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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 11:12 +0100
Organization A noiseless patient Spider
Message-ID <p8886p$s70$1@dont-email.me> (permalink)
References (8 earlier) <ad0acdef-60f4-4a7c-ad5c-cfea269b88a0@googlegroups.com> <p868iu$ci2$1@dont-email.me> <21affba9-db38-4925-98e3-8b557a70030c@googlegroups.com> <zSzpC.138012$u94.93725@fx08.iad> <065473a9-bfe1-472a-b859-8f4895254d62@googlegroups.com>

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On 12/03/18 20:20, supercat@casperkitty.com wrote:
> On Monday, March 12, 2018 at 1:42:47 PM UTC-5, Scott Lurndal wrote:
>> supercat@casperkitty.com writes:
>>> On Monday, March 12, 2018 at 11:07:04 AM UTC-5, David Brown wrote:
>>>> The code would have been source-code compatible anyway - as long as
>>>> people don't make silly, unnecessary and invalid assumptions about sizes
>>>> without checking them.  And the code would never have been object code
>>>> compatible.
>>>
>>> A module that assumes "int" is 16 bits could be object-code compatible
>>> with one that assumes "int" is 32 bits if inter-module references use
>>
>> Why would anyone ever possibly want such a thing?
> 
> If an existing project is being migrated from a 16-bit CPU to a 32-bit CPU,
> being able to have the 16-bit portions continue to work as they always
> have would seem useful. 

If you wrote in C, there wouldn't /be/ 16-bit and 32-bit portions.

Now, I can agree that some aspects of the way C is designed make it easy
to make mistakes such as assumptions of sizes, and the way integer
promotion happens makes the sizes inconsistent (so a 16-bit short on a
32-bit system behaves differently from a 16-bit int on a 16-bit system).
 With 20/20 hindsight, it could have been done differently.

So it takes a bit of care to make some kinds of code independent of the
size of int - even C99 sized integer types don't eliminate all possible
issues.  But it can still be done.

Usually there are few issues in using code based on the assumption of a
16-bit int and compiling with a 32-bit int.  The typical problems are
alignment and sizeof issues - this may mean that some cases of "int"
need to be replaced with typedefs "int16_t" (or similar).  Going the
other way is more likely to be problematic.

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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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