AVR-GCC Inline Assembler Cookbook

About this Document

The GNU C compiler for Atmel AVR RISC processors offers, to embed assembly language code into C programs. This cool feature may be used for manually optimizing time critical parts of the software or to use specific processor instruction, which are not available in the C language.

Because of a lack of documentation, especially for the AVR version of the compiler, it may take some time to figure out the implementation details by studying the compiler and assembler source code. There are also a few sample programs available in the net. Hopefully this document will help to increase their number.

It's assumed, that you are familiar with writing AVR assembler programs, because this is not an AVR assembler programming tutorial. It's not a C language tutorial either.

Note that this document does not cover file written completely in assembler language, refer to avr-libc and assembler programs for this.

Copyright (C) 2001-2002 by egnite Software GmbH

Permission is granted to copy and distribute verbatim copies of this manual provided that the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

This document describes version 3.3 of the compiler. There may be some parts, which hadn't been completely understood by the author himself and not all samples had been tested so far. Because the author is German and not familiar with the English language, there are definitely some typos and syntax errors in the text. As a programmer the author knows, that a wrong documentation sometimes might be worse than none. Anyway, he decided to offer his little knowledge to the public, in the hope to get enough response to improve this document. Feel free to contact the author via e-mail. For the latest release check http://www.ethernut.de/.

Herne, 17th of May 2002 Harald Kipp harald.kipp-at-egnite.de

Note

As of 26th of July 2002, this document has been merged into the documentation for avr-libc. The latest version is now available at http://savannah.nongnu.org/projects/avr-libc/.