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Groups > comp.lang.c > #127732

Re: Compiling and linking code from different places in the file system

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.lang.c
Subject Re: Compiling and linking code from different places in the file system
Date 2018-03-13 08:39 +0100
Organization A noiseless patient Spider
Message-ID <p87v7f$4sj$1@dont-email.me> (permalink)
References (16 earlier) <748d0aaa-e82a-4437-b6bd-f70e69c82904@googlegroups.com> <p7tid4$fmm$1@dont-email.me> <56b524f9-afaf-4ffa-b9f4-25c762cbf9c4@googlegroups.com> <p8150c$bg2$1@dont-email.me> <cf61aeff-1099-4317-a9cb-65640f21aa6d@googlegroups.com>

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On 12/03/18 16:54, supercat@casperkitty.com wrote:
> On Saturday, March 10, 2018 at 11:35:17 AM UTC-6, David Brown wrote:
>> On 09/03/18 21:09, supercat@casperkitty.com wrote:
>>> Many embedded toolchains would be considered freestanding implementations,
>>> and as such the Standard imposes no requirements on any library that might
>>> be bundled with them, beyond those the compiler itself might use when
>>> evaluating operators that don't map to CPU instructions [e.g. integer
>>> division or floating-point math] which would be required to behave like
>>> the operators in question.
>>
>> Your ideas about embedded toolchains are as fantastical as your ideas 
>> about the standards and about other C implementations.
> 
> If a target platform lacks any means of specifying command-line
> arguments, performing any kind of file or console I/O, or even
> requesting memory allocations at run-time, would it really be
> proper to call an implementation targeting it a "hosted" one?
> Or would it make more sense to describe implementations that target
> such platforms as "freestanding"?

A "hosted" environment is one where there is an OS providing services,
library, filesystem, etc., separate from the application code.  A
"freestanding" environment is missing at least some of that.  It is up
to the implementation to decide if it is hosted or freestanding, and
freestanding implementations don't need much of the standard library to
be conforming.

In practice, most embedded toolchains are freestanding - and yet most of
them provide as much of the standard library as they can (possibly
requiring user-defined hooks to actually output characters from printf,
and that sort of thing).

They invariably provide full printf and friends (to the extent that they
are conforming compilers - an embedded compiler with a 32-bit "double"
would not support 64-bit floating point printf output).  They sometimes
have optional extra libraries of reduced features and size.

> 
> Certainly many (probably most) implementations that target such
> platforms do support much of the Standard Library, but the Standard
> explicitly does not *require* that freestanding implementations do
> so.

I know that.  So do most people, I think.  So what?  There are lots of
things that the standards don't require but which useful implementations
provide.

>  If a freestanding implementation which targeted a "bare-metal" CPU
> with no floating-point unit would process something like
> 
>     double result=float1 * double1;
> 
> into code equivalent to something like:
> 
>     __fpLoadFloat(&float1);
>     __fpMulDouble(&double1);
>     __fpStoreDouble(&result);
> 
> it would be obligated to include implementations of the fpLoadFloat(),
> fpMulDouble(), and fpStoreDouble() functions.  

That is true of freestanding and hosted implementations, and such
functions are not part of the C standard library.  These are part of
what is usually termed the "language support library" - a library of
functions needed for the language itself, not for the standard library.
 (For example, in gcc this is usually provided directly by gcc rather
than from a separate source, such as newlib, like the C standard library.)

There is nothing "freestanding" about the use of such functions.

> I see nothing in the
> Standard that would require it bundle code for any Standard Library
> functions, however.
> 

The standard library headers which freestanding implementations are
required to provide to be conforming are header-only files - there is no
need for any library code behind them.

In reality, /all/ embedded toolchains come with an extensive library
covering as much of the standard library as practically possible, and
often containing other functions the vendor deems useful.

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Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-01 14:40 +0000
  Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-01 14:55 +0000
    Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-02 21:05 +0000
      Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-03 01:18 +0000
        Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-09 01:03 +0000
      Re: Compiling and linking code from different places in the file system Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-02 22:37 -0800
      Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-09 01:23 +0000
  Re: Compiling and linking code from different places in the file system "James R. Kuyper" <jameskuyper@verizon.net> - 2018-03-01 11:11 -0500
    Re: Compiling and linking code from different places in the file system "James R. Kuyper" <jameskuyper@verizon.net> - 2018-03-01 13:51 -0500
      Re: Compiling and linking code from different places in the file system Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-01 11:02 -0800
    Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-03 09:48 +0000
      Re: Compiling and linking code from different places in the file system Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-03 04:06 -0800
        Re: Compiling and linking code from different places in the file system Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-03 05:24 -0800
          Re: Compiling and linking code from different places in the file system Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-03 06:43 -0800
    Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-06 13:51 -0800
  Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-01 22:46 +0000
    Re: Compiling and linking code from different places in the file system Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-01 15:27 -0800
    Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-03 12:25 +0000
      Re: Compiling and linking code from different places in the file system Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-03 04:53 -0800
      Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-03 15:32 +0000
        Re: Compiling and linking code from different places in the file system Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-03 08:02 -0800
        Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-04 07:52 +0000
        Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-04 08:43 +0000
          Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-05 07:58 +0000
            Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-06 21:37 +0000
              Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-07 21:02 +0000
          Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-05 15:29 +0000
            Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-07 04:54 +0000
              Re: Compiling and linking code from different places in the file system Robert Wessel <robertwessel2@yahoo.com> - 2018-03-07 00:33 -0600
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-07 09:55 +0000
      Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-04 07:39 +0000
        Re: Compiling and linking code from different places in the file system Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-03-07 05:00 -0800
          Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-07 14:09 +0000
            Re: Compiling and linking code from different places in the file system Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-03-07 14:26 +0000
              Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-07 16:35 +0000
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-07 09:32 -0800
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-07 10:11 -0800
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-07 11:12 -0800
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-07 12:01 -0800
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-07 15:43 -0800
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-07 19:18 -0800
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-08 09:59 -0800
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-08 10:28 -0800
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-08 13:36 -0800
                Re: Compiling and linking code from different places in the file system bartc <bc@freeuk.com> - 2018-03-08 21:47 +0000
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-08 15:03 -0800
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-09 09:59 +0100
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-09 10:33 -0800
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-09 12:27 -0800
                Re: Compiling and linking code from different places in the file system scott@slp53.sl.home (Scott Lurndal) - 2018-03-09 20:48 +0000
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-09 13:31 -0800
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-10 18:31 +0100
                Re: Compiling and linking code from different places in the file system Robert Wessel <robertwessel2@yahoo.com> - 2018-03-10 13:22 -0600
                Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-10 19:15 +0000
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-09 13:28 -0800
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-09 14:13 -0800
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-09 14:45 -0800
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-10 17:39 +0100
                Re: Compiling and linking code from different places in the file system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-10 19:00 +0000
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-12 08:26 -0700
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-12 17:06 +0100
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-12 10:23 -0700
                Re: Compiling and linking code from different places in the file system scott@slp53.sl.home (Scott Lurndal) - 2018-03-12 18:42 +0000
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-12 12:20 -0700
                Re: Compiling and linking code from different places in the file system scott@slp53.sl.home (Scott Lurndal) - 2018-03-12 20:27 +0000
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-12 14:12 -0700
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-13 11:12 +0100
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-12 09:23 -0700
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-12 10:38 -0700
                Re: Compiling and linking code from different places in the file system David Kleinecke <dkleinecke@gmail.com> - 2018-03-12 11:41 -0700
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-12 12:10 -0700
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-09 12:09 -0800
                Re: Compiling and linking code from different places in the file system scott@slp53.sl.home (Scott Lurndal) - 2018-03-09 20:46 +0000
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-10 18:35 +0100
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-12 08:54 -0700
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-13 08:39 +0100
                Re: Compiling and linking code from different places in the file system Tim Rentsch <txr@alumni.caltech.edu> - 2018-03-17 11:03 -0700
                Re: Compiling and linking code from different places in the file system James Harris <james.harris.1@gmail.com> - 2018-03-11 07:37 +0000
                Re: Compiling and linking code from different places in the file system David Kleinecke <dkleinecke@gmail.com> - 2018-03-11 14:22 -0700
                Re: Compiling and linking code from different places in the file system Spiros Bousbouras <spibou@gmail.com> - 2018-03-11 21:48 +0000
                Re: Compiling and linking code from different places in the file system David Kleinecke <dkleinecke@gmail.com> - 2018-03-11 17:50 -0700
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-11 15:54 -0700
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-12 09:38 -0700
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-08 10:48 +0100
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-08 09:58 -0800
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-08 22:03 +0100
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-08 13:55 -0800
                Re: Compiling and linking code from different places in the file system Spiros Bousbouras <spibou@gmail.com> - 2018-03-08 22:38 +0000
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-08 15:03 -0800
                Re: Compiling and linking code from different places in the file system Spiros Bousbouras <spibou@gmail.com> - 2018-03-08 23:15 +0000
                Re: Compiling and linking code from different places in the file system Tim Rentsch <txr@alumni.caltech.edu> - 2018-03-17 10:44 -0700
                Re: Compiling and linking code from different places in the file system Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-18 03:47 -0700
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-09 10:10 +0100
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-09 10:10 -0800
                Re: Compiling and linking code from different places in the file system jameskuyper@verizon.net - 2018-03-08 14:21 -0800
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-08 15:10 -0800
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-09 10:13 +0100
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-09 10:10 -0800
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-08 10:28 +0100
                Re: Compiling and linking code from different places in the file system supercat@casperkitty.com - 2018-03-08 10:28 -0800
                Re: Compiling and linking code from different places in the file system David Brown <david.brown@hesbynett.no> - 2018-03-08 22:17 +0100
                Re: Compiling and linking code from different places in the file system Keith Thompson <kst-u@mib.org> - 2018-03-08 13:26 -0800
  Re: Compiling and linking code from different places in the file system "Pascal J. Bourguignon" <pjb@informatimago.com> - 2018-03-14 13:39 +0100

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