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Re: Compile Assembly and C files together

From The Natural Philosopher <tnp@invalid.invalid>
Newsgroups comp.lang.c, comp.sys.raspberry-pi, comp.programming
Subject Re: Compile Assembly and C files together
Date 2018-03-09 17:40 +0000
Organization A little, after lunch
Message-ID <p7ugti$2i2$2@dont-email.me> (permalink)
References (10 earlier) <p7rs5o$ijd$2@dont-email.me> <p7tiqm$hl5$2@dont-email.me> <87muzh4nhk.fsf@LkoBDZeT.terraraq.uk> <p7tk7d$r1p$1@dont-email.me> <p7u3qu$v3u$1@dont-email.me>

Cross-posted to 3 groups.

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On 09/03/18 13:56, Tauno Voipio wrote:
> On 9.3.18 11:30, The Natural Philosopher wrote:
>> On 09/03/18 09:17, Richard Kettlewell wrote:
>>> The Natural Philosopher <tnp@invalid.invalid> writes:
>>>> On 08/03/18 17:33, mm0fmf wrote:
>>>>> On 08/03/2018 15:27, Martin Gregorie wrote:
>>>>>> On Thu, 08 Mar 2018 13:34:57 +0000, The Natural Philosopher wrote:
>>>>>>> I would at least put in a bit more
>>>>>>>
>>>>>>> int myfunction(int bufflth, char* buff)
>>>>>>>       {
>>>>>>>          return (int)buff[bufflth-1];
>>>>>>>       }
>>>>>>>
>>>>>>> So you know where on the stack buff and bufflth are...
>>>>>>
>>>>>> Why would you want to know that? All the assembler operations 
>>>>>> using the
>>>>>> arguments will be inside myfunction() and, unless the code is 
>>>>>> calculating
>>>>>> a result to be returned and used elsewhere, the returned value is
>>>>>> probably to report success or failure.
>>>>>>
>>>>>
>>>>> If it returns success or failure, why return 1 of 4 billion possible
>>>>> values?
>>>>
>>>> Another personm who has never coded assmebler for C..
>>>>
>>>> It not what you are rurining, its how to access (bufflth, char* buff)
>>>> which are LOCAL stack based variables.
>>>
>>> The first few args are passed in registers on many modern systems. See
>>> e.g. 
>>> http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042f/IHI0042F_aapcs.pdf 
>>>
>>> for instance.
>>>
>>
>> Even so, the method still reveals WHICH registers
>>
>> But it is not a feature of the ARM per se, merely a convention.
>>
>> I assume gcc follows it, but there is no gurantee
> 
> GCC follows the ARM EABI specification:
> 
>   - stack on 8 byte boundaries,
>   - arguments in r0 - r3
>   - return value in r0
> 
> I still suspect that the OP does not have a clue of the assembly
> code he's attempting to link in.
> 
That is very useful info, which I will remember in case I ever program 
an ARM chip in assembler...


Your final sentence?

Its quite likley. A lot of people are coming into Pis not from Linux, 
but from Sinclair Spectra!

Or similar.

Which is great, but there are some knowledge gaps...



-- 
Ideas are more powerful than guns. We would not let our enemies have 
guns, why should we let them have ideas?

Josef Stalin

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Re: Compile Assembly and C files together "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2018-03-06 19:20 +0800
  Re: Compile Assembly and C files together druck <news@druck.org.uk> - 2018-03-06 13:53 +0000
    Re: Compile Assembly and C files together Rob Morley <nospam@ntlworld.com> - 2018-03-06 14:59 +0000
      Re: Compile Assembly and C files together David Brown <david.brown@hesbynett.no> - 2018-03-06 16:35 +0100
    Re: Compile Assembly and C files together "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2018-03-06 23:01 +0800
  Re: Compile Assembly and C files together ray carter <ray@zianet.com> - 2018-03-06 15:44 +0000
    Re: Compile Assembly and C files together "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2018-03-07 00:07 +0800
      Re: Compile Assembly and C files together Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-03-07 22:39 +0200
        Re: Compile Assembly and C files together "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2018-03-08 18:18 +0800
          Re: Compile Assembly and C files together Martin Gregorie <martin@mydomain.invalid> - 2018-03-08 12:37 +0000
            Re: Compile Assembly and C files together Martin Gregorie <martin@mydomain.invalid> - 2018-03-08 13:13 +0000
              Re: Compile Assembly and C files together The Natural Philosopher <tnp@invalid.invalid> - 2018-03-08 13:34 +0000
                Re: Compile Assembly and C files together Martin Gregorie <martin@mydomain.invalid> - 2018-03-08 15:27 +0000
                Re: Compile Assembly and C files together mm0fmf <none@invalid.com> - 2018-03-08 17:33 +0000
                Re: Compile Assembly and C files together The Natural Philosopher <tnp@invalid.invalid> - 2018-03-09 09:06 +0000
                Re: Compile Assembly and C files together Richard Kettlewell <invalid@invalid.invalid> - 2018-03-09 09:17 +0000
                Re: Compile Assembly and C files together The Natural Philosopher <tnp@invalid.invalid> - 2018-03-09 09:30 +0000
                Re: Compile Assembly and C files together Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-03-09 15:56 +0200
                Re: Compile Assembly and C files together bartc <bc@freeuk.com> - 2018-03-09 14:13 +0000
                Re: Compile Assembly and C files together Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2018-03-09 11:14 -0500
                Re: Compile Assembly and C files together The Natural Philosopher <tnp@invalid.invalid> - 2018-03-09 17:44 +0000
                Re: Compile Assembly and C files together David Brown <david.brown@hesbynett.no> - 2018-03-09 17:16 +0100
                Re: Compile Assembly and C files together Robert Wessel <robertwessel2@yahoo.com> - 2018-03-09 11:19 -0600
                Re: Compile Assembly and C files together bartc <bc@freeuk.com> - 2018-03-09 18:11 +0000
                Re: Compile Assembly and C files together Robert Wessel <robertwessel2@yahoo.com> - 2018-03-09 13:41 -0600
                Re: Compile Assembly and C files together David Brown <david.brown@hesbynett.no> - 2018-03-09 19:20 +0100
                Re: Compile Assembly and C files together Robert Wessel <robertwessel2@yahoo.com> - 2018-03-09 13:48 -0600
                Re: Compile Assembly and C files together Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2018-03-09 13:16 -0500
                Re: Compile Assembly and C files together scott@slp53.sl.home (Scott Lurndal) - 2018-03-09 18:29 +0000
                Re: Compile Assembly and C files together Jack Fearnley <jack@alcor.concordia.ca> - 2018-03-09 19:07 +0000
                Re: Compile Assembly and C files together scott@slp53.sl.home (Scott Lurndal) - 2018-03-09 19:13 +0000
                Re: Compile Assembly and C files together Michael J. Mahon <mjmahon@aol.com> - 2018-03-10 13:16 -0600
                Re: Compile Assembly and C files together Martin Gregorie <martin@mydomain.invalid> - 2018-03-11 19:39 +0000
                Re: Compile Assembly and C files together Michael J. Mahon <mjmahon@aol.com> - 2018-03-12 01:16 -0500
                Re: Compile Assembly and C files together David Taylor <david-taylor@blueyonder.co.uk.invalid> - 2018-03-12 06:39 +0000
                Re: Compile Assembly and C files together Martin Gregorie <martin@mydomain.invalid> - 2018-03-12 20:49 +0000
                Re: Compile Assembly and C files together scott@slp53.sl.home (Scott Lurndal) - 2018-03-12 16:11 +0000
                Re: Compile Assembly and C files together Michael J. Mahon <mjmahon@aol.com> - 2018-03-12 14:58 -0500
                Re: Compile Assembly and C files together scott@slp53.sl.home (Scott Lurndal) - 2018-03-12 20:38 +0000
                Re: Compile Assembly and C files together scott@slp53.sl.home (Scott Lurndal) - 2018-03-12 16:06 +0000
                Re: Compile Assembly and C files together Michael J. Mahon <mjmahon@aol.com> - 2018-03-12 14:58 -0500
                Re: Compile Assembly and C files together Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-03-09 21:27 +0200
                Re: Compile Assembly and C files together The Natural Philosopher <tnp@invalid.invalid> - 2018-03-09 17:40 +0000
                Re: Compile Assembly and C files together Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-03-09 21:30 +0200
                Re: Compile Assembly and C files together Richard Damon <Richard@Damon-Family.org> - 2018-03-09 13:16 -0500
                Re: Compile Assembly and C files together Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-03-09 21:33 +0200
                Re: Compile Assembly and C files together mm0fmf <none@invalid.com> - 2018-03-09 17:40 +0000
                Re: Compile Assembly and C files together The Natural Philosopher <tnp@invalid.invalid> - 2018-03-09 17:47 +0000
                Re: Compile Assembly and C files together mm0fmf <none@invalid.com> - 2018-03-09 18:05 +0000
                Re: Compile Assembly and C files together The Natural Philosopher <tnp@invalid.invalid> - 2018-03-09 09:05 +0000
                Re: Compile Assembly and C files together Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-03-09 16:01 +0200
          Re: Compile Assembly and C files together Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-03-08 17:25 +0200
  Re: Compile Assembly and C files together The Natural Philosopher <tnp@invalid.invalid> - 2018-03-07 07:36 +0000

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