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Re: [avr-gcc-list] forcing address

From: Theodore A. Roth
Subject: Re: [avr-gcc-list] forcing address
Date: Tue, 20 Aug 2002 08:37:14 -0700 (PDT)

Here's the generic directives for gas:


I didn't see the AVR specific ones there though. :-\

Ted Roth

On Tue, 20 Aug 2002, Marlin Unruh wrote:

:) Hi J"org,
:) Ten years ago I wrote some assembly language for the Motorola
:) MC68HC11 and we are still selling that product. But anyway, it must
:) have been an absolute assembler.  The code was passed thru a
:) linker. Using the org "origin" directive the code was placed where
:) you wanted it. I thought maybe the compiler had way to pass info to
:) the linker, and the linker would pack the code and place it at a given
:) location. But, I understand what you are saying.  It is as it is.
:) Where could I get a list of the directives for the GCC assembler?
:) Thank you for you reply.
:) Marlin
:) At 02:08 PM 8/19/2002 +0200, you wrote:
:) >Marlin Unruh <address@hidden> wrote:
:) >
:) > > I am writing an assembly file to include some time, and sequence
:) > > sensitive code. I have a lookup table that I defined in the .s
:) > > file. I cannot get the compiler to place the lookup table at a given
:) > > location.
:) >
:) >Sure.  This is a linker issue, and usually, in an environment that
:) >uses compilation that results in relocatable object files, you cannot
:) >arbitrarily place your code at predetermined locations.  This is only
:) >possible when using absolute assembly.  (Even in the old days of the
:) >Z80, it was common to use relocatable assembly, and have the linker
:) >put all the pieces into place.)
:) >
:) >Using linker directives, you can tell the linker at which address to
:) >place the beginning of your program.
:) >
:) >How else would you expect the whole thing to work?  Say, you want some
:) >particular piece of code at address 0x100, but the startup code starts
:) >at 0x0.  How should the compiler be told that there are some XXX bytes
:) >free between the startup code and your code at 0x100 (that could be
:) >filled by the compiler)?
:) >
:) >--
:) >J"org Wunsch                                           Unix support engineer
:) >address@hidden        http://www.interface-systems.de/~j/
:) >avr-gcc-list at http://avr1.org
:) avr-gcc-list at http://avr1.org

avr-gcc-list at http://avr1.org

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