuccessfully straddling two
stools".  However, it has, in fact, been remarkably successful for both
purposes.  It has been pushed out from many "general purpose high-level
language for application" uses - mainly because there are alternatives
that give far better productivity rather than because C is so bad for
the purpose.  And C reigns supreme for "low-level near-the-silicon" code.

> 
> 
>>> Maybe having a memory model will help, but it is astoundingly
>>> difficult to get that right across multiple architectures.
>>
>> That is why much of it is left undefined by the C standards.
>> Nonetheless, people seem to manage.
> 
> Emphasis on "seem", especially with XP and TDD programming
> practices. Multithreading errors are notoriously difficult
> to reliably provoke during testing. As a hardware engineer,
> it has always surprised me how many such errors are made
> by most programmers.

You can't get multi-threading correct by trial and error - you have to
know what you are doing.  That applies in all languages.  C gives you no
help there (though some C compilers do, with tools like gcc/clang's
sanitizers), and certainly some other languages make it easier to get
multi-threading right.

> 
> 
>>> C++ is worse; the designers *discovered* they'd created
>>> a monstrosity where you can cause the compiler to emit
>>> the sequence of prime numbers during compilation. The
>>> designers didn't believe it until someone demonstrated it!
>>
>> The flexibility of templates was unintentional, but it is not a
>> "monstrosity" - it opened a new set of possibilities in the language.
>> The fact that you can compute prime numbers at compile-time with
>> templates does not mean that you /must/ compute prime numbers at
>> compile-time with templates - it is not a disadvantage in any way.  Many
>> assemblers have powerful enough macro languages to let you generate
>> primes at compile time - no one makes a big deal out of that.
>>
>> With C++11, the language designers realised that powerful compile-time
>> computation functionality was actually very useful, but templates were a
>> cumbersome and inefficient way to do it - so they introduced constexpr
>> to make it easier.  C++14 made it even more flexible and convenient.
> 
> That's a strawman argument that avoids the point, to wit:
> "... the designers *discovered* they'd created ..." and
> "The designers didn't believe it until someone demonstrated
> it"
> 
> I prefer languages to be designed, not uncovered.
> 

With any tool sufficiently complex, uses will be found beyond those
conceived by the original designers.

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Thread

Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 15:43 -0800
  Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-07 10:58 +1100
    Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-06 19:09 -0500
    Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 18:30 -0800
      Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-06 21:43 -0500
        Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 19:02 -0800
          Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-06 23:26 -0500
            Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 21:05 -0800
      Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-07 13:55 +1100
        Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 20:00 -0800
          Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-07 19:31 +1100
          Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-07 10:29 +0100
            Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-07 07:39 -0800
              Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-08 12:24 +0100
                Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-09 08:36 -0800
                Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-10 08:15 +1100
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-13 15:37 +0100
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-13 15:35 +0100
          Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-07 08:05 -0800
            Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-08 12:30 +0100
  Re: Arduino / compilers on uC mrdarrett@gmail.com - 2017-02-06 15:59 -0800
  Re: Arduino / compilers on uC Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-06 16:04 -0800
    Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 18:41 -0800
      Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-07 14:08 +1100
        Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 20:14 -0800
          Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-07 08:00 +0000
            Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-09 05:42 -0800
              Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-09 15:07 +0100
                Re: Arduino / compilers on uC Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-09 09:54 -0800
              Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-09 15:55 +0000
                Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-09 08:46 -0800
                Re: Arduino / compilers on uC Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-09 14:42 -0500
                Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-11 06:54 -0800
                Re: Arduino / compilers on uC pcdhobbs@gmail.com - 2017-02-11 07:31 -0800
                Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-11 07:59 -0800
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-11 17:01 +0000
                Re: Arduino / compilers on uC pcdhobbs@gmail.com - 2017-02-11 12:52 -0800
                Re: Arduino / compilers on uC krw@notreal.com - 2017-02-11 18:46 -0500
                Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-12 10:20 +1100
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-13 16:07 +0100
                Re: Arduino / compilers on uC Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-09 14:16 -0500
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-09 22:39 +0000
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-13 16:06 +0100
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-13 15:29 +0000
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-13 16:49 +0100
                Re: Arduino / compilers on uC Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-13 10:55 -0500
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-13 17:09 +0000
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-14 09:49 +0100
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-13 16:07 +0000
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-14 10:01 +0100
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-14 09:49 +0000
                Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-17 04:21 +1100
                Re: Arduino / compilers on uC pcdhobbs@gmail.com - 2017-02-16 14:47 -0800
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-17 00:17 +0000
          Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-07 19:49 +1100
            Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-09 06:22 -0800
          Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-07 10:42 +0100
            Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-09 06:57 -0800
              Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-09 16:12 +0100
              Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-10 08:24 +1100
  Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-06 19:08 -0500
    Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 18:47 -0800
      Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-06 21:51 -0500
        Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 20:39 -0800
          Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 20:55 -0800
            Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-07 20:05 +1100
              Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-08 12:26 -0500
                Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-08 12:32 -0500
                Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-09 08:31 +1100
                Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-09 08:21 +1100
                Re: Arduino / compilers on uC Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-08 13:33 -0800
          Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-07 08:15 +0000
            Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-09 05:51 -0800
              Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-09 16:22 +0000
                Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-09 16:45 -0500
                Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-09 16:51 -0500
                Re: Arduino / compilers on uC Clifford Heath <no.spam@please.net> - 2017-02-10 09:11 +1100
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-09 22:45 +0000
                Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-15 10:11 -0500
          Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-07 10:57 +0100
      Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-07 08:07 +0000
        Re: Arduino / compilers on uC rickman <gnuarm@gmail.com> - 2017-02-07 04:01 -0500
          Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-07 09:40 +0000
            Re: Arduino / compilers on uC rickman <gnuarm@gmail.com> - 2017-02-07 05:52 -0500
              Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-07 11:26 +0000
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-07 12:58 +0100
                Re: Arduino / compilers on uC Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-09 14:52 -0500
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-09 22:47 +0000
              Re: Arduino / compilers on uC bitrex <bitrex@de.lete.earthlink.net> - 2017-02-09 14:00 -0500
                Re: Arduino / compilers on uC Tim Wescott <seemywebsite@myfooter.really> - 2017-02-09 13:24 -0600
      Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-07 10:52 +0100
    Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-07 10:50 +0100
  Re: Arduino / compilers on uC rickman <gnuarm@gmail.com> - 2017-02-06 19:49 -0500
  Re: Arduino / compilers on uC "David Eather" <eather@tpg.com.au> - 2017-02-07 12:45 +1000
    Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-06 18:51 -0800
      Re: Arduino / compilers on uC "David Eather" <eather@tpg.com.au> - 2017-02-08 06:35 +1000
        Re: Arduino / compilers on uC "David Eather" <eather@tpg.com.au> - 2017-02-08 06:44 +1000
      Re: Arduino / compilers on uC M Philbrook <jamie_ka1lpa@charter.net> - 2017-02-07 17:11 -0500
        Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-08 12:40 +0100
          Re: Arduino / compilers on uC pcdhobbs@gmail.com - 2017-02-08 07:01 -0800
            Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-08 17:25 +0100
              Re: Arduino / compilers on uC jack4747@gmail.com - 2017-02-09 06:51 -0800
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-09 16:41 +0100
                Re: Arduino / compilers on uC M Philbrook <jamie_ka1lpa@charter.net> - 2017-02-09 19:44 -0500
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-13 16:14 +0100
                Re: Arduino / compilers on uC John Devereux <john@devereux.me.uk> - 2017-02-16 12:57 +0000
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-16 14:11 +0000
                Re: Arduino / compilers on uC John Devereux <john@devereux.me.uk> - 2017-02-16 14:40 +0000
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-16 15:58 +0100
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-16 15:56 +0000
                Re: Arduino / compilers on uC John Devereux <john@devereux.me.uk> - 2017-02-16 16:45 +0000
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-16 17:18 +0000
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-17 14:59 +0100
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-17 14:24 +0000
                Re: Arduino / compilers on uC Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-02-17 21:07 +0200
                Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-17 20:16 +0000
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-17 23:28 +0100
                Re: Arduino / compilers on uC Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-17 10:21 -0500
                Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-17 16:34 +0100
                Re: Arduino / compilers on uC M Philbrook <jamie_ka1lpa@charter.net> - 2017-02-09 19:43 -0500
  Re: Arduino / compilers on uC Tim Wescott <tim@seemywebsite.com> - 2017-02-10 10:41 -0600
    Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-11 07:06 -0800
      Re: Arduino / compilers on uC Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-11 17:09 +0000
    Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-13 16:28 +0100
  Re: Arduino / compilers on uC Tim Wescott <tim@seemywebsite.com> - 2017-02-14 09:59 -0600
    Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-14 13:46 -0800
      Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-15 10:04 +0100
        Re: Arduino / compilers on uC dagmargoodboat@yahoo.com - 2017-02-15 05:57 -0800
          Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-15 16:02 +0100
            Re: Arduino / compilers on uC David Brown <david.brown@hesbynett.no> - 2017-02-15 17:15 +0100
          Re: Arduino / compilers on uC Tim Wescott <tim@seemywebsite.com> - 2017-02-16 14:19 -0600

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