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Re: [avr-gcc-list] error in inline assembler docu found at: http://www.n

From: Joerg Wunsch
Subject: Re: [avr-gcc-list] error in inline assembler docu found at: http://www.nongnu.org/avr-libc/user-manual/inline_asm.html
Date: Fri, 24 Aug 2007 22:58:03 +0200 (MET DST)

Johannes Krude <address@hidden> wrote:

> The documentation stats: "The linefeed and tab characters will make
> the=20 assembler listing generated by the compiler more readable",
> this is far fro= m=20 the truth, instead the compiler relies on the
> linefeed and tabs. If you omi= t=20 the linefeeds and tabs the
> compiler complains about: "garbage at end of lin= e"

Please write a bug report at


> There is an important point missing about the input and output
> operands. IO= =20 registers always have to be input operands, even
> if you only use them as=20 output. Otherwise the compiler wails
> about: "invalid lvalue in asm statemen= t"

This is not a bug in the documentation, but I agree the documentation
might be clearer on this.  If you've got a suggestion for a better
description, feel free to write another bug report.

The point is, the terms "input" and "output" refer to the
communication between the surrounding compiler environment and the
inline assembly statement, so they tell what goes *into* the inline
asm statement, and what is *returned* from it into its environment.
The address of an IO port is an input to the inline asm statement,
even if the IO port outputs something from the MCU to the outside
world -- this MCU output operation doesn't make it return anything
from the inline asm to its environment.

> I don't read tihs list so don't expect me to answer if you don't
> write to m= e=20 personaly.

Well, this is a members-only list.  It would be better to subscribe to
it in order to communicate with other participants, even if your
subscription is only intended for a few days.  Sorry, but this is
mainly the price of spam, as closed (members-only) mailing lists prove
to be rather efficient in fighting against being spammed.

cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)

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